PS Audio PerfectWave DAC

[NekoAudio]

If the bare wire doesn't help (it may just reduce the problem, but not solve it, based on my experience) you can also try using an XLR ground lift adapter. They're a few bucks and you can find them for sale on pro audio web sites. Not sure if your local pro audio shop would carry them.

While you're out shopping, I also suggest buying a tripod for your camera.

[minimus]

I'm hoping somebody can help with with a problem doing this with my PWD.

I am getting hum and noise (not a clean hum) when both my Woo WES is connected via XLR and my EC ZDT is connected via RCA at the same time.

That's a bummer. I heard no noise from the PWD when I used it pretty much the same way. PS Audio is very helpful with technical support, so you might want to run the problem by them for suggestions. They may even send you a new unit to check if the root cause of the problem is their DAC or a ground loop.

[grawk]

That's generous of you to make that offer for them

[HeadphoneAddict]

Thanks guys, I'm gonna head down to the basement tonight to try the wire between amps, after I comfort my son to sleep without his cat. He's one of those "can't sleep without the cat" kids, and we've been drugging him with Benadryl at night while hoping that the cat comes back soon. It's only been a week but my wife mentioned possible "kitty heaven" to him tonight and sent him off the deep end.

If the wire doesn't work I'll contact PS Audio about a possible XLR ground lift adapter and whether that should be next.

[GPH]

"kitty heaven"

I hope I'll end up there too when I die.

[HeadphoneAddict]

I hope I'll end up there too when I die.

It might be better than banking online with First Bank (bunnies).

[HeadphoneAddict]

Well, the wire fixed it for sure. The PWD is now silent with black background, even at max volume on the ZDT/HD800 with the music paused. Thanks guys!

[n_maher]

Well, the wire fixed it for sure. The PWD is now silent with black background, even at max volume on the ZDT/HD800 with the music paused. Thanks guys!

I'm glad the wire helped but the result might imply that something in your system does not have its chassis tied to the earth ground connection (at the IEC socket) or that one of your outlets is not properly grounded. Otherwise all of these things should already be tied together. It might be worth investigating at some point.

[Salt Peanuts]

See, that's what we pay Dan for.

Wait, Dan gets paid?

[grawk]

That wasn't a solution, it was to help isolate where the problem is.

And of course I get paid.

[NekoAudio]

If you don't already have one, I recommend buying a 3-prong outlet tester from your local hardware store. It has little blinky lights on it that tell you if your outlet is wired correctly when you stick it into the socket.

Are you sticking your PWD onto a different electrical circuit?

[HeadphoneAddict]

I'm glad the wire helped but the result might imply that something in your system does not have its chassis tied to the earth ground connection (at the IEC socket) or that one of your outlets is not properly grounded. Otherwise all of these things should already be tied together. It might be worth investigating at some point.

That wasn't a solution, it was to help isolate where the problem is.

And of course I get paid.

Right, I suspect the problem is the ZDT, because if I connect my Travagans Red to the PWD with the WES the noise isn't there. I have crappy iPhone photos of the inside of the ZDT that I took a while ago, after I lost a screw at RMAF. I didn't post these before out of courtesy to Craig, and because sadly I thought they looked closer to Mikhail's work than Woo's. If anyone can see an immediate problem let me know.

Dan, I am in your debt for helping me.

[n_maher]

The ZDT has an external power supply, correct?

And fear not, I see nothing mikhail-esque about that wiring job. It's functional and pretty well laid out (at first glance).

[spritzer]

It's certainly not SP like but there have been issues with EC amps in the past. Now Craig doesn't build any of them (it's all outsourced) but it's hard to see if anything is wrong here.

[cetoole]

Agreed. Good wiring does not necessarily mean it is pretty, and while it might not be a Nugget Audio build, it certainly doesnt look like the Mikhail builds I inspected in Florida.

[HeadphoneAddict]

I just meant in terms of not the wiring not looking like a street map like the Woo amps. I agree it's not really like Mikhail's work, and all the solder points looked nice. But I just thought it would look a little neater.

Yes, the ZDT has an external PSU. I found that without the wire between the two amps, that if I touch one of the screws on the cable plug between the PSU and the ZDT that the hum/noise gets much quieter.

[n_maher]

I'm hardly the expert here but it would seem pretty likely, based on your description, that the amp chassis is floating. If you have a multimeter try testing the continuity between the ZDT amp chassis and the power supply chassis. I would suggest doing this at a screw so that if the probe leaves a mark it won't be noticeable. If the amp chassis is indeed floating I'd talk to Craig about it. It makes me uncomfortable to think about and I don't want to speculate further.

[nikongod]

I just meant in terms of not the wiring not looking like a street map like the Woo amps. I agree it's not really like Mikhail's work, and all the solder points looked nice. But I just thought it would look a little neater.

There are a few schools of thought & "styles" at play here. If you want to get techy I'l pick the other side and well duke it out until we come to an agreement, which will be never.

Woo amps have a very right angle design. EVERYTHING is at right angles. They all use ground bus bars (no star grounds).

The amp you have follows what apperas to be the "shortest wire" design. It looks like there is a star ground point although more of a "x-mas tree" style ground system.

pros & cons.

Having all of your components layed out at right angles makes the layout of the amp a decent bit cleaner looking (visually...) and is MUCH easier to assemble. This is key when the realities of mass production are concerned. taking 10% less time to build its 1 amp more a day in some cases... That is important.

The "shortest wire" camp argues that the shorter wires have lower parallel capacitances, lower inductances, and generally work more like ideal wires than not. The downside is that these amps are MUCH harder to layout and build. They also take more wire to build. A STRONG advantage to this camp is that the layouts easily accommodate modifications on the fly. "hard right angle" layouts are generally too dense to modify mid production or as a custom option. For sure it can be done, just not was easily.

The "ground bus" camp lives and runs on efficiency and "good enough". A well thought out ground bus amp saves a TON of wire which consequentially lowers cost and reduces build time.

The Star ground camp argues that there is 1 ground in the amp. 1, and only one. The star ground point. There are conditions which will throw a ground bus out of whack that have NO effect on star grounds. heh. The downside is that star grounds require a metric assload of wire (half of the wires in a SP amp are grounds) and a ton of time to build.

Somewhere in the middle of those 2 is what is called a Christmas tree ground. Its basically a cross between those 2 ground schools. It tends to act more like a star ground than a ground bus while saving a little wire. On a production piece it is common to see what you can group together without screwing up the amp in the prototyping phase and going from there.

[HeadphoneAddict]

I'm hardly the expert here but it would seem pretty likely, based on your description, that the amp chassis is floating. If you have a multimeter try testing the continuity between the ZDT amp chassis and the power supply chassis. I would suggest doing this at a screw so that if the probe leaves a mark it won't be noticeable. If the amp chassis is indeed floating I'd talk to Craig about it. It makes me uncomfortable to think about and I don't want to speculate further.

I will check that later tonight or tomorrow. Didn't Craig just create a new amp that has a floating chassis and someone said that was a feature, and then others chimed in saying it was not such a great idea?

Anyway, this is straying off topic except that the issue was discovered by connecting two amps to the PWD. If I find the chassis might be floating I'll contact Craig about it, and post a brief note about what he says we should do. Nikongod, thanks for the explanation.

[spritzer]

I'm with Ari here, real star wiring is the way to go though I admit on very large amps (the ESX for instance) it did make sense to use a tree version instead of just piling on wires. As for the SP amps, Mikhail used the chassis a lot for ground wiring on his later amps leading to groundloops from hell. Kevin posted a picture once that showed them in an Extreme he was working on.

[HeadphoneAddict]

I'm hardly the expert here but it would seem pretty likely, based on your description, that the amp chassis is floating. If you have a multimeter try testing the continuity between the ZDT amp chassis and the power supply chassis. I would suggest doing this at a screw so that if the probe leaves a mark it won't be noticeable. If the amp chassis is indeed floating I'd talk to Craig about it. It makes me uncomfortable to think about and I don't want to speculate further.

Well, the chassis appears to be floating and there is no continuity between the ZDT PSU and Amp. With the wire I installed between the ZDT and WES still in place there is continuity between those two amps, as well as between my phono preamp, PWD DAC and the Travagans Red amp that is connected to the WES loop-out. But the ZDT PSU seems to be totally isolated from everything else.

I suppose I'll have to phone Craig and see if this is intentional and/or a problem.

[nikongod]

As for the SP amps, Mikhail used the chassis a lot for ground wiring on his later amps leading to groundloops from hell.

I had not seen this.

Every SP I have seen an internal picture of or poked around in has a dedicated star ground point and no obvious other chassis grounds. Mikhail did always tie signal ground HARD to chassis ground though.

Well, the chassis appears to be floating and there is no continuity between the ZDT PSU and Amp. With the wire I installed between the ZDT and WES still in place there is continuity between those two amps, as well as between my phono preamp, PWD DAC and the Travagans Red amp that is connected to the WES loop-out. But the ZDT PSU seems to be totally isolated from everything else.

Just to make sure, you measured impedance between the various chassis, and got something other than 0?

Call Craig.

[spritzer]

I tried to find the picture on my system but I must not have saved it. If Kevin sees this then he's sure post it. My ES-1 used the chassis and standoffs for the ground wiring (the ground from the PSU was tied to the chassis and not connected to the signal ground).

Edited March 11, 2010 by spritzer

[HeadphoneAddict]

Okay, half of what Craig said to me today was over my head, since I'm a doctor and not an EE. Craig said the ZDT PSU is grounded via the wall plug's 3rd ground pin, and then the ZDT chassis is grounded to the ZDT PSU's 3rd pin ground via "high frequency ground", where there is a resistor and capacitor between the wire and where it is connected to the case.

He says this will appear at first to be floating when I was testing it for continuity, but it isn't. He said that if I want him to install a switch where I can bypass the resistor/capactor he can do that, or I can by pass it myself if I think this is causing an issue, or I can run a wire from the ZDT PSU to the Amp, or from the AMP to WES. Or he said I can try to figure out why the PS Audio PWD is causing the WES and ZDT to not be on the same level when connected at the same time (although it could also be the WES, or my power filter).

So, basically he thinks there is some kind of differential between the WES and ZDT that may be coming from the PS Audio or something else like my power distribution device, and that is why tying the two amps together helps. He suggests that I try a power distribution device without noise filters or noise cancelation stuff (fancy term for simple power strip). And also said I could contact PS Audio if I think their DAC is doing this.

I have spoken with Alex a couple of times at PS Audio, and if changing how everything is plugged into the wall doesn't help I will pass this by him to see if they have heard of anything similar with hum/noise with two amps connected. I have to check back with him anyway because they put the warranty down as expiring 3/2/12 instead of 8/29/12, and I need them to update it for the extra 6 months I am missing.

So, this weekend I will try a few more things and report back.

Sorry I am so ignorant about this stuff, but not everyone who uses the gear knows how it works in order to enjoy it. I still can't understand how a computer knows what a 1 or a 0 is, and makes a "decision" to do anything. It all seems magical to me. (Techy peep says, "Well, see if it sees a one, it opens a gate"... "Interrupting here, but how does it see anything? Does it walk over and say, let me get that door for you?", "No, it sees a signal"... "Stop, how does anything know to send a signal?" "If you'll let me explain, there are 0's and 1's..." "Um, How does it know the difference between a 0 and 1?" - it's a chicken and egg thing to my mind, so don't worry, you don't have to explain it to me here, I'm too stupid to get it. )

[blubliss]

So how does it sound?