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Guitar Amp Stand / Sound Enhancer DIY

I've been meaning to post this for awhile now, and finally got around to it.

So, I built three of these thingies a few months ago. A bandmate and I were having lunch, and talking about various pieces of gear. He asked me if 8'd ever heard of the "Sound Enhancer," a passive device used to do the following:

1) Take the back pressure wave from an open backed guitar amp speaker, and send it forward, resulting in
2) increased volume with the amp running at lower gain levels
3) increased bass frequency response, giving you a warmer stage tone, and
4) tilting the amp up toward your ears so you can hear better what you're playing.

Here's a vid from 2012 Summer NAMM of the inventor and his device:

https://www.youtube.com/watch?v=WLcZN4Sa-bA

I researched it, including the patent, and decided I could build one myself. I ended up building 3 of them.

The first, smaller one (pic 1) was based on an attempt at scaling a picture of a Sound Enhancer Mini from the TDPRI website. I slapped it together out of 1/4" plywood.

The second (center of pic 2) was an upscaled version, based on a discussion with the inventor on TDPRI, where he revealed the height, width, and depth dimensions. It's the one with the amp sitting on it.

The third (left side of pic 2) was my attempt at building the actual patent schematic.

Soundwise, they all have measurable (as in 10 dB) increases in volume versus just the amp itself, for the same gain setting. The center one had the best overall tone, with increasing warmth, and the bass frequencies seemed to be in phase with the speaker. The smaller one works OK with a smaller amp, like my Fender Champ 600, which definitely needs help with bass response from the 8" speaker. The patent schematic clone had the largest overall volume increase (it has a slightly larger interior volume than the middle one) but had a discernable warble or filter of the bass frequencies: loud, but unbalanced.

This was a fun afternoon project. Each one took about two hours to cut out and build. They are glued and screwed together, and are actually fairly lightweight.

Unfortunately, I forgot to record video / audio of my buddy playing through them. I can get drawings and dimensions for you if you PM me.

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Permalink Reply by Ron "Oily" Sprague on July 1, 2017 at 4:47am

And here's how to get the max amount of wood out of a 4' x 8' sheet of plywood; I recommend 1/2" or even 1/4" Baltic birch.

Materials list:
1) 4' x 8' sheet of Baltic birch plywood - ~$20 at Lowe's or Home Depot
2) Titebond II wood glue - ~$4-5 at Lowe's or Home Depot
3) Approx 50 1-1/2" wood or drywall screws - ~$8-9 at Lowe's or Home Depot
4) Amp strap handle - ~$7-8 from www.amprepairparts.com
5) 4 to 8 1-1.5" rubber feet - $5-8 per pack of 4 from www.amprepairparts.com

Tools:
1) This is really much easier and faster with a table saw, but cut out can be accomplished with a saber or circular saw, a jig saw, or, if you're really masochistic, a hand saw.
2) Phillips screw driver
3) Powered drill to pre-drill screw holes to prevent tear out / splitting
4) Sand paper, orbital, or belt sander

Optional:
1) Non skid adhesive strips to prevent amp slippage (not really necessary)
2) A few rattle cans of matte or satin black paint

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Permalink Reply by Cigar Box Nation on July 1, 2017 at 5:01am

Hell, my problem is that all my amps are too loud for the venues I play. I've been bringing a damn baffle to place in front of the speaker just to keep the owners from shutting me down... and the amp is still only on 1 1/2 or 2

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Permalink Reply by Ron "Oily" Sprague on July 1, 2017 at 5:08am

But they are neat little amp stands, too...

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Permalink Reply by Ron "Oily" Sprague on July 1, 2017 at 5:09am

Just re-read this: have you ever tried a Pignose 7-100?

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Permalink Reply by Clark Rowden on July 1, 2017 at 9:07am

Haven't seen this before, this is awesome. Hmmm, why not just build an amp into the cabinet? I wonder if it could be scaled down for a CBG amp?

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Permalink Reply by Ron "Oily" Sprague on July 1, 2017 at 10:55am

Clark,

The Sound Enhancers were first developed about 20 years or so ago. I suppose you could build an amp directly into the cab; that's a neat idea. Harold Smith's idea, though, was that this would work with ANY open backed amp. There's a fair amount of research Mr. Smith put into his design, which uincludes figuring out the mathematics of folded horns as applied to speaker size, something the Scandinavians have taken about as far as it can go, to boost bass and lower mid frequencies. The research I've done into their folded horn and transmission line passive speaker designs, has convinced me that the lower speaker size limit for effective bass boost is 8" (yes, I know, car companies use 6.5" speakers and tuned enclosures, but they also use electronic magic to boost apparent bass response).

Which doesn't mean you (Or anyone else) can't try this with a CBG amp. But I don't think it scales precisely linearly. Although, there are examples of the Swedes taking the dimensions of a human cochlea, and scaling them up in wood; IIRC, they still had to tweak the dimensions of the upscaled version to get it to work properly.

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Permalink Reply by darryl kernaghan on July 1, 2017 at 11:31am

Did any of them experiment with a curved [ from top to bottom [ rear deflector that you know of Ron?

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Permalink Reply by Ron "Oily" Sprague on July 1, 2017 at 4:37pm

Darryl,

As a matter of fact, they did! Those seemed to give the best sonic response, but they also required the greatest wood working skills. A few of them als experimented with variable angle deflection baffles: they found that the frequencies that were enhanced changed depending upon the angle of the baffles - meaning that they were tunable, to a certain extent.

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Permalink Reply by darryl kernaghan on July 1, 2017 at 4:42pm

Thanks for the reply, i've got some 1/8" ply that's pretty flexible i might try, i'll let you know how it goes

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Permalink Reply by Ron "Oily" Sprague on July 1, 2017 at 4:46pm

Darryl,

Yeah, some of the examples I saw online were 6-8 ft tall, and had used steamed and bent thin plywood for the curve. They were rather elegant looking.

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Permalink Reply by J.D. on July 1, 2017 at 11:15pm

I have built one amp stand and used flake or particul board and that thing was heavy ,odd shaped "similar to the looks of a chair ,but had a pitch/angel where you would set in a re actual chair. It weighed almost as much as the dang amp & wasn't worth the heavy load ,so needless to say I ended up giving it away. If I were to want to build another ,I would use a welder and a light weight metal ,but I'm running a half stack and monitors now ,so I really don't need anything else, but I agree a thin plywood would probably be your best bet if you are set on using wood and need a amp stand.