Why .02 between second gain and PI

[atmars]

Just wondering. Although it is not marked on the classic fender 5E3 schematic, in is my understanding that the coupling cap between the second gain stage and the phase inverter is .02uf. Every other coupling cap in he 5E3 is .1uf. Why is this one not .1uf as well?

[tubeswell]

Hi Atmars - yep 0.02uF - you'll see it on the 5E3 layout diagram.

I reckon 0.1uF would make the signal too flabby there, but try it if you like.

Actually as an afterthought, I built on recently whereby I used 22nF (mustard caps) on both coupling caps after the first stage and on the coupling cap into the PI as well. It sounds great.

[clyde]

I suppose that there could be too much bass for that stage to handle and causing blocking distortion?

I know that Aiken has a paper on the LTP and using a low value cap just before the PI to prevent blocking dist. Not sure if it would be an issue with the split load PI.

[Chris / CMW amps]

0.02 is stock and does work pretty well

like the input on LTPIs the input-impedance on that point is higher than the 1M resistor because of "boot-trapping". You can even try using a lower value coupling-cap on that point (let's say 0.002-0.01) to prevend some farting low-end but most of the time changing the other coupling-caps to lower value ones is the way to go.

[clyde]

Chris, what you said seems to make pretty good sense. Decrease the bass response gradually over several stages, rather than trying to remove a large amount of bass with one single cap.

[tele-tubby]

Are you talking about the coupling caps from the 12AY7 and the caps from lug 6 and 8 off of the 12AX7?

I might try this too. What guitar do you frequently use with the amp?

Actually as an afterthought, I built on recently whereby I used 22nF (mustard caps) on both coupling caps after the first stage and on the coupling cap into the PI as well. It sounds great.

[tubeswell]

Are you talking about the coupling caps from the 12AY7 and the caps from lug 6 and 8 off of the 12AX7?

I might try this too. What guitar do you frequently use with the amp?

The ones off pins 2 and 6 of the 12AY7, as well as the one off pin 2 of the 12AX7

For the ones off pin 6 and 8 of the 12AX7 I just used the stock .1uF