I was using the cheater plug. As I said, I've been doing this for years, as a matter of course. I don't care to A/B this stuff. I just hated the loose fit of the cheater plug and the cheap metals involved.
or death!it's imperative to understand that lifting grounds can have really serious consequences. So one must understand exactly what they are doing and why. having 150a-200a run through an interconnect in case of a fault can lead to damage and fire.
or death!
I have been the least path of resistance to ground before and I am fortunately here to tell you it does not feel good.
This can have deadly consequences, dying in the name of better sound is not in the cards for me,except for the occasional subwoofer in a big wooden box.
Definitely not steel boxes in steel racks.
What sort of "feedback"? Ground loop? How's everything connected electrically when that happens?
As far as I can tell it is a ground loop. What I have today is the following electrically:
4 separate circuits:
1) 20 amp with a Spectral 400 mono block and Spectral preamp
2) 20 amp with a Spectral 400 mono block and Berkeley Ref. 2 DAC
3) 15 amp with Shunyata DPC-6 (all digital gear plugged in here, including Mac Mini, WD hard drive, Eero WiFi access point, Synergistic Research Transporter, Sonore Signature LPS, Berkeley Alpha USB)
4) 15 amp with Synergistic grounding block and Synergistic FEQ
I've tested out isolating the preamp (no connections at all to inputs) while keeping interconnects to the mono blocks in play. Whether the preamp is powered on or not the amps exhibit a low level hum when the mono blocks are not floated. I've also tried floating the preamp while not doing so for the amps and still get hum. There are slight variations in the degree of hum if I reorient things. By putting both amps in a single 20 amp circuit and the preamp in the other. And using this same setup adding a cheater to the preamp lowered hum a tad more. I'm beginning to believe that I'm getting a loop from somewhere in the overall building wiring that will be rather hard to troubleshoot. But I may be quite wrong.
I know that the amps are very sensitive. Even placing the preamp within a foot of the amps degrades sound appreciably.
If you have ground loops, the equipment will reveal it; Pass and others are the same way. So best to fix the ground loops. Steve, in this case, may be falling into the "dedicated" line trap, with different length power lines and primarily ground wires. Dedicated lines must have the exact same length wires (including ground) from the distribution box, of the exact same gauge and metal purity - read: entirely, 100% identical, or there will be ground impedance issues; consequently, the power cords must also be identical (including in length), as well as any conditioners, etc. If necessary, just "tie" the grounds between the power lines. If using sub-panels, are the the ground and neutral bonded together... etc. There are electronic tools at places like Home Depot to solve all these problems.
See also http://www.whatsbestforum.com/showthread.php?19492-Shunyata-DENALI&p=414903&viewfull=1#post414903
It seems to me the easiest test is to "tie" the grounds - run a ground wire from one outlet of one circuit to an outlet on the other circuit - I suspect this will get rid of the hum
Thanks for your feedback. I know the two circuits intimately. I watched the electrician run the same gauge cable of equal lengths from the breaker to the 4 outlet receptacle. And the three Zcords from MIT are all the same length. As I've noted, I can induce the hum with only the three Spectral devices connected into the two 20 amp circuits - and even with the preamp powered off. I'm not aware of how breakers operate. If the circuits are separated and the only common connection is from the breaker to ground, then it's well beyond what I can ascertain.
I plan on bringing in a Shunyata D6000/T next week for testing. My plan is to plug this into one of the two 20 amp circuits via a single Sigma HC power cord. The two amps will get connected into the 2 HC outlets of the D6000 and the remaining 4 outlets will serve the preamp, DAC, USB to S/PDIF converter, and Sonore LPC. That should begin to tell me more, I hope.
There is leakage current to the chassis inside your electronics which causes ground currents/hum with no contributions at all from your electrical wiring. The solution to this is to use balanced interconnects. I see that your power amps have this. Are you able to connect them this way?Thanks for your feedback. I know the two circuits intimately. I watched the electrician run the same gauge cable of equal lengths from the breaker to the 4 outlet receptacle. And the three Zcords from MIT are all the same length. As I've noted, I can induce the hum with only the three Spectral devices connected into the two 20 amp circuits - and even with the preamp powered off. I'm not aware of how breakers operate. If the circuits are separated and the only common connection is from the breaker to ground, then it's well beyond what I can ascertain.
No, not exactly. Everything must be plugged into the same circuit, as a starter, using a power distributor - that gives you star-grounding. Then, you can move the amps into a separate circuit, and I am almost certain the hum will return, to one degree or another. All of these will simply confirm you have ground potential, and the dedicated lines are not identical. What you are doing right now by lifting the ground on the amps is to star-ground at the preamp's inputs through the interconnects; that's fine, I do that too, but I do it for sonic reasons, even though I plug everything into one distributor (which kills hum to start with); this configuration just stands the chance to offer ever so slightly better sonics; but your primary goal here is to kill hum, then worry about ultimate sonics.
There is leakage current to the chassis inside your electronics which causes ground currents/hum with no contributions at all from your electrical wiring. The solution to this is to use balanced interconnects. I see that your power amps have this. Are you able to connect them this way?
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