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  1. #31
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    I'd have to agree that if your box is vibrating and walking you must be leaking energy badly.

    It occurs to me that many of the current range of HIFI bass drivers they have simply increased cone mass in an effort to reduce resonant frequency.
    Some of these drivers would have twice or three times the cone mass I would expect from a high power pro type driver.
    Start whipping that back and forth and you will produce more vibration and less sound out..... this probaly accounts for the very low (by pro sound standards) sensitivity specs on some of these drivers.

    I sort of agree and disagree about the horn loading thing.
    I grew up with big horn loaded boxes like altec 816, 828 and 817 boxes which were all horn loaded.... while lots of others were using front loaded stuff and some of the early band pass stuff.

    I remember one job I was on we had some horn loaded boxes subd in to supliment the clients bose rig......his tandem tuned bass boxes were beside the horn loaded boxes........ the TT boxes sounded like they werent pluged in.
    Believe me I am very pro hor loading.

    BUT

    to get an effect on low bass the horn does need to be big......very big.
    To get maximum transfer efficiency the horn needs to be long and the mouth needs to be wide....... monumental proportions.

    However the "turbosound bass device" (complete with lapsed patents and registered trade marks) did effectively fly in the face of a lot of excepted wisdom about the size and length of the horn required to achieve results in the mid bass region 80 to 250 Hz.

    It is true that almost all major manufacturers are currently offering horn loaded designs in the ranges..... BUT..... almost without exception they offer a traditional bass ported design for low bass.

    The old given driver argument in reality simply dosn't hold up in the real world.
    Yess I've been guilty of making it my self in the past, but in reality there is such a large variation in drivers these days the argument comes unstuck very fast.
    Lots of drivers will work well across a number of design types, other drivers will work very well in specific types, many drivers will disapoint if put in the wrong design.

    One thing is certain......... what goes arround comes arround......When you've beed arround a while you recognise the latest new thing as an old thing from half a generation ago packaged in a diferent shape with a new trendy technical name.

    The collumn is dead, long live the horn loaded stack.....the horn loaded stack is dead, long live the flown array....... the flown array is dead, long live the line array(oh isn't that a collum speaker? )..........The line array is dead,hail the horn loaded box (back again are we).

    I notice that the transmission box that was popular in the 60's and 70's is making a resergence......... now where did i put those "J" bin plans

    cheers
    Any thing with sharp teeth eats meat.
    Most powertools have sharp teeth.
    People are made of meat.
    Abrasives can be just as dangerous as a blade.....and 10 times more painfull.

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  3. #32
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    Quote Originally Posted by soundman View Post

    to get an effect on low bass the horn does need to be big......very big.
    To get maximum transfer efficiency the horn needs to be long and the mouth needs to be wide....... monumental proportions.

    However the "turbosound bass device" (complete with lapsed patents and registered trade marks) did effectively fly in the face of a lot of excepted wisdom about the size and length of the horn required to achieve results in the mid bass region 80 to 250 Hz.
    I agree with pretty much everything you said. But in this bit, you didn't account for the effect of multiple horns cabs used in conjunction. If you line up several ported subs, they get louder, but they don't get much lower. If they were -3dB at 50 Hz on their own, they're still pretty close to -3dB at 50 Hz when you use several. Sure you end up with more bass, but that's because the efficiency in the frequency range between 50Hz and 100 Hz increases.

    Horns are a bit different in that every extra cab effectively increases the mouth area, resulting in a lowering the cut-off frequency. If one cab was -3dB at 50 Hz, the second cab effectively doubles the mouth area, so the -3dB point could very well drop to 40 Hz (estimate only). Adding more cabs again lowers the usable frequency range further. This is apparently unique to horn designs. As far as I'm aware, no other cab type shares this characteristic.

    Further, horns are quarted wavelength devices. So it stands to reason they work best in quarter space (ie open air divided by two walls, usually a floor and a one wall). Eight space (a room corner) is better again, but not often available in gig-land.

    So if that Turbosound sub you mentioned was bottoming out at 80Hz in an anechoic chamber or outdoors, it concievabe that it could have got down to 50Hz or even 40Hz by placing it against a wall or by adding more cabs to increase the mouth area.

    Gee I'm starting to sound like Bill Don't get me wrong I don't endorse horns in any big way, but they do have a place. I don't know that a coffee table qualifies, other than the fact that at least the speaker itself isn't visible making the whole thing a little more convincing as a piece of furniture.


    Quote Originally Posted by soundman View Post
    One thing is certain......... what goes arround comes arround......When you've beed arround a while you recognise the latest new thing as an old thing from half a generation ago packaged in a diferent shape with a new trendy technical name.

    The collumn is dead, long live the horn loaded stack.....the horn loaded stack is dead, long live the flown array....... the flown array is dead, long live the line array(oh isn't that a collum speaker? )..........The line array is dead,hail the horn loaded box (back again are we).

    I notice that the transmission box that was popular in the 60's and 70's is making a resergence......... now where did i put those "J" bin plans

    cheers
    Aint that the truth. I notice EA bass guitar cabs are available in Australia now and guess what - they're transmission lines.

  4. #33
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    Block stacking front loaded boxes does not only increase the amount but also MAY result in a lower response....... but it depends and isn't as pronounced as a horn speakers.

    I think its a factor of shaping the response and changing the curve..... the effectiveness depens on the frontal area of the box and the alignment of the box ( relationship of port freq to resonant freq).

    All this is pretty well irrelivant to the home HIFi boys because they dont get to stack up 16 bass drivers a side nor do they get access to rooms worth doing it in.

    cheers
    Any thing with sharp teeth eats meat.
    Most powertools have sharp teeth.
    People are made of meat.
    Abrasives can be just as dangerous as a blade.....and 10 times more painfull.

  5. #34
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    "I have never seen a respected commercialy produced studio monitor with sand in it or cement blocks or cement sheet or any of the dosens of crackkpot things that " enthusiasts" enjoy fiddling with."

    What do you mean "crackpot things"? You seem to have a closed mind.
    Let us keep in mind the "comercially produced" are driven to a larger or smaller degree by profit considerations.
    Development comes about through many contributions over a whole historical period including this very forum, and is always bound up with the needs and aspirations of society. It is always a social product of society and not bound up to any one group including the commercial operators. If it takes a contradictory road spiralling through its developmental life through trial and error including chance discoveries and mistakes - then so be it.

    I added a 20kg block of cement to the base of each of my old Spender monitors and the sound improved, albeit slightly, but never the less an improvement. I base that on a 15 year familliarity with the speakers.

  6. #35
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    no far from a closed mind.

    there are a great many "interesting things" I have seen and heard of, that various "enthusiasts" love to fiddle with...... in my opinion they are nothing more than fiddles.......... the question I always ask is....... yes it ( whatever) may have made a difference.... but was that difference an improvement or just different..... and how do you prove that or quantify that.........if you can't prove it or quantify it...... it is nothing more than a personal impression another may not have the same taste and may not agree that it is an improvement.

    if adding sand or cement to a speaker makes any provable improvement to the sound of a speaker the mechanical design of that speaker must have been deficient in the first place.........inadequate bracing, distribution of mass and a variety of other factors.

    if such a speaker was a simple box made from 16mm chip board I rest my case.


    the reason I say commercialy manufactured studio monitor......... because that is what the recordings are mixed on and these people have plenty of money to spend...... the top end studio monitors are far from a mass produced product in the true sence of the word.

    there are time when fiddleing arround the edges with afterthaught patch up methods is all that is open .

    But the preference surely must be adequate design in the first place.


    I may have mentioned in the past that a friend of mine has a customer that insists on haveing his concert boxes made of 25mm ply.
    My view is that it would be wiser and more effective to select the type and quality of the ply better and to achive better rigidity by introducing more effective bracing.

    cheers
    Any thing with sharp teeth eats meat.
    Most powertools have sharp teeth.
    People are made of meat.
    Abrasives can be just as dangerous as a blade.....and 10 times more painfull.

  7. #36
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    I have just joined this forum and came across this thread so am resurrecting what is now an old thread. There is so much rubbish talked about solid timber speaker cabinets, mostly from people how have never made one. I have been making solid timber cabinets for years, and if you get the design right and the timber right they WILL sound better then plywood or MDF. A peice of timber, MDF or plywood will resonate to a certain frequency which is determined by it's mass and stiffness. The length of time it will resonate will be determined by it's quality factor, which depends on the internal damping properties of the material. Some species of timber has a high Q factor e.g. Blackwood, Western Red Cedar. Others have a low Q factor, lower even than MDF - e.g. Jarrah. There is an enormous variation between timbers. You want to avoid high Q timbers for speaker cabinets, but if the timber has a lower Q factor than MDF then you are on to to good thing. Even better if the timber is stiff and heavy because then it will take more energy to make it resonate. Jarrah is excellent in all these respects. However, as already mentioned, solid timber is not dimensionally stable. Contrary to popular opinion, MDF is also not completely stable, but the difference is that MDF expands and contracts equally in all dimensions. Solid timber will expand and contract something like 20 times more across the grain than along the grain. You can safely ignore movement along the grain, but movement across the grain is a problem. It is a problem because with speakers the cabinet must remain airtight, but at the same time you need to allow for movement across the grain. A difficult problem, but not impossible to solve. You can't just glue up a piece of timber into a box and expect it to survive without splitting or glue joints to fail. With time and changes in weather one or the other is guaranteed to happen. How to solve this problem? Keep the cross grain dimensions as short as possible, and make the joints flexible. This sort of rules out big subwoofer cabinets, but tall thin shapes are possible. TL designs fit into this category, and this is what I have made very successfully. Jarrah is a very unstable timber and joints opening up more than 1mm is not uncommon. So, make sure the cabinet is at EMC before you put it together, and the joins must be be able to move at least 1mm.

    So you can make very successful solid timber speaker cabinets, with some significant restrictions. Mine have survived through droughts and high humidity, and they definatlely sound better than MDF. I have made identical cabinets from MDF and Jarrah, and have chosen Jarrah every time because they sounded better. I believe that is because Jarrah has a lower Q factor than MDF and is heavier and stiffer than MDF so you get less sound coming from the cabinet. There are other timbers with similar properties, but most are more expensive and/or more difficult to get. Solid timber cabinets also look like a very fine piece of furniture, which gets solid approval from SHMBO, and that must be good.

  8. #37
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    I think you are reading too much into this "Q" argument.

    if your silid timber cabinets perform any better I expect it will be in mass alone.

    If you have resonances of any form in the walls of your cabinet you have a bad strutural design problem.

    If you want to compare benifits of various materials, Mass is a major consideration.

    so if you have an MDF box that is the same mass as a solid timber box you may have a reasonable basis for the comparison.

    Ther reason that both MDF and chipboard are chosen by some constructors is on the basis of mass. Such designers are relying on mass rather than good structrual design to gain rigidity in the boxes.

    cheers
    Any thing with sharp teeth eats meat.
    Most powertools have sharp teeth.
    People are made of meat.
    Abrasives can be just as dangerous as a blade.....and 10 times more painfull.

  9. #38
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    I strongly disagree. You will ALWAYS have resonances in the walls of your cabinets. This is basic physics. Any material will have normal modes of vibrations, but they will vary in frequency depending on the stiffness and mass, and the patterns of vibrations will also vary according to how the cabinets are braced. The amplitude will depend on the amount of energy involved, and the Q factor of the material. Making it stiffer will increase the frequency of the modes, increasing mass will lower the frequencies. You cannot just consider mass alone. The Q factor is vitally important. Why do you think many manufactures use damping materials on the walls of their speakers - to lower Q. You can see the normal modes of vibrations by using the Chlandi pattern method and I have written a paper on Chladni patterns in mandolins. The aim is to put the modal frequencies so high as to be irrelevant or so low as to be irrelevant, and/or to increaqse Q so the amplitude becomes irrelevant. e.g. increasing stiffness from bracing may increase the frequency of the modes of vibration into the treble region so the box is not then excited at all by the woofer.

    MDF and chipboard are not used because of mass. There are plenty of other materials that have greater mass (and stiffness) - e.g. steel. However steel rings like a bell, i.e. has a high Q so is not really suitable. The fact is, MDF and chipboard are cheap and easy to work with and have a workably low Q. However, some solid timbers have a lower Q (and often higher stiffness and mass as well), but they are not cheap and not so easy to work with.
    Last edited by mandoman; 15th June 2008 at 11:26 AM. Reason: Missing text

  10. #39
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    Quote Originally Posted by mandoman View Post
    Why do you think many manufactures use damping materials on the walls of their speakers - to lower Q.
    Nope. They do it to prevent standing waves and internal reflections of the frequencies with wavelengths small enough to be fully formed within the cabinet - i.e. the mids and highs. And those are not the frequencies which make panels vibrate. They simply don't carry enough acoustic power. Lows and damping are completely independent of each other.

    Quote Originally Posted by mandoman View Post
    MDF and chipboard are not used because of mass. There are plenty of other materials that have greater mass (and stiffness) - e.g. steel. However steel rings like a bell, i.e. has a high Q so is not really suitable.
    Steel is also so darn heavy it's not practical. You'd need 4 guys to get the cab into the back of the van. MDF and chipboard are used because they provide the necessary stiffness Vs Portability compromise. Even still, the demand for lightweight speaker cabinets is growing all the time....... I'm following a thread in another forum where someone is experimenting with a cab made of fibreglass. He figures if it's strong enough for aeroplanes and boats, he should be able to make it stiff enough for a speaker cab and achieve considerable weight savings. He's even posted considerable data regarding stiffness of various composite materials Vs Ply and MFD. I know you hate this guy and everything he represents. It may not work, but it's got a lot of people excited, myself included. Pardon me for getting bored when people start talking about weight being tonal God.

  11. #40
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    mando mate, you have got the proportions of the physics all out of order.

    there is no comparison between a hollow bodied string instrument and a speaker box.
    In a holow bodied string instrument the cabinet is very light in comparison to the forces that excite it, and the cabinet is designed specificaly to transfer energy from the strings to the air.

    In a speaker box the physics are completely different.....if you have any significant contribution from resonances in the walls of the cabinet you have major problems with the design.

    Saying ALWAYS, is simply not true, it isnt popular now but in the 60's & 70's it was the done thing to make speakers out of concrete, or lead, or to fill the panels with sand or lead shot...... and a whole pile of rediculous things.

    in the 80's & 90's, with the advent of a variety of methods of measuring and analising things we realised that the paranoya over panel resonance was simply not justified.

    There are a variety of miscnceptions concerning how internal damping material effects speaker performance.

    one thing that is certain is that light soft material typical of speaker stuffing will do absolutely nothing to improve the performance of the speaker walls, from the pointn of view of vibration or flexure at any frequency of significance.

    The single most important thing to understand is that a speaker box is a preasure vessel and the single most important factor after having airtight joins is rigidity.

    Mass in many cases is a direct result of attempts at achieving rigidity.

    Now i wont try and say that mass and deadness (damping) arent important, because without adequate mass and structural damping you will have excessive panel resonances.

    Assuming reasinably conventional construction methods and a reasonable thickness of material you sholud not be able to find a significant resonance in a speaker cabinet.......and if a resonance can be found, it will be insignificant in comparison to the far more significant imperfections that abound in speaker design........further that resonance will be insignificant in comparison to the "desired output" of the drivers.

    There are a great many speaker boxes that do not have adequate box rigidity or damping on the market ( most of the tupperware speakers), but resonance is most certainly not the problem.

    The major problems are non resonant radiation from the box sides, and the boxes failure in rigidity effecting the performanece of the box as a preasure vessel this playing havock with the "Q" of the enclosure as it relates to the theile/small design process.
    The resonance we speak of here is not in the panel but in the volumetric design of the box.

    In most cases the walls cabinet will not resonate BUT there will be a irregular stifness curve that causes the walls to work inperfectly to a greater or lesser degree at different frequencies.

    even considering a mando, or voilin or conventional guitar, a well designed piece should not have significant resonances in the true meaning of the word, otherwise the instrument not perform smoothly across its voice range. it would sound peaky and nasty.
    The goal it to allow the strings to freely resonate ( strings resonate in the true sence of the word) the body shoul as much as posible not resonate but simply act as a cuppler to connect the bridge to the air.

    I think perhaps there may be some confusion in the use of the word "resonate". Musicians use the word an a manner that would not be considered appropriate in engineering or physics.

    something that vibrates does not necessarily resonate, further it is a myth that everythig has a resonant frequency........(if we exclude neucular physics)

    The music and HIFI industries are famous for giving imperfect explanations for actual physics and even more famous for getting effects out of proportion.

    unrelated example.....yes I heard this one from a operaticlay trained singing teacher.

    " Don't lean on the piano when you sing, the timber will take the resonance out of your voice"
    Complete BS
    the truth in the myth
    " Don't lean on the piano when you sing, it will ruin your posture, which effects both your breathing and how you present your throat and head. this will effect both your power and you vocal quality"


    Yes there are good reasons to have adequately rigid, sufficient mass and reasonable damping in speaker box materials, but if any of the above are inadequate you have bigger problems than panel resonance, especilay when you start playing with high power drivers.

    cheers
    Any thing with sharp teeth eats meat.
    Most powertools have sharp teeth.
    People are made of meat.
    Abrasives can be just as dangerous as a blade.....and 10 times more painfull.

  12. #41
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    "there is no comparison between a hollow bodied string instrument and a speaker box."

    Rubbish. The physics is exactly the same, it is just the aims are diametrically opposed. A stringed instrument still has a helmoltz resonance and the physical equations are exactly the same. The difference is with a musical instrument you are aiming for a high Q - i..e lots of resonance from the walls of the box. In a speaker you want the exact opposite, but the physical equations ae exactly the same as in a musical instrument. I agree that when talking about "resonant" it is probably better to talk about normal modes of vibration because things such as boxes, flat plates, or musical instruments will vibrate at a number of frequencies, not just one frequency. Musical instruments are incredibly complicated with non linearities that years of research has not come up with much understanding of the physics of what makes an instrument sound good. Most of what instrument makers do it is done impirically. Fortunately with speaker boxes the situation is much simpler - the equations are well known, and try and reduce unwanted vibrations as much as possible

    I still maintain that a speaker box will always have normal modes of vibration. Whether they are significant in terms of frequencies or amplitude is the question, and this is where the disagreement seems to arise. Using lead, concrete etc won't eleiminate the normal modes of vibration, but may reduce them (lower the Q) and/or shift the frequencies such that they then become irrelevant. If irrelevant then effectively they don't exist when you listen to the speakerl, but they are still there.

    There are two kinds of damping used in speakers - (1) stuffing to reduce standing waves e.g. polyester, fibreglass, wool etc, (2) damping material to reduce resonances (oops, normal modes of vibration) of the box e.g. bitumen panels. I was referring to (2).

    There seems to be an awful lot of misunderstandings with this topic.

  13. #42
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    My preference for speakers is called 'constrained layer' construction. Use your hardwood, by all means. However, you are better off using MDF for the actual enclosure and then covering the whole lot with hardwood. Preferably with a compliant layer between. I like Sorbothane™ for that purpose. MDF has surprising advantages for speaker construction. Don't assume that hardwood is automatically superior. Like all things, attend to the inner surfaces with good damping and the whole thing will sound fine, as long as you build the box to the correct internal dimension.

  14. #43
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    Im sorry to get narky but there are massive differences between speaker boxes and stringed instruments.

    a stringed instrument is a box that vibrates when excited by strings via the bridge. the predominat output of the instrument is the cabinet vibrating.
    the performance of the cabinet is not influenced appreciably by the strings and the strings are not appreciably influenced by the cabinet.
    The predomonant physics is that of a complex vibrating mass....a complexity that to my knowelege at this point defies matamatical analasys in any serious detail......and the principle of which are still much argued about.
    Further the performance and properties of the air volume contained within a stringed instrument while significant is only a very small part of the vibrating system. Violing for instance has a very low output from the "F" holes in comparison to the surface radiation.....in fact the "F" holes can be omitted with very little detremental effect.


    the speaker box on the other hand in the ideal situation does not vibrate.
    the predominant physics involve the relationship between the bass driver and the air contained by & within the box.


    The maths and the analisis of such systems is pretty well researched, pretty well understood and the subject of a variety of commercialy available design programes.

    I state again that the predominant physics in a speaker box is a relationship between the bass driver and the air volume contained in the box.
    The vibrating surface is the driver cone its self and as the system transitions thru resonance the port in an enclosure will predominate in output as the resonance of the air in the box and the resonance of the driver interact

    In speaker box design we strive and generaly achieve a state where the vibrations of the cabinet are insignificant and irrelevant.

    I beleive you have some typical misunderstandings of the roll of damping material in speaker boxes........these misunderstanding and very common and popularly held.

    The perdominant role of damping material inside a speaker box is to manipulate the "Q" of the air volume and its resonance which is used to play off against the resonance of the bass driver's sprung mass.

    The supression of standing waves within the speaker box is a minor effect in both its importance and its effectiveness.
    If the damping material was to be effective at supressing standing waves it would have to be significantly absorbtive at the frequencies involved and be at least a quarter wave in thickness.


    For the damping material to be effective in supressing panel resonance it would need to be significant in mass in comparison to the box material... like at least 10% to have a measurable effect and it would have to be intimately connected to the panel, ie glued or bonded over its whole surface.

    In the vast majority of cases this is not the case.

    It is a common mistake to cover all interior sides of a speaker box with damping material, depending on design choices this may or may not produce a desirable effect.........in most cases with the types of drivers I use I would place damping material on 3 interior sides.
    Some designs benifit verry little from damping material at all.
    The amount of damping material is important in a design and can significantly effect both the optimum volume and a variety of other outputs.

    It is interesting to put a box thru a simulator and change only the amount of damping and see what it does to the results.
    Some designs and some drivers it will have a significant effect others less so.

    All the important and significant factors in speaker box design can be redily calculated and simulated...........cabinet wall resonance is not one of them.


    I sugest you get hold of some good science bassed texts on speaker box design.........there has been a great deal written on speaker box design..........there is quite a lot that is sound science............there is a vast quantity more that is out dated, misconcieved, partly factual or totaly rubbish.

    I have been reading about speakers since I was a spotty youth, I can tell you I have read,... and held some misgiuided views in the past only to correct my views after more scollarly information came to my attention.


    cheers
    Any thing with sharp teeth eats meat.
    Most powertools have sharp teeth.
    People are made of meat.
    Abrasives can be just as dangerous as a blade.....and 10 times more painfull.

  15. #44
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    Of course there is a massive difference between a musical instrument and a speaker box, but the basic physical principles are the same. A musical instrument is far more complex and there are no matematical models that can adequately predict the sound. As you say, a lot of the sound emanates from the box. Speaker box models assume no sound emanates from the walls of the box which greatly simlifies the model. There has been a lot of research on violins, but little in the way of really useful information. As far as reading the research goes, I have to admit I stopped reading JAE papers when it became dominated by boring digital papers. Mea culpa, but I do have photocopies of all the original papers by Richard Small and Colin Thiele, and a swag of other classic papers on speaker crossovers and various other things. I was making so called D'Appolito WTW speakers years before they became fashionable.

    I would strongly dispute the assertion that removing the F holes on a violin (or mandolin) will have little detrimental effect. That is just plain wrong. The surface area of the soundhole and the internal volume, and the stiffness of the plates, determines the helmholtz resonance frequency of the soundbox of the instrument (otherwise known as hte A0 mode). This most very definately does affect the sound. In musical instruments, box vibrations as well as air vibrations are both important to sound, and the frequency response is anything but flat.

    If anyone thinks they have eliminated all box colourations in their speaker designs, just get yourself a full range elecrostatic or other open panel design, plonk it in your lounge room and listen. I did this some 8 years ago and never made another speaker for the next 3 years. However, eventually the challenge to try and beat the electrostatic was too great! Not there yet, but am getting close.

  16. #45
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    If you claim that the "F" holes are esential have you proved it by building a violin ( or a mando) without "F" holes.

    You can not say my assertion is wrong unless you can prove it.....I have heard expert testimony from one who has done the experiment and many besides.
    This gentleman stated that he could easily build a violin that sounded good without "F" holes but no one would buy it. this gentleman was one of the top 5 makers in europe.

    The sound hole contribution in a guitar is far greater than that of a violin or mando...... but yet we find quite a number of holow bodied acoustic guitars that do not have a sound hole opening, being commercialy made.

    I most certaily did not claim that the response of a stringed istrument was flatt. but a poor one can be very nasty and peaky. Then you would probably call it a banjo.

    The comparison between electrostatic speakers and any conventional speaker is not relivent, as the driver technology is completely different.
    Nobody of inteligence will dispute that a good electrostatic will sound vastly different will have better transient response and less colouration than a conventional cone based speaker........but the colouration from the box materials will be the least of the difference.
    For the most electrostatic speaker are impractical and irrelivent to most people.


    you must also consider if the comparison is with a box of equal sofistication and price.

    You may claim that the principles are the same but their reality and application of those principles is vastly different.
    it is like saying that a dynamic microphone and 1000 watt bass speaker work on the same principles which they do....microphone will work as a speaker and a speaker will work as a microphone, buy the design practicality makes them do the job them do the job they werent designed for very poorly...the reality and practicality are vastly different. A microphone and a speaker are very much closer than a speaker box and an instrument body.



    cheers
    Any thing with sharp teeth eats meat.
    Most powertools have sharp teeth.
    People are made of meat.
    Abrasives can be just as dangerous as a blade.....and 10 times more painfull.

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