[Bob I]

D wrote:

On Oct 19, 1:37 am, Bob I wrote:

D wrote:

On Oct 17, 10:13 pm, Bob I wrote:

The problem is likely caused by the combination of "speakers" being
disconnected by the insertion of the head phones AND the volume knob of
the speakers being cranked up rather high. Now the speakers are
amplifying the hum of the little power wart.

D wrote:

On Oct 17, 1:44 am, "Richard Crowley" wrote:

"D" wrote ...

It does not hum when no headset is plugged in.

Then you can eliminate any problem with the computer,
the sound card, or any software including drivers, etc.

One of the headsets is brand new and checked.

What does "checked" mean? Do either of the headsets work
OK on another computer?

Yes, the hum changes when I move the headset around the room: the
further from the computer case the louder.

I would take a wild guess that it has a shielding or grounding problem.

Yes, it hums when I try using a differen computer mic: both headsets.

The problem may be with the basic design if both headsets
show the same symptoms.

Thanks Richard Crowley for your suggestions!
The hum is from speakers, not from the case.
Yes, either of the headsets work OK on another computer.- Hide quoted text -

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Thanks Bob I for your explanation!
How can the speakers amplify the hum of the little power wart if they
are disconnected by the insertion of the head phones?
A Sony ECM-T6 microphone and another desk-top microphone don't hum! A
new Koss sb/45 headset and Philips SBC HM300 headset hum from their
microphones.
How to make Koss sb/45 headset microphone work?
Best regards,
Dima

The speakers are only disconnected from the audio source, the "wall
wart" is still powering the speakers amplifier. Try turning the volume
knob down or unplug the speakers little power supply.



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Thanks Bob I for your explanation!
The speakers are in a headset. There are no other speakers. A "wall
wart" is not powering a headset.
Why does the hum appear from a headset microphone only, not from a
separate microphone?
Best regards,
Dima


The confusion comes from the misuse of the term "speaker". The sound
producing components in a headset are called "headphones" or "earphones"
not "speakers", the condition I described applies to powered speakers
not headphones or earphones.