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Cracklin' valves ???

Posted: Tue Sep 09, 2014 4:22 pm
by Ivor
I replaced the four EL34 tubes on my amp recently as they've been doing sterling service since 2008! In fairness I never noticed a drop in sound quality but I had 2 matched pairs of new JJ tubes set aside for the eventual replacement and did the swap over. No biggie, just like popping in a new bulb. I then adjusted the bias. But... I noticed after I turned on the amp from cold that I got a crackling noise in the right channel. It went after less than a minute but still... so I swapped over the pairs and, predictably, the crackling went to the left channel (this exercise was really to eliminate any problem with the amp). The crackle through the left side is less pronounced, more of a sharp hiss really, and seems to fade away quicker, maybe 30 -40 seconds.
Does this indicate a significant problem with the tubes? Could it damage the amp/speakers? My instinct tells me it's no big deal really just and annoyance. I bought the valves about 18 months ago in XMusic and although they've sat unused in their plastic protective tube and in a wooden "odds & sods" box I can't reasonably expect the shop to accept I haven't been using them all along so returning them isn't an option.

I'm not sure if they're RF or AF. Or if that matters much. They do sound bloody good though!

Re: Cracklin' valves ???

Posted: Tue Sep 09, 2014 8:05 pm
by Fran
I hear lots of complaints about JJ and other new manufacture octal valves. Could be a contact - try giving the valve pins a once over with a bit of sandpaper.

Fran

Re: Cracklin' valves ???

Posted: Tue Sep 09, 2014 8:08 pm
by Ivor
Fran wrote:I hear lots of complaints about JJ and other new manufacture octal valves. Could be a contact - try giving the valve pins a once over with a bit of sandpaper.

Fran
Will do... are JJ (Tesla) not around for the proverbial donkeys years?

I'm tempted to go to Jim Mc Shane's site and get a matched 4 of the Genalex Gold Lion KT-77s. They're not mad money.

Re: Cracklin' valves ???

Posted: Tue Sep 09, 2014 8:56 pm
by tony
Will dig out the link where I got my genelex KT88's from as a comparison. They were 'cryoed' whatever that entailed but the price was quiet good delivered.

Re: Cracklin' valves ???

Posted: Tue Sep 09, 2014 9:07 pm
by Diapason
JJ aren't "real" Teslas, I think they just bought the name or something. They have a somewhat mixed reputation...

Re: Cracklin' valves ???

Posted: Tue Sep 09, 2014 9:17 pm
by Ivor
Diapason wrote:JJ aren't "real" Teslas, I think they just bought the name or something. They have a somewhat mixed reputation...
fair enough, I've used the smaller ones before with no issues...

Re: Cracklin' valves ???

Posted: Tue Sep 09, 2014 10:32 pm
by Fran
They are rebranded Sovteks.

I have a quad of genelex reissue KT66 - lovely valve! just sayin....

Re: Cracklin' valves ???

Posted: Tue Sep 09, 2014 10:40 pm
by Ivor
Fran wrote:They are rebranded Sovteks.

I have a quad of genelex reissue KT66 - lovely valve! just sayin....
I'm tempted.. but the JJs sound nice for now. Is it long until Christmas?

Re: Cracklin' valves ???

Posted: Tue Sep 09, 2014 10:57 pm
by Fran
Sure, they're sitting here, if you want to try them. Its not worth selling them as you can pick them up new for small money I think.

Re: Cracklin' valves ???

Posted: Tue Sep 09, 2014 11:11 pm
by Ivor
Fran wrote:Sure, they're sitting here, if you want to try them. Its not worth selling them as you can pick them up new for small money I think.
sound.
We'll work something out.