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HeadScratcher
5th December 2011, 07:23 PM
Greetings...

Well the time has come for me to step it up a notch a make another lot of speakers. In the late 90’s I made these guys using Vifa drivers and Polk Audio tweeters, which actually sounded fairly impressive considering I had never made speakers before.

Last time around I did it the hard way with a drill, a jigsaw, a few half moon files, infinite patience, and more hours than I want to think about. Well this time I want to try using a router... I don’t see why my brother who is a cabinet maker should have all the fun. In fact I really don’t know why I didn’t use one last time; I guess I saw it as one of those tools that only professionals use.

Last time around I used the facilities at a company in Brisbane called Wood ’n’ You to cut all of the boards to size, this time I want to use the router to do most of the cuts and not have to rely on a massive table saw to get perfectly parallel sides (besides not sure if there is a company that lets you do it yourself in Sydney).

For this project I really want to step it up in every way. For drivers I am looking at the ScanSpeak Illuminator 15WU/4741T00 5.25" Midwoofer and the Scan-Speak Illuminator D3004/664000 Berylium Tweeter. For the centre speaker and mains I will do additional boxes with 2 Scan Speak 18WU4741T00 Illuminator 6½" Midwoofers in each. To kick off the project I want to focus on just the five Midwoofer and Tweeter boxes.

Originally when I first started designing the boxes I was looking at building tapered shapes inside a square box to reduce the acoustic issues associated with square boxes, but as the various iterations of the box progressed I eventually decided that I would be better off trying to build the box in slices.

I want to taper the inside of the box (and 3 of the outside faces leaving the bottom flat) so it gradually reduces as it makes its way back to the port opening. I looked on line and I can get an 11.25 degree router bit with a 15/16 cutting face which should be pretty close to spot on.

Now this is probably fairly ambitious for someone who has never used a router before, but I seem to have a knack of being able to make most things work. I would really appreciate any design tips that you be able to pass along to a total novice.
I have already spotted a few decent router circle cutters, and think I probably need to start my project there.

3RU
5th December 2011, 10:29 PM
Good luck to you HS,

I like your style and you obviously know something about speaker box design which is fine if you are doing it for yourself, possibly a very good friend. Sadly from experience there is a stack of stuff available for very little in terms of $.

I have some very nice speaker boxes (Linear Design and Philips Resarch) sitting my shed which are virtually no value. Sounds good value $0

Dave

HeadScratcher
5th December 2011, 11:26 PM
Thanks for the encouragement Dave. I guess part of wanting to do it myself is it feels more satisfying if you put something of yourself into the end product.

I didn’t wind up using the speakers I build above... I sold them to a good mate of mine for what they cost me to build (~$3000 for all 5 including the Jaycar amp, he bought a Polk Audio centre). To be honest I thought there would come a day when they would sound “ordinary” to me, but every time I would visit they still sounded fantastic. The mains were made of 19mm MDF and the sub box 32mm MDF. They are still going strong today a good decade later.

I am allowing myself about a $10k budget for this lot of speakers and I have good reason to believe they will sound phenomenal when they are done (all going to plan). You see I currently own a set of Sonus Faber Cremona speakers (pre M series) which I pulled the drivers out of to see what they had in them. The drivers I plan to use in these new speakers should blow what I have into the weeds.

So I really want the boxes to reflect the same level of craftsmanship that is on par with the sound. I was blessed with a great deal of patience and have spent countless hours before hand sanding thing to make them perfect.
Having never used a router before I think I will probably trash a number of pieces of scrap, but I am excited about what could be if everything turns out right. On the back I was planning on putting some plexiglass or something similar to show off the cross over network. When you start spending big money on crossovers they can become a bit of a feature themselves with the gold writing etc.

Calculations show that I need a port length of just shy of a meter to get the best X-max, so I was planning on building a slot port into a plinth that goes under the speaker. The good thing about making the port external to the speaker cabinet is I can play with port lengths to my hearts content. Because PVC is as cheap as chips I can just grab a length and keep lobbing some off and testing until I get the right length, then make my plinth to suit and then retest it.

Edit:

Here is a link to the tweeters http://www.madisoundspeakerstore.com/hard-dome-tweeter/scanspeak-illuminator-d3004/6640-00-1-tweeter-beryllium-dome/
here is a link to the mid woofers http://www.madisoundspeakerstore.com/approx-5-woofers/scanspeak-illuminator-15wu/4741t-00-5-woofer-4-ohm/
and here is a link to the woofers that will be used in mains and centre http://www.madisoundspeakerstore.com/scanspeak-woofers-6-7/scanspeak-illuminator-18wu/4741t-7-woofer-4-ohm/

HeadScratcher
6th December 2011, 10:18 PM
Here are a couple of photos I took while I had the speaker apart. I don’t want to give too many of their secrets away (not that the design is anything revolutionary, just known sound basic principals) but I figure I should be able to make this transition to the rear port area much smoother than using straight boards like those shown.

harrysin
10th January 2012, 07:59 PM
Here are a couple of photos I took while I had the speaker apart. I don’t want to give too many of their secrets away (not that the design is anything revolutionary, just known sound basic principals) but I figure I should be able to make this transition to the rear port area much smoother than using straight boards like those shown.
I must confess that I don't understand the principles involved in the unusual design of the speaker enclosures that you intend to make. Am I right in thinking that each disc has a smaller hole than the previous one and that there is a slight taper so that the resulting horn is smooth. If this is so, have you calculated the angle that the bit needs to be and in fact if such a bit is available.
My own extensive experience is that a good selection of Imperial and metric template guides and bits is capable of a very wide range of offsets by mixing and matching..
Your project is rather unusual and I hesitate to say, difficult for a newcomer to routing. Rest assured however that providing you supply photos/drawings and sufficient information, there are members here who will do their best to assist you with advice.
The photograph appears to show a conventional fabricated horn , if this is so, why go to the enormous trouble of dramatically changing the method of construction,

HeadScratcher
13th January 2012, 04:18 PM
In a lot of ways I guess you could almost look at the cavity as being similar in design to many horn speakers… But the cavity in question is designed to control the volume of air behind the speaker.

As you are probably aware… all speaker drivers have a preferred volume to create the desired frequency response. So the challenge that lies ahead is twofold.

The first is to taper the walls of the cavity in such a way that it creates the desired cabinet capacity. This is going to be tricky but shouldn’t be too difficult as it’s a matter of just of working out the volume with math for each slice of the cabinet.

The tricky bit is going to be working out how much to increase or decrease the internal size to meet the target volume without altering the length.

The second hurdle that needs to be conquered is shaping the internal cavity in a way that helps reduce the pressure wave reflection.

For those reading the thread that aren’t familiar with speaker design, it is important that the pressure wave of the speaker driver doesn’t run back into itself.

Let’s see if I can explain this in simple terms without confusing everyone…

Imagine a cube and in the front dead centre of that cube, you put a speaker driver that has a speaker cone that is a perfect right angle. When negative voltage is applied the speaker cone moves back.

Now this backward movement of the driver cone pushes the air / sound waves towards the four sides (if the cone was flat it would have pushed it towards the back wall). Now remember that old Tennis video game of the 80’s. Remember what happens when it hits one of the walls…

That’s right it comes off the wall at the same angle as it hit it. Which presents a problem because the next step is the rear wall, then the opposite side wall, then back into the speaker.

The trick is to design the cavity is such a way that the pressure wave either never makes it back to the driver cone or is severally delayed and weakened. You see when the pressure wave is allowed to run into itself it causes distortion. Imagine two trains on the same track heading towards each other…

Now think of the speaker driver in the same way but it is essentially a piece of coated paper. It is imperative the pressure wave is neutralised as much as possible, hence why in the photos above you will notice they crudely tapered the rear of the cabinet to delay the return, and help port the air out the back speaker port.

If you can imagine that, you can now see why I am aiming for something that could roughly be viewed as a truncated pentagonal pyramid.

Harry in my mock ups I calculated the angle of the taper to be ~9 degrees, and I can get a cutter around the 11 degree mark, which means I should with a bit of juggling be able to get the volume I want without have to compromise on other parameters like length.

IMPORTANT NOTE:
Before you all go running off and getting eggs stuck in milk bottles, or testing to see if you can get the speaker you have floating around move. Please remember that most speakers are designed to work with roughly 1 volt, so don't go sticking a 9 volt battery on the terminals to try it out.

harrysin
13th January 2012, 05:26 PM
I reckon that you have a big task ahead of you considering all the variables, not the least of which are things like the amplifier's damping factor. Whilst the electronics can easily be performance tested using the right test gear, there are only two ways that I know of to assess speaker performance, using a white noise generator and calibrated microphone hooked up to a spectrum analyser in an anechoic chamber or subjectively using the ears of what we in the trade called the "golden eared brigade" , some who swore that they could pick the difference between speakers connected using mains cable and "Oxygen free copper monster cable". There also on the market were so called "Oxygen free mains cables" with instructions saying that they required I think it was several weeks to be "run in"!
I couldn't openyour link, and finally, "speakers designed for only 1 volt", as Pauline would say,"please explain"!

HeadScratcher
13th January 2012, 09:47 PM
1 volt RMS is the nominal voltage for Line Level

“The reference voltage for the decibel volt (0 dBV) is 1 VRMS, which is the voltage required to produce 1 milliwatt (http://en.wikipedia.org/wiki/Watt) [mW] of power across a 1 kiloohm (http://en.wikipedia.org/wiki/Ohm) [kΩ] load.[1] (http://en.wikipedia.org/wiki/Line_level#cite_note-0) The reference voltage for the decibel unloaded (0 dBu) is the voltage required to produce 1 mW of power across a 600 Ω load (approximately 0.7746 VRMS).[2] (http://en.wikipedia.org/wiki/Line_level#cite_note-1) “

1 watt or 2.83v is what most speaker manufacturers rate there speakers at.

“Sensitivity – The sound pressure level produced by a loudspeaker in a non-reverberant environment, often specified in dB and measured at 1 meter with an input of 1 watt (2.83 rms volts into 8 Ω), typically at one or more specified frequencies. Manufactures often use this rating in marketing material.”

Subjecting a speaker to too much voltage can damage the speakers’ voice coil, as a speaker is just a big role of wire (voice coil) wrapped around a metal rod, applying positive or negative charge moves the metal rod back and forth.

You are basically creating a short circuit, and applying too much voltage is going to fry the voice coil.

I was looking at purchasing one of the EarthWorks measurement microphones to measure the finished speaker and get the cross overs sorted out. Not cheap but think it will be handy for all sorts of setting up. http://www.earthworksaudio.com/our-microphones/m-series/m30/ (http://www.earthworksaudio.com/our-microphones/m-series/m30/)

harrysin
13th January 2012, 10:34 PM
I'm aware of most of what you say but the word "sensitivity" hadn't been mentioned. I don't see what line level has to do with speakers other than to compare sensitivity
Please tell me, a woofer of 8 ohms impedance dissipating 50 watts from an amplifier being fed with a 1Khz sine wave, what is the voltage across the voice coil? By the way, I started re-coning speakers in 1962 and only stopped in about 1987 when a clever young electronics engineer here in Perth commenced business designing and building class A amplifiers and needed some cash flow and so started to repair speakers, including cone tweeters by re-winding the voice coils, and making new formers and surrounds where necessary. From that point onwards I sent all my incoming speaker repairs to this young man.
I'm really not trying to have a go at you, it's just that from years of experience I've learnt that theory, where speaker enclosures are concerned, is only part of the story for a successful speaker system and if the results are measured subjectively then we must remember that one man's meat is another man's poison!

HeadScratcher
14th January 2012, 12:23 AM
Getting slightly off topic but the point of mentioning sensitivity was if speaker manufacturers only deem it necessary to use 2.83v to reference speakers, I didn’t want people testing speakers with a 9v battery.
Anyway totally agree... what works in theory on paper may sound terrible in the real world. Really won’t know until I fire them up, but if I try to stick to sound audio principles I have half a chance of them sounding ok.
Staying away from what is known not to work well i.e. square sided cabinets, I have to be at least heading in the right direction.

harrysin
14th January 2012, 01:12 AM
Please do post a few shots taken during the routing, I'm fascinated as to what you're doing. Finally it would be nice to "hear" your unbiased opinion when they are completed, also what equipment is hooked up to them. Good luck.

HeadScratcher
14th January 2012, 11:11 AM
I think the truly great thing about the design is the ability to custom make the wall thickness, I will be in control of both ID and OD, so I can make the walls as thick or as thin as I like. Kind of excited to hear them myself, but being a realist I will be very self critical.

I won’t know straight away because all the drivers will be brand new and green, so it will probably take about 100 hours of playing before they start to sound right.
I progressed through the Sonus Faber range, and every speaker I bought needed a good break in period to sound like they should. Even my current Cremona’s sounded ordinarily when I took them out of the carton for the first time.

The only speakers I brought home and sounded fantastic were my Electa Amator series 2 which were demonstrators and had quite a number of hours already on them. I still regret selling them they were superb speakers. It was a real pity they were only a bookshelf.

You mentioned earlier about different cables... to be honest you can pick the difference between the different cables, but the difference often doesn’t justify the price.

For many years I was running cheap old NeoTech KS1226 Super Base Line Speaker cable (2 x 8AWG) and I replaced it with some Cardas Crosslink 2x. I could pick there was a difference in the lower frequencies between the NeoTech and the Cardas with all other things being equal (The NeoTech had slightly stronger bass, but the Cardas are slightly more defined).

You asked about equipment, leading the way is the Oppo BDP83 Special Edition (the SE is well worth spending the extra $500 just to get the better DACs) into a Rotel RSP 1570 into a Rotel RB1091 (Centre) and RB1092 (Mains) and an analog Rotel RB1075 for surrounds. I use IXOS interconnects exclusively, the Poms sure do know how to make a good interconnect cable.

By the way I got a quote for the 5 tweeters and 5 mid woofers they came in at $4360. Might be able to squeeze a few more bucks off that, but don’t expect much. Even with some decent crossovers (~$2-3k) I am only still looking at the same kind of money that I paid for the Electa Amators but I will have 5 speakers not just a pair.

harrysin
14th January 2012, 02:45 PM
"I won't know straight away because all the drivers will be brand new and green, so it will probably take about 100 hours of playing before they start to sound right."


I hate to have to tell you, but there is no such thing as a GREEN driver. Nothing changes with a driver, have you not considered the more rational explanation that over time one's ears become accustomed to the new sound?

HeadScratcher
14th January 2012, 06:12 PM
Hate to disagree with you Harry but there is definitely an audible difference between a green speaker and one with some miles on it. I appreciate your experience in this field but beg to differ.

I would liken it to putting on new set of disc brake pads; there’s a bedding in period where the new discs mate to the rotor surface. The cone of the driver is no different, as you know from your experience the driver cone has a certain amount of give in it despite the manufacturer best attempts to keep it solid.

Think about the surface of the cone at a nano level. Just like a piston engine the cone stops and reverses direction constantly. Where the cone is held at the centre is where the energy is introduced into the cone.

Now think about shaking out a tea towel... the ripple effect starts at your hands and makes its way to the other side of the tea towel, this is exactly the same thing that takes place in the driver cone.

Now try the same thing with an old tea towel and a new one and you will see that they shake completely differently and in different patterns, the new one is much stiffer because the fibres of the cloth have not been subjected to wear and movement created by drying up over time.

At a nano level the fibres of the paper have to achieve this same state, the constant backward and forward movement of the cone settles the grains of the cone into a position where they are properly aligned and happy.

You probably wouldn’t notice it so much on driver that has an aluminium cone (but you pay for it in a very unnatural sound), but every material known to man has some form of settle in period. Even glass which is actually a viscous material is in a constant state of flux. Don’t believe me look at the windows in a very old church, the windows are thicker at the bottom then they are at the top where the glass has moved over the centuries. It is this extremely minute movement in the cone that has a significant difference in sound.

I can back this up with having heard some floor stock that had been in place for quite some time and hearing the exact same speakers that were straight out of the box that were going on the floor as new demo stock, and there was a world of difference between them. So I believe there is much more to it than merely getting used to them. Just my opinion and you are welcome not to agree.

harrysin
14th January 2012, 08:11 PM
Likewise, I hate to disagree with a fellow forum member, but your analogies are way off the mark, exactly the sort perpetuated by non technical Hi-Fi salesmen, I know, I've worked side by side with such people. Whereas brake discs actually WEAR to match the disc, as you have rightly said, a cone is a piston, suspended at it's outer edge by a very resilient foam or rubber surround and at it's centre by by a fabric suspension. Modern cone materials do not change their molecular structure, unless of course the speaker box is used without it's front cover in a room with bright sunlight! (as I've seen so many times)
As for the tea towel, the first several washes gets rid of the starch which is introduced during manufacture to make it look nice and crisp.
I mentioned in an earlier post the mains cords made from "Oxygen free Copper" selling at an exorbitant price, if the instructions didn't claim a long "running in" period, everyone would immediately return them for a full refund because they, quite rightly couldn't hear any difference, but at the end of the "running in" period, how could one really tell if there was any difference. Consider the miles of cables and the number of transformers between the power station and the audiophile's power point and one wonders how a 2 metre cable will improve the fidelity! In a similar vein, how can a few metres of "Monster" cable improve the fidelity of a loudspeaker, it's fractionally lower resistance you might say but what is a fraction of an ohm compared to around 6 ohms for a typical 8 ohm driver. I could go on but she who must be obeyed is calling me for my evening meal.

oppmeetprep
7th February 2012, 10:44 PM
Thanks for letting us know about your project.
In my humble opinion, if you spend more than $2000 for the parts, it would be better off buying a second hand audiophile speaker unless you have the schematic and build procedures for the speaker that you want to build.

It would be nice if you can build the sonus faber Amati.

HeadScratcher
8th February 2012, 08:06 PM
Value is really a subjective thing... but I take your point. Mind you if I was to produce speakers that were anywhere remotely close to their $45,000 a pair Amati's, spending $10k isn’t such a big deal.

I couldn’t justify spending $45k on a pair of speakers (at least on my current salary), but I can easily justify spending 10 to produce 5 speakers.

What does need to be considered is what happens if they don’t work as expected? What do I do with a whole bunch of drivers? Well I guess that is a calculated risk I just need to take.

In a lot of ways it is probably a similar risk to the first set I built, $3k in the late 90’s is probably like $10k today, like for like.

Anyway I have put a temporary hold on the build until I look into other driver combinations. I want to make sure I get the absolute best result possible, as it is still a lot of money regardless of if I can afford it or not.

I have also been looking into a new box design, if you look at the initial design I was looking at putting the slices horizontal, but I am now working on a vertical design.

Why the change you might ask? Well while the horizontal design gives me more options for the outside of speaker cabinet, it does restrict the chamber shape behind the front panel. If I use the horizontal design I am restricted to pretty much a set taper for the inside.

If I go with a vertical stack I can design a very smooth curved area behind the speaker but the top and bottom suffer as a result and the outside of the cabinet is a little less curvy. I am speaking generically of course but you get the idea.

The attached picture will give you a better idea of the direction I am heading. The rounding bit would get a bit of a workout on some of the square edges.

HeadScratcher
8th February 2012, 09:21 PM
I could still incorporate a chamfer with the curved rear section, but it adds a level of complexity...Guess this isn’t so different from the horizontal design, just shifts some of the design aspects.

HeadScratcher
12th February 2012, 01:02 AM
Been busy with SketchUp again....

Still trying out different designs, but I quite like this one. Would be reasonably easy to make and very few jigs involved. No bottom driver yet as I have fully finished it.

HeadScratcher
18th February 2012, 11:42 AM
Spent some time looking into a completely different aspect of the cabinet build... I have been investigating active crossovers instead of the passive crossovers I was planning to use for this build.
This in turn would mean that I wouldn’t need a separate cavity built into the cabinets for the passive crossovers (so as not to be part of the acoustic chamber), nor would I need to fabricate some clear panels to show off the crossover (high end cross over part actually look quite nice to the geek).
It also opens up a whole new world of cabinet making since the crossovers are external, and all that needs to make its way inside the cabinet are the two wires for the driver, no consideration need to be given to getting the signal to each of the drivers from a single crossover point.
But most importantly it would appear that the active crossover arrangement would allow much more flexibility in tuning out any cabinet problems that might result of a poor design.
Cost obviously goes up with the additional amplifiers required, but I think it would be money well spent.
Might even give the nautilus design that SawDustSniffer has been talking about a go...

HeadScratcher
25th February 2012, 03:53 PM
"I won't know straight away because all the drivers will be brand new and green, so it will probably take about 100 hours of playing before they start to sound right."


I hate to have to tell you, but there is no such thing as a GREEN driver. Nothing changes with a driver, have you not considered the more rational explanation that over time one's ears become accustomed to the new sound?

I knew soon or later I would come across something that backed up what I heard. The following is from a website of a guy who has provided drivers to some of the biggest names in the industry... AudioTechnology

Does Vas and fs change with usage or is this just a fairytale? (http://www.audiotechnology.dk/iz.asp?id=4|q|195|||#)
You once manufactured a pair of custom-defined drivers for me (that perform excellently by the way !!!!!! ).
When I fist installed them I broke them in, using a sweep generator at very low frequencies. I had the feeling that they slightly improved that way but I may also be waaaaaaay off.


You are not way off!! The suspensions change a lot over time.

When we measure a driver, it has been run in - not necessarily the drivers supplied to the customer, but at least the test driver made prior to the supplied drivers.

When we run in the drivers, it is done with a relatively high wobble sinus tone around the expected resonance frequency (fs) and for

approximately 24 hours. We know that there are companies that only run in their drivers for 1 hour, before measuring Thiele/Small data (T/S data).

Our experience says, that the drivers change for weeks - even months, when playing, but the change after running for 24 hours, does not have any technical influence on the performance. An example:

After 24 hours of running a driver has reached an fs that is lower, a Vas that is higher and a Qts that is also lower than the original "cold" driver.

A simulation is made on the "run in" data and a nice frequency response curve is found. After ½ a year, the driver is taken out of the box that vas build according to the simulation program, and the T/S data are measured once again. We then find that fs and Qts has dropped further and the Vas is yet higher.

But - the simulated frequency response curve, in the same box, does not change.

We hereby conclude that: When a driver has been run in for 24 hours, the changes of the T/S data, do not have influence on the performance of the bass output of the driver in cabinet.

You could also say: After 24 hours of running in a driver, there is a certain balance in the T/S parameters that stabilizes the bass performance of the driver in cabinet.

Another thing is that the sound and performance of the drivers change for a long period of time. This is caused by softening of the moving parts and from small fractures in the glue joints, etc....

A speaker is like a good wine: It gets better with time.

Oldneweng
1st March 2012, 05:48 PM
I am not going to get involved in a discussion on running in speakers or differences in cables etc as I have about 5 mins before I leave for a 12 hr night shift, and I am not that argumentative.

If anyone would like to follow up on any of these subjects a look at AudioKarma.org Home Audio Stereo Discussion Forums - Powered by vBulletin (http://audiokarma.org/forums/) would I imagine give you plenty to think about. There are many threads there about these subjects. I have not looked at many of them myself. My comments are based on the "tone" from reading one. Here we go again attitude etc.

Most interested in the build as well as I am considering building myself.

Dean

HeadScratcher
4th March 2012, 03:08 PM
Thanks for the link Dean... I recently joined a dedicated DIY speaker builder forum. Funny but I always thought there was a right and wrong way to do things, but it would seem that all the experts have their own unique way of defining nirvana. In fact the more I read, the more I come to realise that sound is purely subjective.

Everybody's ears / brain interprets the sound as they hear it, so what is right? If you like the tinny sound of metal drivers and the frequency response is perfectly flat and technically perfect, it is still going to sound terrible to someone like me who likes the more natural tones of hard paper drivers. Research suggests that polypropelene drivers might actually give the most natural tones, even though paper gives a destinct edge to the sound that I like.

Anyway I degress from the build thread which I started...

I have now comitted to going active and have ordered a DCN28 digital crossover from Ground Sound Ground Sound (http://www.groundsound.com/dcn28.php)

I will probably hold off ordering the additional amplifiers until I have purchased drivers, but this will now be a 4 way system as a result of the purchase.

Now looking at some Accuton and AudioTechnology drivers instead of the Scan-Speak drivers I started the project with in mind.

HeadScratcher
10th March 2012, 06:13 PM
Like your missus with an empty credit card this thing is starting to get a bit out of control....

Just purchased a matched set of Raal 140-15D AM ribbon tweeters for the project which is going to alter the box design once again. http://www.stonessoundstudio.com.au/stone/Raal/raal_14015d_ribbon_tweeter.htm (http://www.stonessoundstudio.com.au/stone/Raal/raal_14015d_ribbon_tweeter.htm)

Clearly I need to see what direction I am going in with drivers before trying to go much further.

Will probably now need to go MTMWW (mid - tweeter - mid - woofer - woofer) now to match the SPL of the tweeter.

hybridfiat
18th March 2012, 06:45 PM
Forgive me if this is a little off topic but you should remember that the 'law of diminishing returns' applies to audio equipment as well as most other things. after a certain point the audible difference in sound reproduction will be so small as to be negligable.
Where is that magic point?
Good queston and it will probably elicit much discussion but Id hazard a guess at around $4000 for speakers and $2000 amps. Im not familiar with the other componants so Ill let others chip in if they will.

harrysin
18th March 2012, 07:01 PM
Forgive me if this is a little off topic but you should remember that the 'law of diminishing returns' applies to audio equipment as well as most other things. after a certain point the audible difference in sound reproduction will be so small as to be negligable.
Where is that magic point?
Good queston and it will probably elicit much discussion but Id hazard a guess at around $4000 for speakers and $2000 amps. Im not familiar with the other componants so Ill let others chip in if they will.
I don't know if we've ever met, but I spent many years in Perth in the esoteric audio field as service manager for Douglas Hi-Fi, The Audio Centre and Alberts Hi-Fi and during these years the words "law of diminishing returns" would exit my lips almost every day. Sound is subjective, everyone having their own idea of how a particular instrument sounds, and so it always intrigued me as to what our high spending customers based their ideas on. Let's face it, sitting in a centre row at a concert, the sound will be somewhat different if sitting to one side or the other, even though concert halls use electronic equalisation.

HeadScratcher
18th March 2012, 08:07 PM
I figure when you can stop hearing a reasonable difference it is time to stop spending money, there is no set money value on that point, I can still hear what is missing and I know how much better it can sound.

Once I build this set of speakers I think it is going to be hard to beat them on the budget I have available. So this really is going to be my last big purchase for a while.

I have done a few more mock ups of the tweeter cabinet with the Raal tweeter in place of a round tweeter I was going to use earlier.

I am going to run a corner rounding bit over the top and bottom lids but it is hard to draw a curve on a curve in Sketckup so you will need to imagine that bit for the time being.

harrysin
18th March 2012, 09:54 PM
Oh how we would have loved to have you as a customer in the 70's and 80'S, you would have received the very finest service anywhere in the world. Those were the days when a Mark Levinson pre amp. cost three and a half grand and his ten watt a side pure class A power amp. five grand. Never ever did we disagree when a prospective customer claimed to hear a "difference", even if that difference was about to cost him (it was always males) a small fortune. Who were we to argue! Some people get their pleasure by changing cars at regular intervals, others by simply counting their money, yet others by seeking the ultimate in sound reproduction.

HeadScratcher
18th March 2012, 11:16 PM
What can I say I am a sucker for the dream of audio nivrarna :)

You may not believe that you can tell the difference between a pair of $12k Cremona's and a $55k pair of Gryphons, but I can definately tell a diffference.

If I can build the same for less without the name brand then I have to go for it. Only time will tell if it was a good gamble...

harrysin
18th March 2012, 11:44 PM
If not for the risk of embarrassing you, I would love to put you through some blind tests. The results of these tests are usually not much better than 50-50.
But that's enough from me trying to save you money, from now on I'll try to confine myself to giving you any routing help that I can.

HeadScratcher
28th March 2012, 05:50 PM
Thanks Harry I appreciate you leaving me to my imaginary differences ;)

Purchased 10 ScanSpeak 12MU/x731T00 drivers yesterday. 6 of the 8 ohm and 4 of the 4 ohm versions. Planning to run two in parallel in each of the front three speakers.

Been brainstorming in Sketchup on some "fairly out there" designs. Attached are a couple of the ideas I am working with. Nothing in concrete, nothing to even say it's doable...

Should be fairly obvious why I have nick named the idea the "Jelly Bean".

HeadScratcher
29th March 2012, 06:13 PM
While I'm kicking the imaginary ball around I thought I might try a few variations...

This time the drivers in the top cabinet are to scale (unlike the others)

Working on the principal of keeping the accoustics right but separating the bass from the more delicate tweeter.

harrysin
29th March 2012, 06:29 PM
I'm genuinely pleased that you're getting so much enjoyment out of designing these speakers and spending big dollars! I really do hope that you aren't disappointed when you come to actually make the boxes, let alone when you first hear them.

HeadScratcher
29th March 2012, 07:23 PM
Thanks harry, I have set my initial expectations low as not to disappoint. When I built the last set of speakers I was very dissapointed when I first put then loosely together on the floor with some make shift crossovers.

To be honest the drivers were brand new and the crossover weren't right, but little by little I tweaked the crossover until it started to sound right. By the time I had them in some nice solid cabinets with ports and padding they sounded amazing.

So deliberately setting expectations low. Expect that with going digital it won't take as long to get the crossover right. Last time I had to juggle values around and solder and unsolder lots of parts, this time around it will just be a quick software adjustment.

Had to laugh... I thought what if I add some top arms to match the bottom legs, then I can use them to further support the back arch.

So I started drawing it up and realised that I have just drawn the same ugly man that my partner got while she was overseas. She bought this revolting CD rack made out of wood with this skinny African tribes man standing behind the CDs with his chin resting on the top, low and behold I subconciously drew the same thing I hate :doh:

Edit:
Added a photo of the ugly CD stand..

harrysin
29th March 2012, 11:04 PM
It's because of useless, and in your case gross DVD storage systems that I've started to collect timber to build one, a cabinet with doors about 450mm high with the storage system set back on top and will hold 90 discs. This design will avoid bending to select a disc.
Back to your speakers, you mention "tweaking the crossovers" are you relying on your ears to judge a flat response, or have you access to test equipment. What type of crossovers are they, the ubiquitous Butterwoth filters with a 12db/octave roll-off?

HeadScratcher
29th March 2012, 11:34 PM
It has sentimental value to her... I did try to suggest that it wouldn't hold the bin lid open, but she wanted to keep it.

Like yourself I am not a fan of CD holders that only hold a few CDs and are exposed. I try to keep all of my CD / DVD / BR out of the sun.

I was using my ears back in the late 90's when I built them, and money was very tight (IT student). I have one of these coming (V1) in the next few days. Dayton Audio OmniMic V2 Precision Audio Measurement System 390-792 (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=390-792)

The options available in the active crossover are numerous, the main types Butterworth, Lnkwitz Reily etc and does up to a 96dB slope, so there is no shortage of choice.

harrysin
30th March 2012, 12:16 AM
Once the test mic arrives, all that you'll be short of is an echoic chamber!

HeadScratcher
30th March 2012, 09:53 AM
That and 20 years worth of testing experience...

Like all thing in life I will have to make compromises like using a couple of hundred dollar mic instead of a couple of thousand.

The place i'm in at the moment is quite noisy and I have been racking my brains to work out how to get some kind of base level testing done, to at least get me in the ball park.

Perhaps make some temporary accoustic dampened walls... don't know still working on that one.

harrysin
30th March 2012, 12:34 PM
I wonder what the chances are that your beloved will allow you to stick egg cartons on the walls and ceiling!

HeadScratcher
30th March 2012, 01:18 PM
Probably better than most :U She understand the obsession...

Was thinking along the lines of geting some of those accoustic pads and fixing them to thin sheets of MDF and building something temporary. Kind of like room deviders, that way when I'm finished I can reuse the pads for the walls in the yet to be purchased home theatre room.

harrysin
30th March 2012, 01:39 PM
That sounds like a good compromise. About six years ago I gave away six free standing acoustic panels about 6' 6" tall to a studio in Morley.

HeadScratcher
30th March 2012, 07:21 PM
Just down at Bunnings getting some line trimmer chord and I had a quick squiz at the thin MDF sheets, the 6mm which are 2440mm x 1220mm might be already they seemed light enough to move around.

The 3mm of the same dimensions seems a little wobbly and would need a fairly decent frame to stop it bending and flopping on the floor.

Better half who was reading my posts over my shoulder just made a really good suggestion. She said I should get some of those foam wave shaped matress protectors that are used on top of the mattress to make it more comfortable.

Probably a crappy substitiute for a decent bed, but might make a fairly decent acoustic deadener :2tsup:

Comes in one piece and can you can get queen sizes...

Online The Big Sleep Foam Underlay - Queen Discounts | The Big Sleep Foam Underlay - Queen | Online @ Deals Direct.com.au (http://www.dealsdirect.com.au/p/the-big-sleep-foam-underlay-queen/)

And she is ok with me hanging it from the ceiling :D

How big would a chamber need to be? or more to the point how small could you make it and it still work?

SawDustSniffer
7th April 2012, 01:13 AM
don't mount your " high end(Hz)" speakers like that just yet , one thing i learnt from instrument making is " node points " , run the tweeter section at the hz it will play at , sprinkle salt on the surfaces , the salt will move to the least movement spot , those spots are where you mount them from

but then again it might be better to grab them by the corners and deadern the most movement spot with a strong frame .to stop the "negative wave" from getting out

an all thread running across the sides between the max points of movement ( shown from salt ), hold them solid ( same force on both sides ) , will spread the " node point " to a ring around it , at ,at least 1/4 of the strength, but stop the rod from resonating as well ( tube over it with rubber/ cork mounts to surface )

HeadScratcher
9th April 2012, 02:23 PM
Not game to get salt anywhere near the tweeter, they are so easily damaged that they say not to even put a fan near it, because the breeze can damage the element, and there is no way to clean it if something got in it.

Think I will stick to the more traditional testing methods, just to be safe.

HeadScratcher
10th April 2012, 06:38 PM
It may not be everyones cup of tea, but I think I am close to a design I want to use...

Using the slice method discussed earlier, I believe the cabinet won't be anywhere near as complex as it looks. I figure this should be achievable with only a few templates.

I haven't quite worked out how to cut the speaker holes in the front of the top cabinet, as the face won't be flat. I can't go from behind because of lack of clearance, and I can't really cut the idividual slice properly, so that only leaves making the cut from the front.

Edit:
Reminds me a bit of K9...

Oldneweng
10th April 2012, 08:43 PM
It may not be everyones cup of tea, but I think I am close to a design I want to use...

Using the slice method discussed earlier, I believe the cabinet won't be anywhere near as complex as it looks. I figure this should be achievable with only a few templates.

I haven't quite worked out how to cut the speaker holes in the front of the top cabinet, as the face won't be flat. I can't go from behind because of lack of clearance, and I can't really cut the idividual slice properly, so that only leaves making the cut from the front.

Edit:
Reminds me a bit of K9...

I would cut the holes using a router template designed to locate on edges etc and with spacers underneath to set it on the right plane after an initial rough cut with a jigsaw. You could use bolts to adjust the angle, do one hole in one set then readjust for the next hole etc.

Using different sized router guide bushes Brass Router Bushing Set : CARBA-TEC (http://www.carbatec.com.au/brass-router-bushing-set_c10001) you could do the inside thru hole, a rough and a finish inset hole using the same template.


Dean

HeadScratcher
10th April 2012, 10:24 PM
Thought I would draw up one slice to better describe the method.

As you can see from the attached pic, the middle section, outter sections, and both side plates could be all done with the same jig.

Figure to get the tightest corners possible I would use the smallest guide available that the straight cutter would fit through.

Could possibly screw the template to the piece of board being cut and trim off mounting points after all cutting is done.

HeadScratcher
14th April 2012, 08:39 PM
Picked up some 20mm MDF today from Bunnings (cover sheets for 18mm sheets) so I am nearly ready to take router to wood. I just need to wait for a couple of router guides to turn up and I can get started.

Also picked up a Dewalt jigsaw while I was at it, so the first thing I need to do is draw out the template and cut it out.

Attached is the first cabinet I plan to make. Still deciding on placement of the mids and factoring is BSC.

HeadScratcher
16th April 2012, 12:35 AM
Spent a few hours today drawing out the design onto wood. Don't want to cut the board until the router guide turns up but I think it turned out ok... Needed to do some reconfiguration to take into account the actual cut size once the template guide difference is applied.

Figure I will cut the corners as per drawn, and the round of the router guide will stop it going right into the corners, and give it a nice rounded edge.

HeadScratcher
25th April 2012, 11:32 PM
Spent all day shaping the template and making pieces for the cut outs so the router doesn't fall into any of the holes. Only three more to go and I will be finished. Still waiting on the template guides to arrive...

harrysin
26th April 2012, 05:42 PM
I don't know if you've done anything about the acoustic treatment of the room, but I was thinking that foam mattresses wouldn't be very efficient, also not very pretty or easy to fit. I think that a better answer would be heavy curtains from ceiling to floor, like cinamas use. This would be accoustically good, easy to fit on rails and aesthetically more acceptable. A few trips to charity shops could make it a cheap solution.
Regarding your drawings, I'm now not sure if it's superb sound that you're after or a couple of pieces of modern art, I doubt that the former can be achieved together with the latter!

HeadScratcher
26th April 2012, 07:21 PM
I have pretty much given up on sound proofing the room as a futile excersize. Sitting here in my home office the ambient noise is up to 90dB at times. Short of some very serious measures I doubt there is little I could do in this place that would make a significant impact until I move later this year. Doesn't help that the flight path moved and we are now right under it.

Funny but the road noise doesn't sound anywhere near that loud, but that is what I measured.

Ummm I kind of see it the other way around, trying to harmonically isolate the high frequency from the thumping sub frequencies is more about keeping the cabinets free from vibration than it is attempting to create art, I think being creative in one has produced the other, moreso than a desire to seek it out.

Dust Mite
8th July 2012, 09:40 AM
Haven't visited this thread for a while. Good to see you are getting underway now. Thats a hell of a challenge you have set yourself and I will be interested to see how you get around some of the quirks that always crop up when doing a project of this nature.

I have just recently finished another set of enclosures, which are currently being run in in our lounge. I have them up for sale, it will be interesting to see if they go quickly.
I've had a few folk listen to them, and they have been compared to the B&W 683/684 series for tonality but have more presence. English speakers for me tend to always seem a little reserved in their characteristics.
Like you my wife understands my obsession/hobby as I'm an ex '70s audiophile :) One of those ones that the shop owners loved to see in store.

I have a build thread for those interested here (http://techtalk.parts-express.com/showthread.php?232183-Build-No-3-2-way-tower)

This is a prototype for a series that I'm going to produce as a partime hobby/income earner to help fuel my obsession :) I have refined the characteristics of the cabinet now and I'm pleased with it. There is almost no cabinet resonance with them operating at ear pain levels, they aren't tiring to listen to for extended periods and have a very nice warmth about them.
I played Peter Gabriel's "Dont Give Up", the version with Kate Bush, the other day with my wife having a listen. She was absolutely gobsmacked, and her comment was, she had never known how much vocal nuance there was in Kates voice. What I discovered in this track is the bass syncopation that I'd never heard before. Without doubt these are the best mid-sized two-way speakers I have built to date.

I just wish I could be there when you fire up your new beasts and see the smile spread from ear to ear :) I love that bit, its when you know all the worry and nail chewing was worth it.

Oldneweng
8th July 2012, 11:33 AM
Dust Mite. I am also following this thread with some interest although the style of box does not interest me. Not much happening lately tho.

I read your thread Build No. 3 ... 2 way tower (http://techtalk.parts-express.com/showthread.php?232183-Build-No-3-2-way-tower)and was very impressed with the work and result. I too am interested in building a set of speakers but as I own 2 pair of 12inch 3 ways I am aiming at that size of speaker. To find a good traditional design for enclosures like this is very difficult. I have spent a lot of time on the net and have yet to find anything suitable.

I have a copy of Speaker Workshop which can do the calculations and also check sounds via mic. 2 problems. The only computer I have that is capable of running it due to sound card requirements of the program, has now got a stuffed soundcard and as this PC is rather old I want to do a full upgrade including soundcard. It is rather flaky in its running. Money is an issue here and it is nowhere near the top of the list for priority.

The other problem is that I am a total newby to speaker building and will be a bit of a learning curve. Did I mention time? I don't have any spare time for the next several years at least. Sigh.

I found a speaker manufacture in Adelaide, which we visit several times a year. Only seen the web site so far. Adelaide Speakers - Ascension (http://www.adelaidespeakers.com/)

Summoner 1293PRTL 12" 3-way Transmission line.


$1495 pr complete or $895 for a kit less cabinet. I doubt that I can make a set myself for that price. They have Peerless drivers.


I could always go the Jaycar way but I was trying to get away from the budget type driver and go for a top end. It is a lot of work just to try it. I did have plans to build a small set of speakers for the bedroom and maybe I should just do this and see what the result is like.


Dean

Dust Mite
9th July 2012, 09:34 AM
Hi Dean.
Don't underestimate the Jaycar drivers. For entry level Hi-Fi they are very good.
Thats what I used in the Aria2. The woofer are Peerless design and the tweeter is a older vifa design. Both have almost identical freq response to the original driver designs. It took me a few weeks of hunting to get hold of the information. Apparently they are manufactured in China and produced specifically for Jaycar. I have to thank the guys at my local Jaycar for this info, and it took them some time to confirm what we initially thought.

For a two or three way design they work very well. The real key to getting good response lies in how you construct your cabinets and even mores so in how you construct your crossover. There are those who suggest the the crossover is the most important component and they may well be right.

I know that a 2nd or third order crossover using the same drivers is hugely different in sound to a simple first order crossover.

Being a newcomer to this I would suggest that a read of the following would be beneficial. It certainly has for me. I hadn't until recently build a speaker for over 35 years and a lots changed since then.

For crossover info Crossovers Without measurements (http://www.diyaudio.com/forums/multi-way/189847-introduction-designing-crossovers-without-measurement.html) the system I currently use.

One of my favourites and where I got the idea for the Aria's Paul Carmody (https://sites.google.com/site/undefinition/) site
Plus I spend a lot of time with the folks at the Parts-Express forums (http://techtalk.parts-express.com/) and the more intense Diy Audio Forums (http://www.diyaudio.com/forums/multi-way/)

Using these and other sites I was able to upgrade the knowledge that I had pretty quickly.
One of the things I found was that technology today is vastly improving the drivers available. The 8inch woofer that I use would easily match and possibly exceed my 1970's 12inch woofer based studio monitors as well as the Kef Concertos I used to listen to in the 70's. That and new cabinet designs now means studio quality sound from 6 inch woofer based enclosures, something I really like as it means I dont have to build huge speakers to get really good sound.

In our local NZ market here there is one company that shares a similar train of thought with cabinet design and I love both the look and sound of these. Theopany make some very nice gear (http://www.theophany.co.nz/theophany-loudspeakers-new-zealand-rhapsody.html).

I'm kinda wondering what it is you do that is going to take years of your time, hopefully you do have a little me time somewhere.

Oldneweng
9th July 2012, 08:50 PM
Some interesting reading there to follow up. I have had a few threads / posts on AudioKarma.org Home Audio Stereo Discussion Forums - Powered by vBulletin (http://audiokarma.org/forums/) I found this forum while looking for information on my current speakers. Both 12 inch 3 ways from Realistic. I was surprised with the result. One set was not mentioned anywhere except on that forum after I posted about them, the other set got lots of hits. The forum had a thread from a person who had rebuilt the crossovers for these speakers and said that the result was outstanding. I was interested and got hold of the details. This was an old thread but was still running. Unfortunately the cost of the crossovers is in the range of $260 for the pair and I don't have this money at the moment.

I would still be looking at 12 inch speakers. I like the sound. I don't have a sub woofer because I don't need one.


I'm kinda wondering what it is you do that is going to take years of your time, hopefully you do have a little me time somewhere.

I work in a winery. For about 3 months of the year I work such long hours I have no time for anything but essentials. When that is finished the days are getting shorter. I live on a hobby farm. Money is scarce so I have to do a lot of stuff myself. Fencing is one thing. Still working on getting them replaced. We use a wood fired stove in the kitchen and another wood heater in the lounge. Firewood is all cut and split by me. I do have a hydraulic splitter I built myself. See http://www.woodworkforums.com/f132/firewood-splitter-design-154231/ for a pic. I am currently adding a 13m long second hand verandah to the front of the house and we are in the process of renovating the house although this is a long slow process. I have a lot of plans on the drawing board. Post driver, trailer rebuild, splitter improvement...............

Dean

HeadScratcher
9th July 2012, 10:04 PM
Quick update since it has been a while...

Been working on developing a few tools of the trade to continue on with the speakers. Built a work bench and part way through building a dust extraction system.

Once I am ready to start cutting again I have another design for a temporary cabinet in mind, this one will have horizontal slices instead of the vertical slices like the other design.

Here is a sneak preview of what the new cabinet will look like http://www.woodworkforums.com/attachments/f20/213301d1340278002-first-time-router-use-imag0563-1.jpg

Dust Mite
12th July 2012, 01:31 PM
Very interesting. Going to have a high waste factor on the MDF front?

I saw a set of speakers here in a high end audio shop where they had done horizontal slices using 19mm plywood. Birch ply I think, although Meranti would do if you cant get Birch. I have to say they looked amazing and sounded amazing as well. They were a mid sized standmount two-way and looked to be using top line Morell drivers. They had a nasty price tag too, $10000.00 plus as I recall.
I dont know who the maker was, but they must have used a fair amount of ply. One thing that was noticeable was an almost complete lack of cabinet resonance. It was there but you had to look for it. Still trying to find who made them. Ring any bells your way?

Dust Mite
12th July 2012, 01:42 PM
Yikes I just found a local retailer who has them. You better be sitting down cos the price has gone up a little.
They are currently on special with a saving of $17750.00, for the absolute bargain price of $27250.00

Have a look at them here (http://www.audioreference.co.nz/product/magico-mini-mk2-stand-mtg-speakers-incl-dedicated-stands-balitic-birch)

http://www.audioreference.co.nz/sites/audioref/files/imagecache/300wide/productimages/MAGICO%20MINI%202.%20A.jpg

HeadScratcher
12th July 2012, 05:03 PM
Yeah $27,250 NZ is only like $1.50 AU :q

Very poor review in my mind... He failed to really capture anything about the speaker, only go on about how great he was...

One of these days I am going to come up with an idea before everyone else. I keep coming up with original ideas only to discover someone beat me to it.

I had a set of Sonus Faber Electa Amator II that cost $7200 AU a pair, and while they sound great, I don't believe any two way bookshelf is ever going to deliver a full floor stander performance.

I am looking at yet another design change... A whole lot simpler than any design so far, I am currently looking into Open Baffle. It is said that not having a cabinet at all removes the large majority of the resonance issues (some slight baffle resonance maybe).

Dust Mite
16th July 2012, 08:40 AM
Yes there are some intriguing designs for open baffle speakers and I'm looking at them as a possible project in the near future. I have a couple of stand mount midsize units to make and then I'm going to look a little closer at the open baffle idea.

In the mid 1970's I went to an Audio show in Brisbane, in the days when B&O were all the rage and electrostatic towers. There were some really interesting looking speakers there that I remember being open baffle and as I recall they sounded excellent.

I had thought of doing some transmission lines as well but that seems a little hit and miss design wise.
Keep up the good work and whaddyah mean $1.50 :~

HeadScratcher
17th July 2012, 10:03 PM
I was looking at Transmission Line then I somehow wound up looking at folded horns and playing with Hornsrep.

I don't particularly like have the back of the speaker facing forwards, but those in the know seem to think push / pull on OB helps dampen distortion.

Apparently it cancels out the even frequency harmonics.

HeadScratcher
11th September 2012, 04:16 PM
Certain sense of irony in the following sentence… The reason I joined the forum almost doesn’t exist anymore!
I joined to learn how to build some tricky speaker cabinets, but through a process of evolution, I have almost made the cabinet obsolete.
I have gone through numerous ideas, but I am currently investigating a modified version of an open baffle (for those that don’t know what an open baffle is, it is basically the front board of the speaker, without sides or a back)
I am currently looking at a no baffle or naked baffle, which means the one piece of wood that was involved is now removed. Basically the speaker is suspended on wire from a frame.

232194

Oldneweng
19th September 2012, 07:35 PM
Certain sense of irony in the following sentence… The reason I joined the forum almost doesn’t exist anymore!
I joined to learn how to build some tricky speaker cabinets, but through a process of evolution, I have almost made the cabinet obsolete.
I have gone through numerous ideas, but I am currently investigating a modified version of an open baffle (for those that don’t know what an open baffle is, it is basically the front board of the speaker, without sides or a back)
I am currently looking at a no baffle or naked baffle, which means the one piece of wood that was involved is now removed. Basically the speaker is suspended on wire from a frame.

232194

I will be watching this with interest. I bet the woofers are not suspended on wire. Sort of changes the decor aspect a bit tho. Interesting toy for toddlers too I would think.

Dean

HeadScratcher
1st December 2012, 07:00 PM
Been a while since I have posted an update, so time for a picture... As mentioned earlier I am looking at basically going frameless.
It has taken longer than expected to import drivers from various sources, and I still have some on back order.

These frames are just quick prototypes. I am still trying to work out what the final speaker configuration will look like. Quite possibly there might not even be a frame at front at all (mount the drivers by the magnets at rear)

Dean correct woofer is a little hard to suspend by wire, especially when the magnet weighs 15kgs alone. Little fingers are not a problem.

harrysin
1st December 2012, 07:39 PM
Been a while since I have posted an update, so time for a picture... As mentioned earlier I am looking at basically going frameless.
It has taken longer than expected to import drivers from various sources, and I still have some on back order.

These frames are just quick prototypes. I am still trying to work out what the final speaker configuration will look like. Quite possibly there might not even be a frame at front at all (mount the drivers by the magnets at rear)

Dean correct woofer is a little hard to suspend by wire, especially when the magnet weighs 15kgs alone. Little fingers are not a problem.
I hate to be the bearer of bad news, but those drivers were never designed to operate in free air. If you really have a keen ear, you are going to be bitterly dissapointed at the results.

HeadScratcher
1st December 2012, 09:47 PM
Think I would be far more dissapointed if I paid $188,000 for those same drivers in these not to work...

harrysin
1st December 2012, 10:11 PM
Think I would be far more dissapointed if I paid $188,000 for those same drivers in these not to work...
How are the drivers wired and what is the final impedance presented to the amplifier? Also what type of crossover are you using?

HeadScratcher
1st December 2012, 10:43 PM
There wired in series / parallel, so it comes back to the same 4 ohm that the drivers started at.
x-over is courtesy of a Ground Sound DCN28 Ground Sound (http://www.groundsound.com/dcn28.php)
The DCN28 is far from cheap but worth every DKK.

harrysin
2nd December 2012, 12:37 AM
There wired in series / parallel, so it comes back to the same 4 ohm that the drivers started at.
x-over is courtesy of a Ground Sound DCN28 Ground Sound (http://www.groundsound.com/dcn28.php)
The DCN28 is far from cheap but worth every DKK.
Who actually designed the speaker system?

HeadScratcher
2nd December 2012, 04:53 PM
A few people have chipped in with suggestions / help. The select few I am listening to own their own businesses doing speaker design and building.
Sound is quite subjective, so I am basing most of the design off what I already know and like. I have been running a pair of $13,000 Sonus Faber Cremonas for about the last 8 years, this project is designed to be a step up from what I already have.

The Cremonas use the older ScanSpeak Revelator series drivers which are used in quite a few high end speakers, the ScanSpeak Illuminators I am using in this build are designed to be the top of the ScanSpeak range. The also have the underhung neo magnet motors which are well suited to OB.

I could have used more exotic drivers but decided to stick with what I know, I like the sound of the ScanSpeak drivers, I just wanted to take it to the next level. I got interested in the open baffle design while testing out the 12MU drivers. Listening to them in free air I come to realise I liked the uncoloured sound of open baffle, that the cabinet unavoidably introduces.

I realise that going open baffle doesn't come without a cost, and the drivers roll off far quicker when not in a cabinet, especially bass which requires much greater thought about how to counter act the natural 12dB roll off. But each of the drivers are being used well within their respective ranges and having virtually infinate x-over options, I can easily avoid cone breakup through simple active adjustment. I can also EQ the bass to bring the bass back into spec.

I have deliberately chosen low Q drivers for the greater driver control, whilst it does cause the driver to roll off even sooner those in the know have no problems in using them for OB, provided proper xovers slopes can be implimented to stop xmax.

A fair bit of research has gone into what I have come up with. Whilst I only have one prototype finished and I have the second side only half complete the sound coming out of what I have already exceeds what the Cremonas are capable of.

Here is a picture of what the finished speakers might look like, not much in the way of skilled wood work but there will be some.

harrysin
2nd December 2012, 06:13 PM
A few people have chipped in with suggestions / help. The select few I am listening to own their own businesses doing speaker design and building.
Sound is quite subjective, so I am basing most of the design off what I already know and like. I have been running a pair of $13,000 Sonus Faber Cremonas for about the last 8 years, this project is designed to be a step up from what I already have.

The Cremonas use the older ScanSpeak Revelator series drivers which are used in quite a few high end speakers, the ScanSpeak Illuminators I am using in this build are designed to be the top of the ScanSpeak range. The also have the underhung neo magnet motors which are well suited to OB.

I could have used more exotic drivers but decided to stick with what I know, I like the sound of the ScanSpeak drivers, I just wanted to take it to the next level. I got interested in the open baffle design while testing out the 12MU drivers. Listening to them in free air I come to realise I liked the uncoloured sound of open baffle, that the cabinet unavoidably introduces.

I realise that going open baffle doesn't come without a cost, and the drivers roll off far quicker when not in a cabinet, especially bass which requires much greater thought about how to counter act the natural 12dB roll off. But each of the drivers are being used well within their respective ranges and having virtually infinate x-over options, I can easily avoid cone breakup through simple active adjustment. I can also EQ the bass to bring the bass back into spec.

I have deliberately chosen low Q drivers for the greater driver control, whilst it does cause the driver to roll off even sooner those in the know have no problems in using them for OB, provided proper xovers slopes can be implimented to stop xmax.

A fair bit of research has gone into what I have come up with. Whilst I only have one prototype finished and I have the second side only half complete the sound coming out of what I have already exceeds what the Cremonas are capable of.

Here is a picture of what the finished speakers might look like, not much in the way of skilled wood work but there will be some.
When you determine how a system sounds, what do you use as a reference. Do you go to concerts that don't have amplified sound systems? You did of course use the correct description when you said that how one processes sound is SUBJECTIVE. I can't help wondering how an amplifier even with a damping factor of 16 can control cones that are flapping about in mid air, it goes against everything that I was taught and learned in all the years that I was actively involved with high spending audiophiles, the ones who we affectionately knew as the "golden ear brigade".

HeadScratcher
3rd December 2012, 11:13 AM
Hi Harry, after 30 years of chasing the perfect system, I would say I have fairly decent ears myself, maybe not golden but age is starting to catch up with them. I am still capable of hearing thing others can’t, so they can’t be too bad.

Yes real life is the only thing to compare to, which requires different sound stages i.e. concerts, pubs, open air etc. to build up a compilation of mental notes of the varying sound characteristics of the surroundings, also I find various horns and wood instruments very good as a mental bench mark.
When an instrument sound exactly the same as it does in real life you know you’re on a winner. Piano is a particularly hard one to reproduce well. If I can close my eyes and feel the concert in front of me and all the subtle nuances around me, I know I have reached my goal.
But as I say sound is extremely subjective and there is no right and wrong only what you like. We could both go to the same concert and sit side by side and come away with completely different interpretations of what we heard.

The problem with the cabinet is that not only does it colour the sound, but it compromises the notes being played. in open baffle there is no cabinet pressure trying to supress the cone. When a key on the piano is struck in OB it is allowed to decay in a much more natural manner like it does in real life.
But there are no free lunches controlling issues like cancellation through reflection is a much harder issue to deal with, and far more thought needs to go into room acoustics and placement.

Drivers have come a very long way since the early days, there have been many advance in all areas that allows for far greater driver control under varying and extreme circumstances. In fact I would question how golden the ears were of yesteryear… while they might have stood out in their day as being masters of their craft, did they really hear the faults of the drivers that were inherent of the time? Only as you advance technology and remove the faults can you retrospectively look back and see the faults. This would be akin to comparing the driving of Fangio to Senna.

Fangio is a legend in his own right, but how would he have gone up against Senna in a much faster era, where the speeds are significantly different. Likewise should we really compare our speaker knowledge of yesterday with what we have in front of us today? While we are the sum of our knowledge, we almost need to let some of it go to let new stuff in, otherwise we get stuck trapped in yesterday’s thinking, and don’t embrace the ideas of today. Not everything that is new is good, and not everything that is old is bad, but we need to be adaptive to pick the best and discard the rest.

For me I think I would be hard pressed going back to listening to music in anything where the driver was trapped in a cabinet. Movies are a whole different ball game.

harrysin
3rd December 2012, 01:27 PM
Hi Harry, after 30 years of chasing the perfect system, I would say I have fairly decent ears myself, maybe not golden but age is starting to catch up with them. I am still capable of hearing thing others can’t, so they can’t be too bad.

Yes real life is the only thing to compare to, which requires different sound stages i.e. concerts, pubs, open air etc. to build up a compilation of mental notes of the varying sound characteristics of the surroundings, also I find various horns and wood instruments very good as a mental bench mark.
When an instrument sound exactly the same as it does in real life you know you’re on a winner. Piano is a particularly hard one to reproduce well. If I can close my eyes and feel the concert in front of me and all the subtle nuances around me, I know I have reached my goal.
But as I say sound is extremely subjective and there is no right and wrong only what you like. We could both go to the same concert and sit side by side and come away with completely different interpretations of what we heard.

The problem with the cabinet is that not only does it colour the sound, but it compromises the notes being played. in open baffle there is no cabinet pressure trying to supress the cone. When a key on the piano is struck in OB it is allowed to decay in a much more natural manner like it does in real life.
But there are no free lunches controlling issues like cancellation through reflection is a much harder issue to deal with, and far more thought needs to go into room acoustics and placement.

Drivers have come a very long way since the early days, there have been many advance in all areas that allows for far greater driver control under varying and extreme circumstances. In fact I would question how golden the ears were of yesteryear… while they might have stood out in their day as being masters of their craft, did they really hear the faults of the drivers that were inherent of the time? Only as you advance technology and remove the faults can you retrospectively look back and see the faults. This would be akin to comparing the driving of Fangio to Senna.

Fangio is a legend in his own right, but how would he have gone up against Senna in a much faster era, where the speeds are significantly different. Likewise should we really compare our speaker knowledge of yesterday with what we have in front of us today? While we are the sum of our knowledge, we almost need to let some of it go to let new stuff in, otherwise we get stuck trapped in yesterday’s thinking, and don’t embrace the ideas of today. Not everything that is new is good, and not everything that is old is bad, but we need to be adaptive to pick the best and discard the rest.

For me I think I would be hard pressed going back to listening to music in anything where the driver was trapped in a cabinet. Movies are a whole different ball game.
Rechearch into speaker design has been going on around the world by scientists and physisists, most if not all being true audiophoiles, for decades and proveable theories have evolved. Such established theory is set in concrete, the only things that have changed over time are cone and magnet materials making for more efficient drivers and cones that act more like well controlled pistons. I am not familiar with any rechearch on cabinet-less systems, the only mention I could find on the internet was this snippet on the site of "common Sence Audio"

Open Baffle Cabinets
Open Baffle cabinets are basically just flat pieces of wood supported by two 'wings' to hold them upright. Since cabinets exist mainly to generate bass, one has to ask 'why' these are used. They don't generate much bass and what they do produce rolls off below 63 cycles, even with the largest full-range speakers. With 6.5 or 8 inch speakers, this rolloff can occur below 100 hz. The situation can be helped somewhat by placing them close to rear walls or corners.
The answer lies because they have a 'different' sound to box type speakers. Because there is no damping material behind the speaker cone, the sound from the back of the speaker is free to reflect off rear walls and join the sound from the front of the speaker. This time delay gives a 'fat' sound that some people like for classical music. And some people just like this type of sound. Supplemented with a quality subwoofer, the missing bass can be replaced, but not as seamlessly as with bass reflex systems.
Open Baffles give an unusual presentation. Initally, they can be quite interesting, but for many listeners they soon grow tiresome when you realize both what's missing and what's being (inaccurately) added. But they're extremely easy to build and we would encourage everyone to give them a try to see what all the fuss is about. They work best with the largest full-range speakers, which can generate more bass without an enclosed cabinet.

I really would be grateful if you would give me links to further reading on this subject, in the meantime it is you who has spent the money for YOU to enjoy the results and I do hope that you listen to the music rather than the system, listening for "faults"

HeadScratcher
4th December 2012, 12:11 AM
I have found this website extremely fascinating Loudspeakers (http://www.linkwitzlab.com/speakers.htm) his work is referenced a lot by people in the know.
Whilst the basic cabinet may be simpler on the surface, probably far more effort is actually required for proper design, than a regular cabinet.

Yes any one can route or jigsaw a hole in a flat board, but to make it work properly requires a massive amount of math, and there is an absolute ton of setting up to be put into practice.
When set up properly they can sound absolutely magic, but half do it and you would be better off sticking with a sealed or bass reflex cabinet.

So unlike the advice you quoted I wouldn’t suggest people try it unless they are prepared to commit to it properly, or you will wind up with the acoustic issues they mention in spades, but that is not what a proper setup sounds like.

Here’s a pic of the ball park I see the finished speakers looking like.

harrysin
4th December 2012, 01:52 AM
I have found this website extremely fascinating Loudspeakers (http://www.linkwitzlab.com/speakers.htm) his work is referenced a lot by people in the know.
Whilst the basic cabinet may be simpler on the surface, probably far more effort is actually required for proper design, than a regular cabinet.

Yes any one can route or jigsaw a hole in a flat board, but to make it work properly requires a massive amount of math, and there is an absolute ton of setting up to be put into practice.
When set up properly they can sound absolutely magic, but half do it and you would be better off sticking with a sealed or bass reflex cabinet.

So unlike the advice you quoted I wouldn’t suggest people try it unless they are prepared to commit to it properly, or you will wind up with the acoustic issues they mention in spades, but that is not what a proper setup sounds like.

Here’s a pic of the ball park I see the finished speakers looking like.
I found that to be interesting reading with no surprises but I was disappointed that nothing was said about systems without cabinets which is what I want to study because as I've said earlier, it goes against everything that I've ever learned about loudspeaker system design.

B80
12th January 2013, 04:43 AM
Hi there,

Admiring your artistic talent and sketchup skills. Also admiring the drivers you've acquired... some of the best money can buy. Flipping through the pages of the post, I found myself really looking forward to seeing the build progress to a finished product... you can imagine my disappointment when I got to about page 5... NO WOOD?!! :-) Whadda you mean no wood??? Where's the thingy's gonna go???

On a somewhat serious note, being an acoustic engineer, I can see some issues with your no baffle idea. It won't give you the sound you were hoping for, at least not below about 2.5kHz, where you're likely to cross your RAALs. Open baffles are a somewhat different story, but the response will not only depend on the length & shape of the baffles, but also the size, shape and finish of the room and the speaker positions within the room. It's finnicky.

An unmounted driver cone is a "dipole" source, compessing air on one side of the cone while rarefacting it in on the other as it oscillates. The baffle prevents the high pressure air to "leak" to the low pressure at the back and vice versa. The leakage is the worst when the edge of the baffle is less than half a wavelength away from the speaker cone. With wavelength being inversely proportional to the frequency, the lower the frequency, the greater the baffle dimensions required. (i.e. Speed = Frequency x wavelength, where speed is a constant at ~340m/s). With a no-baffle situation, the air is just going to be moved backwards and forwards around the edges. You'll likely end up with a very inefficient speaker with horrible, frequency dependant off-axis directionality.

To add to this, although driver properties (cone suspension stiffness and damping, excursion etc) determine if they're "best" suited to sealed or ported box applications, most can usually be used in both. The leap from drivers in enclosures to open baffles is much greater, requiring a completely different driver design (stiffer suspension, longer travel etc). If you want to design high end speakers to rival your Cremonas, you may need to understand more of the physics behind loudspeaker design (acoustics, vibration, electrical systems) and check what the drivers you bought are best suited for. You may even want to invest in a loudspeaker design software package down the track (SoundEasy, LspCAD, LEAP to name a few), so you can model everything from enclosure design, driver characteristics and crossover design to room characteristics and loudspeaker placement within the room prior to building them. Some of the packages also combine ability to measure various driver / box / room properties as well as measuring the finished speaker response. A word of caution tho, I would strongly recommend brushing up on loudspeaker design theory (if you haven't already) before sinking any coin into design programs. They require a fair bit of background knowledge to master... especially SoundEasy.

Anyhow, good luck, and I look forward to some progress in the new year.

Cheers

Boyan

Dust Mite
18th September 2013, 05:14 PM
Howdy scratcher, how is the project? Did you bring it to a conclusion or is it still evolving?

I've been a mite busy over the last year or so, with my current build being a set of PMS speakers. (http://www.audioenz.co.nz/forums/showthread.php/15121-New-Speaker-Build-...-PMS)

Heres where I'm up to at the moment.

285843285844285845

HeadScratcher
28th March 2015, 11:41 AM
Hey Dust Mite. Project is still ticking along... I am just putting some final touches on a CNC I built from scratch. Now I can build whatever I want :D

First audio project is to build some lute shaped cabinets for the 18" bass drivers. I am still running open baffle speakers after all these years.

Dust Mite
4th January 2017, 08:12 AM
Yo headscratcher ... you ever finish this project?
How about a sitrep, its been nearly 3 yeras now.

HeadScratcher
22nd April 2017, 04:14 PM
Dust Mite I have procrastinated and procrastinated until I think I have run out of excuses to make. I haven't used the CNC in 12 months since my last water pump died. Sick and tired of being slack I have ordered some bits to get the CNC going again and get some of these projects back on track. All going well I should have most of the parts I need to get the CNC going again in the next two to three weeks. I am also trying to fix up many of the half finished things on the CNC like limiting switches and drag chains. I have built a new Z axis out of block of billet alloy which got rid of all the chatter problems I had and I got around to putting the second X axis ballscrew in so now it stays more square driving evenly from both sides. Promise by the end of May it will be working and woodchips will fly.