Full retube on a Studio .22

[ftwizard]

Hi everyone, my first post.

I bought my Studio .22 new in 1985 from Chandler in Kew, London. It broke about twenty years ago, and I've just got round to fixing it.
I've carried out the footswitch circuit mod and I'm now thinking of a full retube.
If I use JJ tubes as replacements, do I need to worry about bias on the power amp tubes?

Thanks.

 

[>Photi G<]

No, if you order from Eurotubes, probably the best US distributor of JJ's, tell them what amp it's for and they will give you the proper set. Either way, I wouldn't worry, as Mesa's EL84 amps are biased pretty warm. Just put a strong pair in there.

 

[tonejam]

FTwizard, to what footswitch mod are you referring, please? I have a Studio 22, so would like to know, thanks.

 

[ftwizard]

Tonejam. The circuit mods are to do with the uprating of R131 from 680? to 1K? and C9 from 470? to 3300?
There are various references to the circuit diagram on the web.
Cheers.

 

[>Photi G<]

Footswitch mod is included in the .22+ schematic release. It adds a larger filter cap to the LDR supply, and offers quieter performance.
http://www.schematics.ca/modules/PD...ogie Studio 22 Caliber Plus Schematic Diagram