Using PV9a as Phono without line stage tubes

[Robbie]

Hello, my question is pretty much in the object...
Given that I use my CJ PV9a just as a phono stage, connecting its tape out to another preamp, the line stage is un-used and it's a shame to let the precious line stage tubes slowly consuming without a sound produced.

Can I operate the preamp without the line stage tubes (4) fitted? Am I risking something? My gut feeling is that the circuit would be open sparing tubes and components from useless stress, but I'm far to be an expert...

Thanks in advance
Roberto

[Big Dog RJ]

Yes, that's a good question mate.

In fact, it's usually the other way round... where you can use the Line Stage section without the Phonostage. With this sort of set-up, usually the Phonostage is redundant until the user wants a functional phono section. After all the PV9 is a fully functional preamp, so the Line Stage section will always remain active although the phonostage is being used regardless.

You may need to reach out either to Jeff or someone who has direct experience with the PV9, sorry I'm not much help here.
Hope it goes well. Apart from that, even though you're using only the phonostage section, those tubes used in the Line stage, are very small signal tubes, not high powered Output tubes. So, they wouldn't consume all that power... and burn out quickly. It will takes years to deteriorate gradually, even then you may not even notice after 10yrs. These small signal tubes aren't that pricey compared to Power amplifier Output tubes. So overall, I think you'll be alright.

Cheers, RJ

[admin]

I took a quick peak at the schematics of the PV9. Although the phono stage is relatively isolated, I don't think you will be able to just run the unit without tubes in the mains.

As RJ mentioned, these are luckily input tubes so even if they periodically need replacement they shouldn't cost and arm and a leg.

But I have a suggestion if you don't want to use tubes in the mains. Try to find a solid state tube replacement. I think if you search "solid state rectifier" and the tube type you are trying to replace you may find some options. I would never recommend one of those due to the sub-optimal sound output, but since those tubes are not going to be in the signal path, in this particular case it doesn't matter. Those should pretty much last forever and you can save your input tubes for one day that you may use the main outputs on the PV9.