Class D amp head decides to go on walkabout whilst playing

[InhumanResource]

OMG...You must be English....I grew up with Blue Tak holding all my posters up....Until I later discovered over time it leaves an oil mark on the wall !!!

American checking in but I used it too and also left oil stains all over my "Dream Team" poster of Michael Jordan at the Olympics!

 

[bassopotamus102]

Looking for a simple and easy fix for my problem.

I’m playing a Mesa TT-800 through a Barefaced Two 10S, and everything sounds great, practice is going well...

And then I notice the amp head is hanging off the cab.

I moved it back into position and resumed playing. A few minutes later, same thing.

What’s happening is that the vibrations, combined with the light weight of the head, are causing the amp to decide to go on walkabout. I’ve never owned a lightweight class D head before, so this is certainly a new experience.

Anybody have similar experiences and have a fix that doesn’t involve permanently attaching something to the tolex of the cab?

i was using a Bugera Veyron Mosfet head on top of two Bugera 410's. apparently, the resonant frequency of those cabs is the "B" note (no, not the brown note...) the lightweight head would dance around anytime i hit that note. used a black bungee cord around the handle, over the top of the head, and around the other handle of the cab. that solved the issue.

i then moved to a Fender Bassman 800 and it did the same thing. still have to use a bungee to stop it.

 

[jnewmark]

This whole issue could be due to insufficient cab bracing, no ?

 

[troy mcclure]

I had a Markbass F1 and a Genz Benz Shuttle , I had a bungie cord from the side handles of my cab over it. I forgot it a few gigs and just used duct tape. looked goofy but it worked. I bought a roll of rubber shelf liner at the dollar store and put it under the heads and that stopped it from moving.

 

[agedhorse]

This whole issue could be due to insufficient cab bracing, no ?

Yes, it can certainly be the root cause. When designing lighter weight cabinets. The bracing needs to be effective, it’s not there for looks.

The matching Subway cabinets should be quite resistant to this issue, though I do recommend a pad of some kind between the amp and cabinet as a backup just in case.

 

[HolmeBass]

Double benefit: you always know where your towel is.

True! I actually bring two and a micro fiber cloth because sometimes I sweat a lot. But one towel will always be clean and dry to wipe down my bass at the end of the gig: the one my amp was sitting on!

 

[jmlee]

Nope, it’s British Raging Green tolex! I do wonder how long carpeting would last against repeated uses of Velcro.

Going to try some of the rubber pad / kitchen drawer liner ideas in the other thread referenced.

Hehe! My two Fearless F112s are painted Raging Green! It's a stock Benjamin Moore colour (SW6474). I thought the colour would be fun since I live in Halifax, Nova Scotia where we often have a raging sea. In the bottom pic you can see I use a piece of that interlocking foam flooring that they sell to put down in kids' playrooms to keep whatever's on top from skidding around. It's cut to shape for the odd cross-section of the tilt-back cabs. They're both okoume: light and strong but they do make things bounce a bit at volume.

 

[Slpbass81]

I haven’t read the entire post but nobody has commented on this my WD-800 had the same issue but it came with 4 felt pads to put under the feet. It hasn’t moved since using them.

 

[Ellery]

It's not pretty but the foam block works for me.
Something I should do for all rigs, I had an amp fail when a screw vibrated off the chassis and fell onto the circuit board.

 

[punchdrunk]

Easy fix

 

[MrLenny1]

A thin rubber pad should help that issue.

 

[Downunderwonder]

The matching Subway cabinets should be quite resistant to this issue, though I do recommend a pad of some kind between the amp and cabinet as a backup just in case

I expect most cabs are quite resistant to it but the same can't be said for the floors where we park them.

 

[ToneMonkey]

Perhaps try buying some of that lightweight rubber sheeting that people line their rollaway toolboxes with. I bet just a bit of friction underneath the head will solve the problem. A whole roll of the stuff costs like $10. You'll have lots left over.

 

[droo46]

And you can put your drink right there...

I do not recommend putting your drink on your amp. lol

 

[RumbleBot]

I do not recommend putting your drink on your amp. lol

Not even whiskey in a sippy cup?. No fun.

 

[g-dude]

Yeah, the first time you see your Class D amp walking around on your amp (or hanging off of it), you experience a moment or two of sheer panic!

I use soft foam (both on top of the cab and underneath the cab). And when I know things are gonna really be shakin' I'll add a bungee strap or two.

The last thing I wanna see is the amp walking off the cab during "Born to be Wild"!

'Course the crowd may think that's all part of the show!

Ironically, I think that is exactly the song we had just finished playing when I noticed it one of the times.

 

[g-dude]

Likewise. I usually run a stacked pair of the 1-15 cabs with the WD800 on top--and gotten pretty loud sometimes. The amp's not skated around even then.

Maybe I missed it in the discussion above. Is the cabinet tilted back at all? I could understand the amp moving in that condition!

Nope. Totally flat.

It’s literally a vibration issue, and I’m not even pushing it nearly as loud as it can go.

 

[agedhorse]

Nope. Totally flat.

It’s literally a vibration issue, and I’m not even pushing it nearly as loud as it can go.

I can tell you that a lot of thought and effort went into the bracing scheme of the Subway cabinets. Bracing of panels is not just important to audio performance, but also for controlling sympathetic resonance of the wood panels that make up the cabinets.

Where there is a vibration issue with a cabinet, there are several possible causes. One possible cause is inadequate bracing or inadequately designed bracing. FEA (finite element analysis) can be used to evaluate the effectiveness of a design if necessary.

Another possible cause is if the design utilizes a highly under damped response as part of the philosophy, additional attention must be paid to the effectiveness of the bracing as well as the design of the grill which can also vibrate in problematic manner.

a third possibility is that some panel materials can be especially resonant, so additional techniques may be necessary to control vibration.

 

[Wicked G]

I haven’t read the entire post but nobody has commented on this my WD-800 had the same issue but it came with 4 felt pads to put under the feet. It hasn’t moved since using them.

I did way back on post 5 and 7. While some on here have given good ideas, the OP already has the answer with those felt pads.

 

[J de Villiers]

Please share why? and from which amp to which amp now?

A couple of light ones 2x TC. Now Trace Ah500x and Albion Abh800. Not a gigging person, have access to a big space for jamming / practice. Writing @ home a little practice cab and a hotone.