Hi Piersma,
I am really enjoying my Circlotron amplifier. Something about the sound is quite musical and non-fatiguing.
No adjustments were necessary or even possible - this is different than most of my other amplifiers. Bias was about 205ma and DC offset was only 3mV.
Attached is a picture of my build. Configuration is dual-mono in a Modushop 2U chassis. Power is supplied two Connex SMPS300RE +/-36V power supplies that had been sitting on my shelf for about two years due to disappointing results when tested with a class AB amplifier (sound was rather lifeless and flat). Using a capacitance multiplier to cleanup any SMPS noise, add more per-rail capacitance, and improve transient response seems to have made a huge difference. I had planned to eventually replace the SMPS power supplies with a simple linear power supply but may now stay with the current configuration.
The only surprise was quite a loud turn-on pop. This can be easily fixed by adding DC speaker protection with a small power-on delay. Until then, I am using an external speaker selector switch box to temporarily disconnect my speakers.
Thank you for making your PCBs available to the diyaudio community and for your support.
I am really enjoying my Circlotron amplifier. Something about the sound is quite musical and non-fatiguing.
No adjustments were necessary or even possible - this is different than most of my other amplifiers. Bias was about 205ma and DC offset was only 3mV.
Attached is a picture of my build. Configuration is dual-mono in a Modushop 2U chassis. Power is supplied two Connex SMPS300RE +/-36V power supplies that had been sitting on my shelf for about two years due to disappointing results when tested with a class AB amplifier (sound was rather lifeless and flat). Using a capacitance multiplier to cleanup any SMPS noise, add more per-rail capacitance, and improve transient response seems to have made a huge difference. I had planned to eventually replace the SMPS power supplies with a simple linear power supply but may now stay with the current configuration.
The only surprise was quite a loud turn-on pop. This can be easily fixed by adding DC speaker protection with a small power-on delay. Until then, I am using an external speaker selector switch box to temporarily disconnect my speakers.
Thank you for making your PCBs available to the diyaudio community and for your support.
Attachments
Hi Sjerko,
After all this time I finally got around to test both J-Fet Circlophone channels.
The addition of the (optional) 5.6 ohm resistor next to the output pin got rid of the oscillation I was experiencing.
Everything works fine now even with faster MJL4302 outputs.
Thanks again.
Jacques
After all this time I finally got around to test both J-Fet Circlophone channels.
The addition of the (optional) 5.6 ohm resistor next to the output pin got rid of the oscillation I was experiencing.
Everything works fine now even with faster MJL4302 outputs.
Thanks again.
Jacques
High Ft devices O.P.S.
hi Jaqcues,
Good to hear you got rid of the modest oscillations you experienced with the high Ft (10MHz) MLJ-4302. The Zobel is network is not strictly needed and that why it is optional with the MJL21193 with an Ft of 4MHz.
Can you confirm the sound-qualities (SQ) Pronk experienced?
Enjoy your build!
best regards,
Piersma
hi Jaqcues,
Good to hear you got rid of the modest oscillations you experienced with the high Ft (10MHz) MLJ-4302. The Zobel is network is not strictly needed and that why it is optional with the MJL21193 with an Ft of 4MHz.
Can you confirm the sound-qualities (SQ) Pronk experienced?
Enjoy your build!
best regards,
Piersma
Hi guys,
I ran into these Circlophone threads and I'm afraid there is a Circlophone in my future.
In learning about the architecture, I found that Schiit Audio is selling 2 amps that use "circlotron-style topology". Their Ragnarok amp has been very well reviewed. It's nice to see old ideas being reborn and made better. Even better, doing it DIY style.
Nice.
I ran into these Circlophone threads and I'm afraid there is a Circlophone in my future.
In learning about the architecture, I found that Schiit Audio is selling 2 amps that use "circlotron-style topology". Their Ragnarok amp has been very well reviewed. It's nice to see old ideas being reborn and made better. Even better, doing it DIY style.
Nice.
So don't know if this thread is dead or not?? Anyway Piersma I have built your earlier version on the green boards years back. You sent me a handful of red boards that I havent used yet. So it is a little confusing between the different versions. Can I just build the amp and go by the values that are silkscreened on the board? Using the MJL21193 outputs what is the max power I can operate at? I'm assuming +/-50v rails. What is the function of the Q4/Q5 in the schematic? Current source? If I want to operate single ended what input terminals do I use? Anyway good to talk with you again, thanks
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