Tube amp has static noise (clip inside)

[Lublin]

So I picked up a Mesa Boogie Bass 400+. It's a 12 6L6 and 4 12AX7 beast. It wasn't working but I got it really cheap so I took a gamble.

Brought it home and opened it up. Noticed one 6L6 was milky and had cracked glass. Went to pull it and it fell apart. Bingo - there's the issue. Replaced the 6L6 an its neighbor with a matching pair as well as the 8 amp slo blo fuse. Fired it up and it works. Lucky.

The only now is that there's a crackling sound when I play. I can actually stop playing and tap on ANYTHING within the chassis and the crackling happens. Below is a recorded sound of what I'm hearing.

Any guesses? Any help is super appreciated.

http://soundcloud.com/lublin-1/mesa-40/s-zeHNa

[xtian]

Loose connection. Dirty tube pins, dirty pots, dirty effects loop jacks, etc. Give it a good cleaning and inspection.

TWELVE 6L6?!? Wow. Please post a photo of that transformer set. Amazing.

Never mind, plenty of good photos on Google:

http://www.gospel.bo.it/albums/userpics ... CT1013.JPG

What a beautiful layout for the power tubes!

[xtian]

Loose connection. Dirty tube pins, dirty pots, dirty effects loop jacks, etc. Give it a good cleaning and inspection.

TWELVE 6L6?!? Wow. Please post a photo of that transformer set. Amazing.

[Lublin]

Thanks. I'll try to investigate further.

Photos. Lots 'o glass!

[IMG::]http://i346.photobucket.com/albums/p419/RichieDubs40/Mesa%20Boogie%20Bass%20400/5BA996A9-A7C8-4DAF-B514-21C1A36455C2-2218-00000106A9FFE17A_zps3d2adef6.jpg[/img]
[IMG::]http://i346.photobucket.com/albums/p419/RichieDubs40/Mesa%20Boogie%20Bass%20400/8E44BE08-FD22-4FB7-B8E1-0D5DE269EEF4-1955-000000F4E02BC555_zps7688a5db.jpg[/img]
[IMG::]http://i346.photobucket.com/albums/p419/RichieDubs40/Mesa%20Boogie%20Bass%20400/84D825F5-8498-46E2-9FEE-A8337922A022-10684-00000461F2D88924_zps9b86e09d.jpg[/img]
[IMG::]http://i346.photobucket.com/albums/p419/RichieDubs40/Mesa%20Boogie%20Bass%20400/79053784-FAFF-4E6B-8567-BA8B5EF18D38-10684-00000461F72B8748_zps851b0b8c.jpg[/img]

[Blackburn]

Do the lights in your house dim when you flip the switch??

That's disgusting.... For guitar anyway. For bass it's probably just right. It's gonna suck having to buy three matched quads when the time comes to replace all the tubes.

[Lublin]

HAHA!

Going to re-tension all of the tube sockets and replace all of the preamp tubes. If the noise persists then I have to dig deeper.

I gotta tell ya - for bass, this amp is out of this world. The earth shaking tones this thing puts out are extraordinary.

[Phil_S]

I'm gonna cook dinner on it. Move over.
That's impressive, a dozen big bottle tubes. I had thought about an octet of 6AQ5's just because I have many of them, but this?

[Lublin]

Replaced all preamp tubes
Cleaned tube sockets
Retentioned tube socket springs (took forever)

Still having the issue. I can tap on anything on the amp and get that static noise.

I'm thinking it may be a loose connection somewhere. Finding it is going to be a nightmare.

[eddie25]

Have you jumpered the effects loop yet?

[xtian]

Finding it is going to be a nightmare.

That what the Chinese invented the chop stick for.

+1 on the FX loop.

[Lublin]

OK. I think I isolated one power tube socket as the source. When I push down firmly on the top of that one power tube the static scratchiness stops. As soon a I let go it starts up when I tap on anything. I checked underneath the socket and looked at all the solder joints and they look solid. Weird.

[Lublin]

Fixed! Got fed up and jus replace the tube from the suspect socket and its mached neighbor. Scratchiness and static = gone and the amp is perfect. One of the pins on the tube must've been corroded or something. Wish I tried that a while ago. D'oh!!!

[Structo]

Whoa, what a beast!

Must be a small fortune to retube that beast.

Do you have to run it on a 20A breaker?

[Jackie Treehorn]

Nice amp. I would have guessed a leaky coupling cap based on that noise clip and the burned up tube.

[Structo]

That is a lot of 220uF filter caps.

Maintaining that amp sounds like a money pit.

But I'd bet it could drive a really loud subwoofer!