Decoupling cab using foam pad ?

[garagebassman]

I've read some info after searching, and am aware of the auralex pad available.

I ran into a hollow boomy stage condition and know i'll be playing there again. I rolled off some low and all worked out ok for the night.
I am wondering, since this cab 212MBE is considerably smaller footprint and lighter than what the amp riser/isolators are designed for, could I get away with a dense foam rubber type pad that I could cut to fit ? or would I have better luck using one of the milk crates we carry cords in ?

The cab is a bit too light to put wheels on, which I know would help.
btw, I do not have pa support so I am trying not to get into the habit of rolling lows off\
So i'm wondering what other material(s) have been used successfully for a de-coupling type application !

thanks

[azureblue]

Grip liner

Con-Tact Grip Liner - 5 Rolls / 25 Feet - eBay (item 140524956002 end time Mar-23-11 11:56:57 PDT)

Lowe's, Home Depot, etc...

Cut a few pieces to match the size of the 212, and layer them until you are happy, then duck tape them together.


and your cab won't walk, either.

[Passinwind]

Originally Posted by garagebassman

I've read some info after searching, and am aware of the auralex pad available.

I ran into a hollow boomy stage condition and know i'll be playing there again. I rolled off some low and all worked out ok for the night.
I am wondering, since this cab 212MBE is considerably smaller footprint and lighter than what the amp riser/isolators are designed for, could I get away with a dense foam rubber type pad that I could cut to fit ? or would I have better luck using one of the milk crates we carry cords in ?

There's a smaller square Auralex Gramma type pad that works great for me. It's called the SubDude.

[Foz]

These help a good bit

Interlocking EVA Foam tiles - Google Search

put the extras in the garage in front of the tool bench or the practice room - any hard floor area you stand around

[JimmyM]

i'd rather buy a little throw rug at walmart.

[BassmanPaul]

Originally Posted by JimmyM

i'd rather buy a little throw rug at walmart.

You're so domesticated Jimmy.

[GrowlerBox]

If my understanding is correct (and this is far from certain), using a pad will help with reducing direct transmission of vibrations from the cab into the floor, but may still leave you troubled by acoustic coupling of the low frequencies, which may be helped by backing off the low-end, and/or raising your cabinets from the floor by a quarter wavelength (i.e. a good few feet).

Waiting to be corrected/shot down, etc.....

[Passinwind]

Originally Posted by JimmyM

i'd rather buy a little throw rug at walmart.

Post a link Bro. There's a lot riding on this...

[madmatt]

Isn't this what cats are made for?

[stflbn]

The Gramma Pads work IMHO. Helps with both hollow stages as well as boomy concrete type areas.

[bassbrad]

I have a SubDude pad that came with a Producers pack, it works really well with my Polytone MiniBruteIII to prevent the positive and negative effects of coupling for live and recording.

[billfitzmaurice]

Originally Posted by GrowlerBox

If my understanding is correct (and this is far from certain), using a pad will help with reducing direct transmission of vibrations from the cab into the floor

It doesn't. A cab so flimsy that it vibrates that badly would be unplayable. The commonly assumed source of boom isn't mechanical coupling between cab and floor, because there's no such thing. All of the boom is the result of the stage resonating in response to the cab output. That can cause the stage to vibrate, and in turn the stage may vibrate the cab, not the other way around. Pads can help with that.

acoustic coupling of the low frequencies... may be helped by backing off the low-end, and/or raising your cabinets from the floor by a quarter wavelength (i.e. a good few feet)..

About 3 feet, to be exact.

[RickC]

Is the SubDude just a smaller Gramma?

/rick

[Zoa]

Originally Posted by JimmyM

i'd rather buy a little throw rug at walmart.

Not milk crates, Jimmy?

[billfitzmaurice]

Originally Posted by Zoa

Not milk crates, Jimmy?

There's a lot to be said for a rug in front of the cab. Floor reflections in the mids off a hard surface can result in phase sourced cancellations, suppressing the mids and making the boomy frequencies of the midbass seem more prominent. A rug will soak up the floor bounce and make for a much cleaner sound.

[JimmyM]

btw, the rug idea i got from bill

[bassteban]

I prop my cab up slightly w/a roll of ductape- I may be deaf, but I'm convinced/fooled that this reduces the boom just enough.

[JimmyM]

Originally Posted by bassteban

I prop my cab up slightly w/a roll of ductape- I may be deaf, but I'm convinced/fooled that this reduces the boom just enough.

it doesn't reduce boom...what it does is aim speakers more at your ears so you hear mids and highs better. the boom is still there, but you don't hear it nearly as prominently because the mids and highs sound more in proportion rather than blowing past your knees, so it comes across as a reduction in boom.

yet another tidbit i got from bill

[GrowlerBox]

Originally Posted by billfitzmaurice

It doesn't. A cab so flimsy that it vibrates that badly would be unplayable. The commonly assumed source of boom isn't mechanical coupling between cab and floor, because there's no such thing. All of the boom is the result of the stage resonating in response to the cab output. That can cause the stage to vibrate, and in turn the stage may vibrate the cab, not the other way around. Pads can help with that.... About 3 feet, to be exact.

Thanks for the explanation/correction/reinforcement, more or less in that order. Much obliged.

[billfitzmaurice]

Originally Posted by GrowlerBox

Thanks for the explanation/correction/reinforcement, more or less in that order. Much obliged.

To tie things in with Jimmy's rug, what happens when you lift the cab is that there's some loss of acoustic coupling with the floor in the midbass, and at the same time the floor bounce distance is increased, lowering the cancellation frequencies from the mids that you don't want to lose to the midbass that you do want to suppress. Then factor in the higher intelligibility of the mids by lifting the cab closer to ear height and the sum total can really make a big difference.

Or you can do what I do and dial the boom out with a parametric notch filter.