Finally put power to one amp... I installed the pico mod....relied on heat gun to set bias..ended up with .300mv with dc offset .001....was about 178F @ .500mv..148F @ .300mv. Heat measured was right on mosfet hold-down.
I must have installed blue led backwards as it did not light up.
I must have installed blue led backwards as it did not light up.
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Was that with heatsink laying flat down like in the picture?
The bias voltages are only meaningful if you state what resistors you have.
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Yep.
Measure it again when the heatsink is mounted on the chassis. It will most likely be cooler.
Thanks for the pictures, indeed my JFET are copies.
I am awaiting the return of Alweit, for my order of 2SJ74, and I will resume the tests.
in the meantime I took care of my Black Amp, it works wonders.
I also have a question: is it worth using this amp as a pre-amp or using a passive volume control with the F6?
No it just indicates you have power to the board but you have the green led references, so you don't even need the blue led.
You could remove it entirely if you want.
Finally I have got Isabellenhutte PBH 100R 3w from company called Burklin Germany.They didn't answer my email but could buy thru web/paypal.
For gate stopper,100R 1w was much cheap.
Source resistors are powertron.
Bass is completely tight, soft and warm high/mid same time.
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Exactly those babies!
Ran for about 3 hours last night, ran freq sweep, very symmetrical wave on both channels. Outputs stayed right around 110 degrees. Offset remained stable. Only had bench speakers driven by my iPhone. Zero hum/hiss or any artifacts.
Will hook up a couple different preamps & speakers in the days to come & report back with thoughts. Indeed once the chassis is bolted together the heat dissipates more so I will let soak and turn up & synchronize both amps.
Awesome project. Of course I bought spares of all parts in case of failure. Just my habit.