In pursuit of the cleanest sound, this is what is now under construction. Using the WSF-4 cascode transimpedance driver, 6BX7's are chosen to drive a pair of 27W channels
The thread title sounds like a Zen Koan - the sound of one hand clapping. The schematic would take me many years of intense contemplation too. I'm not denigrating your design BTW, just struggling to decipher it.
Hope it turns out well. Andy.
Hope it turns out well. Andy.
Interesting details, I hope it will go well.
What tool did you use for the schematics drawing? I like its vintage style.
What tool did you use for the schematics drawing? I like its vintage style.
That's a lot of iron inside that feedback loop, you're a braver man than I. Good luck!
Interesting you use a 115N060. I would like to know if you experience sparks across the contacts after the 60 seconds delay. What current is drawn by the tubes?
Regards, Gerrit
Regards, Gerrit
The 115N060 is used in Tektronix 54X series oscilloscopes. Nope, no sparks
The interstage transformers are ones I had made with 5 tightly coupled, same inductance windings. the schematic has a typo on the primary
The schematic uses LT-Spice for schematic capture and spice model verifier. I just happen to like rounded turn corners when I'm done. I think it looks better
The interstage transformers are ones I had made with 5 tightly coupled, same inductance windings. the schematic has a typo on the primary
The schematic uses LT-Spice for schematic capture and spice model verifier. I just happen to like rounded turn corners when I'm done. I think it looks better
The 6BX7's are operating at 11W each or about 20-25mA/plate. These tube are very linear and have a mu of 10. The interstage transformer is driven by a two triode (6SN7) transimpedance OP-AMP fed by a 6SF5 high mu triode and preamp stage because I wanted more glow. A 6SF5 is an octal based half of a 6SL7. The three triode configuration provides 43db of gain and a low output impedance to drive the coupling transformer. I invented that configuration for the Watt Sucking Fireball #4 which was an adaptation of the triode version 10 years earlier. So back to tubes, where I started using them 60 years ago
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After several paper doll layouts, I think this is what the layout will end up being with the 6BX7's in the back, the 6SF5's in the front, and 6SN7's in the middle. Output and interstage transformers left and right, power transformer and 6BX7 filament transformer in the middle and voltage regulators and delay timer for the plate voltage in the front. The filter, inductor and floating filaments are under the chassis. The interstage transformers are different than what I mentioned, before, but almost identical.
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