Altec 604 build

As for damping material, my experience with speakers like that would rate them this way for sound quality and effectiveness.
  1. Pure wool felt (soft)
  2. Bonded Logic denim insulation
  3. Rockwool panels
  4. Fiberglass panels
  5. Fiberglass loose.

Works for me ;), though with the first three, I 'see' an over damped cab once one of each parallel walls are covered enough to quell any 'hollowness'; whereas with acoustic FG, it's more likely still a bit under damped that can be tuned out by 'critically' damping the vent using the 'click' or impulse test, which historically results in a bit more 'lively' response with wide BW drivers, hence a better match to OB, IB, horn systems since there's less acoustic mass loading [damping] of the driver: Click Test | GM210 | Flickr

GM
 
Hi GM

Bit more then that... 750 Triumph. Custom frame, rest NOS or rebuild. Work in progress, probably another year...

Thanks
 

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Ah! Sweet! :D Couldn't see enough at the angle blown up [lack of] clarity, just knew that in my time/locale folks tended to use the 250 for 'flat tracking' city traffic whereas us 'Bonnie' owners preferred Cafe style racers ['66 in my case]. Gees, do I miss 'sickle' riding/racing. :(

GM
 
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Yeah, one can overdo the damping. The nice thing about the felt and the denim is their nice even broadband absolution. A felt curtain behind the driver has worked well in big cabs to reduce mids coming back out of the box.

All those material will work well, of course. It's just a matter of audiophile level tweaking. :)

Great bike! Love the look. Sure does dress up a listening room.
 
Yeah, I've used 'hanging blankets' suspended diagonally across large sealed/IB cabs and more recently some folks have used it in some pipe horn terminus including the popular 'BIB' series, but didn't like it in the various MLTLs I built early on with mostly < 8" 'FR' drivers, consequently didn't try it on my large ones.

GM
 
Some might be interested in this, the German DIY hifi magazine Klang + Ton built in 2014 an Altec 6xx alike speaker. They used a 12" Celestion TF1225CX coax driver and kept the enclosure extremely close to the Altec cabinet. With just over 300€ per side rather affordable and it sounds excellent.

Celeste K+T
Unfortunately the TF1225CX is no longer available :-(
 
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