one more thing. I did removed the toroid from the chassis and laid it on top of the heatsink,
with thin piece of wood isolating toroid from heatsink. I powered only one channel opposite side of the toroid position.
the hum was still present. this tells me if I rotated 180, toroid and cap bank, it would not make any difference, is this a wrong assumption?
the point was moving the toroid further away from the signal input which I did.
the hum has been consistent level volume wise, it does not get louder or lower in volume
with everything that I have tried so far.
with thin piece of wood isolating toroid from heatsink. I powered only one channel opposite side of the toroid position.
the hum was still present. this tells me if I rotated 180, toroid and cap bank, it would not make any difference, is this a wrong assumption?
the point was moving the toroid further away from the signal input which I did.
the hum has been consistent level volume wise, it does not get louder or lower in volume
with everything that I have tried so far.
Less "hum with ear next speakers" than before?
Step by step,-)
I would use both secondary windings for (+) and (-).
I would use only one RCA-ground to connect the source. ONE RCA - ground-star/-plate. You would avoid a big ground-loop - as Rodeodave written. RCAs are one of the biggest stupidities: To many circuits and to much diameter.
What are the values of your input-resistors?
Step by step,-)
I would use both secondary windings for (+) and (-).
I would use only one RCA-ground to connect the source. ONE RCA - ground-star/-plate. You would avoid a big ground-loop - as Rodeodave written. RCAs are one of the biggest stupidities: To many circuits and to much diameter.
What are the values of your input-resistors?
all these different exercises of rewiring, moving toroid away from input jack, aleph board. Hum level remained constant in volume, not lower or higher.
its all stock values for aleph. I am not connecting any sources right now,
just 100ohm between signal input and ground. minus input shorted to ground.
Attachments
I went back to your post #52. My cheap toy scope, I cannot measure frequency at speaker output, it barely registers, with DMM it reads around 2mV.
If the hum frequency is mains frequency the problem is before the rectifiers. If it is double the mains frequency the problem is after the rectifiers.
I understand that rewiring is a pain. The best thing is to first try to discover what is causing the problem before doing a lot of work.
Try something relatively simple: Move the toroid 1 meter away. If that does not solve the problem you also know that your wiring is not picking anything up from the toroid (i.e. no reason to change wiring).
You can use standard 220V power cable for this test. If you still have mains hum after moving the toroid 1 meter away I have no idea how you could solve it.
Good luck!
try this sort of re-wiring
if that doesn't help , put fat wire bridge (shortest path) between channel pcbs, between central GND points on them
Attachments
Thanks Albert. I will try moving toroid further away.
I have a 24V 200VA I will wire primaries for 12V out
Just to see if its related to the toroid
Hi ZM,
I will rewire per your edit with the star winding. Before I start this, if I move
the toroid 2-3 feet away from the amp with long secondary wires, I know that's bad,
would that tell me if tranformer is the culprit?
From all these exercises so far, it's still either bad wiring, placement of toroid and caps
or noisy transformer. Just my guess, I am no expert, why Im here :-|
I will rewire per your edit with the star winding. Before I start this, if I move
the toroid 2-3 feet away from the amp with long secondary wires, I know that's bad,
would that tell me if tranformer is the culprit?
From all these exercises so far, it's still either bad wiring, placement of toroid and caps
or noisy transformer. Just my guess, I am no expert, why Im here :-|
Try try try. I will learn a lot.
My experience: some amps had the same problem. The only help was to remove the trafo, the rectifier and first caps. They got a separate casing. And all problems went out,-)
If the hum is not loud (R1, 10kOhm, does damp very very well - the amp should be quiet without R1,-), a further chance is to use a CP2500, a poti, that kills hum - I do not know, why,-)
Or to build a x-mini-aleph.
My experience: some amps had the same problem. The only help was to remove the trafo, the rectifier and first caps. They got a separate casing. And all problems went out,-)
If the hum is not loud (R1, 10kOhm, does damp very very well - the amp should be quiet without R1,-), a further chance is to use a CP2500, a poti, that kills hum - I do not know, why,-)
Or to build a x-mini-aleph.
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