Ground Loop DAC Issue

S

Space2013

Junior Audioholic
I have a pair of JBL 305 and a passive controller. I’ve been using a Schiit Modi 2 Uber which I love. However I’m getting some ground loop issues that I cannot seem to solve. Currently the setup is Computer (Laptop) -> Modi 2 Uber -> Passive Controller -> JBL. But often when another grounded device, such as an eGPU or my monitor, is hooked up, I get a high pitched hum. If I remove the power from the Modi 2, it is gone. I’m at a loss. I’ve read a ton of guides on ground loops, made sure everything was in the same outlet, tried different outlets, etc. My only work around is using a Toslink connection from the computer to the Modi 2 as I get no hum, but I’d like to use the USB input. Is it maybe because the Modi 2 uses a two prong power adapter?
 
Kvn_Walker

Kvn_Walker

Audioholic Chief
I have the same problem with my Marantz HD DAC1. USB or Coax gives me a ground loop, so I just revert to Toslink. The Marantz doesn't have a ground plug.

I spent many, many hours and a little chunk of change before I gave up. Switching outlets, buying a line conditioner, plugging different components into different plugs, new Seasonic 80+ Platinum power supply for the computer, you name it. Ultimately, nothing worked. Even the Ground Lift switch on my amp didn't work. Using a "cheater cord" on the amp makes it go away, but I'd rather not defeat my equipment's safety features.

Either this house we're renting has some weird wiring issues, or the problem lies within my computer itself.

All that said, you stand a possibility of driving yourself literally mad trying to hunt this thing down. Try everything you can think of, and everything you can't. I wish you the best of luck.
 
DigitalDawn

DigitalDawn

Full Audioholic
I have a pair of JBL 305 and a passive controller. I’ve been using a Schiit Modi 2 Uber which I love. However I’m getting some ground loop issues that I cannot seem to solve. Currently the setup is Computer (Laptop) -> Modi 2 Uber -> Passive Controller -> JBL. But often when another grounded device, such as an eGPU or my monitor, is hooked up, I get a high pitched hum. If I remove the power from the Modi 2, it is gone. I’m at a loss. I’ve read a ton of guides on ground loops, made sure everything was in the same outlet, tried different outlets, etc. My only work around is using a Toslink connection from the computer to the Modi 2 as I get no hum, but I’d like to use the USB input. Is it maybe because the Modi 2 uses a two prong power adapter?
By any chance do you have a cable box hooked up to the system? We run into a lot of ground-loop, cable line issues and we diagnose them by removing the cable box and/or RG cable from the back of the cable box.

Once we have confirmed it's the cable line, we either have the cable company fix the problem or use a Jensen Transformers VRD-1FF.
 
S

Space2013

Junior Audioholic
By any chance do you have a cable box hooked up to the system? We run into a lot of ground-loop, cable line issues and we diagnose them by removing the cable box and/or RG cable from the back of the cable box.

Once we have confirmed it's the cable line, we either have the cable company fix the problem or use a Jensen Transformers VRD-1FF.
Unfortunately no cable lines. It was just the computer, monitor, DAC, and speakers. Network connection was Wi-Fi for the laptop. I tried two different computers (one is an MacBook Pro and one a custom built desktop), both of which have a hum/whine. It’s quieter on the desktop and only present on the laptop when another grounded device is added (like my monitor).The hum stops right away on both computers if I remove the power adapter from the Modi 2.
 
slipperybidness

slipperybidness

Audioholic Spartan
I have a pair of JBL 305 and a passive controller. I’ve been using a Schiit Modi 2 Uber which I love. However I’m getting some ground loop issues that I cannot seem to solve. Currently the setup is Computer (Laptop) -> Modi 2 Uber -> Passive Controller -> JBL. But often when another grounded device, such as an eGPU or my monitor, is hooked up, I get a high pitched hum. If I remove the power from the Modi 2, it is gone. I’m at a loss. I’ve read a ton of guides on ground loops, made sure everything was in the same outlet, tried different outlets, etc. My only work around is using a Toslink connection from the computer to the Modi 2 as I get no hum, but I’d like to use the USB input. Is it maybe because the Modi 2 uses a two prong power adapter?
Why are you so hung up on using the USB input?

Especially considering that the USB gives you hum, while the optical input resolves the problem???

Use the optical input and be done with this non-sense!

EDIT-- "High Pitched Hum" does NOT suggest "Ground Loop Hum"........Ground Loop Hum is a distinct 60Hz, the same frequency as the mains power.

I will tell you from personal experience, USB connections suck! I have had many problems due to USB.....granted that most of my problems have been in industrial applications. But, my experience and headache with USB has absolutely driven me to choose USB when it is the ONLY option available.

USB has 2 advantages:
1) It is ubiquitous and easy to plug in
2) It carries power on the same connector as the signal

One question for you, How long is your USB cable?

From Wiki:
The USB 1.1 standard specifies that a standard cable can have a maximum length of 5 meters (16 ft 5 in) with devices operating at full speed (12 Mbit/s), and a maximum length of 3 meters (9 ft 10 in) with devices operating at low speed (1.5 Mbit/s).[77][78][79]

USB 2.0 provides for a maximum cable length of 5 meters (16 ft 5 in) for devices running at high speed (480 Mbit/s).[79]

The USB 3.0 standard does not directly specify a maximum cable length, requiring only that all cables meet an electrical specification: for copper cabling with AWG 26 wires the maximum practical length is 3 meters (9 ft 10 in).[80]
 
highfigh

highfigh

Audioholic Overlord
I have a pair of JBL 305 and a passive controller. I’ve been using a Schiit Modi 2 Uber which I love. However I’m getting some ground loop issues that I cannot seem to solve. Currently the setup is Computer (Laptop) -> Modi 2 Uber -> Passive Controller -> JBL. But often when another grounded device, such as an eGPU or my monitor, is hooked up, I get a high pitched hum. If I remove the power from the Modi 2, it is gone. I’m at a loss. I’ve read a ton of guides on ground loops, made sure everything was in the same outlet, tried different outlets, etc. My only work around is using a Toslink connection from the computer to the Modi 2 as I get no hum, but I’d like to use the USB input. Is it maybe because the Modi 2 uses a two prong power adapter?
There's no such thing as a high pitched hum- hum is caused by line voltage (usually) and is lower in frequency. Buzz is what constant high pitched noise is called and if a computer is involved, it's almost always caused by the power supply, especially if it's a 'brick' on the power cord. Try using another USB cable, move the cables away from the computer and power supply and if they must cross paths, do it at a right angle. In some cases, the screen on the computer causes this kind of noise.
 
Kvn_Walker

Kvn_Walker

Audioholic Chief
EDIT-- "High Pitched Hum" does NOT suggest "Ground Loop Hum"........Ground Loop Hum is a distinct 60Hz, the same frequency as the mains power.
Even though the noise I hear is directly through the tweeter, I can say with certainty it is somehow related to a grounding situation. TOSLINK carries no noise, whereas Coax and USB (both chassis-grounded connections) cause the noise. Using a cheater cord with the amplifier also makes it go away, but that again takes the ground out of the equation. I don't know if the OP's situation is identical to mine, but I exhausted myself mentally trying to hunt it down.

It's more like a "whine" than a "hum"... I haven't tried replacing the CPU fan yet. But again, I got tired of dealing with it.
 
S

Space2013

Junior Audioholic
Why are you so hung up on using the USB input?

Especially considering that the USB gives you hum, while the optical input resolves the problem???

Use the optical input and be done with this non-sense!

EDIT-- "High Pitched Hum" does NOT suggest "Ground Loop Hum"........Ground Loop Hum is a distinct 60Hz, the same frequency as the mains power.

I will tell you from personal experience, USB connections suck! I have had many problems due to USB.....granted that most of my problems have been in industrial applications. But, my experience and headache with USB has absolutely driven me to choose USB when it is the ONLY option available.

USB has 2 advantages:
1) It is ubiquitous and easy to plug in
2) It carries power on the same connector as the signal

One question for you, How long is your USB cable?

From Wiki:
The USB 1.1 standard specifies that a standard cable can have a maximum length of 5 meters (16 ft 5 in) with devices operating at full speed (12 Mbit/s), and a maximum length of 3 meters (9 ft 10 in) with devices operating at low speed (1.5 Mbit/s).[77][78][79]

USB 2.0 provides for a maximum cable length of 5 meters (16 ft 5 in) for devices running at high speed (480 Mbit/s).[79]

The USB 3.0 standard does not directly specify a maximum cable length, requiring only that all cables meet an electrical specification: for copper cabling with AWG 26 wires the maximum practical length is 3 meters (9 ft 10 in).[80]
It is higher pitched, so I suppose more of a whine or buzz than a hum. I'm using USB because I have three devices to plug into the DAC, and the DAC has three inputs (optical, coax, and USB). So it would be easiest to use USB, but I can get an optical switch and just route them all through optical.

What is odd is the high-pitched whine happens when I plug the Modi 2 into either of my two computers via USB. Here are the situations:
  1. If I plug the Modi 2 into the laptop with nothing else plugged into the laptop, I get no noise.
  2. If I plug another grounded device into the laptop, such as a monitor or an eGPU, then I get the whine.
  3. If I plug the Modi 2 into my desktop computer (which is grounded) I also get the whine.
  4. The Modi 2 does not whine when it is hooked up to the speakers by itself (not connected to a computer).
  5. There is no whine if either computer is hooked up to the Modi 2 via optical.
In scenarios 2 and 3 the whine stops if I unplug the Modi 2 power adapter. The whine also changes pitch when I change inputs on the Modi 2 (even if nothing is plugged into the other inputs).

Obviously I have a work around (use optical and get an optical switch), but I just thought I'd ask here first incase anyone had any ideas I have not thought of. :)

The USB cable is fairly short. I think 3-6 feet.
 

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