Power Conditioner/Distribution
- Thread starter Penthouse-D
- Start date
Here's my recipe: xport, DAC, pre, amps, phono, turntable speed controller, and sub plugged into one MIT Z-Strip; tuner, speakers and RTR into another Z-strip; shielded cables all around (mostly Shunyata Black Mamba CX, a couple of Shunyata Copperheads to the xport and turntable speed controller; MartinLogan CLX cords to the speakers). The Shunyata CX series appear to not only reduce line noise, but also reject picking up environmental noise around them very well. I go XLR in and out of the phono for additional noise rejection there. All in all, no detectable stray magnetic fields, no phono hum, no noise from all other preamp inputs. The star grounding provided by the Z Strips is easily verifiable, if you start moving stuff out of it and accidentally create ground potential - hum and/or buzz from the phono, amps and/or sub (the sub's input, for example, is two hots - L/R - and one return from one of the amplifiers).
Very close to dead silence with my Spectral gear too. With the volume maxed out I can only hear a slight hiss when my ear is within an inch from my tweeter. Some noise from the phono input though.
I also have a star ground - with mine provided by a Quantum QB8. According to Quantum's literature, a "tiny lift in the earth impedance of all but one of the output sockets routes the signal grounds directly to the centre of the star and the clean earth terminal".
My Nordost Brahma power cords seem also pretty good at keeping noise out. I noticed a drop in the noise floor when I upgraded from Vishnu.
All my RCA inputs are covered with Cardas RCA caps. Not sure how much these really do though.
My Pass Xono phono stage is the quietest phono stage I've owned, but I would still welcome lower noise. The newer Pass phono stages are said to be quieter. I would love to see a phono stage from Spectral.
I wish my Spectral setup was that silence too.
What is a tiny lift in the earth impendace?
Is this an resistor in serial with the earth connection?
10 Ohms or more?
Yes, I came from unshielded cables and all the noise that came with them. I can no longer see how one can live with them, when one can have properly constructed and utterly performing shielded ones, but that's just me. The Shunyatas trounced anything I've had before.
Is the noise something you hear from your listening position? How would you describe the noise? Which cables and power cords are you using?
This is how Art Dudley describes is in his review in Stereophile: "Of its eight outlet sockets, only the one at the center of the strip—labeled Primary Earth—goes straight to ground. For the remaining seven outlets, resistors are inserted between the sockets and the ground, to raise the potential, howsoever minutely. This deliberate unbalancing act is done to 'enhance,' if you will, the strip's behavior as a true star-ground voltage source—rather like tipping the drain board toward the kitchen sink—in an effort to reduce the noisy currents that can come from having multiple ground points of differing potentials within the system."
Nordost/Quantum recommends connecting the QB8 to a "separate, dedicated system ground" as this by doing this "you’ll hear an obvious drop in noise ?oor, with blacker backgrounds, less grain and more vibrant instrumental and tonal colours." I've not yet tried this.
I posted a video by Keith Johnson today; among other things, he talks about noise; I suggest watching around the 50 minute mark, and in the next 5 minutes you may get an idea how important eliminating noise can be; he also restates common-knowledge suggestions about keeping power cables away from signal and digital, how susceptible to noise digital cables can be, etc. Put another way, I don't think anyone can make an argument that noise has any part in high end audio. In the broader subject of everything being important and how carefully designers need to pay attention to details, another fascinating observation on jitter is his demo of the green pen on CD's and the measurable effect, unfortunately for the worst, as he shows...
Hi Kenny,
There is a sizzling noise en humming (both from speaker).
Yes i can hear the humming in listening position.
I use MIT ic and powercables.
I reconnected the cables in several ways (phase) but the humming stays.
The way you connect the PC makes some difference.
How's your equipment exactly connected? Buzzing from the speakers usually indicates a ground loop somewhere, and if you are not star-grounding, a good power distribution center should help; also assert that you have a good ground connection everywhere. I would not exclude a faulty piece of equipment either. Personally, I would move methodically, first by unplugging everything, then starting with plugging in and powering on just the amps (no I/C cables connected) connected to the speakers, and move up from there - at some point you should be able to find out what's introducing the buzzing. Did you also report transformer buzzing in the past, or am I not remembering correctly? If so, is this the same issue? I did have buzzing from the speakers at some point in the past, and traced it to a bad ground connection of the power cord to the preamp, due to the cord's weight. As it turns out, the female EIC connectors used by Shunyata are not large enough for the equivalent Spectral input male EIC's, so I now wrap all of them with a couple of rounds of electrical tape, for a tight and firm fit into the hole. The nut that I am, I actually opened up all components and asserted continuity and very low impedance between the cord's male ground prong and the ground wire behind the IEC plug within each component; careful if you decide to do the same.
Yes Ack you are right.
The hum is in both speakers.
This item is also detected by the distributor but no solution till now.
I did all the things you said except adding a low impedance.
I think is the same you get with the Quantum QB4 (a low impedance resistor in the earth connection)
What is the value of the resistor you placed?
When i connect the pre to poweramp (and speakers) the humm is already there (volume set to "0").
When I said very low impedance, I meant I was making sure there was no detectable impedance; I did not use any resistors (I don't believe in this stuff). You may also have a bad ground connection between the power cord and the preamp; I would suggest testing with the stock power cords as well.
Regarding the use of resistors, the following is copied from wikipedia and is exactly right - you don't want Rg > 0:
How it works
Simplified circuit illustrating a ground loop.
The simplified circuit diagram on the right illustrates in principle how a ground loop works. Two circuits share a common wire connecting them to ground. Ideally the ground conductor should have no resistance (
), so the voltage drop across it,
, should be zero, keeping the point at which the circuits connect at a constant ground potential, isolating them from each other. In this case the output of circuit 2 is simply
. However, if the ground conductor has significant resistance,
, it and
will together form a voltage divider. As a result, if current of magnitude
is flowing through
from circuit 1, a voltage drop
, across
will occur and the ground connection of both circuits will no longer be at the actual ground potential. This voltage across the ground conductor will be applied to circuit 2 and added to the output:
Thus the two circuits are no longer isolated from each other, and circuit 1 can introduce interference into the output of circuit 2. If circuit 2 is an audio system, and circuit 1 has large AC currents flowing in it, the interference may be heard as a 50 or 60 Hz hum in the speakers. Also, both circuits will have voltage
on their grounded parts that may be exposed to contact, possibly presenting a shock hazard. This is true even if circuit 2 is turned off.
Although they occur most often in the ground conductors of electrical equipment, ground loops can occur wherever two or more circuits share a common conductor or current path, if enough current is flowing to cause a significant voltage drop along the conductor.
How it works
Simplified circuit illustrating a ground loop.
The simplified circuit diagram on the right illustrates in principle how a ground loop works. Two circuits share a common wire connecting them to ground. Ideally the ground conductor should have no resistance (
Although they occur most often in the ground conductors of electrical equipment, ground loops can occur wherever two or more circuits share a common conductor or current path, if enough current is flowing to cause a significant voltage drop along the conductor.
That Quantum device is the opposite of what we want. We want to make the loop smaller not larger. We want to reduce the Safety Ground resistance from unit to unit. We want to reduce the end-to-end resistance of all unbalanced analog interconnects.
Bill Whitlock writes:
In reality, many of the benefits often ascribed to “power treatment” schemes are simply
due to plugging all system equipment into the same outlet strip or dedicated branch
circuit. For obvious reasons, this is always a good idea!
From his "UNDERSTANDING, FINDING, & ELIMINATING GROUND LOOPS IN AUDIO & VIDEO SYSTEMS" paper.
http://www.jensen-transformers.com/an/generic seminar.pdf
It's well worth reading this 42 page paper.
Bill Whitlock writes:
In reality, many of the benefits often ascribed to “power treatment” schemes are simply
due to plugging all system equipment into the same outlet strip or dedicated branch
circuit. For obvious reasons, this is always a good idea!
From his "UNDERSTANDING, FINDING, & ELIMINATING GROUND LOOPS IN AUDIO & VIDEO SYSTEMS" paper.
http://www.jensen-transformers.com/an/generic seminar.pdf
It's well worth reading this 42 page paper.
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