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A150 Mod


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Hey guys,

This is actually an extension of: http://www.classicspeakerpages.net/IP.Boar...?showtopic=4984

As it is a repair thread, I thought it best to start anew.

Topic at hand is the viability of replacing the white polyfill in my A150's with fiberglass. The cap.s have been replaced with Dayton polys. My woofers' surrounds have been recently replaced with the correct, thin & pliable ones that have the smooth mid roll to cone angle transition. just after I got the surrounds right I:

1. Tried 19oz. of fiberglass in one cab. Did an A/B in mono with the other cab containing the original 16 oz. of polyfill.

Result - While quite good, the polyfill woofer seemed a bit boomy compared to the fiberglass woofer. The fiberglass

unit had that wonderful early AR type tighteous & righteous bass, but the SPL was reduced to the point that the speaker

was prohibitively unbalanced, bass shy.

Back in went the polyfill. Some other changes in my system produced improvements in bass performance, both SPL & SQ wise. My mind returned to the experiment listed above as I now found my A150s to be unbalanced in the bass heavy way.

2. Tried 12 oz. of fiberglass. Amount reduced as fiberglass is reported to be a superior damping medium. Back to A/B in

mono. Tighteous and righteous to the most pleasant extreme, seems to go a bit lower than the polyfill woofer as well.

The difference in SPL doesn't seem to be quite as great as I remember, either. Fiberglass is the clear winner. Both cabs

are stuffed with 12 oz. of fiberglass and I'm enjoying them immensely. Chris Squires of YES never sounded so good,

seems like I'm listening to him play.

Weights are as best I could manage balancing trash bags of stuffing on a kitchen scale. Audible impressions are by ear only, but trust me, unless the results were obvious and consistent over hours (not minutes) of listening, I wouldn't bother posting.

Next up?

Ya know those cabs have always had vibration I could feel behind the woofer. Maybe more bracing and/or damping. Try modeler's clay, perhaps.

The crossover is right behind the woofer. If I could figure out how to pull the whole unit, maybe mount it on the outside, out of the woofer's vibe path. Hmmmm.

As long as it's out, I've been wanting to try a DIY active crossover.......

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