I don't know about you guys but I find myself listening to this amp pretty much as often as I can. It goes with me everywhere (along with a spare set of rechargeable batteries). On the bus, at work, at home. 
Looking forward to building a few more amps here from this build. I just counted the list and it looks like I will have to find about a dozen matched sets of FETs. I better get busy with the matching. May have to order more raw FETs to fill out all orders so please be patient if you ordered matched FETs.
Looking forward to building a few more amps here from this build. I just counted the list and it looks like I will have to find about a dozen matched sets of FETs. I better get busy with the matching. May have to order more raw FETs to fill out all orders so please be patient if you ordered matched FETs.
I found out a way to test boards fitted just with SMT parts only. I installed a 4pin JST power connector and press-fit an Alps pot with power switch. This lets me check the proper operational bias setting and verifies that all SMT solder connections are good prior to shipping or proceeding with the rest of the build.
One thing I am noticing is that this particular batch of BF862's tends to require R4 value of around 47R to 51R to achieve 50mA bias. So I had to exchange a few R4's to ensure proper bias. At 33R bias was too low (37mA in one case). The sound will be very low distortion but lacks dynamics. Just something to keep in mind when building your amps is to have several values on hand for R4: 33R, 47R, 51R, 68R should do it.
One thing I am noticing is that this particular batch of BF862's tends to require R4 value of around 47R to 51R to achieve 50mA bias. So I had to exchange a few R4's to ensure proper bias. At 33R bias was too low (37mA in one case). The sound will be very low distortion but lacks dynamics. Just something to keep in mind when building your amps is to have several values on hand for R4: 33R, 47R, 51R, 68R should do it.
GB Status Update:
So all the folks with PCB's only (plus Schlomoff's order) was shipped out today. Also, DIYRookie's prize PCB for correctly identifying the top two amplifiers also went out.
One impotant correction I need to make is that the post office weighed the letters with 4 PCB's and that cost me double to ship.
So in the future, I will have to increase cost for 3/4 boards to +$7 (3 boards) or +$12 for (4 boards).
So all the folks with PCB's only (plus Schlomoff's order) was shipped out today. Also, DIYRookie's prize PCB for correctly identifying the top two amplifiers also went out.
One impotant correction I need to make is that the post office weighed the letters with 4 PCB's and that cost me double to ship.
So in the future, I will have to increase cost for 3/4 boards to +$7 (3 boards) or +$12 for (4 boards).
To test out a cncept, I converted the pocket amp to desktop amp with IRF610 and 140mA bias:
http://www.diyaudio.com/forums/head...lass-headamp-without-heat-33.html#post5014537
http://www.diyaudio.com/forums/head...lass-headamp-without-heat-33.html#post5014537