Please, wait till tomorrow when I get home, there are some things I have to check again.
Cheers.
These are not suitable devices I don't think it would work well..
You need 2Sk170GR, 2Sk932,BF872, 2SK3557 or something simillar.
Fan at only 3V5 DC, makes wonders.. It sounds very good, I wouldn't change anything else, maybe compensation caps revisiting after listening tests and square wave measurements... Btw, I tried, and it's stable and does not burst in to oscillation without all 3 comp.caps.
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This works at 35V DC and 0.6A bias at the moment. I'm listening to 96dB/8 Ohm speakers in a 20 sq.meters room and "loudness" and power are not the problem...
One thing, value of the bias resistors (RB1-4) depends a bit of power supply voltage, and values I've sent are for 35V DC. If any other p.s.voltage is used just connect 100K trimmer instead of RB, adjust for idle currents you want, measure the trimmer values and then solder fixed resistors on pcb,.
Cheers, Borko.
Ok, initial bias setup should be done with a 100k pot.
The parts sheet should list RB1-4 as TBD (To Be Determined) with a procedural note to help builders.
I’ll edit the Mouser Project cart to include a 100K trimpot and RB1-4 based on 35vdc power supply, thanks Borko 🙂
Ok Vunce, thanks.
One simple idea I got for the fan supply. 12V /12cm computer fans on lower voltages have lower rpm and are noiseless. With only 3 volts on a 12V CoolerMaster fan thermal capacity of heatsinks is nearly doubled.
The problem is that 12V fan can work on 3 volts but won't start.. That is why i bypassed the resistor with cap. Very simple solution..
One simple idea I got for the fan supply. 12V /12cm computer fans on lower voltages have lower rpm and are noiseless. With only 3 volts on a 12V CoolerMaster fan thermal capacity of heatsinks is nearly doubled.
The problem is that 12V fan can work on 3 volts but won't start.. That is why i bypassed the resistor with cap. Very simple solution..
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Except that that spikes at the full rail voltage on start up, which may burnt out the fan electronics. Add a resistor in series with the cap and a 15V zener across the fan perhaps?
Yes Mark, I have a zener and reversed diode on the fan, forgot to draw it on schematic..It works fine.
Output caps are of course important, for the sake of experiment, first I tried cheap 10mF capXon and it sounded plastic, don't bother with cheap caps, I'm currently using combination of various caps, btw I think I'm going to keep this old nos samsung cap, sounds great (transparent). 😀
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Mouser cart from post #95 has been updated.
6 bias adjustment resistor values to choose from:
(based on 36vdc psu)
0.5A 39K
0.8A 47K
1A 51K
1.2A 56K
1.5A 64K
1.8A 78K
A trimpot has also been added to ‘dial in’ the desired bias current.
6 bias adjustment resistor values to choose from:
(based on 36vdc psu)
0.5A 39K
0.8A 47K
1A 51K
1.2A 56K
1.5A 64K
1.8A 78K
A trimpot has also been added to ‘dial in’ the desired bias current.
Thanks Vunce. Later today, I'll send Rb values for +45V power supply and measurements for 8 ohm load.
