The Phase Inverter tube. How to choose?

[Chickenwings]

Re: The Phase Inverter tube. How to choose?

Not sure that's correct .... the AT7 can deliver 10 times the current (10 mA) than an AX7 (1 mA). I think you may have your wires crossed, so to speak.

yeh. something like that...

 

[erksin]

Re: The Phase Inverter tube. How to choose?

Some would say the opposite, as it is one of the deciding factors on how the power amp will behave. I think it depends a lot on how the amp is designed overall that determines the amount of difference a certain tube will make. V1 in any amp pretty much is guaranteed to be the most noticeable change.

Absolutely this.

If v1 is the gain/EQing slot, the PI slot is the 'feel' slot.

 

[Rick330man]

Re: The Phase Inverter tube. How to choose?

It has now been over seven years since I (and others) originally posted on this thread. I am curious as to how peoples' opinions have changed or been reinforced.

I have two Crate Vintage Club 50 heads that I love. I've had them over 15 years and they keep going strong. The manual calls for 12AX7s in all 4 pre-amp slots. Sticking a 12AT7 in the V4 P.I. slots brings out the best in these amps. By comparison, I have had a pair of Hot Rod Deluxes - though I am now down to one. Using 1980s production GE 5751s in the V3 P.I. consistently brings out the fullest, cleanest tones these amps produce. Other amps don't seem to be impacted much as long as you use the tube the factory specs call for.

 

[esandes]

Re: The Phase Inverter tube. How to choose?

I experimented with preamp tubes for my 1959RR mostly and I like the 12ax7 for more gain. Also be sure to buy a PI tube the best you can afford. Be sure it's not microphonic.