I Call it INFINITRON

The amplifier disclosed here is actually a Circlotron, implemented with bipolar transistors. I call it Infinitron because I found it easier to visualize Circlotron topology not as a circle, but more like a figure 8, or even better, the symbol for INFINITY (see Logo attachment). This same visualization follows to the schematic, and to a certain extent, the PC card.

If one sees a schematic resemblance to Jean Hiraga's 'le monstre', it is not a coincidence. My original plan was to bridge a pair o'monsters' to realize a balanced amp. This 'monster pair' idea eventually morphed into Infinitron.

Infinitron is running class A, with about 1 Amp Iq. Power out is a nominal 20W. Output BJTs are KSA1220Y/2SC5200. The input is a MAT02 with BC550 cascodes, but matched BC550s would work as well for the inputs.

I'm quite pleased with the performance and stability of this amp. I have been using it with a Cambridge Audio DacMagic+ for over a year now, with no issues at all.

Enjoy!..

Attachments are; Infinitron logo, schematic, 20kHz square wave trace, completed 2ch amp in a gutted pro-amp enclosure.
 

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Hi Polyphase !

Thanks for sharing that nice SS Circlotron A class amp design ! :up:

And few question :

- that circle with arrow inside represent some CCS unit ?
- it is possible to run that amp in SE mode ?, but not only in balanced mode , with let`s say IN (-) connected to ground .
 
Polyphaze thanks for your answer !

All is clear now !

With that CCS in tail of input cascoded LTP SE mode is quit possible , ( but as always balanced drive mode is preferable option over SE mode for this type of basically fully balanced amp .) , and yes I like that global balanced negative current feedback design solution .
 
The amplifier disclosed here is actually a Circlotron, implemented with bipolar transistors. I call it Infinitron because I found it easier to visualize Circlotron topology not as a circle, but more like a figure 8, or even better, the symbol for INFINITY (see Logo attachment). This same visualization follows to the schematic, and to a certain extent, the PC card.

If one sees a schematic resemblance to Jean Hiraga's 'le monstre', it is not a coincidence. My original plan was to bridge a pair o'monsters' to realize a balanced amp. This 'monster pair' idea eventually morphed into Infinitron.

Infinitron is running class A, with about 1 Amp Iq. Power out is a nominal 20W. Output BJTs are KSA1220Y/2SC5200. The input is a MAT02 with BC550 cascodes, but matched BC550s would work as well for the inputs.

I'm quite pleased with the performance and stability of this amp. I have been using it with a Cambridge Audio DacMagic+ for over a year now, with no issues at all.

Enjoy!..

Attachments are; Infinitron logo, schematic, 20kHz square wave trace, completed 2ch amp in a gutted pro-amp enclosure.
Good approach and simple design. Check out also the schematics from post #4 and #14 under
http://www.diyaudio.com/forums/soli...-names-commercial-solid-state-amplifiers.html
so as this threads:
http://www.diyaudio.com/forums/soli...no-feedback-classab-buffer-5.html#post2337770 (post #45)
http://www.diyaudio.com/forums/soli...g-schemes-bipolar-transistor-circlotrons.html
 
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Thanks for your interest.

For me, better to listen. As for Iq, (which should be ~1A for this design) it is a function of Iccs, and other components including these resistors on the output.

I don't see how increasing the value of these output resistors in my design (from the original 110R) could increase distortion as long as amp is in class A mode, but maybe I'm missing something. I do know from listening that distortion is quite low, and that the 'tweaks' shown in attached schematic have improved the listening experience.
 

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