I've noticed sometimes DC on the wiper of a pot makes it noisy when you adjust the volume. So if you skip the input cap and you hear scratchy noise on volume adjustments, you'll know what it is. A discrete resistor based attenuator may work better in that scenario.
Instead of using a 15,000uf cap is there any downside to using 12,000uf? I was going to start building today and well, 12kuf is what I have.
Nevermind, took my own advice and reread the article. Down to 1000uf if I want.
Uriah
Nevermind, took my own advice and reread the article. Down to 1000uf if I want.
Uriah
Ready & cool
Here it is. The dual supply no coupling capacitors version of B1.
The offset is no problem. We can null it down to zero by adjusting one PSU side out of opposite balance. The channels keep almost totally together for offset. I used 2x6.9mA and 2x7.1mA Idss 2SK170BL as matched pairs. Because one channel grew a little (1.5mV) for offset when the other was totally null, I adjusted for +/- 0.3mV matched between channels. Had to make the PSUs +16/-15V for that. Watched it for 2 hours. No offset wandering. Then I fed 10kHz & 100kHz 6V peak to peak square waves through it, one channel after another. Could not see any difference from feeding the generator directly to the scope. I fed 6V p-p sine waves too. No deformation or compression. That is 2.1VRMS and the same as the CD output standard. I made it totally point to point and used a 50k Bourns dual Log that I had. Its paralleled with Dale resistors from wiper to ground. There is also a 7sec delay output relay circuit.
Listening tests I will do probably tomorrow, hopefully with the aid of a friend. There is a sequence of tell tale pictures concluding my construction report.
Here it is. The dual supply no coupling capacitors version of B1.
The offset is no problem. We can null it down to zero by adjusting one PSU side out of opposite balance. The channels keep almost totally together for offset. I used 2x6.9mA and 2x7.1mA Idss 2SK170BL as matched pairs. Because one channel grew a little (1.5mV) for offset when the other was totally null, I adjusted for +/- 0.3mV matched between channels. Had to make the PSUs +16/-15V for that. Watched it for 2 hours. No offset wandering. Then I fed 10kHz & 100kHz 6V peak to peak square waves through it, one channel after another. Could not see any difference from feeding the generator directly to the scope. I fed 6V p-p sine waves too. No deformation or compression. That is 2.1VRMS and the same as the CD output standard. I made it totally point to point and used a 50k Bourns dual Log that I had. Its paralleled with Dale resistors from wiper to ground. There is also a 7sec delay output relay circuit.
Listening tests I will do probably tomorrow, hopefully with the aid of a friend. There is a sequence of tell tale pictures concluding my construction report.
Attachments
Impressive 
It would be interesting to compare the no-caps-dual-PS-version against the original NP-B1!
It would be interesting to compare the no-caps-dual-PS-version against the original NP-B1!
Tolu said:Impressive
It would be interesting to compare the no-caps-dual-PS-version against the original NP-B1!
I don't know if all people can detect caps in the signal path, but its a costly affair to employ really good ones. I wanted it small, and cheap.
Rock steady
It's been on for almost 12 hours now, the offset is still the same (vanishingly low, under 0.4mV). Should be safe. I will leave it on overnight just in case and take a reading again.
It's been on for almost 12 hours now, the offset is still the same (vanishingly low, under 0.4mV). Should be safe. I will leave it on overnight just in case and take a reading again.
jacco vermeulen said:
It's just easier. For you, not me. I don't lay awake at night worrying about
the sound of capacitors.
😎
/pass/ Gets a good night's sleep.
!
Then you'll have to pony up the big bucks at www.passdiy.com
The boards are still a couple weeks out.
The boards are still a couple weeks out.
Nelson Pass said:
Damn! This is almost as bad as waiting for Christmas day in 1977 when I was hoping for Star Wars action figures!
(polishes Visa card)
-D
p.s. I was 8.