Crackling on certain notes (solved, preamptube problem)

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Random Hero

Random Hero

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Sound like a power tube issue? It's only done the volume thing once but the crackling is pretty apparent, especially on some notes. I was considering trying 6550s anyway so if it is an issue it gives me an excuse to do so.

What do you reckon?
 
Yes. Not as apparent perhaps but it's still there. For a second I was getting no sound until I realised nothing in the input mutes the amp :lol: :LOL:

But yeah, it crackles still. It's a new cab by the way, so is it possible it's the new speaker at all? Then again, that wouldn't be responsible for volume dips...
 
Last two preamp tubes or powertubes . . .

Swap preamp tubes first, repeat the guitar-into-loop thing.
 
duesentrieb":1g2v2iar said:
Last two preamp tubes or powertubes . . .

Swap preamp tubes first, repeat the guitar-into-loop thing.
Click to expand...

Thanks Olaf. "Last 2", from the back are they on the left or right?
 
V1 is closest to the input jack (orientation).

You need to change V5, V6.
 
duesentrieb":1mv95cv0 said:
V1 is closest to the input jack (orientation).

You need to change V5, V6.
Click to expand...

Thanks

Will get to it now.
 
Update;

I changed V6 and it appears to have cured the issue. I replaced the TAD 12AX7C with a gold pin Tung Sol I had laying around. I'd say it seems a hair brighter but I may be imagining it. Either way, thanks Olaf.
 
My pleasure.

You can use the Tung in V6, but not in the other sockets except V1 and V2.
 
duesentrieb":2fblmyxf said:
My pleasure.

You can use the Tung in V6, but not in the other sockets except V1 and V2.
Click to expand...

Yeh? What's the reason for that?
 
Too complicated to explain. Just don't use Sovtek LPS or Tung Sols in so called cathode follower stages (V3, V4, V5) of amps in general.
 
duesentrieb":10f47e8z said:
Too complicated to explain. Just don't use Sovtek LPS or Tung Sols in so called cathode follower stages (V3, V4, V5) of amps in general.
Click to expand...

Gotcha. Would you recommend a 12AX7C for V6 or just to stick with the Tung Sol?
 
duesentrieb":2lc6513p said:
Too complicated to explain. Just don't use Sovtek LPS or Tung Sols in so called cathode follower stages (V3, V4, V5) of amps in general.
Click to expand...
I know this is an old thread but i'm curious if a JJ gold or mullard would be ok to use in the cathode stages?? Would a 12au7 or 12at7 be a better match for v3,v4,v5?
 
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