Mixer Audio Problem

[IceNine]

Hello people of LLT forums! I'm looking for help from the audio enthusiasts and professionals that may be out there in the world! I have run into an issue regarding my audio set up. I will first give a list of the materials used, say how they have been connected, then give a brief description of the issue.

 

Set Up:

-Asus Maximus IX Hero mother board

-Sennheiser HD7 DJ headphones

-Behringer Xeynx 302USB Mixboard/Preamp

-Antlion Mod Mic 5.0

-A few 3.5mm to Stereo RCA splitter cables

 

Connections:

The goal of my audio set up was to receive audio to the headphones while being able to monitor the microphone in real time. The groundwork for this project what laid out in another LTT forum post which I have been able to find again. In my set up, A 3.5mm to RCA cable runs out of the audio output on the motherboard (which uses on board DAC, enthusiasts please don't eat me Dx). The RCA runs into the Line In 1 of the mixer. A second RCA to 3.5mm cable runs from the main mix output of the mixer to the mic input on the motherboard. The Mic and Headphones then connect in their respective 3.5mm inputs/outputs on the top right of the mixer. The button to the right of the red one is pressed so audio from line 1 does not pass back to the mic input on the motherboard and Mic input from the Mod Mic is input instead. The mixers power is connect to the wall via the included USB to Wall adapter and cable. This allows for mic monitoring with zero latency as well as a full control over the audio experience. Quite fantastic, thank you to the forum poster out there who helped me achieve this.

 

The Problem:

To an enthusiast, EVERYTHING WILL ALWAYS HAVE A PROBLEM. Nothing will ever work exactly as we want it. But that's what makes an enthusiast an enthusiast. Its the pursuit of perfection and ironing every last detail out no matter how small to achieve the best possible experience. My problem lies somewhere on this extreme scale of 1st world problems. Unfortunately, the Mod Mic is so quiet that I have to boost mic input, gain, or headphone levels in order to monitor it as I want to (which is quite loud considering the goal of it is to keep my voice volume down during the night). As a result I have Mic input set to 80%, Gain set to 80%, and headphone output set to 30% on the mixer because I find these settings give minimal status and distortion. Unfortunately I mean minimal with a grain of salt... At this volume there is a background hum (which is separate from the background static) that persists through the Mic Monitoring set up. This hum has a few odd characteristics... which I will list because lists are great...

 

The Problem's... Quirks:

-The hum is completely eliminated when touching a connection with bare skin on the mixer, mic, or headphones (but not the motherboard or computer) This includes occupied inputs, Occupied output, unoccupied inputs/outputs, the mic wire extension housing (exposed metal at connection), and even the USB power.

-The same does not work when touching these parts with a piece of metal that is not touching human flesh...

-If the Mic cable is near the keyboard, it will make a high pitched humming sound (this will not happen with any other cable) *I'm told LED controllers are notorious for making these kind of noises*

-The same noise will occur if hands are hovering over the keyboard... which continues but to a much much lesser degree if the mic is moved away from the user.

-Touching the exposed metal like before eliminates the humming from the keyboard and the background hum.

-Bringing the mic cable close to a power cable or wall outlet increases the hum. Touching the connectors still reduces the hum but not 100% (maybe 5% of it is still audible) *not a problem just adding info*

-While not a solution connecting the headphones and microphone to the motherboard and using "Listen to device" in Windows has no background hum (This was more of a proof of concept to show that the blame does not fall soley on the mic.

-With no mic plugged into the mixer, there is none of the same hum in the headphones even when cranked to 100% (Proof of concept for the mixer... problem in the cable? Then why would touching the mixer's connection eliminate it??)

-When using the Mod Mic's inline mute piece set to mute, the hum is completely eliminated

 

Solution?:

I'm very dumbfounded on this one guys and girls... I currently have the computer plugged into a wall outlet and the mixer plugged into a powerbar that draws from the outlet directly below it. I have tried moving the mixers power adapter to a completely different outlet in the room with no change to the hum. I am beginning to think it is some sort of grounding problem. I had researched and found something called a "ground loop" that occurs when two grounds have separate voltages in a house hold. I decided to give it a shot and bought a 3.5mm to 3.5mm ground loop isolator from amazon. I plugged it into the mic end but the humming persisted even louder and the microphone did not work. I have that now taken out of the set up. I did however try it on the headphone output and the motherboard output with no help there either. I'm a bit dumbfounded. My next idea is to buy a ground loop isolator for the USB connection but that is a bit more expensive and I'd rather not throw money away. 

 

Conclusion:

So there you go members of the LTT forum. In situations where everything seems hopeless, no one makes it work better than people who have seen Linus perform... I call out with a plea to those in the community, help me achieve my enthusiast perfection! I will be watching this thread to answer and additional information or replies as quickly as possible. Thank You!

 

-IceNine

 

 

[Sir Asvald]

I've got the same Mixer. 302usb. I had work with it get what what I wanted out of it. I've got a Phantom powered MIC connected to the XLR and I've got RCA to 3.5mm coming from my PC to the mixer.For the mic. Have you set the gain and the volume? What I did, I completely turn off the gain but increase the volume of the mic and increased the volume and gain in the Windows audio settings.

[IceNine]

Just now, Abdul201588 said:

I've got the same Mixer. 302usb. I had work with it get what what I wanted out of it. I've got a Phantom powered MIC connected to the XLR and I've got RCA to 3.5mm coming from my PC to the mixer.For the mic. Have you set the gain and the volume? What I did, I completely turn off the gain but increase the volume of the mic and increased the volume and gain in the Windows audio settings.

Unfortunately, the Mod Mic seems to be pretty quiet out of the box. I have the Gain set at the second tick from max (directly facing right) and the volume in the same place (directly right). With gain completely down and volume max, I'm unable to sufficiently hear the monitoring until the headphones are turned up so high that the static from amping the headphones becomes more of a problem and the humming is still easily heard as well. Adjusting the volume and gain in windows additionally wouldn't help because I am not running the audio through Windows back to my headphones. Doing so would add latency. I do appreciate your comment though \o/ Thank you for the swift reply!

[Sir Asvald]

28 minutes ago, IceNine said:

Unfortunately, the Mod Mic seems to be pretty quiet out of the box. I have the Gain set at the second tick from max (directly facing right) and the volume in the same place (directly right). With gain completely down and volume max, I'm unable to sufficiently hear the monitoring until the headphones are turned up so high that the static from amping the headphones becomes more of a problem and the humming is still easily heard as well. Adjusting the volume and gain in windows additionally wouldn't help because I am not running the audio through Windows back to my headphones. Doing so would add latency. I do appreciate your comment though \o/ Thank you for the swift reply!

I see. Unfortunately. I don't know about mod mic. If you want a better sound and audio quality. Go for an XLR Mic.  

[anothertom]

So everything you're saying is suggesting two things.

 

1. There's a ground loop between the mixer and the computer. You said the mixer is powered from a different socket to the computer, but it's powered over USB, so how have you managed that?

 

2. The modmic using an unbalanced connection. This allows the emi from other devices to be picked up into the audio. Nothing you can do other than keep it away from anything electrical on your desk.

[IceNine]

22 minutes ago, anothertom said:

So everything you're saying is suggesting two things.

 

1. There's a ground loop between the mixer and the computer. You said the mixer is powered from a different socket to the computer, but it's powered over USB, so how have you managed that?

 

2. The modmic using an unbalanced connection. This allows the emi from other devices to be picked up into the audio. Nothing you can do other than keep it away from anything electrical on your desk.

The mixer came with a wall adapter for the USB much like a phone wall charger so I had tried plugging it into both a separate wall outlet and the same wall outlet as the computer. If this made a difference, it was likely undetectable by ear's alone. Would you advise buying a usb ground loop isolator? Also, I'm no where close to an expert but the connector on the mod mic is TRS Tup Ring Socket. I was under the impression that TRS was balanced and TS Tip Soclet was unbalanced. If I'm wrong than I would guess that the wire picking up emi is the most likely case but I don't understand why using my finger as a ground eliminates this and why hovering my hand over the keyboard causes interfere just like placing the mic wire over it. Thank you for your reply! I'll be around for any follow up questions!

[anothertom]

17 minutes ago, IceNine said:

Would you advise buying a usb ground loop isolator?

I would advise using it as a USB mixer, so connect it to your computer. This means you don't need either the line in or line out from the computer as it can Ben set as both a playback device and as a recording device. This will eliminate any interfer nic on those lines.

 

19 minutes ago, IceNine said:

I was under the impression that TRS was balanced and TS Tip Soclet was unbalanced

The easiest way to think about it is that a cable itself isn't balanced, but an output can be balanced. A cable with three conductors can carry a balanced signal, but if the output outputs a single ended signal then that's what it will carry. The modmic doesn't output a balanced signal, so a cable can't magically convert it to one. This is what's picking up the emi.

 

25 minutes ago, IceNine said:

I don't understand why using my finger as a ground eliminates this and why hovering my hand over the keyboard causes interfere just like placing the mic wire over it.

Using yourself as a ground will eliminate the ground loop as the mixer probably isn't grounded through the wall plug, as most USB wall adapters don't properly ground the output. There is probably some interaction of magnetic fields going on, made worse by the lack of ground and using unbalanced connections.

[IceNine]

13 hours ago, anothertom said:

I would advise using it as a USB mixer, so connect it to your computer. This means you don't need either the line in or line out from the computer as it can Ben set as both a playback device and as a recording device. This will eliminate any interfer nic on those lines.

 

The easiest way to think about it is that a cable itself isn't balanced, but an output can be balanced. A cable with three conductors can carry a balanced signal, but if the output outputs a single ended signal then that's what it will carry. The modmic doesn't output a balanced signal, so a cable can't magically convert it to one. This is what's picking up the emi.

 

Using yourself as a ground will eliminate the ground loop as the mixer probably isn't grounded through the wall plug, as most USB wall adapters don't properly ground the output. There is probably some interaction of magnetic fields going on, made worse by the lack of ground and using unbalanced connections.

I did attempt plugged the USB into both a space on the motherboard directly and on the front IO of the case. Neither helped the situation with the humming and plugging into the back of the motherboard increased a bit of background static. Is there any way for a cable to pick up less emi? Some sort of aftermarket cable extension with a more resistant housing? I understand that a ground loop might be to blame, would you suggest a ground loop isolator for the USB power connection of the mixer?

[anothertom]

Is your computer grounded? You should be using both a properly grounded socket and three prong plug.

 

If you move the mixer so that the USB cable to the PC (to front or rear I/O) is not near any other cables do you still get the noise?

[anothertom]

6 hours ago, lw88 said:

Your problem is behringer. Sorry, not fixable.

That's very unhelpful and not the slightest bit true.

[IceNine]

On 8/17/2017 at 9:55 AM, anothertom said:

Is your computer grounded? You should be using both a properly grounded socket and three prong plug.

 

If you move the mixer so that the USB cable to the PC (to front or rear I/O) is not near any other cables do you still get the noise?

Hopefully I didn't kill my own thread by waiting too long. The PC is plugged in with the proper power supply cable (3 pined) into its own wall socket (no use of power strip) I hope that's what you mean by properly grounded. However, even with this, plugged the usb power into rear I/O, Front I/O or even a usb hub results in a noise that sounds similar to the LED interference from the hand over keyboard scenario at all times.  I've also kept all power cables, monitor, keyboard, mouse, and connecting cables away from the others. I'm beginning to think I have the audio monitoring up high enough that I'm picking up interference from any source of power in the room. This still does not explain why it travels so noticeably through my hand and why grounding with my finger eliminates it

Edited August 20, 2017 by IceNine
Adding information

[IceNine]

This problem would not be so bad if it weren't my interactions with my peripherals causing most of the issues. It seems the hum is at minimum when I'm laid back in my chair. Increase when I lean in (even if the cables stay in relatively the same place) and massively increase when my hands are hovering over they keyboard. No audio cables are near or on the keyboard when this happens so it must have something to do with contact with me right? It just seems so odd...