2. amps-preamps
  3. 129968-7795

Preamp issue?

My Cary Slp3 started to​ act up.
Few days ago I noticed something was off, but didn't have the time to listen critically..... yesterday it was even more pronounced but still not obvious...I realized that right channel is a tiny bit lower level than the left channel.
I eliminated all obvious issues, like bad connections, balance knob turned, etc...
I don't have spare tubes, and before I start opening the chassis and switching the tubes, just want to make sure this is even a possibility.

Thanks

ether
ether OP
64 posts
 
Thanks for the feedback... will swipe the tubes next.
I have replaced tubes in my amps in the past so this isn't anything that I am afraid of doing...I just didn't think that this "symptom" is characteristic of dying tubes.
Kind of weird for the pre-amp to "lose" some power in one channel.
Was more thinking of issues with resistors or other parts.

BTW - I have verified for sure it is the preamp and no other part of the system, including the interconnects etc...

Will get back to you guys tomorrow after testing...

Thanks!
ether OP
64 posts
 
Confirmed it is the tubes.....
Changing the tubes from L to R - made now R channel lower in volume than the L channel.

Question.... The original tubes are electro-harmonix 12AU7A.
I do have relatively new signal tubes Sovtek 6H30

Can I use them in my pre-amp?
kdude66
1,200 posts
 
Ether,

I'm glad you found the problem,you can't use the 6h30 in place of the 12au7's.

The 6h30 need to be used in a circuit designed for them,don't try it.

Best of luck to you,

Kenny.
kdude66
1,200 posts
 
I've had tubes on one channel lose gain or volume before but they usually get noisy and grainy in the sound first.
rotarius
431 posts
 
Please don't put the 6h30 in your preamp!  There are plenty of NOS and new 12au7 options you can try and they are quite cheap.  You can do a lot better than EH.
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