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Discussion in 'Amp Central Station' started by King Fan, Dec 10, 2017.
OK, move to a new room, pronto!
Try standing on one leg, too, while you're at it.
So while I decide to go sleuthing again -- this will be like my fifth try -- maybe another way to narrow the choice between cab and chassis is to eliminate cab, if I can.
Does anyone have tips on how to isolate and identify cabinet buzz if it is cabinet buzz? I already tried leaning and pushing on all cab surfaces inside and out, and removing the back panels, and tightening (and holding down) all fasteners and hardware...
I have an email from Mark Baier years ago; about buzz in a Victoria 35310 (bandmaster)
He suggested isolating the chassis with toothpicks
(inserting toothpicks between chassis & cab)
I would try it (my victoria buzz was actually power tube related)
Have someone else play the guitar at the offending frequencies. Probe around side the cabinet pressing down on everything. Found many problems through the years this way. Do you have a spare speaker cab to try. Voice coil problems are very common.
Thanks. That's a pretty solid source! I've been trying to think of ways to isolate the chassis from the cab. I'll try it.
Thanks, T. Good ideas. I'm starting to question everything, so I'm gonna revisit my initial speaker / cab / chassis recombinations....
Did anyone mention using a looper yet, to generate your tones? Saves you from buying the helper a case of beer...
I've read through this and don't think I have seen this possibility mentioned yet...Is the speaker basket touching the output transformer? They can get really close with either certain speakers or larger transformer upgrades. I've had to index speakers before, or make sure the the chassis is pulled slightly back when tightening the screws to keep from touching the basket in a replacement speaker.
Thanks, milocj. I’ll check, but I don’t think so. I turned the amp up more last night and the buzz did sound more metallic. Hope to get some time today for more testing.
Tightening the chassis mounts could warp the cab, allowing a cab buzz to happen. I would automate the signal input, then see what I heard when tightening the chassis mount screws. I might try tightening them in different orders, amount of tightness, etc. The screws could also be warping the chassis. If there was any easy way to put some rubber strips or grommets between the chassis and cab I might try that. (If that fixed it I would locktite the screws and call it good.)
I liked the suggestion to put the thing upside down, try it every which way, shake it...
Overall, everything you are trying makes perfect sense. Aggravating, ain't it?
Thanks. Another great idea. I kinda wondered about that interaction, since the buzz seems to happen with the chassis tightened in place.
I really appreciate all these new ideas, because as you can guess I've already tightened and tapped and tugged all sorts of the usual suspects.
don't forget to tighten the baffle (if floating) - also chassis shouldn't touch the baffle
also check the speaker cable end (& input jack) tighten it too - & also if the cable is rubbing onto something
you even want to check the casters in the bottom & tighten them
tighten the tube retainers (the clamps) - have them tight on the tube bottom
the trannies - check them/tighten the screws
Two steps forward and only one back! I tried the steps here I hadn’t tried... and behold, isolating the chassis with toothpicks seemed to help. I tried doing that with 3mm window foam strips instead; not so much.
OTOH I can't feel or hear exactly where the resonance lives in or around the chassis. Still, all this helps me feel more confident the noise involves the chassis. Gotta figure out how to diagnose the inside — as I say it doesn’t happen when I uncounted the chassis, even if I rest it on the cab. I’ve got a few more ideas to try to see if some wire or part or even the board itself resonates.
In the meantime, the buzz is definitely a lot less with my high-tech toothpicks between the chassis and cab. I’d say almost gone. But I’m going to recheck. Like all really devilish gremlins, this one is variable. ;-/
Really glad you are closing in on this, @King Fan . I've been watching with interest, hoping to learn from your pain...
One of my my amps is a real shaker! Can't set anything on it
at gig volume...
I put foam weather stripping around the chassis where it contacts
the cabinet, that really killed a lot of the rattle and buzz.
Good idea -- I may have to try stiffer, wider padding strips, as the 3mm are only about 6-7mm wide, and they really compress down easily. The big ol' magnet in that DT10 does pack some punch -- my vintage-y alnico speakers are all like 'wow, check the new guy.'
I'm picturing a chassis suspended on springs, like a reverb tank...
I've been trying to find an old air-hockey table to float it on...
Or the whole thing suspended from the ceiling, like Dick Dale's 6G15!
Is that like bungee jumping for amps~
Magnets will hold it in mid-air.
For 'dividing': Place pieces of (slightly surmounting) foam or sponge everywhere in the chassis where no delicate components will be bent. Then mount the chassis and listen.