Rivera Chubster 40 - crackling noise/preamp tube question

cbell2112

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1,767
Guys, help me out here because I am kind of a noob when it comes to tubes and such. I have the amp listed in the thread title and it developed a crackling sound after I had new power tubes installed. The amp tech said it was the volume pot but I did the amp troubleshooting posted by Rivera on youtube and it pointed to the preamp tube in position #4.

Bought a JJ ECC83S from the local store as they didn't have any 12AX7's. As far as I can tell they are the same thing. First thing I notice is that ECC83s doesn't really light up like the 12AX7's when I power the amp on so I decide to pull a tube from my Maz 18 to see if it lights. I end up pulling a tube labeled TAD 7025/E83cc High Grade. After looking it up, it appears that this is a better version of ECC83s so I try it. And voila the crackling goes away. I want to put that tube back into the Dr Z so I put the new JJ in and the crackling reappears. Does it make sense that higher grade tube takes care of all that crackling noise? The original tube that was in there is unlabeled so not sure what to make of that.
 

xtian

Member
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2,726
ECC83 = 12AX7. ECC83s is just a "short plate" version of 12AX7. It sounds like, by swapping tubes back and forth, you have identified a bad tube. If true, it's not a matter of "higher grade" or not, it's just a faulty tube. Happens.

FYI, whether you can easily see the heaters lighting up in a tube has NOTHING to do with how well they perform.

Good job with your troubleshooting.
 

cbell2112

Member
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1,767
Gotcha but there are 3 tubes in play here.

original tube - unmarked - crackles
JJECC83 S - brand new crackles
E83cc High Grade - marked as TAD - no crackling and this tube is at least 7 years old from my Dr Z

So, I guess they are all just interchangeable? I am glad that it didn't light, otherwise I would be bringing it back in for repair.
 

xtian

Member
Messages
2,726
Yes, all interchangeable.

I'm going to backpedal a little--"crackling" is rarely from the tube. It's more often from plate resistors, dirty or loose pins in tube sockets, cold solder joints, etc. When you moved the "bad" tubes to your other amp, did the bad noises follow the tube?
 

cbell2112

Member
Messages
1,767
The old tube got a little crackle in the Z, the JJ seems to be working fine. I've played the Rivera for an hour and no crackle so not sure what to think other than I am happy it is working properly and I will probably be ordering these TAD E83cc's going forward.

Going to leave both amps on for a while and see if anything develops.
 




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