[pjchappy]

I just got a mini-RCA to RCA plug from BlueJeansCable.com.  I got it in order to mix my songs in HD, as I don't have a HD DAC.  I currently do a rough mix on headphones, mix down to 16/44, listen, then tweak.  It's a PIA.

Anyways, I plugged the new cable in today and immediately noticed hard drive/PC noise (even noise when I simply scroll my wireless mouse), even with the preamp/USB DAC (Peachtree Nova) off!  I unplug the cable and the noise disappears.  Could there be a fault with the cable?  Also, I don't see how the noise could get through with the preamp off.  Could this be a sign of a specific problem?

The PC soundcard is stock and integrated. . .but it is a high-end motherboard (ASUS Crosshair IV Formula).  As I said, I just want this cable to mix my songs in HD.  Other than that, my PC music setup is dead silent. 

I don't have another such cable to swap out. 

I really don't want to have to get a HD DAC at this point. . .but if I can't solve this problem, I may have to go that route, damnit.

Here's my setup:
PC (digital, via USB) --> Peachtree Nova (via USB) --> miniDSP --> amps

Here's the noisy setup:
PC (analog, via mini RCA)--> Peachtree Nova ) --> miniDSP --> amps

Thanks!


Paul

[Nels Ferre]

Just a guess, it seems to me that you are getting interference from your sound card's mini jack that you aren't getting from USB- probably due to the Nova's excellent noise rejection and isolation characteristics on the USB input.

[pjchappy]

Just did an experiment.  Plugged the mini-RCA to the headphone out jack on the PC.  Got the same noise as the mini-output on the back.  Plug in headphones to the PC's headphone jack and didn't have any of that noise. . .

[pjchappy]

OK. . .finally got around to trying a different set-up.

PC --> (via USB) E-MU 0404 (pro audio USB interface) --> (via mini to standard RCA cable) Preamp

I STILL get PC noise with this set-up.  This induces noise in the system on ALL the preamp input options (not just when the mini RCA input is selected).

If I listen to the E-MU via headphones (taking the preamp out of the equation), I get NO PC noise. 

I don't understand why it would be doing this.


Paul

[lcrim]

Paul:
I have never heard the term, HD DAC, what is it?
The noise is probably the motor in the drive.  The circuits are probably not shielded.

[pjchappy]

Sorry. . .should have said a hi-res DAC (24/192).

I get noise when simply scrolling my mouse, too.  Also, I get noise when the standard drives are in sleep mode, as I also have a solid-state drive for the OS.

Should I just try a different cable (the Blue Jeans cable appears to be shielded, too).

Again, I just don't understand why it is so noisy when connected to the preamp, but no noise when using the headphone jack on the interface.  Regardless, I need to figure out how to get rid of this noise. . .and the fact that it exists with this set-up still confuses me.


Paul

[skunark]

Is everything plugged into the same circuit/PLC?   If not give that a go.  If you have access to a UPS can you try running everything on the battery to make sure there's no ground loop issues.  i.e. TV/Broadband modem on same circuit with improper ground.

[guest4954]

Could it have to do wth source impedance matching difference between a headphone (around 300 Ohm) and a pre-amp (xk Ohm?.
Most probably the e-mu is made for an headphone and not for a pre-amp.

my 2cts.

Michiell

[Vincent Kars]

Looks like you don't have the noise if you connect to something without a PSU like a headphone and do have the noise when you connect to something having a PSU.
This might indeed be a ground loop issue as Skunark suggested.
Try same outlet or lift the ground or use a cheater plug etc.

[pjchappy]

Thanks.

With my set-up, I can't try other outlets. . .but I will try a cheater plug for the PC and/or the preamp.

FYI - the preamp and E-MU are plugged into a power conditioner with isolated outlets (a Belkin unit); the PC is plugged into a Tripp-Lite Isobar.  I'm 90% sure the E-MU just has a 2-pronged power plug.  I will check this weekend.

I'm not using the headphone output of the E-MU into the preamp.  The E-MU has separate preamp outputs.

Doesn't a ground-loop issue just induce hum?  If so, that is not the noise I am getting.


Paul

[Russtafarian]

I had the same noise problem with an HP laptop.  Lifting the ground on the laptop's power supply fixed it.

[skunark]

Thanks.

With my set-up, I can't try other outlets. . .but I will try a cheater plug for the PC and/or the preamp.

FYI - the preamp and E-MU are plugged into a power conditioner with isolated outlets (a Belkin unit); the PC is plugged into a Tripp-Lite Isobar.  I'm 90% sure the E-MU just has a 2-pronged power plug.  I will check this weekend.

I'm not using the headphone output of the E-MU into the preamp.  The E-MU has separate preamp outputs.

Doesn't a ground-loop issue just induce hum?  If so, that is not the noise I am getting.


Paul

There are several causes for the noise, it's just that ground loops are the most common, and moving everything to the power strip is a very common solution along with a properly grounded coax cable at the entry of your residence.    You might also check all the cables, keyboard, mouse, etc to make sure they are not frayed (i.e. pet likes to chew on stuff).   Also do make sure you have the latest video drivers, sound drivers, motherboard firmware etc.   It's amazing what a memory leak in software can do

[pjchappy]

OK. . .I now have a cheater plug on my PC.  The noise has SIGNFICANTLY bene minimized. . .more of just a hum now!   I did also did plug in the E-MU into the Tripp-Lite (where the PC is plugged in - regardless, the noise is there if the power cord is disconnected from the E-MU), only so I could use a much shorter USB cable.  SOOO, I'm not sure which stopped that noise (the shorter USB cable vs. the cheater plug), but I have a feeling it was the cheater plug.

Again,I do have a slight hum that I would attribute to a ground-loop.  Although it is very minimal, I may be willing to tear my system apart today to track it down.  Again, this hum is very slight. . . and I only need this set-up for mixing.  So, I could live with it. . .and pretty much any volume out of the speakers masks it.  Nevertheless, I'm up for some more pointers.

Oh, checked all my cables and they appear to be fine.  (The keyboard and mouse are wireless, too).

As before, the noise (slight num now) is present regardless of which input on the preamp is selected. . .and even when the PREAMP AND the E-MU are powered down AND the power cables are UNPLUGGED.  It completely goes away when I unplug the IC from the E-MU.  I also just discovered the noise completely goes away if I disconnect the PC to TV/monitor HDMI cable. 


Paul

[pjchappy]

Edit:  Didn't have my amp on.   Noise still there.


Paul

[skunark]

OK. . .I now have a cheater plug on my PC.  The noise has SIGNFICANTLY bene minimized. . .more of just a hum now!   I did also did plug in the E-MU into the Tripp-Lite (where the PC is plugged in - regardless, the noise is there if the power cord is disconnected from the E-MU), only so I could use a much shorter USB cable.  SOOO, I'm not sure which stopped that noise (the shorter USB cable vs. the cheater plug), but I have a feeling it was the cheater plug.

Again,I do have a slight hum that I would attribute to a ground-loop.  Although it is very minimal, I may be willing to tear my system apart today to track it down.  Again, this hum is very slight. . . and I only need this set-up for mixing.  So, I could live with it. . .and pretty much any volume out of the speakers masks it.  Nevertheless, I'm up for some more pointers.

Oh, checked all my cables and they appear to be fine.  (The keyboard and mouse are wireless, too).

As before, the noise (slight num now) is present regardless of which input on the preamp is selected. . .and even when the PREAMP AND the E-MU are powered down AND the power cables are UNPLUGGED.  It completely goes away when I unplug the IC from the E-MU.  I also just discovered the noise completely goes away if I disconnect the PC to TV/monitor HDMI cable. 


Paul

TV?    Disconnect the antenna/cable tv coax from the TV, if you have a cable box fully unplug it as well.  Key thing is to fully remove the antenna/cable TV out of the system.    My guess now is your antenna/cable tv isn't properly grounded/isolated when it enters the residence

[pjchappy]

TV?    Disconnect the antenna/cable tv coax from the TV, if you have a cable box fully unplug it as well.  Key thing is to fully remove the antenna/cable TV out of the system.    My guess now is your antenna/cable tv isn't properly grounded/isolated when it enters the residence

Tried this earlier (forgot to mention), with no luck.

I also tried reversing the polarity of the E-MU plug (and the cable box plug, prior to complete removal).  These are the only 2-prong plugs in my system.

Also, to be clear regarding my edit post above, I had thought the noise disappeared by moving the Tripp-Lite and associated plugs to another outlet.  It didn't.  The noise is the same as before and is affected the same by the cheater plug on the computer.


Paul

[skunark]

Probably time to give Jensen Transformers a call then.
http://www.jensen-transformers.com/
http://www.jensen-transformers.com/an/ts_guide.pdf

You computer might have a noisy power supply in your PC and could be leaking through the ground of the USB cable even though it should be isolated.    You can probably pick up one of their unbalanced audio isolators at a local stereo store to separate your PC/E-MU from your stereo, might try to "demo" it if you can.

[NekoAudio]

Are you using the MSA-1 audio cable that Blue Jeans Cable sells?

Make sure both RCA connectors are in use (if one of them is floating, you have an ungrounded antenna).

You'll also want to make sure all of the grounds are actually connected properly. This includes your sound card outputs and your preamp inputs. You could try running wires from the RCA connector shields and the 1/8" stereo shield to a chassis ground like a PC power supply screw and see if that does anything.