An annoying USB mixer problem.

[kluetters]

Hey all,


I've recently put together a new studio setup with a Peavey P8 USB mixer, two audio technica AT2020 XLR mics, a headphone amp and a mac G5. Anytime I put on my headphones with the mics potted up, I hear what sounds like an electronic humming noise. I've attached a file to give you all an accurate sample of the issue.

I've tried different USB ports, different XLR and USB cables and still cannot find a solution. I've called Peavey and they mentioned that this is the first time thathey've heard of this issue. Does anyone have an solutions/suggestions or links to other threads?

Any help would be EXTREMELY appreciated.

Thanks!
Kyle Luetters

 

[TimOBrien]

Looking at the waveform in Audacity zoomed in, it looks like a standard power hum.

Do you have EVERYTHING plugged into the same wall socket? (You should)

Do you have the power cords separated from the audio cables?

Do you hear any hum on a radio or audio device plugged into the same electrical outlet?

 

[mjbphotos]

Is there some reason you are using the Peavey mixer as an audio interface? Read this thread about mixers and recording.
If you disconnect the USB do you still hear the humming? Isolate the source of the hum - disconnect the headphone amp, plug headphones directly into the mixer with one mic plugged in.

 

[kluetters]

Ok, thanks for the responses so far!

Everything is plugged into the same outlet.
I've separated the cables the best I can.
The hum gains volume and goes down in volume based on how I adjust the gain/overall volume of the mic input.

We're using a mixer because, a some point, we want to use three mics.
It doesn't make the hum when I unplug the USB mixer from the computer. The moment I do, the hum starts again.

Without the USB cable plugged in, the mixer produces sound without the hum.

 

[ecc83]

"Without the USB cable plugged in, the mixer produces sound without the hum."

That^ has all the hallmarks of a hum loop but I have never heard of it happening with just a mixer and a PC. Sure there is no other earthed mains powered gear in the system?

You could try teasing back the earth braid on a usb lead? Use a very sharp modelling knife and remove about 1cm of braid, don't matter which end, I have never found it worked anyway but them's cheap enough to try! N.B! Never do this with a FW cable! The braid carries the DC power return (the dick'eds!). Could you scrounge a laptop and try that?

Oddly the spectrum of the buzz shows no 60Hz mains but a bit at 120Hz so that is poor DC rail filtering. Then you have a nasty spike at 1kHz and a decaying sequence at every harmonic onward.

Don't know macs at all but I go with the others, get an AI. You will still be able to use the mixer.

Dave.

 

[TimOBrien]

Yup, ditch the Peavy and get another/regular interface.

When I looked at their product sheet is says studio but looks like more of a live mixer to me.

 

[kluetters]

Alright guys, do I need to simply get another USB interface and put that between the computer and the mixer OR should I return the Peavey and get a Alesis Multimix 8 USB 2.0?

 

[mjbphotos]

No, do not get another mixer! Read the thread I linked above about using mixers for home recording. You want an audio interface - and if you are eventually going to use 3 microphones - at the same time - for recording, then you will want an interface with at least 3 mic preamps and simultaneous capability. Did you know that a mixer MIXES the inputs together into one stereo track to send to USB? So you can do 2 separate tracks by panning one input left and one right, but the third will not be separate when using a stereo USB mixer.
I suspect that noise is in fact the a-to-d converter in the mixer.

 

[kluetters]

Alright, can you recommend an interface that has an input for for my USB mixer?

Thanks!

 

[ecc83]

Alright, can you recommend an interface that has an input for for my USB mixer?

Thanks!

Assuming that you cannot do a straight trade with the mixer for an AI and would therefore lose money if you sold it the most cost effective "quality" answer is an AI with two mic inputs and two more independent line inputs. There are several good examples on the market. The Focusrite 8i6 is one but my suggestion would be the Native Instruments Komplete Audio 6.

There are of course interfaces that can give you 4,6,8 and more tracks but they get ever more expensive if you are to retain quality. In any case, since you already HAVE the mixer its flexibility will be found useful.

N,B. If you decide on a different AI from the two mentioned DO run it by us first! How various makers "count" available tracks can be very misleading,

Dave.

 

[kluetters]

So, to make sure I have this clear, I need to buy an AI and run a cable from my USB mixer to the AI and then run another cable from the AI to the computer?


Thanks

 

[ecc83]

Actually you would run TWO* cables from the mixer to an AI. The left and right main outs (there are various ways to use a mixer and an AI, both where you take the feed and how you monitor but leave us K.I.S.Sir for now?)

The AI now connects to the PC via USB. Best to get this all sorted first and get the AI installed and working including monitoring and then think about hooking up the mixer.

So, to be clear. You would end up with two mics recorded on two track from the AI. Then two more tracks recorded from the mixer but, this will be "submix" of up to 4 mics .

You will then have hours of fun deciding on a final mix to stereo!

*TRS jack to jack.

Dave.

 

[kluetters]

Dave,

Thank you so very much for explanation. Is there an AI that you would recommend for around $100?

Thanks!

 

[ecc83]

Dave,

Thank you so very much for explanation. Is there an AI that you would recommend for around $100?

Thanks!

Oooo! Sorry K but you are not going to get a four input AI for 100bucks AFAIK.

For around $150 you can get the excellent Steinberg UR22 but two input and for $250ish the Native Instruments 4 input KA6.

You could try the second hand route? I picked up a Focusrite 8i6 for 110 quid a couple of weeks ago.

Dave.