HELP Digital bad, vinyl good???


OK, boys and girls, I need your help. Besides the obvious philosophical implications, can anyone tell me why two CDPs (Exemplar 3910 and CAL CL-10) using two diff i/cs, and two diff inputs, are highly distorted and my vinyl rig sounds great? VAC Ren Mk2 pre. Doesn't the phono stage feed into the line stage and then to the output? HELP. No XMAS tunes on vinyl.
swampwalker
Yes. For several years. Vinyl relatively new; maybe about 2 weeks. Distortion started becoming apparent a few days ago; I thought the CDP might be going bad, so I plugged in my old CAL, w/diff I/cs and to a diff input.
First thought...have you disconnected the vinyl rig to listen for any change?

Second, this could be a bad tube or tubes. Doesn't the VAC use separate tubes for the phono stage? If you have spares for the linestage, I'd suggest changing them to listen for any improvement.
I have not changed tubes because I always thought that the phono stage provided RIAA reverse eq; and gain to be bring the signal to line level, and then the line stage provided additional gain to the signal to provide sufficient voltage for the amp. If I am wrong (which it seems I must be), then I stand corrected. I will have to disconnect the phone and then check the line stage tubes.

Happy Christmahanukwanzadan everyone.
You might be right about the way the circuit in the VAC works, but since neither of are sure, it seems like a good troubleshooting technique to change the linestage tubes to listen for a change.

I suppose the first thing I'd do is disconnect the vinyl.

Happy Christmahanukwanzadan to you, too.
Swampwalker: your description is right in how most preamps work, but as Tvad mentions, we aren't sure that's how this specific preamp works. His suggestion to disconnect the phono rig from the preamp ( interconnects, ground wire, power cord, etc... ) is where i would start. After that, it is a matter of tracking down the offending tube in the preamp, if there is one ( or two if dual mono ).

As a side note, the phono stage may not drive the line section as hard as your CD players do. As such, you might not hear as much distortion from the phono rig as you do the CD player. This would be due to the increased heardroom / lack of drive from the phono stage. This is just a guess though, so don't put too much faith in it. Sean
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