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Alright guys, here it is! First the parts you need. *C4 amended.From Mouser. Input caps, order 10x because it's cheaper than 4x (yes you'll need 4x)647-UES1H010MDMUES1H010MDM50volts 1uF Power cap 1x661-EKZH250E222MK30SEKZH250ELL222MK30S25Volts 2200uF Shunt/Mute Power cap661-EKY500ETC220ME1EKY-500ETC220ME11D50volts 22uF BuildingOk, so first I recommend getting to this point, the naked board of all the parts you don't need. That is unless you want the volume pot, but I wouldn't recommend it.Here's a clear board, I've labeled the R and L inputs, and their grounds. R1, D1, D2, C1, C2, C3, C4 (not shown removed) C5, CN4, and RP 50k have been removed. Install a wire for the bypass of the diode (D2), I did this on the bottom.Install the Shunt/Mute cap (C3) 22uf, negative side (short lead) goes to the striped pattern on the board. Install the upside C1 and C2 capacitors, 1uf Nichicon Muse. Long leads go toward the input (as circled) Install on the bottom 1uf capacitors with the reverse orientation of the first two (long leads towards the chip), on C1 and C2. This is very important, and can only be done with non-polar caps. Without doing this your amplifier won't be that great unless you got some very nice film caps for the inputs.Install C5, the big 2200uf cap, again stripe to stripes.That's it! My next post here will be about advanced options, this is the simple, but very good build. Use only DC power supply after removing the diode.*do not replace C4, it's a worthless snubber that causes ringing.
I appreciate the feedback, but I already own these boards. But while the folsom board looks interesting, where can you get the board? Does anybody sell it in kit form? I did some searching and couldnt find much info. That link you sent talks about indigogos from 2015 which are long expired.
It really is remarkable how good those cheap amps can sound. Years back, I put one in a large cardboard box and took it to a friends record store, where he sells lots of vintage receivers. We did a comparison to all the Pioneers, Marantz, Sonys that he had on display to demonstrate how the "mystery" amp was better. When I opened the box, he was dumbfounded-- and opened a whole side branch to his business, putting Chinese amps in old radios. That demo has probably made him >$25K over the next several years. He sells every old radio he can get his hands on.
Yes.But I would only run a film cap on the 7297 anymore. There's problems with electrolytic input caps on them.
I just got one of these amps and was going to play around with the mods. Are you saying not to use the original electrolytic caps you suggested in your original post and use film caps instead?Thanks for sharing.
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