Air Line Arm Owners- Compressor Electrical Noise


As mentioned in another thread, I finally got the Air Line arm installed on the XL table, on the finite stand, etc. I installed the arm compressor in a separate 'room' (in reality a large walk in closet off the listening room) and powered the compressor from a 'regular' circuit outlet- the system is otherwise hooked up to its own dedicated lines, per standards discussed many times here.
I have been experiencing a periodic electrical 'zap' (sounds like a big ol' scratch on the record) through the system when the gain is up. Since the room lights dimmed when the compressor kicked on, I figured- why fool with the standard circuit to feed the compressor? I had the electrician come back and set up a separate line just for the compressor- having nothing to do with the system wiring or subpanel. (He had already pulled extra wire through the conduit up into the room, so it was no big deal to do this- he installed a high quality receptacle to this extra line, and terminated it at a different subpanel than that which runs the audio system).

Anyway, still that nasty zap. Never out of options, I decided to plug the compressor into a 240v-120v stepdown transformer I use to power the HT system in the same room. (The HT system is completely separate from the analog hi-fi system we are concerned with here).
So far, so good- the compressor kicks on, but no zap.

Still monitoring the situation- wondering whether other Air Line owners have experienced similar problems (which may be reassuring if this is the cause and I licked it) or I am still chasing electrical gremlins. TIA.
128x128whart

Showing 3 responses by jea48

What is the air line made of? Could be building up a static charge and discharging at the TT. Air moving through some types of plastic lines can cause static electricity. What is the humidity in the room now compared to what it was with the zapping going on? Just A thought.....
Whart posts

I had the electrician come back and set up a separate line just for the compressor- having nothing to do with the system wiring or subpanel. (He had already pulled extra wire through the conduit up into the room, so it was no big deal to do this- he installed a high quality receptacle to this extra line, and terminated it at a different subpanel than that which runs the audio system).

(He had already pulled extra wire through the conduit up into the room, so it was no big deal to do this- he installed a high quality receptacle to this extra line,
>>

I must have missed your statement about pulling extra wires in the same conduit as the feeder, if I understand your statements correctly.

In your first posting of the thread you did not mention a correlation between the "zap" and the compressor cycling off and on. I would agree the contacts that control the compressor motor could indeed cause the pop noise heard through your audio system.

I believe one issue here is the fact the circuit that feeds the compressor motor, via relay contacts, is pulled in the same conduit as the audio sub panel feeder. Current carrying conductors installed in the same raceway, conduct, can interact with one another. A current carrying wire will have a magnetic field around it. Induced voltages, though small, will will cut across to other conductors within the same conduit. Think of it working kind of like a transformer. When the control circuit for the compressor commands the relay contact to close or open a transient voltage spike is sent out on the circuit wires feeding the compressor. Jmo the compressor motor feed should be installed in its own metallic conduit back to the main service electrical panel.
Jim
So, Jea48, when are you going to send me a bill- or at least take a ride over and have a listen?
>>>>>>>
I never charge a friend. Just glad to help a fellow Audio buff.
Jim