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and now for something completely different part 3

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Finished the right channel today. Feedback as suggested by Justin. Bias servo as suggested by Kevin.

IMG_2007.JPG
Red smoke – Super Symmetrical mode.

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Green smoke  –  Zero Feedback mode.

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  • johnwmclean
    johnwmclean

    A CFA2 balanced. Finished this a whiles back.

  • Been working on this for a looong time. CFA3 from scratch mixed smd/thru-hole design. Currently assembled with NOS Toshiba 2SC3381/2SA1349 inputs, NOS MPSW TO-92L thru-hole transistors and bcxxx for t

  • First 2 chassis just arrived. Getting it tested!    

Posted Images

i habe some current mirror amplifier ss/zf version 1.21 here that i like to use for the amp build.

may i ask about two points on the underside of the board (orange marked) look liks place for a jumper on the front siede the are between the two 82ohm resistors. are they for jumper and/or what are they used for. thx

cfa_3_1.21.jpg

reserved for the SMD MLCC 47uF Caps

I used Thru-hole ones

thank ang728 for the info, then im ready to order parts 🙂

  • 3 weeks later...

finished my cfa3 this week, thanks kevin gilmore for the desing and the support from the forum members.

running on +-30v with moderat bias, changed the gain resistors to 3.2k for lower gain.

needed some 3d printed parts so that all fit fine, a cfa3 in a quad 405 chase. no pot this time, i use a dac with volume control or a preamp.

after all amps i build i think the best solution for a 1 case build ist mounting the trafos outside in vertical position, absolut no magnetic hum inducted. i also added grain oriented metal band around the trafos inside the trafo cases.

cfa3_b.JPG

cfa3_c.JPG

Nice! So the trafo is in this box not in an outer case. Would be nice a picture from the front too.

3 hours ago, judo said:

Nice! So the trafo is in this box not in an outer case. Would be nice a picture from the front too.

The first picture he posted was from the front.
Quad 405 cases have the sink on the front 🙂 

I have built a 405 ages ago then let's see the back🙂

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