Rocket with 6V6s

[matt h]

(deleted)

[RB]

I am totally in favor of all the mathematical and theoretical issues/approaches discussed in this thread but the first thing that comes to mind is;

The Rocket uses a VOX style PI and this is used in many Matchless models to drive various output configurations using the VOX circuit values. Also you will find it in TopHat amps driving 6V6s, 6L6s and EL34s with no changes to the original VOX circuit values. All these amps sound great and have dedicated users/following. Oh you can add Badcat and Star amps to the list also.

It should work as drawn just fine - just get the Pi plate voltage high enough to give the desired signal swing.

I am no expert but just another way to verify your design approach.

Regards
Randy

[matt h]

(deleted)

[Tillydog]

Tilly- at the risk of derailing this threadwreck (ha!) did your sim of the XP PI include the gnfb?

No - not for the figures I quoted above. It won't change headroom much, though. Higher B+ on the Express makes most difference.

[matt h]

(deleted)

[Tillydog]

Oh, wait- I think I see what you mean... won't change the headroom as far as "just the PI" is concerned..

Yes, I think we're saying the same thing! - it (NFB) won't change the voltage swing you can get out of the PI very much, but it will change how many volts you need to put into the PI to drive it to the max (i.e. the effective gain of the PI).