Hello everyone, I apologize for my translated English, I am a beginner and I have recently been playing with this preamplifier that I am building, I would like some help from you experts if possible, I made the PCB freehand and installed the components as per Nelson's manual, the preamp does its job, but how do I adjust the two trimmers? I adjusted them some time ago, but now I don't remember how I did it, maybe you can help me? I also have an oscilloscope and can display the amplitude of the output wave:
with 1khz and 3v PP in input I have 22v PP in output is this more or less correct? I used a simple unarmored 10k double potentiometer connected to the output of the rca.., Can I use a 50k Alps? or will I have problems? it's to have better volume control.
in output and without input with volume at max I have no strange hums in the woofers...
R104 and R204 heat up a lot, now they are 3w as per the manual, even Q101 and Q201 with heatsink heat up I can't keep my finger on it, R1 heats up, it's 1/2W, these components heat up but they never blew...
I inserted a LED with resistance in series, to signal switching on and off, on D4 and D2, the LED turns on when switched on but when switched off it takes a while to go off, where can I connect this LED?
I am grateful to you who help me, maybe in my small way I can also help on this forum on things that I am better at, thank you.
with 1khz and 3v PP in input I have 22v PP in output is this more or less correct? I used a simple unarmored 10k double potentiometer connected to the output of the rca.., Can I use a 50k Alps? or will I have problems? it's to have better volume control.
in output and without input with volume at max I have no strange hums in the woofers...
R104 and R204 heat up a lot, now they are 3w as per the manual, even Q101 and Q201 with heatsink heat up I can't keep my finger on it, R1 heats up, it's 1/2W, these components heat up but they never blew...
I inserted a LED with resistance in series, to signal switching on and off, on D4 and D2, the LED turns on when switched on but when switched off it takes a while to go off, where can I connect this LED?
I am grateful to you who help me, maybe in my small way I can also help on this forum on things that I am better at, thank you.
Greetings and hello!
The LED is staying illuminated for a long time as the PSU has a lot of capacitance, and it’s showing the capacitors discharging.
Bride of Zen is different than most preamplifiers is that the volume potentiometer is on the output… because of this you want the potentiometer value to be as close to the specified 5K as you can obtain.
Adjust potentiometers to set 8V at node of R103 and C102 -
Ciao,
Jim
The LED is staying illuminated for a long time as the PSU has a lot of capacitance, and it’s showing the capacitors discharging.
Bride of Zen is different than most preamplifiers is that the volume potentiometer is on the output… because of this you want the potentiometer value to be as close to the specified 5K as you can obtain.
Adjust potentiometers to set 8V at node of R103 and C102 -
Ciao,
Jim