Whenever I tap anywhere on the amp it comes thru the speakers

robd · #1 03-10-2013, 09:19 PM

Traynor Yba-200-2

I moved a pedal on top of my amp last nite, and I heard it thru the speakers. Thought, gee, that's weird. So I tapped the top with my finger and heard it through the speakers. Whenever I tap anywhere on the amp it comes thru the speakers. The taps are very light.

So I figured a microphonic preamp tube.

Changed all the preamp tubes - still there.

Had a friend who builds and fixes amps give it a quick listen. He tapped all over and heard the noise but said he never heard anything like it before. He can't get around to looking at it in earnest for a few days but I would like to if anyone hear has any ideas?

Thanks

two fingers · #2 03-10-2013, 09:23 PM

Someone secretly planted a mic inside the amp? Seriously, that's odd though. I can't wait to read what the problem is/was.

Sid Fang · #3 03-10-2013, 09:23 PM

A better description of the noise would be helpful. Sometimes it's a microphonic tube, sometimes it's a dirty or damaged socket, sometimes it's a dirty or damaged jack...

Downunderwonder · #4 03-10-2013, 09:27 PM

Microphonic power tube?

beans-on-toast · #5 03-10-2013, 09:30 PM

Yes it could be a microphonic power tube. Or it could be that one of your replacement tubes is also microphonic. At least these are the easiest things to check out.

christw · #6 03-10-2013, 09:36 PM

If you think you have a microphonic tube use a single known good tube and go through and swap them one by one. Interesting issue though...

Sid Fang · #7 03-10-2013, 09:46 PM

That's a 4-tube power stage, so in principle one could rotate through the power tubes running with only one on either phase to isolate a microphonic one. But have you cleaned all your sockets?

phtee · #8 03-10-2013, 09:46 PM

I had a ampeg amp that use to do that, it turn out to be a cold solder joint.
A faulty joint in electric wiring which results from the application of insufficient heat at the joint; the solder merely covers the joint and is not physically united with it.

darius8 · #9 03-10-2013, 10:09 PM

Does it do that with the bass guitar unplugged?

will33 · #10 03-10-2013, 10:23 PM

With it fired up, go through and tap on each tube with the eraser end of a pencil. All may make a very slight noise, any that are louder than the rest are suspect.

remainthesame · #11 03-10-2013, 10:25 PM

did you try NOT tapping it?

stepswork4me · #12 03-10-2013, 10:29 PM

Quote:

Originally Posted by remainthesame

did you try NOT tapping it?

That's about as funny as the clap.

dincz · #13 03-11-2013, 12:23 AM

Microphonic tube, bad/dirty jack or connector, bad solder joint. If you're careful and/or experienced with poking around in amps, you could try gently tapping components with something INSULATED (so NOT a pencil!) to identify the sensitive area or component.

**mjac28** · #14 03-11-2013, 12:37 AM

Quote:

Originally Posted by dincz

Microphonic tube, bad/dirty jack or connector, bad solder joint. If you're careful and/or experienced with poking around in amps, you could try gently tapping components with something INSULATED (so NOT a pencil!) to identify the sensitive area or component.

+10000 don't kill yourself tube amps can be very dangerous even unplugged take it to a tech let them get your amp in top shape.

darius8 · #15 03-11-2013, 01:02 AM

Quote:

Originally Posted by dincz

Microphonic tube, bad/dirty jack or connector, bad solder joint. If you're careful and/or experienced with poking around in amps, you could try gently tapping components with something INSULATED (so NOT a pencil!) to identify the sensitive area or component.

Pencils made from wood will work. Wood is a terrible material for conducting electricity.
So don't use metal pencils.

greencow · #16 03-11-2013, 01:28 AM

When working with tube amps, you must discharge the power suply caps before poking around in there. If you don't know how to do that, then take it to a tech.
A wooden pencil may have a conducting core and is not something I can recommend using for said activity.

dincz · #17 03-11-2013, 03:03 AM

Quote:

Originally Posted by darius8

Pencils made from wood will work. Wood is a terrible material for conducting electricity.
So don't use metal pencils.

If you can find a pencil with the graphite core also made of wood

JimmyM · #18 03-11-2013, 04:03 AM

I always used the butt end of a wooden spoon. Chopsticks work well, too. I'd say almost certain it's a microphonic tube. Solder joint might be possible but the tube is most likely IMHO.

Feral Feline · #19 03-11-2013, 05:18 AM

Use a CHOPSTICK!

Wood or bamboo; not plastic, nor metal.

Maybe even wear a rubber glove to hold the chopstick...

Hey, stop that! Just 'cause I'm paranoid doesn't mean you have to laugh at me.

Downunderwonder · #20 03-11-2013, 05:37 AM

A chopstick recently dipped in chop suey could conduct 500V quite well....