drdna wrote:

No, when the PP2000 is totally unplugged from the wall (and hence the neutral path which is also grounded is removed), the hum disappears. Then the whole stereo is functioning like some giant battery operated device. This is odd, since it seems to be the AC mains connection that is leading to hum. There is only one path to ground at that point, the neutral path through the AC plug. Is it possible that there is a ground loop problem within the PP2000 creating the hum, which is eliminated when there is no external reference to ground? Or what do you suggest?

drdna wrote:

There is only one path to ground at that point, the neutral path through the AC plug.

beachbum wrote:

Did so cause i was still using my BPT for everything but my amps. I had a hum and high pitch buzz from my speakers. Replacing the power cord feeding my amps was the cure.

Romy the Cat wrote:

drdna wrote: There is only one path to ground at that point, the neutral path through the AC plug. But if you lift the PP2000 output then the path is not there anymore!

Romy the Cat wrote:

drdna wrote: No, when the PP2000 is totally unplugged from the wall (and hence the neutral path which is also grounded is removed), the hum disappears. I still have no idea what the isolation transformer that you mention does in your system.

Romy the Cat wrote:

What I would do next is to lift ground at the 2000PP input – and then ground the PP2000 to your own ground. Make sure that no other devises on your playback use the main’s ground. When you do so let me know how much AC voltage you have between neutral and ground.

drdna wrote:

Exactly. Thus, it suggests a ground loop internal to the PP2000, doesn't it?

In my view it is highly unlikely as a definition of loop itself implies two contacts to ground and PP2000 has only one.  I do not think that you will go anywhere with accusing the PP2000 in humming. If the PP2000 has zero point zero Ohm from input to out grounds, the 500 mV between the neutral and ground and output no DC then I think it is absolutely out of blame. Might be I am wrong but only by the fact that you have the hum it is self-evident to me that you have ANOTHER, additional to the PP2000, path to ground from your system. It has nothing to do with your need of house rewiring and it has nothing to do with quality of wires – it is just a second path that you need to found. You are multi-amping with the refrigerator subs runs own SS amps. If your refrigerator amps and your horn amps referenced to deterrent power grounds then here is a perfect loop for you as they are most likely have single-connectors and this signal grounds are connected via RCA jacks. It is very difficult to trace the ground look without being there but I do feel that it is your loop. If your PP2000 is completely broken then where do you see in it a SECOND path to ANOTHER ground? So, I think that it is externals problem.

jessie.dazzle wrote:

Be sure to connect the chassis of only ONE audio component to the dedicated ground, allowing the other audio components to source ground via the interconnects.

I am very convinced that in Adrian case he has more than one path from his components to ground, the whole definition of “LOOP” suggest that it is NOT only via the PP2000 the system has ground reference. The fact that Adrian lifts ground on power amps and it changes hum only proves the point: in his amps the middle ground wire of the power cords apparently is connected to the amp chasses, which is how all committal amps are done. 

I hate that connection pattern even though it is the most secured from a perspective of faults.  In ALL my equipments I discount the middle ground wire of the power cords from chasses of my equipment where the chasses are connected to the negative terminals of my single-ended RCA connectors. So, my entire playback runs with grounds connected via negative terminals of RCA connectors and all RCAs lead my 11 input Placette preamp. The Placette connection deck acts as main negative bass terminal and the power cable from Placette to power source (would it be a wall of PP2000 or whatever)  is THE ONLY one my reference to ground. I might run Placette power to the power source with all 3 pins or lift ground on the Placette and use the grounding post (on the back of the Placette) connect it to my own custom ground. So far I concluded that to use PP2000’s ground (effectively the wall ground) is preferable for me (better imaging) then to use my own private ground.

Anyhow, what I important in this whoa story is that I have the only one element of my playback connected to ground. If I lift the ground on my Placette then my playback has no reverence to ground of any kind and I did run very successfully my playback for a while with 150V on playback’s ground.

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PostID=6552

It is not what I advise to do but it is an indication that the while system of mine (19 components) is completely floating above any ground if it necessary. So, ground if from a main point is an assurance that it will not be any ground loops.

Romy the Cat wrote:

drdna wrote: Exactly. Thus, it suggests a ground loop internal to the PP2000, doesn't it? In my view it is highly unlikely as a definition of loop itself implies two contacts to ground and PP2000 has only one.  I do not think that you will go anywhere with accusing the PP2000 in humming. If the PP2000 has zero point zero Ohm from input to out grounds, the 500 mV between the neutral and ground and output no DC then I think it is absolutely out of blame. Might be I am wrong but only by the fact that you have the hum it is self-evident to me that you have ANOTHER, additional to the PP2000, path to ground from your system. It has nothing to do with your need of house rewiring and it has nothing to do with quality of wires – it is just a second path that you need to found. You are multi-amping with the refrigerator subs runs own SS amps. If your refrigerator amps and your horn amps referenced to deterrent power grounds then here is a perfect loop for you as they are most likely have single-connectors and this signal grounds are connected via RCA jacks. It is very difficult to trace the ground look without being there but I do feel that it is your loop. If your PP2000 is completely broken then where do you see in it a SECOND path to ANOTHER ground? So, I think that it is externals problem. The Cat

drdna wrote:

3. When the PP2000 is plugged in, the neutral AC connection adds an additional ground reference.

Paul S wrote:

It is confusing, but the NEUTRAL is not only "referenced to ground", but in properly-designed components it is THE ground. If the PP2000 is a 120V device with a 3-prong plug, then it has 2 references to ground within its chassis, depending on how it is configured, and thus it MIGHT be possible for it to contribute to a ground loop or loops. How it winds up using either or both ground connections will be determined not only by its internal configuration but also by the configurations of each and every piece hooked up to it, along with the ultimate configuration of the super-circuit this creates

Antonio J. wrote:

Considering that PP2000 isn't plugged into a dedicated line and that line can be shared by other electric devices plugged into the grid, I wonder if the hum noise is getting into the PP2000 not from the ground wire, but the neutral wire for some defect in other device. Maybe leaving the system on playing music which allows hearing the hum, and making a ride all over the house unplugging electric devices and switching off lights discovers the cause.

Romy the Cat wrote:

I advised you do not plug all your components into PP20000 but to plug all your components into a power strip and then to plug your power strip I not ONE out of PP20000. My rational was is that if the PP20000 introduce some kind of differences of ground potential between the outlet number 1 and outlet number 5 (that I SERIOUSLY doubt but if it is the case then it would constitute a faulty unit) then using just one outlet you will not have this problem.

drdna wrote:

Antonio J. wrote: Considering that PP2000 isn't plugged into a dedicated line and that line can be shared by other electric devices plugged into the grid, I wonder if the hum noise is getting into the PP2000 not from the ground wire, but the neutral wire for some defect in other device. Maybe leaving the system on playing music which allows hearing the hum, and making a ride all over the house unplugging electric devices and switching off lights discovers the cause. This would be disturbing, because this is exactly what the PP2000 is supposed to cure, isn’t it? .... It is interesting to note that even though there is this buzz, I still consider the PP2000 to be a success. To me the buzz is like the clicks and pops on an old record. It can be annoying at some point, but it does not change what piece was recorded or what musicians were performing it. And overall, the improvement to the ability to deliver the Sound is improved. Adrian

Paul S wrote:

"Success" equals better except for added hum?

Paul S wrote:

Any dimmer switches within a mile and a half of the system? Any variable inductors connected anywhere in the house?

Paul S wrote:

Since the system did not hum before, I remain hopeful that the "proper" ground configuration will eliminate the new-found hum.

Paul S wrote:

It still sounds like something either wants bleeding or something like a cable sleeve should be lifted from a chassis that now makes it redundant.

Paul S wrote:

Does PP2000 manual say anything about lifting its ground?

Spoke last night with PurePower people and have good news.

First, after the “agonizing research efforts” (satire) the APS have discovered that source of fuzziness that I reported above and claim that they have a very simple fix that would not require shipping the unit and can be easily performed on a file by an average Moron. That is good but it needs to be verified that it would not kill the Sound.

Second, it is possible that the serial port that that PurePower unit has on the back would be able to turn the unit on and off from PC. If so then I will writhe up a simple telnet window application (I will make is available for whoever interested) and I will be all set with my frustration of remote recording.

Paul S wrote:

Adrian, may I assume that if your unit was finally sorted out, then you would have said as much by now?