Allison One woofers - original vs. "Kentucky" replacement

[rnathans00]

I've had a set of Allison Ones since 1979. In the 1990s, given "surround rot", I replaced all the woofers with drivers from the revived Allison then down in Kentucky. I found I was getting more bass, assuming it was because these were "new", rather than flawed like the ones replaced. Or evidence of my "flawed" acoustics.

Reading about the enhanced (and much more costly) versions of the One, Four, etc. from that short-lived revived Allison, I noticed reference to their higher efficiency compared to the originals. I've long wondered if I was using a woofer intended only for the newer Allison One, rather than the original.

Recently I acquired a pair of Outlaw bookshelf speakers - similar to Snell's K-7 and actually made for Outlaw by Snell. Really nice (and no longer available as Snell is no more), and even more natural sounding than my Ones. So again I have to wonder about those woofers. Assuming they *are*, in fact, not a proper match for my original Ones, is there a way to tone them down to better replicate the behavior of the originals?

[Pete B]

Do you have the T&S parameters for old versus new?

[rnathans00]

I have no idea what those "T&S parameters" are you refer to.

[Pete B]

"Thiele/Small" commonly refers to a set of electromechanical parameters that define the specified low frequency performance of a loudspeaker driver"

More here:

http://en.wikipedia.org/wiki/Thiele/Small

If the issue is that they are a few dB more efficient you could try adding mass in steps of about 10 grams to lower the efficiency and the closed box resonance of the system. Non-hardening putty type materials such as Mortite work well for this but it can leave a mark or discolor the cone so I'd try it on the back of the cone for experimentation. This is purely a guess so try it at your own risk and I would not go over 40g for added mass.