That's a start, just reverse the last mods step-by-step and see what happens. But on the other hand it shouldn't matter whether the circuit gets its supply from the board or externally, as long as the right voltages are present. If there's 5V off each reg but only 1.6V at the board, maybe there's a wiring problem. Are the grounds of the board and the external PSU properly connected?
Ray
Ray
6h5c said:
Hi Ray and Simon (oz)
Regarding with my experience, wiring problem in the regs (5V) can get 5V but if connected with other DC source will get different result so I have a tips to final check with a few of DC source, the right wiring will be get the same result, always.
Lately I got 4.94 V (2 zener seri with green led in the adj pin), can I use for 5V supply ?
Regards
aquar
martin clark said:That circuit does work, but it needs very careful trimming to get the best noise rejection.
It also sounds grim!
Lowest noise out of a regulator seems to be a lot less important than its dynamic response (maintaining low impedance over the audio band). The shunt delivers low noise at the cost of rather high impedance in the supply... not good for audio, though very useful for many instrumentation uses.
Hi martin,
Tks for your kind answering, I'll keep in my mind.
Regards
aquar
Aquar, it is possible the voltage collapses as soon as it is loaded with current. A measurement with a (high-impedance) DVM will show a neat 5V, but as soon as you hook it up to anything the voltage drops. If the common ground is poorly connected or the regulator is wired incorrectly this can occur.
So you managed to get the circuit to work? 4.94V is perfect for 5V, you can't get any closer I guess
Which zener values did you use?
Ray
So you managed to get the circuit to work? 4.94V is perfect for 5V, you can't get any closer I guess
Which zener values did you use?
Ray
Malefoda said:
No - if anything they will isolate the two parts of the circuit from each other.... it certainly won't cause a negative effect on the RCA. This offset may be (probably) coming from the filter op-amps - does it measure roughly the same there? Is it a similar offset on your RCA outs?
If it does, these caps would block it. If it doesn't, re-instating them would not get rid off your offset and it's coming from the headphone circuit itself anyway.
If you decide you need them you could replace them with decent film caps... a couple of uF is all you need.
I doubt that 30mV is going to fry your cans but getting rid of it might help you sleep at night.
Glenn
Glenn2 said:
Glenn you know me!
I won't sleep until this is defintly over and under control
Even if for a very stupid volume control hphones...The RCA show 30/25mV and hphones 27/32mV. Very close! I think I'll have a try with caps back, I've in hand 1uF Wima MKS. I use to see electrolytic caps on audio path, no? Will they do fine? OEM is 47/25.
Thanks Glenn
Errr.....ummmm......(cough)...........yes............well.........I haven't grounded the power supply
What was that?
I....umm..... haven't grounded the power supply
You what!!!! You fool!!!! Why not?!?
I thought that the wire going back to the tranformer was the earth
Well I'm surprised that you haven't electrocuted yourself you gormless twit!!
I'll get right on it
What was that?
I....umm..... haven't grounded the power supply
You what!!!! You fool!!!! Why not?!?
I thought that the wire going back to the tranformer was the earth
Well I'm surprised that you haven't electrocuted yourself you gormless twit!!
I'll get right on it
OFF TOPIC - schroeder diffuser
Sorry this is off-topic, but if anyone is interested in what was for me a very very important upgrade, have a look at this. It's a diffuser built on the maths of quadratic residues. I can whole-heartedly recommend F. Alton Everest's "Master Handbook of Acoustics" for anyone wishing to make their room sound less rubbish.
Sorry this is off-topic, but if anyone is interested in what was for me a very very important upgrade, have a look at this. It's a diffuser built on the maths of quadratic residues. I can whole-heartedly recommend F. Alton Everest's "Master Handbook of Acoustics" for anyone wishing to make their room sound less rubbish.
Attachments
Still off-topic
Here's the diffuser in situ, "modelled" by my friend "Hairy John", who said "that picture better not go on the Internet!"
In this position the too-close rear wall is made less evil by having lateral reflections diffused so as to minimise conflicting left-right information. The sound is great: images have more of a solid position now and I can play loud with great clarity!
Potentially a useful mod for anyone who has trouble hearing their CD player upgrades.
Simon
Here's the diffuser in situ, "modelled" by my friend "Hairy John", who said "that picture better not go on the Internet!"
In this position the too-close rear wall is made less evil by having lateral reflections diffused so as to minimise conflicting left-right information. The sound is great: images have more of a solid position now and I can play loud with great clarity!
Potentially a useful mod for anyone who has trouble hearing their CD player upgrades.
Simon
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