46 replies to this topic

[lollo85]

Hi! I've got a pair of speakers Allison one.
I've to replace the woofers. Could you recommend a replace woofer for this model, the closer one to the original specifics?






Regards.

[JKent]

Why do you need to replace the woofers? If it's a case of foam rot on the woofer surrounds that's an easy fix. If the woofers are otherwise destroyed or missing, replacing them (finding the right drivers) is not so easy.
Kent

[lollo85]

Thanks for reply, JKent; Unfortunately, the original woofer were lost many years ago.
Therefore i am forced to seek an alternative woofer.

Searching on the web, I found some people talking about that you can replace it with the model Goldwood GW1034, but not having the original specifications of the allison woofer, I don't no know if it can be the right choise.

What do you think about it?
Can you help me?

Thanks

[JKent]

ooooo that's too bad. You need 4 woofers, right? Bummer.
I am not an expert on the Allison One. But I'm skeptical about putting in different woofers. Take a look at this thread. I think Minh knows what he is talking about, and he wrote "There is no new replacement woofer for the original Allison One" http://www.classicsp...?showtopic=2997
As I've suggested to others, You are WELCOME on this forum and we'd like to help, but I think you should also check out the Yahoo Allison forum. I got some advice there on replacement tweeters for my Fours and sometimes Roy himself even posts comments: http://tech.groups.y...lison-speakers/
Good luck with your quest. Those are great speakers that you'll want to get singing again.
btw--are the tweeters good? They seem to be a weak link (excellent but fragile) and they're pretty much 100% "unobtainium".

I "borrowed" these specs from the Allison Yahoo group. Hope they don't mind. Can't vouch for the accuracy.

kent

Attached Thumbnails

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Edited by JKent, 29 February 2012 - 11:03 PM.

[lollo85]

tweeters and mids are still good, I miss only woofer,
I'll try to ask questions on yahoo forum,
thanks for your answer

[Pete B]

tweeters and mids are still good, I miss only woofer,
I'll try to ask questions on yahoo forum,
thanks for your answer

I would not use Goldwood woofers. I posted on the yahoo forum
and let's see how they respond.

[Pete B]

Do you need four?
Do you have a total cost budget?

If you want a real budget solution use 4 of the 10"
woofers listed here as "10" 150Watt at $12.50ea":
http://apexjr.com/speakerstuff.html

One thing we don't know is the Xmax for this driver,
you could buy one, since they are inexpensive, and
remove the voice coil cone assembly to measure
the length of the coil winding, and the top plate
thickness, the diameter and determine if a metal
former is used. Or ask Steve at Apex if he knows or
is willing to take one apart to find out.

That looks like an Infinity logo on the dust cap and
chances are that these are fairly good woofers.
You should add 25g of mass to them. 5 US Nickles
would work fine and use epoxy or silicone glue to
hold them on. I would put them at the joint of the
dust cap and the cone leaning against the dust
cap. Raise them away from the cone when you
apply the glue so that they do not vibrate against
the cone with motion.
There does not seem to be a real good replacement.

[JKent]

Apex Jr is a good resource and Steve is a good guy. But I'm trying to imagine that conversation: "Hi, Steve? Listen, would you tear apart one of your woofers and measure the length of the winding?"

Anyway.... another thing to check out is the actual diameter of the frame to see if it will fit the Alli's without having to modify the cabinets. 10" does not always mean 10".

As Pete and Minh (and others) have pointed out, there is no perfect replacement. Your speakers will no longer be Allison Ones, but they MAY be perfectly nice speakers. Infinity drivers don't suck. I'd say it's worth the $50 investment as long as the drivers are drop-in fits. Worst case, you may need to do some mods to the xo. Pete knows infinitely (accidental pun) more about that than I do, maybe he'd be able to help if it comes to that.

Good luck with this project.

Kent

[lollo85]

is it usefull?

http://imageshack.us...electrical.jpg/

[Pete B]

is it usefull?

http://imageshack.us...electrical.jpg/

I have seen that and used it to come to some of my conclusions.
I ran some simulations with both the original Allision specs and the
Apex Jr. woofer with added mass. I would add 35 grams instead of
25 as I suggested above. It is not 100% right but probably far better
than a woofer taken at random from a catalog. I can provide more
tips if anyone is interested in using that driver. The suspension is too
stiff, the added mass at least lowers Fs somewhat.
The motor is also a bit too strong.

I'm not going to do anymore with this unless someone is interested
in trying them.

Are you going to give us some idea of your budget lollo85? It is hard
to look for a replacement not knowing a cost limit.

[lollo85]

Thanks for reply Pete. My budget is around $ 450, but i prefer to find something from the catalog, are not very experienced in making these experiments.
Searching the internet, I found 2 interesting woofer, what do you think?
I enclose the translation of the original specifications of the woofer allison.

Sensitivity (dB-SPL)2.83volts@1meter 87+
Nominal Loudspeaker Imp. (Ohms) 4
Voice Coil DC Resistance (Ohms) 3,1
Magnetic Gap Flux Density (Gauss) 8.000
Magnet Weight (Oz.) 19
Magnet/Assembly Weight (Oz.) 53
Magnetic Gap Height (Inches) 0,37
Voice Coil Winding Total Length (Inches) 0,87
Total Voice Coil Overhang (inches) 0,5
Voice Coil Linear Excursion Xmax (+/- inches) 0,25
Nominal Voice Coil Diameter (Inches) 1,5
Effective Diaphragm Piston Diameter (Inches) 8,4
Diaphragm Weight (Grams) 54
Fs - (Hz) - Free Air Resonance of Driver 22
Voice Coil Damping/Cooling Material None
Qms - Q at Fs, Mechanical Resistance Only 2,74
Qes - Q at Fs, Electrical Resistance Only 0,59
Vas(cubic inches) - Volume of Air with Same Compliance as the Driver Suspension 9.281
Continuous or Avg. Power Handling at Any Frequency (Watts) 250


check out this woofer, and tell me what do you think:

http://www.scan-spea...26w-4534g00.pdf

also this:

http://www.ciare.com...logo/CW256Z.pdf

[Pete B]

The SCAN is a more modern driver and it is close but it has shorting
rings to reduce the voice coil inductance and therefore it is too low
which will effect the crossover network loading. It works reasonably
well with .5 mH added in series with each woofer to bring the effective
Le back up. Here is roughly what the simulator says:
Fb = 45.3 should be 40 Hz as in the original
F3 = 40.6 should be 35 Hz
Qtc = .79 should be 1.0
The higher F3 is due to a lighter cone and higher Fb, and a stronger
motor causing a lower Qtc. If you add a .5 mH inductor to raise the
inductance and make it .5 ohm DCR then the Qtc goes up to .875
and F3 down to about 39 Hz.
I'd use it if you really like the driver, check mechanical fit and add .5 mH
per driver or 1.0 mH (.5 to 1 ohm DCR) total.
Push any damping material as far away from the woofers as you can.
If it is fiberglass consider taking it out from the bottom of the cabinet
up to the top of the woofers - this will help bring Qtc closer to 1.0. You
could add pillow stuffing or acoustistuff in place of that lower portion but
do not replace the rest back up into the cabinet since they have very
different characteristics. The poly stuffings do not lower Qtc as much,
very little actually.

The SCAN driver works even better, much better with 10g of mass added.
It has an aluminum cone so you have to be very careful adding mass so
as to not bend it. You should be able to do 10g with a gentle application
of poster tack, Mortite, etc.

Thanks for reply Pete. My budget is around $ 450, but i prefer to find something from the catalog, are not very experienced in making these experiments.
Searching the internet, I found 2 interesting woofer, what do you think?
I enclose the translation of the original specifications of the woofer allison.

Sensitivity (dB-SPL)2.83volts@1meter 87+
Nominal Loudspeaker Imp. (Ohms) 4
Voice Coil DC Resistance (Ohms) 3,1
Magnetic Gap Flux Density (Gauss) 8.000
Magnet Weight (Oz.) 19
Magnet/Assembly Weight (Oz.) 53
Magnetic Gap Height (Inches) 0,37
Voice Coil Winding Total Length (Inches) 0,87
Total Voice Coil Overhang (inches) 0,5
Voice Coil Linear Excursion Xmax (+/- inches) 0,25
Nominal Voice Coil Diameter (Inches) 1,5
Effective Diaphragm Piston Diameter (Inches) 8,4
Diaphragm Weight (Grams) 54
Fs - (Hz) - Free Air Resonance of Driver 22
Voice Coil Damping/Cooling Material None
Qms - Q at Fs, Mechanical Resistance Only 2,74
Qes - Q at Fs, Electrical Resistance Only 0,59
Vas(cubic inches) - Volume of Air with Same Compliance as the Driver Suspension 9.281
Continuous or Avg. Power Handling at Any Frequency (Watts) 250


check out this woofer, and tell me what do you think:

http://www.scan-spea...26w-4534g00.pdf

also this:

http://www.ciare.com...logo/CW256Z.pdf

[Pete B]

Eminence made the Allison One woofers for the later Kentuky run of Allison products so you might email them and ask if there is anyway to get 4 more woofers: http://www.eminence.com/support/faq/

Huw at Human Speakers rebuilds EPI woofers and there was a 10" 4 ohm woofer. It had a loose suspension, 6mm Xmax, and a magnet of about the right size. You might ask him if he can rebuild one with a 60g moving mass: http://www.humanspea...man/america.htm

[bigyank]

I haven't been here in a while but my timing seems good. I have a nice pair of Model Ones and planned on testing the woofers and can post the T&S parameters. One of my woofers has a slight buzz when I play certain material like DSOTM. Bill LeGall of MillerSound swears he can rework the woofers and even replicate the coating so I was going to test a couple of them before he performs his "magic". I have had him clean up and reform a couple of the mid domes to where they look like new.

[lollo85]

Thanks for reply Pete, what do you recommend? the SCAN'S procedure does not seem difficult;

do you think the SCAN is the best choise? and what do you think about "Ciare"?:

http://www.ciare.com/pdf/catalogo/CW256z.PDF

I also contacted the Human speaker, and the Eminence and i'm waiting for an answer.

[Pete B]

The Ciare is not even close.

I was going to mention that the SCAN is probably not as rugged as the original Allison's.
It has a non-thermally conductive former so I expect that it will have more thermal compression.
And I'm not sure if there is as much room for overshoot on Xmax.
You're probably OK if you are using 100-200W/ch and you don't push them too hard.
More than 200W and I'd want a metal voice coil former.
I beleive that they are overpriced but will probably work fairly well - my estimate is
that F3 will be about 5 Hz higher than the original 35 Hz is that OK with you especially
for such a high cost per woofer?
Do you plan to add the 10 grams?
Is there fiberglass in the bottom of the cabinet near the woofers?

Do you have even the old frames for the original woofers, or were they thrown out?

The 10" Advent Legacy woofer is probably also a good magnet, motor, frame
to work with, but I think it is 6 or 8 ohm and the cone is probably far too light.
Perhaps someone could rebuild a set with a 4 ohm (~3.1 DCR) voice coil and
the required added mass to the cone.

Bill LeGall of MillerSound is legendary and might have some ideas.

Thanks for reply Pete, what do you recommend? the SCAN'S procedure does not seem difficult;

do you think the SCAN is the best choise? and what do you think about "Ciare"?:

http://www.ciare.com...logo/CW256z.PDF

I also contacted the Human speaker, and the Eminence and i'm waiting for an answer.

[lollo85]

I will buy the scan, considering all the informations, i think it's the only solution; but i will make larger hole (272 pitch diam).
Huw and the Eminence support, I haven't had an answer yet.

For the fiberglass, i took some photos:

[Pete B]

Just push that fiberglass away from the drivers, but clearly there is none toward the bottom.
Don't add anymore for any of these drivers that are already too low in Q.

[Pete B]

This low cost Rockford Fosgate auto woofer actually models fairly well and has a 2" voice coil with an aluminum former:
http://www.rockfordf...x?itemid=112931

It is about 1 dB more efficient from about 100 Hz up.
But the stronger motor results in lower Q, so the response is down about 1 dB around 80 Hz,
and 2 dB around 40 Hz. Fb is lower due to the heavy cone at about 38 Hz, but F3 is around
40 do to the stronger motor and lower Q.
It is not a bad choice especially considering the price.

Check mechanical fit of course.

[lollo85]

This low cost Rockford Fosgate auto woofer actually models fairly well and has a 2" voice coil with an aluminum former:
http://www.rockfordf...x?itemid=112931

It is about 1 dB more efficient from about 100 Hz up.
But the stronger motor results in lower Q, so the response is down about 1 dB around 80 Hz,
and 2 dB around 40 Hz. Fb is lower due to the heavy cone at about 38 Hz, but F3 is around
40 do to the stronger motor and lower Q.
It is not a bad choice especially considering the price.

the specification show a vas at: 87.7
isn't it too little? original allison has 150

I believe that the SCAN are more suitable (i found it in italy at 118 dollars each)