Possible grounding issues?

[mosshorn]

Well some excellent news, but still not an answer. I used an RCA to 3.5mm connection with my phone to see if it was causing any of the same issues that my other two devices have been doing (crackling in the DAC, one channel on my TT), and it had both channels, but one was EXTREMELY quiet (the same one on the TT). Perplexed, I flipped it over.....to notice I had my jumper cable down there from the prior troubleshooting! I took it off and both channels came in loud and clear, and no tracking noise from my TT. Dead quiet too. So I'm figuring it's something to do with my DAC, I'm going to try a couple more things and report back with results:


-Change USB cables for the DAC
-move setup closer to computer
-see if running from 3.5mm on computer to RCA on amp resolves anything


EDIT:

From this move, I found out the culprit (at least as far as I can tell) is my own computer (or the sound card I have in, or something else inside it). I swapped everything over, and ran my dac through both USB and optical to see if anything changed. Nothing. So then I unplugged that, and set my RCA to 3.5mm up. Still produced the same noise! It should be noted also that when my DAC is plugged in exclusively to USB (not usb power/optical input) that a clicking noise is also heard.

So now that I've taken the DAC out of the picture, the grounding issue is out (at least I believe the TT/phone resolved this) , and the DAC isn't the issue (resolved by bypassing the DAC itself). I'll try going through a laptop that's plugged in, just to see if I can localize it to my PC individually. If it is that, what would my options be?

Once again, thank everybody for being so helpful.

EDIT 2:

So I finally isolated (as far as I can tell) where the noise is coming from: a ground loop from my amp through my dac to my computer, in particular my power supply. I'm thinking of picking up a ground loop isolator from radio shack (most affordable option at the moment) before class tomorrow to see if that helps. I've heard horror stories of severely degraded performance, but also heard they don't affect the sound at all. Anyone have any experience with these?

[Laudanum]

Yesh, it may very well eliminate some or all "hum" but also the bass, and probably more, with it.   I tried one years ago in car audio installation.  A member here recently tried one as well.   Seems they havent changed much if at all over the years.   Keeping working on a real solution.  The ground loop isolator is probably going to be a bandaid, and not a good one. 

link to recent thread in Seduction forum ... http://www.bottlehead.com/smf/index.php/topic,2491.0.html

[mosshorn]

Worse come to worst I might try one of those cheater plugs, it's worth a shot, as long as it doesn't burn my house down at least

Just tried something else with very unenjoyable results. I thought "hey, what if I isolated the noise by plugging the dac usb power in via an external source, since its data is run via toslink?


Called up Audioengine, guy was like "sure, that would work"

SO I decided to experiment using my phone's charger as the usb psu. Plugged it in, light turned on, no issues. Turn my Crack on, everything seems fine. Plug in headphones and start playing a track, and I'm noticing there's no sound. I adjust the volume pot and touch the metal....

.....and apparently that usb power was still coming, because I got quite the shock (the creepy chill one) coming from my amp. Safe to say, I promptly turned everything off and dismissed that idea. Maybe running a lower current power supply would work (it's specced to 200mA, this one is 700mA, same voltage reading though)

[Jim R.]

Do you have an electrical out let polarity tester?  Do you know if your outlets are wired correctly?  That's certainly not a safe assumption these days.

-- Jim

[mosshorn]

No, but I can ask around to see if someone does. the usb power was plugged in a power strip, so maybe inverting the way it was plugged in would produce a difference?

Also, I'm giving a usb isolator a thought. Since it's just for the power, and not for audio, I don't "think" it would affect quality like a rca based ground loop isolator would.

[Jim R.]

I don't think that will help -- sounds like you may have your house wiring backwards -- hot and neutral reversed -- a unsafe situation no matter what and really not good with audio gear.

Those power supplies are also typically isolated because of the internal transformer, and something just sounds very wrong.

The outlet testers can be had at rat shack or harbor freight for probably $5 or so -- the little gizmos that plug into an outlet and have lights on them to indicate if there is a problem or not.  Every audio person should have one.

HTH,

Jim

[mosshorn]

If I can't find anybody with one, I'll pick one up today or tomorrow Thanks for that idea, if it brings anything to light I'll let you know!

[Laudanum]

The 700ma shouldnt matter as long as the voltage it correct.  The device only draws the current that it needs.   Yep, something isnt right if you are getting shocked by touching the chassis plate.  Definitely check the wiring suggested.  Home Depot and Lowes also sells the simple plug in testers.  Ive seen them at Walmart as well.

[mosshorn]

Thank you so much for the help all! That truly sounds like the culprit, but is there any way to alleviate this situation other than messing with the house's electrical? I don't know if I'll be able to change that.

[mosshorn]

So I figured out the issue (well 99% of it, I hear a very tiny tiny bit left.)

If anyone has these issues:

tighten the screws in your PC. After checking everything as good, I tightened every screw I could find. This allowed for a better ground, and the problem is almost entirely gone (I'll check for more screws tomorrow). Thank you so much for everyone that has helped, I cannot believe how much of a difference this made to my music

[howardnair]

moss-i just can't help myself--i always thought you had a few loose screws!!!!

all in fun--- howie

[mosshorn]

haha thanks