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Need help C-J monoblock LP-140M with Siemens CCa

I am new to the tubes world and this is the first time ever I have tubes power amp in my audio gear.

I have been used 3 different sets of NOS/NIB Siemens CCa tubes in my Conrad Johnson LP-140M amplifier, and all have started to fizzle, crackle and/or pop within a few days.

Just curious if others have had this problem? My dilemma is that I like the sound of these CCa tubes, and don't like any junk tubes (Electro-Harmonix was supply with the Amp from C-J factory) in this amp. I don't believed they sound nearly as good as Western European make tubes.

I have hear about Ediswan CV2492 from UpscaleAudio.com, is it really equivalent or better than (Siemens, Telefunken or Valvo) CCa?

Thank you so much for all your feedback and/or suggestions for alternative tubes.
vinhusc
cmalak
681 posts
 
How long have you had the NOS/NIB Siemens tubes in your CJ LP-140Ms? Did you just install them and they started going bad a few days after you installed them? Did you follow CJ's tube bias directions to make sure you installed the tubes with the right bias setting? I hope you installed them without touching the tubes with your naked hand (should always use a cloth or gloves etc) as the oil on your hands when in contact with the tube glass can make them "pop" and go bad. I would call CJ for proper tube installation and bias settings for your mono blocks. With some of your tubes going bad you may have also blown some resistors in the circuit boards, so if your dealer has a technician who is familiar with CJ gear check your amps out to make sure it is only the tubes that need replacement that would be your best path forward. Good luck.
vinhusc OP
11 posts
 
Cmalak, I have them about 4 months in my LP-140M. and all the tubes is very very good when tested with TV7 tube tester.

CJ tech (Ed Deitemeier) told me: do NOT substitute any 6922s for the factory supplied tubes (that is Electro-Harmonix) ... it's suck since I do NOT like Electro-Harmonix at all.

They do have 4 screwdriver to adjusting 6550 output tube bias, but NOT for the input driver tube (which is 6922). Is there anyway to bias/setting these driver/input tube?

Thanks
cmalak
681 posts
 
Sorry..I misunderstood. It's the input/driver tubes that went bad not your power output tubes. So the answer is there is no bias adjustment for input/driver tubes. The bias setting is for the output tubes. Then replacing the 6922s is relatively simple and is a matter of trying out different variants to see what you like best. Good luck.
rleff
1,065 posts
 
Does this happen for both monoblocks or only one?
is your tv7 a tested and verified 100% operational tester?
vinhusc OP
11 posts
 
Rleff, both of them but after few months now only 1 side!

They not happen all the time. Sometime I power ON about 2-5 minutes you should hear big crackle/pop and after that is good!
Yes, my friend TV7 tube tester is good.
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