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Southman's Achievements


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  1. I replaced the input transistor to 5N5564 (second hand) then got the the amazing result. Beside, i replaced the volume control to step volume control. The sound hearing clear, warmth and have good feeling of spaciousness, the dynamic very high and strong. The treble are very smooth and bright, the bass are taut and rich, the alto are got high transparency and clarity. The cables looks in disarray, next time try to tidy it up.
  2. By the way, i found a capacitor ESR very low compare with Nichicon FW 1000uf/35V, but it is for 50V The following are my testing results. Nichicon FW 1000uf/35V Aishi RS 1000uf/50V
  3. I solved the Hummmmm sound issue after made grounding correctly. As i checked my volume control have problem, so i have not install it now. and next time i will change the signal cable to OCC copper and the 2SK366 to 2N5564, hope this changing will get positive effect. The amp's sound are petty good, high resolution and very clear, but the sound hearing cold. Maybe the R-type transformer or 2SK366 input transistor affected the sound, so i don't know why. Anyone have idea for this issue, i want the sound warn. About the sigma22 PSU information, as i asked the seller and got that the circuit is same as AMB sigma22 but the PCB layout is not. So it is not a factor to caused the Hummmmm sound. But i Thank you very much for your concern and gave me idea. Revise, the transformer is dual 25.4vac, not 27vac. the PSU voltage regulation are from 25.4vac to 22.0vdc. I think it have a little bit high after understand your comment.
  4. Dear Pars, Thank you for your quick reply, and constructive comments. As i have not look all of the post before i do, so i don't know the 2SK389/LSK389 or 2x2SK170BL can instead of it. The 2SK389/LSK389 or 2x2SK170BL are very difficult to order from RS, Digikey etc, i can find some of its in Tabao, but i can't sure that they are genuine. I know the 2sk366-BL gm is not same as 2N5546 or 389/170, but the value are nearly, and i had done the 1% device matching of it, so maybe it is OK but not sure. The MPSA06/56, MJF15030/31 are genuine and the MPSA06/56 had done the 1% device matching. so i have not worries . The machine run is not hot when i use sigma22 PSU, just can said warm. I don't know why, it is out of my expectation (i think it run hot so). I will try KG PSU with 22VAC after i finish sigma22 and KSA5 chassis mounting. Dear Jose, Thx for your reminder. _________________________________________________________________________________________________________________________ I will mount the sigma22 on chassis the coming few day. This is sony R type transformer(from Sony audio machine).27-0-27 This is customer make E type transformer. 28-0-28
  5. Dear all, I did my first KSA5 Clone and tested everything are normal. The sound is good but i heard some Hummmmm sound when i turn the volume to highly and the sound is not clear compare with my Audioquest dragonfly and Denon DA-300. I don't know the reason, maybe i have not mounted it in chassis. I can't order 5N5564 because this transistor was stop manufacturer, so i use two 2sk366-BL to instead it (2 N channel). And PSU are sigma22 and use 100W 27-0-27 VAC transformer(E type) to provide +/- 22VDC. (i want to change to 100W R type transformer). The below shown the board photos and some waveform about the it. More details will updated future.
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