Cab vibration vs amp electronics

[NKBassman]

I posted in another thread but throwing it out to general population....
Is there any data ( or long term study) on the effect of vibration from the cab to amp on the electronics longevity?
Seeing most of us stack our heads on top of the cab, I was wondering what (if any) steps are taken in manufacturing to minimize vibration effects on the amp circuitry.
Vibrations should eventually loosen solder joints, connections, and rattle components, so might we all be better off placing our amp heads separated from the cab, whether next to it or on a dampening pad?.... just thinking out loud.

I had a new production cab for a while from a then-popular (and subsequently defunct) company out of Chicago that vibrated so so bad that it once shook my ~40 lbs SVT-3PRO right off the top at modest volume, and I was constantly taking my heads in to have solder joints fixed. I started putting my amps on a layer of foam between the head and cab, which stopped the damage, but eventually I opened the cab up and added a bunch of bracing to the interior which solved the problem (and also made it sound a lot better!). After I was done with my modifications, loose change wouldn't even vibrate if left on top of the amp.

The problems that cab had taught me everything I now know about bass cabinet design, and why it's much more complicated than just plopping some speakers in a pretty looking box. After doing my own research I couldn't believe what these guys were passing off as a "custom bass cabinet", or basically just a plywood shell with pretty stain job and some street cred from bands I liked at the time. Total Form over Function design, which works in some cases for guitar cabs (where the frequency response is less demanding), but not at all for bass cabs.

 

[NKBassman]

that sounds like the plot of a horror movie

 

[Ewo]

I've been using one of @bucephylus 's isolation pads for several years--the model with the Sorbothane center. Works very well; I can't feel much vibration on the top of the amp case, even when the volume is high and the notes are low.

(No affiliation with the merchant; just a happy customer.)

Link Removed

 

[micguy]

...and the heavy components also glued to the board. This type of construction has well documented reliability metrics over decades of use in our industry.

The examples of vibration failures I'm familiar (and cited here) with would almost certainly have been avoided had this gluing been done at the point of manufacture. So, buy one of the amps AgedHorse designed, and you're probably good.

 

[eldorado2001]

Out of sheer OCD, I've always placed a sheet of thick foam between my rack and the cabinet it's on top of.

Ditto, 2" convoluted foam between cab and amp rack case. No hard parts touch each other. Just in case.

 

[Arthur U. Poon]

Ditto, 2" convoluted foam between cab and amp rack case. No hard parts touch each other. Just in case.

I look at the foam as "Cheap Insurance".

 

[NKBassman]

I look at the foam as "Cheap Insurance".

Certainly won't hurt anything having it there. You can test your cab by setting the head up on the floor beside it and put something smooth and lightweight on top of the cab (like a quarter, iphone, fine china, wedding ring, small child, etc... depending on how adventurous you're feeling), then keep increasing your volume until you see it start to dance. If the cab is adequately braced, you shouldn't see any movement even at medium-high volume.

 

[Bugeyed Earl]

During practice a few years ago, I got lazy and sat on top of a TNT-130 combo. I knew it wouldn't stand for having an open beer on top, but I didn't expect it to be such a wild ride Bass amps vibrate like mad, doesn't seem to hurt a thing.

 

[NKBassman]

Bass amps vibrate like mad, doesn't seem to hurt a thing.

Not all of them do, and not necessarily.

 

[bucephylus]

Not all of them do, and not necessarily.

Perhaps not. I haven’t yet used one that didn’t. When I made my measurements, I used a Bergantino 112 and a Genz Benz 410; also a home made 3/4” ply JBL 115. All stout cabinets, not budget cabinets, and not uncommon cabinets. They all had vibration. Based on that rather limited survey, I suspect most bass cabs will demonstrate vibration at gig volumes.

You may indeed use a cabinet that has negligible vibration. That’s great. Meanwhile, a bunch of the others do it. You may also be correct that adding bracing might help. But, in my way of looking at things, sticking a dampener under the amp is a whole lot easier. Since my Bergantino cabs sound and behave just fine otherwise, I don’t see why I would mess with them. Guess it just depends on which battles you choose to fight.

 

[thetragichero]

one of the reasons i got rid of my orange terror bass is that i was constantly having to move it back to the center of the 1x15 hartke can it sat on
that and because any higher than 1 on the volume dial it shook my old house

 

[bucephylus]

Agedhorse did address this already. .

FWIW, Andy provided a perspective relative to Mesa amps; which he shouldn’t really need to do, because Mesa’s quality and reliability are pretty well established.

My comment was more prompting for what he might or might not know about MI amp testing on actual shaker devices, relative to the OP Q. I’ve never heard of it; and honestly if I were an amp manufacturer, I wouldn’t put the necessary effort in that direction either.

 

[NKBassman]

Perhaps not. I haven’t yet used one that didn’t. When I made my measurements, I used a Bergantino 112 and a Genz Benz 410; also a home made 3/4” ply JBL 115. All stout cabinets, not budget cabinets, and not uncommon cabinets. They all had vibration. Based on that rather limited survey, I suspect most bass cabs will demonstrate vibration at gig volumes.

You may indeed use a cabinet that has negligible vibration. That’s great. Meanwhile, a bunch of the others do it. You may also be correct that adding bracing might help. But, in my way of looking at things, sticking a dampener under the amp is a whole lot easier. Since my Bergantino cabs sound and behave just fine otherwise, I don’t see why I would mess with them. Guess it just depends on which battles you choose to fight.

I only meant to imply that there's a difference between a cab "having vibration", and "vibrating like mad" as @Bugeyed Earl suggested. Obviously bass cabs are going to vibrate, especially at higher input powers. There's a whole lot of shaking going on there and no amount of bracing is going to get rid of all of it. But some will be worse than others. And most amps should be able to handle a bit of vibration without issue, but for the risk-averse crowd, using a foam pad is good advice if you really want to isolate your amp. No argument there.

I was just reporting on my personal experience where an extremely poorly designed cab was actually causing damage to my amps (no less than three trips to the tech to repair broken solder joints on two different amp heads), and by retrofitting the cab by following good cabinet design practices, I was able to reduce the vibration to a negligible and acceptable amount.

That being said, I wouldn't bother or recommend adding extra bracing to a commercial cab unless it's absolutely necessary, which in my case, I decided it was, even if just for the sake of experimenting. After watching a 45 lbs amp rack go dancing across the top of a 2x15 at basement volume and fall to the floor I'd had enough... Unacceptable. By the time I was done I'd added a good bit of weight to the cab, and I was so pissed off that I ended up selling it a short time later out of spite (full disclosure of the "improvements" I'd made, of course).

There are good and bad cabs out there. Observe what you're working with, and then take whatever steps you feel are necessary to protect your equipment.

 

[agedhorse]

FWIW, Andy provided a perspective relative to Mesa amps; which he shouldn’t really need to do, because Mesa’s quality and reliability are pretty well established.

My comment was more prompting for what he might or might not know about MI amp testing on actual shaker devices, relative to the OP Q. I’ve never heard of it; and honestly if I were an amp manufacturer, I wouldn’t put the necessary effort in that direction either.

All IcePower modules go through extensive vibration testing on a programmed shaker fixture (don't use tables in general because the device under test needs to to be positioned and secured via provided mounting points for the test to be done under 3 axis methodology). Below is the published data for the modules.

I do have a vibration test fixture in my shop, though it's a 1 axis fixture so I need to rotate the DUT to extrapolate the other 2 dimensions. Since I have the test data on the assembly methods that I already use, I generally use the fixture to explore for rattles and other vibration induced noises.

There's a difference between a cab "having vibration", and "vibrating like mad" as @Bugeyed Earl suggested. Obviously bass cabs are going to vibrate, especially at higher input powers. There's a whole lot of shaking going on there and no amount of bracing is going to get rid of all of it. But some will be worse than others. And most amps should be able to handle a bit of vibration without issue, but for the risk-adverse crowd, using a foam pad is good advice if you really want to isolate your amp. No argument there.

I was just reporting on my personal experience where an extremely poorly designed cab was actually causing damage to my amps (no less than three trips to the tech to repair broken solder joints on two different amp heads), and by retrofitting the cab I was able to fix that issue. I wouldn't really bother adding extra bracing to a commercial cabs unless it's absolutely necessary, which in my case, I decided it was. After watching a 45 lbs amp rack go dancing across the top of a 2x15 at basement volume and fall to the floor I'd had enough... Unacceptable. By the time I was done I'd added a good bit of weight to the cab, and I was so pissed off that I ended up selling it a short time later out of spite (full disclosure of the "improvements" I'd made).

There are good and bad cabs out there. Take whatever steps you feel are necessary to protect your equipment.

There is no way a cabinet could be so poorly designed as to damage any reasonable quality build. There simply isn't enough vibrational energy present unless there are weaknesses of defects in the mechanical design and/or build quality.

 

[NKBassman]

There is no way a cabinet could be so poorly designed as to damage any reasonable quality build. There simply isn't enough vibrational energy present unless there are weaknesses of defects in the mechanical design and/or build quality.

I suppose the broken solder joints could have come from somewhere else, but two separate amps (Ampeg SVT-3PRO and 2PRO) that had been fine for years then suddenly develop multiple broken solder joints after starting to use this cab, seemed highly suspect to me.

The cab was an Emperor 2x15, basically a 3/4" plywood shell of a box with absolutely no internal bracing.

 

[GrapeBass]

I posted in another thread but throwing it out to general population....
Is there any data ( or long term study) on the effect of vibration from the cab to amp on the electronics longevity?
Seeing most of us stack our heads on top of the cab, I was wondering what (if any) steps are taken in manufacturing to minimize vibration effects on the amp circuitry.
Vibrations should eventually loosen solder joints, connections, and rattle components, so might we all be better off placing our amp heads separated from the cab, whether next to it or on a dampening pad?.... just thinking out loud.

You gotta ask yourself, why are there so many products from the 60s, 70s, 80s, 90s, 00s, and 10s still available but also very much used. Our industry is fairly unique in that a lot of equipment gets used for decades, let alone years.

and as
@agedhorse said...

Those of us who design quality amplifiers have put a lot of thought and effort into the mechanical aspects of our respective products, and vibration is generally not an issue over decades of use.

There ya go buckaroo!

 

[agedhorse]

Nope, not going to be the cause.

It takes a lot of effort to design a product with such an inherent weakness, and I haven't heard of this being an issue with the amps you mentioned either.

 

[NKBassman]

Nope, not going to be the cause.

It takes a lot of effort to design a product with such an inherent weakness, and I haven't heard of this being an issue with the amps you mentioned either.

Well then I'll just go ahead and shut up now.

This was the crux of my post anyway:

I only meant to imply that there's a difference between a cab "having vibration", and "vibrating like mad" as @Bugeyed Earl suggested.
(...)
There are good and bad cabs out there. Observe what you're working with, and then take whatever steps you feel are necessary to protect your equipment.

 

[seamonkey]

If anybody wants to test vibration of their cab there are sensitive seismograph apps on IOS and android.

They can log and plot results. Put it on the cab, in front of the cab, on the head, ... and it will measure the shake. I have seen scientific use of this and it can be a solid field test comparable to lab equipment from years back.

Keep in mind that IOS devices like iPhones/iPad and any Adriod device are chocked full of surface mount devices and can handle the shaking.

 

[agedhorse]

If anybody wants to test vibration of their cab there are sensitive seismograph apps on IOS and android.

They can log and plot results. Put it on the cab, in front of the cab, on the head, ... and it will measure the shake. I have seen scientific use of this and it can be a solid field test comparable to lab equipment from years back.

Keep in mind that IOS devices like iPhones/iPad and any Adriod device are chocked full of surface mount devices and can handle the shaking.

Good point, there are so many inexpensive (and good too) testing tools available these days assuming you understand the principles behind the measurements.

My old engineering partner who retired about 5 years ago was a senior engineering technician for one of the big testing labs that did the vibrational analysis on several of the Apollo landing craft. They had a large test chamber with enough mechanical energy available to shred sheet aluminum. They used shaped acoustic energy to simulate the rockets at launch as well as the buffeting by the atmosphere. They also were able to test for the reentry forces including the effects of deceleration. I learned a lot about such mechanics and respect the potential for damage very well.