pucho812 said:
I am working out the best way to remove the PIN 1 hum out of one of our EMT plates at the studio. This has been an ongoing thing. The one with original EMT electronics has more hum then then the other plate which has Martinsound electronics. So far it's a clear ground loop in the electrical because I can get more or less hum depending on which electrical circuit powers it. So in the interest of trying to quiet them as much as possible, See what would be best here.
back on February 5 you wrote:
" The plate with EMT electronics has a light hum, and it can be heard if I crank up the monitors to full. I assume this is normal for a plate that old that has seen little servicing. nothing that can't be addressed in time.
The Martin sound electronics have large amount of hum. I have swapped power around with marginal success, meaning I ran a power extension cord from the control room power circuits and connected to the plate with a reduction in buzz but still low frequency hum. I have tried running audio cables directly from the control room to the plates and still had issues. I have confirmed the patchy connections are solid and working as they should.
The Martin sound plate electronics had recently been serviced and given a clean bill of health by the manufacture. "
un-molested, original EMT 140 plates have very little hum, even when feeding long lines to and from control room.
and frankly never heard of a pin 1 problem with either V54 or type 162 electronics.
if the send and return lines are not bundled together, there could be a large inductive transformer loop.
if you really suspect electrical issues, power the plate from a isolation transformer, preferably an ultra-iso unit such as those made by Topaz.
not that it would fix your problem, but powering original EMT plates from 220 VAC is advantageous, it is "balanced power".