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Alisson 4 woofer


bubu91220
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bubu91220,

An original or properly restored Allison:Four woofer will have a foam surround and a textured paper cone that has a sticky coating. The woofer in the picture you provided has a rubber surround and smoother cone with no coating, and is not an original Allison:Four woofer. 

The only proper replacement for this woofer is another Allison:Four woofer, which has an 8 ohm impedance to match up with the series wired pair of tweeters. Woofers from any of the other Allison two-ways (models Five, Six, CD-6, CD-7) are 4 ohm units and are not direct replacements.

I've included a picture of an Allison 8 inch woofer to illustrate what an unrestored unit looks like (usually with lots of dust on the cone!).

 

 

Allison 8 inch.jpg

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Hello jeff , thank you for the information ! i think is not easy to find a woofers for allison 4 , i live in france and the allison 4 are very rare . I'have a allison five speakers with naim system  and i' like this speakers great sound ! 

What is the more musical the model four and the model five ? 

In france is easy to find model lc110 lc120 , the woofer of this model is suitable ? 

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The Allison Four woofer is actually 4 ohms impedance.  In the model Four,  there is a 2.2 ohm resistor and an inductor in series with the woofer which raises the impedance to 8 ohms.

Here are the specs for the Allison woofers.   The model Four woofer appears to be unique but the LC110 or LC120 woofer may be a fairly good replacement.   If one could be obtained at a reasonable price,  it may be worth a try.

 

Allison Driver Specifications

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The useful spreadsheet that LesE provides nicely outlines the differences among the Allison woofers. Thanks.

Given the information here, if I were trying to find a replacement for an Allison:Four, the only woofer I would avoid from the two-ways is the Allison:Six which has a voice coil Xmax of 0.1625" compared to the 0.25" of the others. I might also give preference to the LC models, whose woofers would have less potential spider sag than the others.

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10 hours ago, JeffS said:

The useful spreadsheet that LesE provides nicely outlines the differences among the Allison woofers. Thanks.

Given the information here, if I were trying to find a replacement for an Allison:Four, the only woofer I would avoid from the two-ways is the Allison:Six which has a voice coil Xmax of 0.1625" compared to the 0.25" of the others. I might also give preference to the LC models, whose woofers would have less potential spider sag than the others.

Could you elaborate on what you mean regarding “spider sag”?

 I have been a bug on Allison spiders within the woofers for years.

I have a lot of experience, going after aging spiders in these drivers. 
For most, the thinking seems to be to just refoam  the speaker and you’re good. 
That’s ok if a driver is perhaps 15 years old or even more.  But if it’s 43 years old, you should think again.

The spider can LOOK fine, but they lose compliance over the years, making it easier to bottom out.

The surround and the spider work together to keep the excursion in check.

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If I were shopping for a replacement woofer for my Allison:Four, and I could choose between woofers that were newer and had been mounted and stored forward facing as in the LC models, or woofers that were older and mounted and stored facing upward with deteriorated surrounds, I'd buy the newer woofer. Having said that, I would give preference to a woofer that came from a Four.

You put a fine point on what I called "spider sag" and we should all use caution when using these older drivers with original spiders.

My experience tells me this: I had a pair of Allison:Sevens that I installed new surrounds on about 15 years ago. They came back to me about 6 months ago for a cabinet refresh. I checked the condition of the surrounds and with them showing no signs of deterioration, I connected them to an amplifier rated at 400W/ch into 4 ohms. I took the volume up. No problems, and they sounded great. Now, I wasn't driving them hard enough to make the clip lights flash, nor would I with any 8" woofer.

10 years ago I put new surrounds on my Allison:Fours. I use them with a 150W/ch amplifier with no problems.

If someone using these Allison 8" models follows the placement recommendations, doesn't add any bass boost, and uses a reasonable amplifier (say, 100-150 W/ch), things should be fine. As you've said in the past, if you want deeper bass while using these speakers, add a subwoofer. 

 

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59 minutes ago, JeffS said:

If I were shopping for a replacement woofer for my Allison:Four, and I could choose between woofers that were newer and had been mounted and stored forward facing as in the LC models, or woofers that were older and mounted and stored facing upward with deteriorated surrounds, I'd buy the newer woofer. Having said that, I would give preference to a woofer that came from a Four.

You put a fine point on what I called "spider sag" and we should all use caution when using these older drivers with original spiders.

My experience tells me this: I had a pair of Allison:Sevens that I installed new surrounds on about 15 years ago. They came back to me about 6 months ago for a cabinet refresh. I checked the condition of the surrounds and with them showing no signs of deterioration, I connected them to an amplifier rated at 400W/ch into 4 ohms. I took the volume up. No problems, and they sounded great. Now, I wasn't driving them hard enough to make the clip lights flash, nor would I with any 8" woofer.

10 years ago I put new surrounds on my Allison:Fours. I use them with a 150W/ch amplifier with no problems.

If someone using these Allison 8" models follows the placement recommendations, doesn't add any bass boost, and uses a reasonable amplifier (say, 100-150 W/ch), things should be fine. As you've said in the past, if you want deeper bass while using these speakers, add a subwoofer. 

 

I understand now where you’re coming from regarding the “sag”!

An Allison user on another forum had concerns about the midrange sagging out of alignment (age related). He made a project out of flipping all of his 180 degrees to counteract this. I felt personally, it was a case in point of overthinking a potential issue. ….that with normal use they would be just fine. That being said, nothing lasts forever….

With yours I would think similarly, in that the woofers excursion is upward when operating, so sagging shouldn’t be an issue. Rigidity is something else, where by the spider cloth gets weak with age, the woofer is free to travel farther than it’s design was intended, having only the surround to keep it in check.

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