12ax7's to 12au7's in SVT 2 Pro preamp?

[ryankself]

Am I going to hurt my amp if I change out a few preamp tubes from 12ax7's to 12au7's, especially the V3 (drive knob?) and the V4 or V5 (extra gain stage tubes?)? I'm trying to tame some preamp OD while keeping the tubey goodness, but I don't want to ruin something with the hardware.

Some people do something like this with the Traynor YBA200, right?

Thanks!

[jastacey]

I would use the 5751's first, I have done this to my SVTII Pro and I like the result, I think the 12AU7 would sound so-so ....but try it

[Bassflute]

Originally Posted by ryankself

Am I going to hurt my amp if I change out a few preamp tubes from 12ax7's to 12au7's, especially the V3 (drive knob?) and the V4 or V5 (extra gain stage tubes?)? I'm trying to tame some preamp OD while keeping the tubey goodness, but I don't want to ruin something with the hardware.

Some people do something like this with the Traynor YBA200, right?

Thanks!

Au7 are lower gain - less headroom = more EASILY driven to distortion. The highest gain, cleanest preamp tube is the one you've got, the AX7. Try different makes (JJ's are nice and inexpensive).

More here...in the 'Preamp tube megathread'...started by yours truly:

Preamp Tube Megathread

Also, a LIFETIME of tube info here...

www.amptone.com

Hope this helps.

Cheers,
Cameron

[ryankself]

Currently I've got JJ preamp and driver tubes. When I put a 12au7 in the V5 position, I get what sounds to me like a cleaner preamp signal (meaning I can turn the gain up higher before overdriving the preamp). From what I understand, the V4 and V5 tubes in the SVT II Pro are an extra gain stage, and I'm trying to mellow that out a bit.

I know it's not a solid state amp, and I do like the sounds I get out of it. I'm just trying to get a bit more of a clean signal.

[Jim C]

Many would say that the V1 position is the "money" slot for tone
I've had good luck with a used Mullard's in this position on Ampeg's - about $40

[ryankself]

Also, could you explain the "low gain retube kit" on this site:
https://ssl.eurotubes.com/cart/index...category_id=88
Why is it getting cleans where the 12ax7's are dirty? I'm confused...