Rocket preamp voltages

[AmpegSVT]

Are these preamp voltages too high? The first stage is on V1a, the second on V2b, cathode follower on V2a. Amp sounds great but once it breaks up it sounds a little harsh. I paralleled the B+3,4 and 5 off of b+2. 27k b+3, 22k B+4 and 100k B+5. B5 started as 27k but I raised it to try to get V1a plate voltage down.

[Blackburn]

Yeah, some of those values are a lot higher than expected. What are your EL84s at? Plates and screens.

David

[AmpegSVT]

297 plate, 305 screen

[Blackburn]

That's about where mine are. Let me guess, you used 500R screen resistors? I've seen some variation in mine compared to the file, but I dig the amp. Maybe you don't like your tubes?

[AmpegSVT]

my screens are 100r

[Blackburn]

Did you use a choke, and if so, how many henries? I don't see why they are that far apart if you used a typical AC30 (20H) or TW style (15H) choke. Mine are that far apart because I used 500R screen resistors. I'm thinking of changing them out for the original 100Rs.

[AmpegSVT]

Hammond 194d 5H 150mA

[AmpegSVT]

Hmmm... the choke question got the wheels turning. I downloaded the Duncan amp power supply simulator and started playing with choke values. I didnt realize that choke made such a big difference in voltage levels.