Asking the experts - How can I fix this hum!?

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ZachAttack83

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I want to start out by saying that I have been googling this for days, and have had 0 success in finding the culprit.

I currently have an Audio Technica AT2020 running to 2 computers. It is connected to each pc in this order: Behringer PS400 power supply -> Behringer HA400 Amp -> Ouput 1 -> gaming pc; Output 2 -> Behringer MX400 Mixer -> Streaming PC.

So, the intention of this set up is to take my mic and go directly to my gaming pc for communications with my pals, which is why output 1 goes to the gaming pc; and to also send it to my streaming pc for when I stream my games. The reason the mixer comes after the amp in output 2, is because I mix the microphone sound with the gaming sound output, and communication sound output form the gaming pc to one single line in on the streaming pc. This may sound complicated, but without going in to too much detail, I assure you its not. If you want more detail, I'll go into that if you ask.

So before I got the streaming pc set up, I had only the mic plugged into a power supply, through the mixer, and then into my gaming pc. With just this set up people have had trouble hearing me. I tried to turn on microphone boost, but that resulted in a VERY LOUD hum, but allowed them to hear me. The hum however was too much for them, and I had to turn off the boost.

When I decided to set up my second pc for streaming, I decided to to add an amp in behind the mixer to try to get more sound out of the mic before it got to the pc.

That should give you a decent idea of what I am working with.

Now where the problem comes in is that I still have the hum on both systems, but its less noticeable on the gaming one. On the streaming one, its real bad. It makes impossible to stream, because its so overbearing. Its not even just a hum, its almost like a fuz hum mix.

I've went through basic trouble shooting of testing cables, removing equipment, etc, to see if it would help, and it did not.

Researching it, I found that an isolator could help with the problem. So I purchased an artcessories Dual transformer / Isolater, as it had the xlr inputs and quarter inch inputs that I have in my system.

So, when I plug this thing in from the 1/4" output of my MX400 and go to the streaming pc, it does nothing.

If I put in line with the xlr between the PS400, and the HA400, it makes a hum so loud you can't barely hear anything the mic picks up.

So, I am not sure if I am not using the isolator properly, or if that wasn't the problem to begin with.

I can upload some sound clips of me recording my voice on the 2 systems if you'd like.

Sorry if this post is a bit all over, was trying to get as much detail out before I had to head out the door.

Please if you can help, and need more details, just ask, I'll provide you with whatever you need.
 
Two thoughts:

1. Pro audio gear usually runs professional line level which is +4dBu. Consumer audio (like your PC sound card's analog input?) is usually -10dBV, which is roughly speaking 1/4 the voltage. That might be exactly what you're using the HA400 for. But it can also have an impact on acceptable noise floor.

2. If inserting a ground isolator between two components increases the noise by a lot, then you probably have a ground problem between the components to begin with. You can try seeing if running a copper wire between chassis screws on the different components helps.

Is there any reason you didn't go with a USB interface that has phantom power to your gaming PC, which can also pass through to a second USB interface connected to your streaming PC and mixed in with your gaming PC's audio output? (Or just routing all your gaming PC's audio directly out to your streaming PC?) This would not only let you manage gain/levels independently on the two interfaces for your mic signal, but you could also probably run the 2nd interface purely digital. And then you'd have no analog noise injected anywhere.
 
Thanks for the reply Neko!

I'm pretty new to the audio aspect of it all, so I am not really sure of what options are available out there.

I will try out the copper wire and see if that helps. What do you think would cause the grounding issue to begin with?

As for the USB interface, I did not know it was an option. When I bought the microphone, I didn't even know it needed phantom power to be able to use it. So I had ordered that, and thats what I used since. When you say usb interface, do you mean that I use the USB to power the mic?

As for the sending out all of my pc's audio directly to the other pc, I do actually do that, but its a bit complicated. I have bad hearing from my time in the Marines, so I actually run a 31 band EQ to adjust for all of the frequencies that I struggle with hearing. To run this, I output from my Asus sound card (ASUS Sound Card Essence STX II) to the EQ (behringer ultragraph pro), and then from there into a mixer (behringer xenyx802). The mixer then goes to a head phone amp (behringer 4-ch headphone amp), and thats where I get my audio. Now this in itself isn't that complicated, but, I do use a separate mixing channel for my communications. So, my game sounds go to the mixer out of my sound card, and my communications go to the mixer out of my motherboards sound ports. This allows me to adjust game and comm's levels using the mixing hardware, rather than hotkeys or software stuff. It seems like much, but I really like it. I also have my xbox one sound ran into a channel on the mixer as well for when I game on that, and still use the pc and mic for my comms with that, but thats not important.

The way I route the sound from gaming to streaming, is that input 1 of the MX400 is connected to an output on my 4-ch headphone amp, so it gets everything that I hear from my gaming pc, both game and comms, and input 2 of the mx400 is where the mic input is. The mx400 output is only connected to the streaming pc.
 
My head has a hum just reading your post, LOL Welcome

I'm not sure I fully understand the entire set up but as Neko, what caught my attention was an amp (high level output) going into a mixer designed for a low level input. That would seem to cause a hum at a minimum.

One other possiblility I had an issue combining my home theater gear into my 2-channel set up, I had a hum I couldn't get rid of. After going mad I used XLR cables as a connection and it cleared up the issue, for some reason the balanced stereo gear I have didn't play well with the single ended HT gear. So mixing XLR and 1/4 connections could be the issue. You might try sticking with one or the other if possible.
 
Thanks Mr Peabody for taking the time to reply.

I just listened to the mic again, and I think that I may have described it improperly. While it does have a constant noise, its more like a high frequency squeal than a hum, and with that being said, it also has the sound like I'm standing by the ocean. Like a constant fuzz, or something, however, there are no noises near the microphone that should be causing that. And if I microphone boost it, you can really hear the high freq, and the fuzz.

Sorry if my description was poor, it does however hum real bad when the isolator is hooked up via the xlr cables.

Does that change the suggestions as far as the amp going into the mixer? On the gaming pc, the mic actually never goes into the mixer, it goes straight from the amp to the sound card input.

I wonder if there is a way to get it all xlr into the pc? I didn't see any options outside of 1/4 or 3.5mm for sound cards =(
 
I think you need a mixer with a balanced input for the mic and then connect the mixer to the pc.
 
The Behringer Ultragraph Pro is also a pro-audio piece of equipment, and while it is doing its EQ in the digital domain, it would be better if you kept your signals digital all the way and performed any EQ (and mixing) on your computer (since that's where the sound is going anyway).

A USB interface (sound card) like the popular Scarlett Focusrite or Clarett (not as familiar with this line) will provide phantom power to your microphone, immediately digitize the audio, and then let you keep it digital as you run it through your processing chain. Your Essence STX II sound card as an RCA S/PDIF digital output, which you could feed directly into your streaming PC with the right hardware, and use software on your streaming PC to mix in the microphone audio with the gaming PC audio—if your gaming PC output didn't already include the microphone audio.

I suspect your microphone noise is either due to the noise floor of the equipment, or you need a windscreen but that seems less likely.
 
Well, good news. I found out why the high pitched squeal was there, and why my microphone was so quiet. It turns out that the phantom power supply that I am using, has a 12v and 48v setting. My mic is 48v, I had it on 12v. So changing that fixed those...

However, the streaming pc still has a real bad static fuz.

I think your suggestion of the usb interface for the streaming pc may be the best way to fix that.

As far as my sound goes from the gaming pc through all that equipment, I found that the analog definitely seems to produce better sound quality than the digital did. I can hear foot steps much easier than I could with the EQ within the pc software.
 
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