I did fiddle around with some shielding, rerouting wiring, and added
filtering without success. There is at least one transformer on the CS
board, and I suspect that the field near the TT power supply transformer is
just too much. Even when the CS board is placed in front of the aluminum
front panel the hum was evident. That being said, I did add circuitry to
completely bypass it when not in use (normally the audio amp is on all the
time in a CS unit and the DSP function is switched on an off), so there is
no issue when it is off. I'm open to other thoughts and ideas, but reading
comments of folks who have had hum induced into their rigs by power supply
placement makes me think this would not be a trivial thing to fix.
As it is, when the DSP is on, the 60 cycle stuff is well below the receiver
audio passband and is just "notched" with no apparent loss of dynamic range
or anything that I can tell and I haven't been able to detect any ill
effects from using it as is. Before this I had experimented with the unit as
a self-contained package outside of the housing and it seems to act the
same. BTW, the last versions of the CS speaker had an audio out jack, so it
could also be used in that manner to feed the TT speaker if one doesn't mind
another box behind the rig.
=Vic=
WA4THR
----------------------------------------------------------------------
Ken Brown <ken.d.brown@verizon.net> said:
...
If the DSP is killing the induced hum, then you are giving up some of the
DSP's dynamic range. If you could do some shielding or balancing to get rid
of that hum using traditional methods, so that the DSP does not have to do
that work, then the DSP might work even better.
DE N6KB
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