HUMMM...
Hi,
Most likely it hums all the time,you may just not hear it at lower volume settings.
The taper of the old 500K may well have a different attenution curve compared to what is commonly used nowadays.
The hum may be a ground loop or some injected hum from AC fed heaters.
It is also possible that a filtercap has dried up and lets the ripple through.
Cheers,
Hi,
It hums when I turn volume past 10'oclock.
Most likely it hums all the time,you may just not hear it at lower volume settings.
The taper of the old 500K may well have a different attenution curve compared to what is commonly used nowadays.
The hum may be a ground loop or some injected hum from AC fed heaters.
It is also possible that a filtercap has dried up and lets the ripple through.
Cheers,
HF problems?
Just a small warning. I once had a hum develop in my power amp when the volume control went past a point. It turned out to b eHF oscillation - I could see it on the scope. WHile you cannot hear the HF ( RF) its effects filter down ! Check to see if your power transistors are heating up suddenly . The RF is usually of very low amplitude.
Just a word of caution. In your case it might be just a hum loop ----- Hmmmm.
Cheers.
Just a small warning. I once had a hum develop in my power amp when the volume control went past a point. It turned out to b eHF oscillation - I could see it on the scope. WHile you cannot hear the HF ( RF) its effects filter down ! Check to see if your power transistors are heating up suddenly . The RF is usually of very low amplitude.
Just a word of caution. In your case it might be just a hum loop ----- Hmmmm.
Cheers.
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