need advice

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sonicwarrior62
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need advice

Post by sonicwarrior62 » Mon Feb 19, 2018 4:23 pm

My understanding of in depth electronics is limited. I can, at a very limited level read the schematic for this model. My PV-10B is hissing loudly in the left channel, not as loud in the right. A very knowledgeable repair guy here said to swap out the tubes with each other on either side of the channel to track down the source. Still hear it either side. The tubes don't appear blackened or discolored.

I have read that this model tends to be hard on the 12AX7 tubes. Should I have it serviced by CJ? I was told by CJ that the upgrade for this model is upwards of 1050.00. Is there a problem with buying new, high quality tubes for the whole unit?

Your patience is appreciated. Much thanks.
Blair

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Re: need advice

Post by admin » Mon Feb 19, 2018 4:36 pm

Just to clarify, did the hiss change with swapping the tubes?
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Current Conrad Johnson Equipment in System: Evolution 2000, PV-12L, and D/A-2b.

sonicwarrior62
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Re: need advice

Post by sonicwarrior62 » Mon Feb 19, 2018 4:55 pm

It did not. It's annoying and really taking away from the "black" of the system, especially during quiet passages.

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Re: need advice

Post by admin » Mon Feb 19, 2018 5:22 pm

In that case most likely it's not the tubes. You may have to go through the schematics and try to identify a bad component. At least it's limited to the left channel components so it does narrow it down a bit.
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Current Conrad Johnson Equipment in System: Evolution 2000, PV-12L, and D/A-2b.

sonicwarrior62
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Re: need advice

Post by sonicwarrior62 » Mon Feb 19, 2018 5:35 pm

It's been like this for a while - the sound hasn't deteriorated. If so, it is undetectable, so gradual that I haven't been able to hear it. No popping or crackling anyways. Sounds just fine with the volume up.

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roberto
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Re: need advice

Post by roberto » Wed Feb 28, 2018 1:23 am

Hola Blair...I am going to chime here. The 12AX7 tube is a dual triode. Sometimes it is better to change the tube, because if you move it inside, swap for another 12AX7, the same channel is going to have the noise. Get only one tube, and change it. If nothing happens, put the old back into its position, and change the other, and so, until you will find the culprit. Here is what the manual says:

The audio circuit of the PV10B uses five vacuum tubes of three different types: two 12AX7 (V1 and V2), one 12AT7 (V3) and two 6189 (V4 and V5). The PV10BL uses two type 6189 (V4 and V5). The brands of tubes we supply have been chosen by first selecting those brands which are known to be most reliable, then by extensive auditioning of these acceptable brands with the final choices being made solely on the basis of sonic performance. We know of no vacuum tubes available which will improve the sonic performance of your PV10B. The tubes in your preamplifier have been tempered by a controlled burn-in procedure that permits them to perform for a greatly extended period without sonic degradation, then selected for minimum residual noise. Replacement tubes are prepared and selected in the same way. Therefore, we highly recommend that you purchase replacement tube sets from conrad johnson design.

You can not exchange the tubes randomly, you have to keep them at their position. Only tubes with the same number can be swap and keep their position. In other words, you can swap V1 for V2.(12AX7)...and so.

Happy listening!
ML CLX speakers, BF-210 sub, Classic One Twenty SE amp. ET-7 C-J pre. Exasound E-32DAC, Mac Mini i7, Anthem MCA-3 power amp, Anthem AVM-60, Oppo BDP-103. ML Stage X Center, Motion 4, BPTSignature 3.5 Plus condiciones.

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