# What is the amp stand thing ?



## shoretyus (Jan 6, 2007)

around 14:39..... some kind of amp stand thing???


[video=youtube;negwO99O_2Y]https://www.youtube.com/watch?v=negwO99O_2Y&amp;list=RDMMYdc1DkrtxP8&amp;index=14[/video]


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## Steadfastly (Nov 14, 2008)

14:39 on a 4:12 clip?


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## Hamstrung (Sep 21, 2007)

At 3:39 I see what I think you're referring too. Looks like a tilt stand that allows for sound to pipe out the bottom instead of coupling to the floor.


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## dcole (Oct 8, 2008)

Would that pipe sound out the bottom or is it a shelf to store things like pedals as he has? Do you think the open back is coupled to the box?


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## guitarman2 (Aug 25, 2006)

I walked across that stage a couple months ago and saw those stands. I wished I had taken a closer look.


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## GTmaker (Apr 24, 2006)

I'm guessing now but I do remember seeing those stands before.
They offer dual function.
First is to tilt the amp up...very obvious.
Second, I do believe that they capture the open back sound and direct it to the front thru the baffle.

looks like a very functional system but I bet it costs more then the amp...
G.


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## Lincoln (Jun 2, 2008)

a fully stocked pedal board at the Grand Ole Opry? What's happening to country music? :smile-new:


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## soldierscry (Jan 20, 2008)

I believe it is the old version of this http://www.soundenhancer.com/the_enhancer.htm

Here is a closer look at the model in the video.


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## mhammer (Nov 30, 2007)

In fact, that is what they doi. These things convert a standard open-backed combo amp (or cab) into a sorted of ported reflex cab.

As with any ported reflex cab, it is not just a matter of redirecting the backward air movement of the speakers so that it comes out front. What comes out the front of the speaker, and what comes out of the port at the bottom need to be in phase so that they sum, rather than cancel. Otherwise, one is not adding volume, but losing it instead.

However, the longer wavelength ot the lows and lower mids is such that the redirected air motion is not likely more than a few degrees out of phase with what comes from the front of the cones, yielding very little audible cancellation. The concern is probably more for mids with shorter wavelengths, and a greater likelihood of coming out the front port anti-phase to what come from the front side of the cone. But that's generally where the overall design and tuning of the added port has to be thought through.


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## dcole (Oct 8, 2008)

If I remember correctly from Hi Fi theory, this coupling of the amp to the box should have the benefit of increasing the bass region of the guitar spectrum. I wonder if the difference is even audible on stage.


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## mhammer (Nov 30, 2007)

It would depend where on stage. Keep in mind that, with the much longer wavelength, bass isn't really _optimally_ heard until a ways out from the speaker. (That is, of course, why the inconsiderate types with the 18" subwoofers and 300W amps in their Honda Civics generate so much annoying bass - they can't hear it because they're too close). So, if you're on the front stage by the window at Tootsie's in Nashville, and your amp cannot physically be more than maybe 3ft behind you, at most, then you won't hear any additional bass. If you are playing the stage at the Opry, like the fellow in the video, then you will be able to stand 10-20ft in front of your cab and you will notice the difference.


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## BMW-KTM (Apr 7, 2015)

My immediate concern would be heat dissipation. Tubes run hot when you're cranking it. This device appears to be for people who need more volume so one assumes the amp will be pushed. There's a reason the rear of tube amp cabinets have slots allowing air to run across the tubes and out the back of the cabinet. A stand like this looks to me like it would block that off. I would need to take a VERY close look at one and do a mock up before trying my amps on it.


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## blueshores_guy (Apr 8, 2007)

Armed with some time and leftover plywood a couple of years ago, I set out to kludge together my own homebrew SoundEnhancer.
Minimal science went into the design--it was sized for my Vibrolux and I guessed at the front port size.

The goal was to, um, enhance the bass response for recording purposes. Nothing more. 

To my amazement, the thing actually worked. An unexpected side effect was a considerable increase in volume from the amp, possibly indicating that the phase length of the sound coming off the backs of the speakers was accidentally augmenting the waves from the speakers' fronts. But low frequency response was definitely improved.
This one has no issues with blocking cooling air to the tubes; the original cab's rear vent area is unchanged.

My total investment in this contraption is about $5...I had to buy a box of wood screws. It was meant to be a proof-of-concept experiment. The experiment worked, and I never got around to making a prettier version.


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## GTmaker (Apr 24, 2006)

Just a short note to say congrats on that build....I love the whole concept and If I get some spare wood soon, I'll build one myself..

Keep on rockin

G.




blueshores_guy said:


> Armed with some time and leftover plywood a couple of years ago, I set out to kludge together my own homebrew SoundEnhancer.
> Minimal science went into the design--it was sized for my Vibrolux and I guessed at the front port size.
> The goal was to, um, enhance the bass response for recording purposes. Nothing more.
> To my amazement, the thing actually worked. An unexpected side effect was a considerable increase in volume from the amp, possibly indicating that the phase length of the sound coming off the backs of the speakers was accidentally augmenting the waves from the speakers' fronts. But low frequency response was definitely improved.
> ...


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## BMW-KTM (Apr 7, 2015)

I'd be interested in the dimensions used in that box, blueshores. Is that half inch ply? And what does it weigh?

I may try my hand at one just for the sake of curiosity.


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## mhammer (Nov 30, 2007)

BMW-KTM said:


> My immediate concern would be heat dissipation. Tubes run hot when you're cranking it. This device appears to be for people who need more volume so one assumes the amp will be pushed. There's a reason the rear of tube amp cabinets have slots allowing air to run across the tubes and out the back of the cabinet. A stand like this looks to me like it would block that off. I would need to take a VERY close look at one and do a mock up before trying my amps on it.


You're certainly right to be concerned about heat dissipation. However I think the intent is not to make a 22W amp behave like a 100W, but to make an open back behave like a closed cab in terms of frequency response, with a little more thud to the solar plexus. If anything, a person might run the amp at a lower volume. Is there enough air circulation "in there" to not overheat the tubes? Hard to say, though certainly some amps are better set up for heat dissipation than others.


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## BMW-KTM (Apr 7, 2015)

I think if I built one to try I would check heat buildup at five minute intervals before taking it to a gig.


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## sambonee (Dec 20, 2007)

Great build of that dyi man. First class. 

Natural air convection would seep through the mini cracks around the back seal. Unless it were totally sealed there might be an issue. I bet the sound difference is noticeable when you take the amp off the spot. 

I'm in collingwood all the time. We should jam.


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## shoretyus (Jan 6, 2007)

Very cool blueshore guy ....I see that the back of your enhancer is lower than the amp case.. and heat rises.


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## blueshores_guy (Apr 8, 2007)

BMW-KTM said:


> I'd be interested in the dimensions used in that box, blueshores. Is that half inch ply? And what does it weigh?
> 
> I may try my hand at one just for the sake of curiosity.



Yes, that's half inch plywood. If I were to build another one, it would probably be 3/4". Half inch is a bit light, and you need to reinforce every corner. I glued and screwed 1x1 pine around all the inside edges, to act as bracing and to give some support. Whole thing likely doesn't weigh 10 pounds, but it's not flimsy. The horizontal piece the amp sits on was a leftover closet shelf, which already had a nice rounded edge. 
And, as you can see, it's not exactly furniture quality. As to size, I used measurements from the Vibrolux to determine overall width, height, and size of the sound opening. Wasn't concerned about making the tilt-back angle too severe, as this thing will never be seen outside of my music room. In fact, it probably didn't need any tilt-back angle at all, and would have been easier to build if everything was right angles. 

Here's a shot of the Vibrolux's back....it has a conveniently rectangular opening behind the speakers, and that's what I attempted to close off with the stand to reroute the sound through what is essentially a folded horn.
The black stuff around the amp stand's opening is nothing more than self-adhesive weatherstripping. A low-budget project, I assure you. 



In an attempt to tame some of the unwanted volume increase, I lined some of the stand's inside surfaces with sound absorbing material (normally installed under drywall in sound-deadening room construction), and this helped considerably. Again, leftover stuff (from my music room build). 



I have run the amp on this stand for several hours at a time, and never had any overheating problem. If the entire back of the amp was closed off by the stand, I can see that happening, but the top of my stand falls below the amp's tube ventilation area.


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## BMW-KTM (Apr 7, 2015)

Thanks for those details.

What can you tell us about that web in the center? It doesn't appear to be visible from the front of the bottom opening. Does it round the corner at all or connect the back to the bottom? I assume it is some kind of stiffening member. How much does the box change the amp into a unidirectional focus? Is the amp "beamie" when played using the box?


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## blueshores_guy (Apr 8, 2007)

The centre brace you see does connect the back to the bottom, and is there only for structural strength.
Don't see how the stand could change the amp to unidirectional...nothing has changed with regard to the speakers' frontal dispersion, except that they are now aimed a few degrees up from horizontal. The net effect of the stand is to add some bottom end heft to the sound, which is all I was after.

I don't have a bass amp, so when I'm recording a bass track, I use the VR on this stand, and position the mic more down towards the front port, rather than aimed directly at the speakers. Although you don't get the floor-shaking 40hz thump from the open low E string like you would with a bass amp, it does the job well enough at low volume to give me an acceptable recording.


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## BMW-KTM (Apr 7, 2015)

What I meant by unidirectional is that open backed combo amps typically have a lot of sound spill out the back going in all directions meaning you don't have to be directly in front to hear it clearly. With the box in place I have to assume that spill will now be focussed directly forward. I'm just wondering how focussed it becomes, ie: if it becomes beamie. I suppose one could always install one of Weber's beam blockers if it became problematic.

- - - Updated - - -

I am primarily interested in this box for the added bass response rather than the volume increase.


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## urko99 (Mar 30, 2009)

I own two of the original Sound Enhancers. One fits a Fender Champ, or Super Champ and one that fits a Fender Deluxe. I use it the larger of the two for my Carr Sportsman. It really increases the bottom end response, and give A considerable volume boost. They are light to carry, and well made out of 1/2" Birch ply. The tilt angle makes your amp into a stage monitor so you can control stage volume better. Sound guys love them. There is a newer version to make it more economical to build, but in my opinion not as good. Light but bulky for shipping, once you get into the larger sizes. There were 5 sizes in all for holding a up to a Twin Reverb, or a Super. Great little tool to make your smaller tube amps sound and feel larger on larger stages and outdoor gigs. Any wood worker can replicate them pretty easily. Pretty happy with mine.


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