Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Cabinets-Speakers => Topic started by: Terry on March 14, 2009, 11:06:09 am

Title: How does one make an Auralex Gramma?
Post by: Terry on March 14, 2009, 11:06:09 am

It really looks like it's worth looking into.  All it is is A thick piece of MDF  board ... what is that!!?? (I'll bet thats comercio babble for chipboard), a piece of carpet and two dense foam rails.  It is susposed to isolate your tube amp & speaker cab.  Joe Bonamassa has something like that and loves it.  C'mon doesn't it sound like a great idea.

How would you go about it.  And where would you find the materials.  If they sell for $59, I'm going to assume $5 in materials.

I always have my amps on 2 by 4's nailed together to make a little lift off the floor, but this sounds even better.

Title: Re: How does one make an Auralex Gramma?
Post by: bluesbear on March 14, 2009, 12:15:20 pm

MDF = medium density fiberboard
You could get everything you'd need at Lowes, Home Depot, etc.
Dave

Title: Re: How does one make an Auralex Gramma?
Post by: Geezer on March 14, 2009, 12:21:19 pm

(http://www.sweetwater.com/images/items/750/GRAMMA-large.jpg)

Title: Re: How does one make an Auralex Gramma?
Post by: tubesornothing on March 14, 2009, 01:03:10 pm

How about a nice set of isolation foam pads for the feet of the amp?

Title: Re: How does one make an Auralex Gramma?
Post by: Terry on March 14, 2009, 01:43:34 pm

Do you mean the amp head that goes on top of the cabinet?

Title: Re: How does one make an Auralex Gramma?
Post by: Frankenamp on March 14, 2009, 02:44:39 pm

You can do it with a half inch sheet of MDF or solid (no voids) plywood. carpet isn't critical, you can paint it yer favorite colour. the trick is in the strips of foam: If I was making one I'd steal a few tricks out of Beranake or another acoustics text and use at least a couple of different consistancies of foam med/soft/firm to damp a broad range of frequencies. (remember the weight on a spring theoretical stuff?) the foam is the spring here, and you want something that absorbs and does not resonate.

Title: Re: How does one make an Auralex Gramma?
Post by: Dynaflow on March 14, 2009, 02:57:51 pm

 Perhaps some of those wrists supports for computer keyboards glued on the bottom? The rubber palm rest pads. I have a 5e3 head thats getting its tubes shaken like crazy that I just built (has 6l6's and through a 2x12 bottom its got some bass)... :D May have to make something like that to isolate the head a bit...

Regards,

Dyna

Title: Re: How does one make an Auralex Gramma?
Post by: Frankenamp on March 14, 2009, 06:20:05 pm

computer wrist pads? good idea! that and some liquid nails* and yer set!

Title: Re: How does one make an Auralex Gramma?
Post by: drew on March 14, 2009, 09:31:05 pm

If you're going to use MDF, get it cut to size at the store.  Sawing that stuff creates a dust storm like you can't believe.

Title: Re: How does one make an Auralex Gramma?
Post by: Terry on March 22, 2009, 07:03:08 am

FINISHED!   So far they work great!  I got foam rails from a guy who saved the exact thing from large shipping crates (they protected voting machines). I got free indoor/outdoor carpet samples.  I used russian birch plywood instead of the MDF...big deal, it cost me $15. to do "4" auralex grammas. They told me that was the densest stuff they had. I had to buy a whole sheet if I got the MDF.  Plus $4. for some plastic tub installation glue in a caulk format.

I'm serious, I tried them at church today as well.  It's like getting everything you worked for to get the amp sounding great back from the "room" your in.