Zen Mod said:
app. 18.5 V
app. 4.3 Amps bias
Power supply ripple
good Amp, app24 mV peak to peak
bad Amp, app24 mV peak to peak
These chokes are ferrite core bobbin types rated for >15 Amps
They reach app. 70°C
Solution
Maybe this helps not only me but all plagued by hum.
It comes from the transformer! Turn the transformer till the amp is quiet.
When the transormer outlets are on 3, 6, 9, 12 o'clock there is hum.
If they are at 1:30, 4:30, 7:30 or 10:30 there is no hum.
Mine where at 12. Seems to be in realtion to the chassis walls.
Try it!
Maybe this helps not only me but all plagued by hum.
It comes from the transformer! Turn the transformer till the amp is quiet.
When the transormer outlets are on 3, 6, 9, 12 o'clock there is hum.
If they are at 1:30, 4:30, 7:30 or 10:30 there is no hum.
Mine where at 12. Seems to be in realtion to the chassis walls.
Try it!
Guido,
Do not dispair,
I also have had that problem with another product......
Please bare in mind its still being picked up by the amps and some thing is acting as a antanna.
Check that all aluminium panels are at ground potential.
What is the bottom panel made of?
Ground the input stage earth with 3 ohms to chassis ground.(A must do)
Also, try to shield all the input wiring. I would suggest splicing the coupling caps into external the cable if it helps reduce the hum.
Re-route those wiring coming over the transformer. That is full of noise! They should be all twisted in a spiral together and be attached to the chassis.
If all that fails put a 4-6 mm plate steel partition across the chassis in front of the board isolating it from the rest of the interior
I just had a look at my X Aleph, no hum no matter what I do.
Ian
Do not dispair,
I also have had that problem with another product......
Please bare in mind its still being picked up by the amps and some thing is acting as a antanna.
Check that all aluminium panels are at ground potential.
What is the bottom panel made of?
Ground the input stage earth with 3 ohms to chassis ground.(A must do)
Also, try to shield all the input wiring. I would suggest splicing the coupling caps into external the cable if it helps reduce the hum.
Re-route those wiring coming over the transformer. That is full of noise! They should be all twisted in a spiral together and be attached to the chassis.
If all that fails put a 4-6 mm plate steel partition across the chassis in front of the board isolating it from the rest of the interior
I just had a look at my X Aleph, no hum no matter what I do.
Ian
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