Techs Please Help ! Balanced Triodes Question

[LevinFan]

I'm getting ready to order some tubes, and since my amp I'm ordering them for is fairly unknown, the guy I talked to at TD isn't sure.

I understand that balanced triodes are important for the phase inverter tubes ?

Here is the schematic
http://www.schematicheaven.com/bargainbin/sano_30_50_WRT.pdf

I know I need a matched pair of power tubes, but what about the 12AU7's and 12AX7's in this amp ? I'm not sure which of these are in the phase inverter section of the amp. Hopefully someone can tell by the schematic, and advise whether I need to get balanced triodes in any or all of the 12AX7's and
12AU7's ?

 

[BassmanPaul]

Ideally the two triode sections of the 12AU7 phase splitter should be balanced. In practice any good quality tube should have its sections close enough. The other tubes don't really matter.

Paul

 

[LevinFan]

Ideally the two triode sections of the 12AU7 phase splitter should be balanced. In practice any good quality tube should have its sections close enough. The other tubes don't really matter.

Paul

Ok Paul, thanks. The 12AU7's I'm ordering are NOS 50's Tung Sol, so they should be ok. Is the phase splitter on the preamp chassis ?

 

[metalmariachi]

No need really, the amp has a cathodine phase inverter which is the second half of the first 12AU7.
On the schematic its ½ 12AU7 amplifier stage, ½ 12AU7 PI, 12AU7 both halves 12AU7 post pi amplifier, power tubes.
You’ll notice slight differences in resister values in that section, that balances every thing out .
Just get good 12AU7 and you’ll be fine.

Sano’s are very nice amps.
The guy who designed them worked For Ampeg in the Everett Hull days before starting his own company.

MM

 

[LevinFan]

No need really, the amp has a cathodine phase inverter which is the second half of the first 12AU7.
On the schematic its ½ 12AU7 amplifier stage, ½ 12AU7 PI, 12AU7 both halves 12AU7 post pi amplifier, power tubes.
You’ll notice slight differences in resister values in that section, that balances every thing out .
Just get good 12AU7 and you’ll be fine.

Sano’s are very nice amps.
The guy who designed them worked For Ampeg in the Everett Hull days before starting his own company.

MM

Ok thanks ! I'll forgo paying extra for the balanced triode test and that will cover the shipping. Cool

And yes, the thing is a beast tone and volume-wise and has a ton of features for such an old amp. Loves pedals.
Here is an old thread on it. http://www.talkbass.com/forum/showthread.php?t=556239

 

[BassmanPaul]

The 12AU7s on the power amp chassis are the ones you're interested in. The one closest to the power tubes should be the phase splitter.

Paul

 

[LevinFan]

The 12AU7s on the power amp chassis are the ones you're interested in. The one closest to the power tubes should be the phase splitter.

Paul

Ok, if there is any noise or other, I'll just swap them around. I've got 4 Amperex Holland 12AU7's as well as the Tung Sol NOS ones on the way.

btw, I had no idea those Amperex were so expensive for even used ones lol. That's ok though, spares are a good thing.