The late cut and cathode feedback are good. Sometimes a Zobel, depending on speaker characteristics. But when I'm looking for a bluesy tone I usually like a more compressed and slightly distorted tone. In my builds it comes from an overdriven 5879 in the hot channel. A dirtier signal seems less sensitive to global feedback than a cleaner signal.
Tube junkie that aspires to become a tri-state bidirectional buss driver.
TUBEDUDE wrote: ↑Wed Aug 30, 2023 6:47 pm
The late cut and cathode feedback are good. Sometimes a Zobel, depending on speaker characteristics. But when I'm looking for a bluesy tone I usually like a more compressed and slightly distorted tone. In my builds it comes from an overdriven 5879 in the hot channel. A dirtier signal seems less sensitive to global feedback than a cleaner signal.
Yes, I dig a compressed tone too.
This is my kind of tone:
It’s a Gibson Falcon, which is a 2x6V6, with tiny OT which generates that compression.
But my quest is to get that same tone from a SE with a cathode follower or perhaps a pentode (like you use) in a later gain stage. Have you tried both ways?
TUBEDUDE wrote: ↑Wed Aug 30, 2023 6:47 pm
The late cut and cathode feedback are good. Sometimes a Zobel, depending on speaker characteristics. But when I'm looking for a bluesy tone I usually like a more compressed and slightly distorted tone. In my builds it comes from an overdriven 5879 in the hot channel. A dirtier signal seems less sensitive to global feedback than a cleaner signal.
When you say cathode feedback do you mean an unbypassed cathode resistor or plate to cathode feedback?
Feedback around the tube, but cathode degeneration is valued also. I also will take feedback from the output of a 2 stage preamp amp and send it to the first stage.
I love your Falcon, I had a '60's GA-17RVT it didn't sound that good though.
I've only designed 5 or 6 SE amps, and they had no hot channel. They were meant to operate relatively clean, so I can't speak to that. Most of those had some power supply browning of the output if chosen to play at high levels but clean was mostly the goal. In one I used a 6DQ5 SE for ~15 Watts. It got stupid loud cleanly.
If you can find a copy of The Radiotron Designers Handbook Vol. 4, there is plenty of inspiration for spectrum shaping and feedback applications.
Tube junkie that aspires to become a tri-state bidirectional buss driver.
TUBEDUDE wrote: ↑Thu Aug 31, 2023 1:16 am
Feedback around the tube, but cathode degeneration is valued also. I also will take feedback from the output of a 2 stage preamp amp and send it to the first stage.
I love your Falcon, I had a '60's GA-17RVT it didn't sound that good though.
I've only designed 5 or 6 SE amps, and they had no hot channel. They were meant to operate relatively clean, so I can't speak to that. Most of those had some power supply browning of the output if chosen to play at high levels but clean was mostly the goal. In one I used a 6DQ5 SE for ~15 Watts. It got stupid loud cleanly.
If you can find a copy of The Radiotron Designers Handbook Vol. 4, there is plenty of inspiration for spectrum shaping and feedback applications.
Thanks! I ment if you compared pentodes to cathode followers for compression. Not a lot if tiny OT’s on the market today. Also, if you don’t mind telling, what setup you use on the pentode screen for compression?
No I haven't experimented with an AB comparison. I like overdriving the 5979 to get a true pentode distortion, that's where the compression occurs, biasing the pentode for operation just below the knee.
Tube junkie that aspires to become a tri-state bidirectional buss driver.
