♫♪ My little cheap Circlophone© ♫♪

From ears to loaf.

Well it has been a pleasure but what a journey. :smash:

  • Read +3000 posts, understand what you read
  • Redraw the PCB twice in KiCad First pcb no good, second better. Yes all files attached.
  • Create pcb gerber files and route the board on the mill (twice!)
  • Purchase all components and assembly
  • Put everything on hold 6 months because my lab power supply was broken:headbash:. So build a new one on top of this..
  • Test assembly, all working :up:
  • Purchase enclosure and the parts needed. Drill holes in enclosure and do final assembly with everything.
All in all around 24 months. Need to step up somewhat, if I shall continue with this. Still need to build my second GainCore and the Q17


Well final figures when everything fitted.
1. Rail Voltage - 25V
2. Offset Voltage - between 0.55mV (Both Channels)
3. Quiescent Current - ~160ma (input short)

Sound. Astonishing, just do it

Would I do it again = Yes
Price wise it is a cheap amplifier compared to other more exotic alternatives here at DIY audio. For the sound. Well read all other posts.
Others. Well from what I can see there is many flavors available. The challenge when attempting this undertaking for unexpired is to decide bjt or mosfet, Decide what power output What type of circuit pcb to select. There is many options in the this thread.
Or just make your own. For a head start, attached my stuff KiCad files. disclaimer, I think everything is OK the amp is playing so probably correct

And please if you’re doing a PCB or other stuff, please share your stuff with source files, and do not just post pictures on your design. Well frankly do not post at all. No one is interested in your property IP pictures. Sharing is caring. Always remember this.

Thanks for all help. And hat off for Elveedesign.

Brgds / Sander
FInally you finshed it heartiest congratulations.
I am yet to put my amp in a box. It is still Lying in my project cupboard assmebled like a assembly ie pbc transitors heatsink in that order ( sandwich).
I ahve managed to get 1.3mv offset on one and the other is 3.2mv, I have used the CCS with transistor and zener circuit instead of resistor. Planned to run it at 28volts with a 40VCT @ 250VA. just not decided on the transistor - my present assembly is TIP 3055 ( RSComponent purchase) but looking for the M/NJW's 21194.
 
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Mr. Katyar,

Well i have absolutely no idea why the offset voltage is so low? Yes Matched transistors the original NOS stock.
I have the Circlo Amp powered up. let it stabilize for an hour or so.
Short the input, and measure the voltage, I have a Fluke DVM and it is calibrated with a certificate with traceability to the national metrologi. so the instrument is ok. 100%. Maybe, your instrument is out of order., have you checked the integrity of your DVM. It can be so that you have better result than your instrument.
 
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The topology is very versatile, and could probably accommodate SiC or GaN, with suitable adaptations.
Versions have been built with inverted polarity, MOSfets, Ge transistors, etc. There is no reason preventing the use of alternative semiconductor materials.
Would there be a benefit? That's a different question, and to answer it, the only reliable method is to build a prototype
 
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