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Allison CD8s - need opinions on next steps


Knadles
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Hi,

New to this forum. Hoping to get some advice from some Allison fans about what to do with my CD8s. Here's my story:

I have a pair that I purchased new back in...I dunno...1990 or so? Over time, the rubber surrounds on the woofers decayed, so I brought them to a very well-regarded local speaker shop (Van L Speakerworks). John, the owner (who does all the repair work and also designs his own speakers), replaced the surrounds and the capacitors.

On my own, I also replaced the grills, a couple of which had cracks from being bumped over the years. There is (or was) as seller on Etsy who makes drop-in replacements that are shockingly close to identical. If anything, I actually think they're even a little higher quality, as they feel a little less brittle.

So aside from the woofer surrounds, the capacitors, and the grills, the speakers are mostly original. My issue is that they just don't seem to have the same "magic midrange" they did when I bought them. It might be my ears, which are much older; or my memory; or it might be the capacitors, which (I assume) are the factory value, but definitely upgraded; or it might be the woofer surrounds, but I doubt this since the bass response doesn't seem to have been affected. (Note: please understand I am NOT impugning the quality of John's work. He knows his stuff; at worst I think maybe the capacitors were TOO upgraded.)

Whatever the cause, I'm thinking of selling, but I don't want to "over pitch" them to a buyer. On the one hand, to my memory, they sound a little different than I remember. On the other, they are certainly Allison CD8s, a somewhat rare and desirable speaker. And they still sound good, just not the same.

My options are:

  • Keep them as-is, but I recently picked up a good deal on a pair of Focals that I'm pretty happy with.
  • Replace the capacitors (as the most likely non-my-own-ears culprits in the altered sound), then sell.
  • Sell them as-is.

Any thoughts? And if anyone here has replaced the caps in CD8s, maybe tell me what model/value the originals were so I can verify my next step if I choose to go with Option 2...?

Thank you,

Pete

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Hi Pete,

Your gut is telling you the same thing I’m thinking (capacitor swap). unnecessary and MAY have altered the sound.

From years of hanging around the Allison forums, I can tell you what my perception is, after members change caps. and then try to get meaningful impressions from them regarding what those sonic differences REALLY are….

The answer is, they have new caps and if properly done, sound as good as new, but no different. I personally will let the Allison high quality capacitors go for 50 years without even thinking about a swap. There’s enough to worry about regarding foam, not rubber surrounds and the spiders that support the back end of those drivers.

these are not high-voltage capacitors that are subject to demands that are placed upon them by an amplifier, or any other high-voltage application. They are essentially filters and can do their job as specified for a very, very long time. The big sell on this has always been capacitors  “drifting from specifications over time“. That being said, measuring from what they were to where they are now, as a system is not so easy, if you’re talking about establishing a baseline for comparison.
I’m running three different models of Allisons in my home, theater system, all with the original capacitors in tow. Nothing to my ears is calling attention to fix something that isn’t broken. They all continue to sound stellar the changes for the better have come from 21st-century electronics, putting the pedal to the metal.

are all of the drivers in those eights still ALLISON drivers?

 

 

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Hi,

Glad to have one person at least back up my gut instinct! Since the original caps are gone, I'll need to find a pic online or something to verify what they originally were, so I can swap them out again. If I do sell, I'd at least prefer to have the speakers acting like their original selves. Seems only fair.

All of the drivers are still Allisons. One of those glorious midranges got a small ding in it when a friend was moving the speaker and rested the grill on his shoulder, but John was able to pop that out. I didn't even ask him to; he just took care of it. I have a pair of CD6s as well that definitely need a refoam :). If I take those to John, I'll make sure the original caps stay in place. Unfortunately, I can't use the CD6s as a guide, since the two-way crossover would almost certainly have different values from the three-way.

Thanks!

Pete

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19 hours ago, Knadles said:

Hi,

Glad to have one person at least back up my gut instinct! Since the original caps are gone, I'll need to find a pic online or something to verify what they originally were, so I can swap them out again. If I do sell, I'd at least prefer to have the speakers acting like their original selves. Seems only fair.

All of the drivers are still Allisons. One of those glorious midranges got a small ding in it when a friend was moving the speaker and rested the grill on his shoulder, but John was able to pop that out. I didn't even ask him to; he just took care of it. I have a pair of CD6s as well that definitely need a refoam :). If I take those to John, I'll make sure the original caps stay in place. Unfortunately, I can't use the CD6s as a guide, since the two-way crossover would almost certainly have different values from the three-way.

Thanks!

Pete

allison-speakers@groups.io
 

Probably someone lurking here who can give you the exact specs on the original Allison, eight or cd eight capacitors

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On 11/1/2022 at 1:13 PM, Knadles said:

at worst I think maybe the capacitors were TOO upgraded

 

On 11/1/2022 at 1:13 PM, Knadles said:

My options are:

  • Keep them as-is, but I recently picked up a good deal on a pair of Focals that I'm pretty happy with.
  • Replace the capacitors (as the most likely non-my-own-ears culprits in the altered sound), then sell.
  • Sell them as-is.

 

First a disclaimer: Although I have owned and loved Allison: Fours I've never been inside them (and I no longer have them). A little Google search found pretty standard looking NPEs of 50 to 100V in Allison 8 crossovers. If the upgraded caps are film they would have a different ESR. Maybe replacing those with NPEs would restore a more original sound. Some members here are very fond of Mundorf NPEs.

OTOH, if you have decided you prefer the Focals and want to sell the Allisons, I'd leave them as-is and tell prospective buyers you had them restored by a reputable shop, with new surrounds and new caps.

On 11/1/2022 at 1:13 PM, Knadles said:

they just don't seem to have the same "magic midrange" they did when I bought them. It might be my ears, which are much older; or my memory;

"magic midrange" is pretty hard to quantify and I think it is VERY likely your perception that is the key. You are A/B-ing speakers separated by decades. There may be other variables, such as different room characteristics and certainly hearing changes over the decades. I do not believe it would be dishonest to not mention your impressions to prospective buyers. "Just the facts, ma'am." New surrounds. New caps. Reputable shop.

If this is still gnawing at you, why not go back to John and tell him your concerns. He could listen and test them and give you his impression. Based on your description he sounds like one who stands behind his work and, I would think, be willing to discuss this when you present it as you did in a non-accusatory way.

Just my 2 cents...

Kent

PS: SOME people say new caps need to "burn in". Probably hooey but what do I know? Also, new foams may need to break in a bit. So maybe let the speakers play for several hours or days and then listen again.

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  • 1 month later...

I did minor crossover work on a set of CD6’s, and had a major reworking done on a set of CD7’s. The CD6 set was bought off eBay, and one of the tweeters wasn’t working. Further testing showed the tweeter was fine; the problem was in the crossover. Since it is just a simple coil a cap design, I replaced the capacitor with an Erse cap costing just a few bucks, and it came back to life. The results were so good I replaced the cap in the other to match.

One of the CD7’s had a tweeter that was working, but its frequency response was all over the place. A local speaker designer took on the challenge of “reworking” the system, putting in place a more “modern” tweeter, and building a new and complex crossover for it, and the same for the second (otherwise working) speaker. The results were less than satisfying, and I eventually sold this set, which was not easy as it was no longer a “real” Allison.

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2 hours ago, rnathans00 said:

I did minor crossover work on a set of CD6’s, and had a major reworking done on a set of CD7’s. The CD6 set was bought off eBay, and one of the tweeters wasn’t working. Further testing showed the tweeter was fine; the problem was in the crossover. Since it is just a simple coil a cap design, I replaced the capacitor with an Erse cap costing just a few bucks, and it came back to life. The results were so good I replaced the cap in the other to match.

One of the CD7’s had a tweeter that was working, but its frequency response was all over the place. A local speaker designer took on the challenge of “reworking” the system, putting in place a more “modern” tweeter, and building a new and complex crossover for it, and the same for the second (otherwise working) speaker. The results were less than satisfying, and I eventually sold this set, which was not easy as it was no longer a “real” Allison.

Over 20 years now since the final demise of Allison Acoustics. Since then, there has never been a drop in replacement for either the pulsating dome tweeter or midrange that RA developed exclusively for his systems. I have maintained longevity only by getting educated as to interchangeably between those drivers and the various models so I could shop the used marketplaces and keep a sufficient inventory.

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