Where's the phase inverter in my Studio .22+?

[hverlind]

First post, simple question (see topic title)...

Today I got a new set of JJ tubes for my Studio Caliber .22+ (I bought them from Bob at eurotubes.com). One preamp tube is balanced for phase inverter use but I don't know where to put it. I did use the search function, but I couldn't find a conclusive answer. My best guess is that the PI tube is the first one on the left if you're standing behind the amp and looking at the back, but I would rather be sure. As an aside, am I correct that I don't need to bias this amp after retubing?

Thanks for any help...

 

[fdesalvo]

Your PI is closest to the power tubes.

~F

 

[hverlind]

Your PI is closest to the power tubes.

That's one of the answers I got from using the search function. The problem is that the preamp tubes are on a row behind the power tubes rather than on the same row next to it.

In the mean time, I have discovered that I somehow have only ordered 4 preamp tubes while I really need 5 (sigh). So now I am also wondering which tube I should leave unreplaced, considering I rarely use the lead channel and I'm not a fan of high gain. Is there a tube that is used only by the lead channel? If so, which one?

Thanks again...

 

[hverlind]

Ok, I've been looking at both this picture and this schematic and I have concluded that:

- If you look from behind the amp at the back of the amp, the tube locations are: V5 V4 V3 V2 V1

- V1, V2 and V3 are used in the preamp

- V4 is used for the reverb (I guess I could leave this one unreplaced)

- V5 is the phase inverter

Please correct me if I'm wrong...

 

[fdesalvo]

Yes, in this case, V5 is the PI. It's always the one on the end of the preamp chain as it hands off the signal to the power section for further amplification.

~F

 

[LHanson]

Your PI is closest to the power tubes.

That's one of the answers I got from using the search function. The problem is that the preamp tubes are on a row behind the power tubes rather than on the same row next to it.

In the mean time, I have discovered that I somehow have only ordered 4 preamp tubes while I really need 5 (sigh). So now I am also wondering which tube I should leave unreplaced, considering I rarely use the lead channel and I'm not a fan of high gain. Is there a tube that is used only by the lead channel? If so, which one?

Thanks again...

No. The lead channel uses the second half of the rythym channel tube.

 

[hverlind]

Thanks. I think I'll just leave the old reverb tube in place then.