pioneer speakers

[tanii51]

need to build a couple of boxes for pioneer ts a6955 3 way speakers to bring an old jvc hifi system back in to use for quiet computer room listening of cds etc. any clues on sizes volumes design etc would be greatly appreciated

[MrFixIt]

Hi

need to build a couple of boxes for pioneer ts a6955 3 way speakers to bring an old jvc hifi system back in to use for quiet computer room listening of cds etc. any clues on sizes volumes design etc would be greatly appreciated

Speaker box design can be a fine art, so you question is quite open ended.

There is some basic info here...

http://www.patentstorm.us/patents/5012889-description.html

You could make a relatively small acoustic suspension type box that is completely air-tight, or you could build a bass reflex type that may or may not have baffles and a tuned port usually a tube. There is an acoustic science behind the calculations for the size and volume of the box and the length and diameter of the tube.

Etc,etc, etc. :D

IF your
to use for quiet computer room listening of cds is for background listening then almost any size box in which the speaker can be mounted/fitted will do the job.

According to the specs here...

http://www.fixya.com/support/p162212-pioneer_ts_a6955_coaxial_car_speaker

The freq resp is 30-28,000hz. So the bass response is not so good. This will be improved by enclosure installation but I would not expect anything like "hi-fi" quality, but they should sound quite acceptable.

Make the box a convenient size based on space or materials available to based on trying to create a superb sound (because you won't get a superb sound).

There is prbably something here that might help you.

http://www.audiogrid.com/audio/

HTH

[Harry72]

Is the old JVC capable of driving a 4ohm load safely?

[tanii51]

now thats a good point i just checked and its rated at 8 ohms so that means ill have to do some more homework . why cant things be simple like just add 2 speakers to an amp :~( amp is jvc A-K100b)i just checked the volume level probably 2 to 21/2 is heaps so amp wouldnt be driven too hard .(getting to old for that) it would be a pity to waste a couple of usable speakers

[MrFixIt]

Hi

now thats a good point i just checked and its rated at 8 ohms so that means ill have to do some more homework . why cant things be simple like just add 2 speakers to an amp :~( amp is jvc A-K100b)i just checked the volume level probably 2 to 21/2 is heaps so amp wouldnt be driven too hard .(getting to old for that) it would be a pity to waste a couple of usable speakers
For a given setting on the volume control, the 4ohm speakers will be (roughly) twice as loud. There are too many technical variables to be very specific about volume and "load" etc.

However, if the amp is only going to be used at low volume levels then the 4ohm load "should" be ok. There is no guarantee of this of course as there may be other variables involved.

If you are REALLY concerned about this you could add a 4ohm resistor in series with the speaker, to present an 8ohm load for the amp. This will diminish the current volume level and you will then have to inccrease the volume to maybe 4 or 5 to get the volume you had at 4ohms.

Adding a resistor is not really the answer though as there are other factors to consider. The resistance "load" is not really the answer, as it is the speaker impedence that is of concern and this impedence varies with frequency - it's all too technical for what you want to do :D

Check these links for some other technical details that you probably don't need to know :D

http://www.mmxpress.com/technical/resistance_impedance.htm

http://www.bcae1.com/resvsimp.htm

If you have the manual for the amp, check the specs. Some older amps could handle different speaker impedence values.

If I were you, I would just use the 4 ohm speakers at the low volume level you mention and I am sure they will be ok :)

[tanii51]

well i think thats what ill do just make some speaker boxes to hold the speakers and hook it up & go, the whole system didnt cost much only bought the unit for the turn table so i could play some old vinyls and i doubt i will drive the amp into self destruct mode cos its only used in a small 10ftX 8 ft room with 2 old fogies in there thanks for the help guys :2tsup:

[Harry72]

Guess what... those 6by9's will need about 1/4 of that room(box size)to get their designed bass response!
They're designed to use the whole car boot(thats a "trunk" for the seppo's)as an enclosure... infinite baffle as they say.

[tanii51]

thanks guys for all the thoughts i didnt realize it was so complicated (i just had a brain wave harry if i mount them in the ceiling it can use all the roof space as an infinite baffle:;) it will save making a box:doh:

[Harry72]

That'll do it!
You might still want too make a baffle to screw to the ceiling(stud to stud) as the bass will vibrate most ceiling materials.

[Petebass]

Hi

If you are REALLY concerned about this you could add a 4ohm resistor in series with the speaker, to present an 8ohm load for the amp.
In this case this isn't such a big deal but in case anyone reads this and ponders this as a solution to other speaker impedance matching issues, I feel the need to issue a warning.

Yes adding a resistor in series creates a nominal 4 ohm load to the amp. However, the resistor will steal half the power from the amp. 2 problems here. Firstly your speaker only gets half the watts you thought it would. And secondly the resistor will heat up very quickly. Give it enough juice and it'll burn our completely. When it does, the amp again sees a 4 ohm load and there's a very good chance the amp will overheat and blow as well.

Can you get your hands on 2 more speakers? If so consider a design which has 2 of those speakers in each enclosure, connecting them in series for an 8 ohm load. In other words, use a second speaker instead of a resistor.

[Harry72]

Wouldnt running them in series be affected by their Xovers?

[Petebass]

Wouldnt running them in series be affected by their Xovers?Not sure what you mean, but if you're worried about the crossovers suddenly seeing a different impedance, dont. You're essentially wiring the woofer sections in series. The crossovers themselves are still wired directly to the voice coils from the respective woofer and tweeter drivers, so they'll still function as they were designed to.

[Harry72]

I didnt think running series was any good if there was Xovers involved... its ok to wire speakers in series after the xover providing the speaker spec's work out the same as originally intended(can affect Hz point and roll off).
Might be ok if the woofers are not high passed, but it will affect the tweeters xover point/roll off... could be a disaster!
When I use to do car installs we'd always wire full range 2~3way speakers in parallel to obtain an 2ohm load, never the other way because of this reason(not saying its right tho???).

[soundman]

:doh: :no:
looks like we have a variety of problems here.

Yes you probably can get away with connecting your 4 ohm speakers to your 8 ohm amp but it is a risk...... it might just blow up on you too.
The amp design may nt be stable at any power into 4 ohm

not realy recommended.

yes you could connect your 4 ohm speakers thru a 4 ohm resistor.... but.... the resistor will need to be quite large.... equal in power rating to the speaker... this sort of big resistor is a bit hard and expensive to get.... unless you want to muck arround with jug eliments and stuff

secondly the resistor will take half the power..... no a problem if you have power to spare.

thirdly it will badly effect you damping factor..... in fact it will go out the window..... damping factor is a measure of the amps ability to control the speaker and return it to rest between excursions..... it will make your bass sound.... um..... er....sloppy.

All in all not a good idea at this power level.

A 4 ohm speaker, in theory will be louder than an 8 ohm speaker at the same drive level..... in practice most 4 ohm speakers (being car speakers) are very insensitive..... so depending on the 8 ohm speaker used for comparison, it may not be the case.

As for box size
most retail car speakers ( I assume this is a car speaker) defy any sort of inteligent speaker design, and can very easily sound very crappy outside a car.

now to the crossover issue
these car speakers have very simple crossovers... usualy little more than a capacitor or 2......running 2 identical speakers in series will not effect the operation of the crossover in theory or practice.
no matter how you do the math or what model you use it will come out the same... as long as the speakers are identical.


Getting some cheap speakers is never as easy as it seems.

think about this
either go out and buy yourself a cheap set of 8 ohm bookshelf speakers.... there are heaps arround and some of them sound quite respectable.

or if you want to build something and you want it simple and easy
Altronics do an 8 inch 8 ohm two way coaxial speaker at $45 each (C2005)(altronics.com.au) they have a dealer in adelade or they mail order.
build youreslf a nice simple sealed box about 250x250x400 out of 15mm MDF
and bobs your uncle.... very simple, no maths..... & will worke better than the options you have seen previously.

I'm not saying this is a wonderfull speaker just something cheap and easy to build that will work.

cheers

[tanii51]

well the decision has been made thanks guys last night i was qiuietly playing a tape and guess what one speaker took off in uncontrollable oscillation i would call it lucky i was sitting along side it and stopped every thing before it destroyed itself . well off to the junk shops to find some 8ohm book shelf speakers (any hints on good quality names )