Andre Visser said:
You need two PSU's.
Did you try to connect only one channel and see if it still hum, as Nordic suggested?
Two PSU's indeed - two totally independant channels...
I did try a single channel but unfortunately hum still features.
Also connected the transistor B-E as zener but no noticable difference...
D
Hi GD,
When you dangled the B-E junction over the 100mfd cap in the multiplier did you re - read the voltage at the amps themselves. It should have dropped to around 7 or 8 volts. This would "prove" it was working OK as a zener. It would prove a lot as to whether it really is a PSU ripple issue ! You ask about overvoltage. That in itself will not affect the hum. I am a little suprised it made no change at all, I think we could do with making sure the multiplier is working correctly. If you disconnect the 4.7 K resistor the voltage to the amps should drop to zero. Could you try that as well. Something does not sound quite right here.
The quality thing is interesting. Quite a few years ago now I had a Pioneer A80. If specs meant anything at all this was the ultimate. Sadly, although I tried to convince myself there must be other shortcomings in the rest of the system it wasn't so. The amp was unmusical, cold sounding. That's how I ended up with my present design, it's not perfect technically, but it sounds fantastic, now 95% of my music collection sound fabulous, the music shines through whatever the shortcomings of the recording.
When you dangled the B-E junction over the 100mfd cap in the multiplier did you re - read the voltage at the amps themselves. It should have dropped to around 7 or 8 volts. This would "prove" it was working OK as a zener. It would prove a lot as to whether it really is a PSU ripple issue ! You ask about overvoltage. That in itself will not affect the hum. I am a little suprised it made no change at all, I think we could do with making sure the multiplier is working correctly. If you disconnect the 4.7 K resistor the voltage to the amps should drop to zero. Could you try that as well. Something does not sound quite right here.
The quality thing is interesting. Quite a few years ago now I had a Pioneer A80. If specs meant anything at all this was the ultimate. Sadly, although I tried to convince myself there must be other shortcomings in the rest of the system it wasn't so. The amp was unmusical, cold sounding. That's how I ended up with my present design, it's not perfect technically, but it sounds fantastic, now 95% of my music collection sound fabulous, the music shines through whatever the shortcomings of the recording.
Whoa-hey!! What did I tell you??
All the amplifiers needed were a simple regulator.
The sound, using the mains transformer, is now breathtakingly brilliant. Dead quiet background - ZERO hum or buzz.
I am using a 1A, 7812CT regulator with a 400mfd cap on output. Works like a charm!
D
All the amplifiers needed were a simple regulator.
The sound, using the mains transformer, is now breathtakingly brilliant. Dead quiet background - ZERO hum or buzz.
I am using a 1A, 7812CT regulator with a 400mfd cap on output. Works like a charm!
D
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Mooly said:
Well Mooly
I also built one of these today: http://www.diyaudio.com/forums/showthread.php?s=&postid=1547659
See last post.
I would like to expand on that subject as well.
D
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