High Efficiency Speaker Asylum

RE: Damping material for Altec 817A horn

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kef

In Reply to: RE: Damping material for Altec 817A horn posted by Bill Fitzmaurice on March 14, 2023 at 08:00:09

Yes, I'll have to experiment. Do you have any thoughts on the foam vs mineral wool or cotton bats?.
Thanks
Keith

Follow Ups:

RE: Damping material for Altec 817A horn - Bill Fitzmaurice 10:29:08 03/14/23 (0)
Foam is the least effective, being of the lowest density. Also note that pyramid foam consists of air in between the peaks, so it's effective thickness is much less than it appears to be. Then comes cotton, then mineral wool.
RE: Damping material for Altec 817A horn - Hornlover 09:59:33 03/14/23 (6)
Altec used fiberglass back then. Maybe the most authentic if that matters to you.
- RE: Damping material for Altec 817A horn - Bill Fitzmaurice 10:31:14 03/14/23 (5)
  Fiberglass, specifically Type 700 rigid boards, is the most effective damping material. Fiberglass insulation should not be used, as it falls apart.
  - How about... - Vinyl Valet 07:22:26 03/18/23 (2)
    this stuff?
    
    Open up your mind, in pours the trash. - Meat Puppets, 1987
    - No Rez (Open in New Window)
    - RE: No Rez? No. - Bill Fitzmaurice 08:47:48 03/18/23 (1)
      It has a heavy layer that doesn't do anything for a well constructed cabinet. The foam layer is OK, but no better than any other brand of foam. If it didn't cost four times what other materials do I'd say sure, but it does. I use heavy vinyl mastic in my car, where it's the only way you can control panel resonance.
      On the subject of price, foams sold as acoustic foam cost considerably more than furniture upholstery open cell urethane foam that works just as well. You can get that at Walmart and at fabric stores, like Joann's.
      - Thank you for your sage advice. (nt) - Vinyl Valet 09:06:33 03/18/23 (0)
        
        In Reply to: RE: No Rez? No. posted by Bill Fitzmaurice on March 18, 2023 at 08:47:48
        
        nt
        
        Open up your mind, in pours the trash. - Meat Puppets, 1987
  - RE: Damping material for Altec 817A horn - Hornlover 09:02:52 03/15/23 (0)
    I get the stuff made to insulate ductwork. Its not the paper backed stuff used for insulation between studs. It comes in a roll, and keeps its shape quite well.
  - RE: Damping material for Altec 817A horn - Coner 15:45:36 03/14/23 (0)
    I staple using 6" spacing never an issue. I've seen cheese cloth used on top though. Roxul is a good brand of rock wool, fairly dense and 2-3" thick panels.

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