?Noisey PWD DAC II > CJ ET3SE

[medward0]

Happy New Year everyone!

In my quest to remove noise from my system, I've been doing a lot of troubleshooting. I love my Sophia's, but they reveal everything and that is good and bad.

The net is that using the PWD DAC as the source on any preamp input creates a preamp volume-dependent buzz that sounds like a ground loop hum. It is very noticeable when the pre volume is above 20, but virtually inaudible with the volume at 2. Ironically, using the iPod, the cable TV, or FM tuner as source results in (near) zero noise, even with the pre turned waaay up. My other DAC has no noise at all.

I've tried just about everything I could think of and cannot get rid of this noise (see the list below).

I know that at least one on the forum have the PWD into a CJ preamp (Vhiner), but I don't know how to contact other than to post.

Have others had this issue with the PWD into a CJ preamp?

Is this likely just one of those horribly frustrating ground loop issues? I've never heard a ground loop noise that increased with volume before, but I suppose that the pre could just be amplifying the noise.

I'm beginning to wonder if the PWD needs to go back for evaluation at PS Audio.

Thoughts?

Thanks,
ed

Here's what I have tried:

• Hum buster x on the DAC power cord, no change
• Hum buster x on the Preamp, no change
• Various combinations of Hum busters on the power cords
• Different interconnects from DAC > Pre, no change
• Rerouting cables, no change
• Different power cords, no change
• Using different preamp inputs for the DAC, no change
• Turning up or down the output volume from the DAC, no change
• Hooking the DAC directly into the amp, caused a very nasty pulsing noise from the amp...no music. ?

I finally solved the ground loop issue with my amp, but that involved using a Hum Buster X on the amp power cord, which limits current. I hate to limit current…

[Coppy]

You'll want to isolate the component(s) in your system that's leaking AC back through your system. You may have done all this but here's how I would proceed:
Connect the power amp to your speakers with no input. Turn it on.
If there's no hum, connect the preamp. If there's hum, lift the ground on the preamp. If not connect each source, separately, one at a time. When you get to the item causing the hum, lift the ground on that component. That should solve your problem. You may want to check with the manufacture of the offending item about running it with the ground lifted but most don't seem to care. c-j has ok'd my ground lift on their amps in the past.

Good luck.

[Saab77]

I had an ET3SE and ET250S and had the same issue( Recently ,the ET5 and Prem 350- hum persists ) . I had executed the drill of unplugging all the components and adding 1 component into the chain at a time. I found that the offenders ,in my case, were my Oppo BDP 95- (which I only use for SACD/Blu Rays) and the plasma TV. I havent worked around to find a solution for this , but when I listen to music, I unplug these 2 culprits and have the M-Dac feeding the Preamp and NO NOISE . ]

I know this isnt a solution , but I just thought I'd mention this to clarify that this is not the fault of the CJ gear. Something about the grounding issues of these componenets doesnt match well with the audio chain .

Regards
Sabu

[Coppy]

Saab7,

Just lift the ground on the two offenders, You might also lift the ground on your P350 and see if that doesn't solve the problem. I lift the grounds on all my c-j power amps to good effect.

[Saab77]

Sorry to ask a total newbie question, but how do I lift grounds on a device ?
Thanks
Sabu

[Vhiner]

Ed,

You might try plugging the 350 into a dedicated receptacle and then defeating the ground on that receptacle. This will allow you to avoid the nasty cheater plug which I personally find degrades the amplifier's sound. As long as the 350 is then connected to other equipment that is properly grounded, you should be fine and the hum will likely disappear.

[Coppy]

Originally Posted by Vhiner

Ed,

You might try plugging the 350 into a dedicated receptacle and then defeating the ground on that receptacle. This will allow you to avoid the nasty cheater plug which I personally find degrades the amplifier's sound. As long as the 350 is then connected to other equipment that is properly grounded, you should be fine and the hum will likely disappear.

Vhiner may have meant "and then defeat the ground on the amplifier". Sounds dangerous to entirely defeat a ground on an entire "mains" outlet. If it bothers you the cheater can be eliminate by sniping off the ground prong on the amp power cord. Don't like that much... especially on that 20 amp cord. My amps go into a non current restricting Shunyata conditioner and then into a dedicated 20 amp line. Anyway, just loose the ground on that amp.

Good luck,
Bob

[medward0]

Thanks everyone.

I've been working with the DAC mfg (PS Audio) on this noise issue. They want me to send it in for repair...there are some other symptoms that have come up recently. I'm relieved that there might actually be something wrong with the device as I'm losing my mind on this noise issue.

I've tried a bunch of things, re:cable TV. My HT and 2Ch are on two different dedicated outlets, so I've tried unplugging the HT from the pre, unplugging the HT from the wall, put a ground thingy (?) on the cable line, unplugged the cable box from the power, etc. None of those helped the DAC noise issue.

So, right now, it looks like I have an errant DAC to get fixed.

On lifting the ground on the CJ amp...I did that when I first got the amp, but I really am keen on the Shunyata power cords and I didn't want to use a cheater plug or cut off the cord's ground prong. So, I've been using a Hum Buster X, which tames the noise, but is current limiting...it's all tradeoffs, isn't it?

[Coppy]

medwardo... why not try the cheater plug? The c-j folks say it's okay to do as necessary and won't harm your equipment.

[medward0]

@coppy...something about putting a .99 cent cheater plug on the business end of a very expensive power cord makes me fret (a little OCD, I am) and think that I'm not getting my bang from the expensive power cord.

Of course, a Hum buster is hardly a reference component....

Also, it drives me crazy that I have to use a cheater plug on an $8K amp. You know...audiophile nervosa.