DIY Amp Isolation

You can get the same kind of ground separation, if you get one of those mover's rollers. You know, four boards bolted into a square, and four casters underneath it. Pretty cheap and helps you roll your gear off stage. But it raises your cab off the ground and gets rid of the coupling effect. Give it a try. If it doesn't work, at least you have an easier way to roll your rig off the stage!

Otherwise, I'd say get some chunks of seat cushion foam from an old sofa, or maybe egg-crate foam from some packaging material. Glue it to a 1/2" plywood board the size of your bottom cab. The foam will reduce extraneous vibrations from transferring into the stage.

 

Stage resonance is primarily caused by the acoustic output of your speaker, not vibrations of the cabinet, so isolating the cab is usually of little benefit. OTOH, the most problematic resonances tend to be in the midbass from 100-300 Hz, or so, and those can be minimized by lifting the cab two to three feet off the floor. Doing so also improves your ability to hear the mids.

 

If your cab is vibrating that badly then you're losing a lot of output, because energy that vibrates cab walls is energy that doesn't end up in the audience in the form of sound. If that's the case it needs to be opened up and braced properly. If it's not the case then you're trying to fix something that isn't broken. As I said before, what's probably vibrating the floor is the soundwaves produced by your cab. Isolation won't affect that. Lifting the cab will. If you can't then get a parametric EQ that will allow you to dial out the frequency band that's vibrating the floor without killing your overall sound.

 

Not a waste, they do what they're supposed to, but what they're supposed to do is absorb physical vibrations that occur between two objects. Very good between the cab and head, for instance. Also very good between a drum riser and a resonant stage. But between a cab and stage the vibrations that they will absorb account for only a small percentage of a resonant loop.

 

Let me weigh in. Let me start by saying I am neither a technical expert or a DIYer.

I use the GRAMMA Pad with my 2x10 cabinet when I am playing on either a hard wood floor or a hollow stage. It seems to help a little bit in terms of lessening the woof to the others on stage, enough so that I continue to bring it out. I have never removed it in mid gig to see what the difference would have been.

It seems to me to clean up the tone in those rooms that would otherwise be a problem. I however also have a few venues with large hollow stages and it is not as effective. In those cases I leavce the GRAMMA at home and tend to cut my lows and boost the mids to solve my problems.

Bill is the resident expert and gives good advice, if he doesn't think it yields good results I will question it's effectiveness and maybe do that AB test..

Pete

 

Again, it does what it's supposed to do, but a two square foot pad is not going to dampen the vibration of a two hundred square foot stage. OTOH, a parametric EQ can notch out the boom with the twist of a knob. Both tools are effective, the question is which is the more effective tool for the particular job at hand.

 

I have recently run into this problem at a local club, everything was very bassy on stage (two guitar rigs and a bass rig) yet when I went out into the audience area (thank God for wireless) everything lost all bass, so we cranked the low end to compensate for the audience and we just dealt with it. The problem was guitars on stage could not be heard. I guess we could try amp stands but one guitar uses a 4x12 cabs, hard to get that off the floor. It didn't help that the PA did not have subs.

So I guess this is addressed to Bill mostly, you think a parametric on each rig would help us out in this situation? How about a graphic eq? I have a parametric I could put in my loop, but I'm not sure about the other two in my band.

Peter - we may be playing in some of the same clubs, I'm on LI also.

 

I am playing the (2) Nutty Irishman in Bayshore and Farmingdale and I don't play Mulcahey's but they have a similar set up. Both of these clubs have very sufficient subs so the FOH sound does not have the same issues we have on stage.

Sounds like the best solution is to use subs in the FOH system, if the PA is provided and not sufficient I can't think of a good solution other then bringing your own PA which we do in clubs that don't have a good system.

Sounds like a difficult situation your in. Muddying up the stage with low end may or may not put out the FOH sound your looking for but it will surely make your stage levels worse.

Good luck!

 

You can try it, but it sounds like the problem is mainly room related and the only cure is to have PA support. Graphic EQs don't work nearly as well as notch filters as parametrcis as their filter bandwidths are too wide to remove the bad stuff without killling the good stuff too.
As to the 4x12, they made sense in 1968, when 25 watt drivers were the norm and PA support didn't exist. They haven't made sense since about 1980.

 

Lucky us, house sound has no subs. Place is JD's in Famingdale. Have a great time while playing there, it's just the stage sound is terrible.

Bill - I understand about the 4x12's but it's is used as 2 2x12's one side for guitar the other for a guitar synth with a separate amp(not used at the same time of course)

Either way the other guitar player uses a 2x12 avatar and getting the issue also, of course it would be much easier to get his off the ground. Thanks for the answers.

 

I just got this to do exactly that...

http://www.quiklok.com/catalog/?p=productsMore&iProduct=30&sName=WS-540

 

Getting them off the ground is key, as those resonant boom frequencies are so easily contolled when you do so. If you can get the 4x12 into the room in the first place it can't be too heavy to lift onto a stand. The one in James link looks ideal.

 

That fold-a-rack looks ideal on several fronts.
I use a Quik-Lok dual-X for my Hammond keyboard, and it is rock solid.

Q: does it fold up tight?

 

yeah, a big 'T' that's just a couple inches thick

 

Don't know where you might get them in the US, but I'm certain you must have them, ....I've used an ABS/Aluminium foldiing work surface that you get from DIY/Woodwork places.

Mine's similar to this except it does not have the central pole.
http://benchmark.20m.com/reviews/Husky_X-horse/Husky_X-HorseReview.html

Usually cheaper than MI branded support frames.

 

Lowes, Home Depot, etc.