high pitch humming noise from my mixing deck

[Superfreak]

I just recently bought an Allen and Heath Zed10 mixing desk, and long story short -

I've hooked it up, got it running by USB to my iMac, set as my soundcard I/O, running to my monitors via the Main Mix output (XLR), and for some reason, when i turn the Main Mix Level knob up, theres a high pitch humming noise. which get's louder the further up I turn the knob...

Is this normal or? Surely it should just be quiet...

EDIT: While writing this, I was trying to eliminate the source, and I seem to have got it, kinda.

It's boiled down to the Roland TB-3 that I'm using on one of the Line inputs on the mixer. So I changed USB leads, around, changed the patch cable that connects the TB3 to the mixer, still noise, until i changed from using the Line input for the TB3, to the GTR Hi Z input, weird... Is this normal? Should this happen?

Would prefer to have the TB3 on the 2nd line input next to my drum machine, both on Line...

[deevey]

Are you using balanced TRS cables ?



Are you running in Mono or Stereo ?
Is it on L&R channels or Just one ?
Does the same buzz happen if you use one of the Stereo Line-In channels instead of the mono ones ?

Pictures speak a thousand words

[Superfreak]

Right, these are the patch cables that I bought: Soundlab J-J Patch Lead 6 Pk 100cm https://www.amazon.co.uk/dp/B000KMCE..._LuKIvbBW86P65

It doesn't say if they're balanced or not but, judging by your image, they're just TS cables, they have one black ring on them but not a proper sleeve like those TRS cables...

I'm running the TB-3 via mono, one patch cable out of the back, (I'm not sure if the tb3's mono out is L or R, I know the TR505's mono is R.

I think I have tried the two Stereo inputs of the mixer and the noise still occurred. But will double check tomorrow when I'm home!

Could it be a matter of using balanced cables and/or using stero w/ two cables from both the L&R of TB3?

[deevey]

Guessing its probably the Lack of Balanced cables. Also switch your patch cables around just in case its a dodgy one. - the TB-3 has balanced outputs.

Left on the TB-3 for Mono, However, you have loads of channels left over, including 2 stereo's so you shouldn't even need to use the Mono's at least not for recording purposes.

[Superfreak]

I'll have to look into getting the cables changed over for Balanced ones then, see if that works.

I've got two cables each now for the 505 and TB3, both going into the 2 stereo inputs of mixer, and something weird is happening...

I still get the humming noise when the Main Mix level is turned up but, when i turn the level up on stereo channel 1, the humming noise is a low frequency humming noise... then when i turn the stereo 2 level up, its a high frequency humming noise... so having them both turned up together is not nice....

I've really got no idea what to do to stop this, all's I'm thinking is simply its to do with the cables not being balanced (some thing I am not clued up on), so... Maybe i should just try that? The patch cables I am using are from amazon, by SoundLab, 'Set of 6 single core screened 6.35 mm Mono Jack Plug to 6.35 mm Mono Jack Plug..(here http://www.amazon.co.uk/gp/product/B...ilpage_o01_s00)

It doesn't say if they're balanced or unbalanced, but I'm getting the feeling that I'm missing it and it's in the name...

I've found these ones on amazon, d'ya think they are okay? : http://www.amazon.co.uk/gp/product/B...=AYTOIPMDVLT36

I've taken some example videos on vine that you can watch, so you can see/hear the problem.

Here: https://vine.co/v/e1d5QbgB73W &
https://vine.co/v/e1d5rtO060z

[deevey]

The cables you have are unbalanced, the ones you linked to are balanced.

Get the new cables and see how you fare. I wouldn't expect miracles with cables that cheap mind you

If I were in your shoes I'd grab 2 half decent cables for a fiver to tenner a piece and you can run mono as you originally intended and grab a few more later if you decide to run stereo for recording.

http://www.amazon.co.uk/Right-Angled...TD5VXHZ1RCA6W3

[Superfreak]

Figured so.

Well yeah, I don't want to buy too cheap cables so will splash out a little more for decent cables. The las tones I linked to you, they're dispatching, so let me see how they are and i'll get back to you!

[Superfreak]

Hey.

Balanced cables arrived, noise is still happening exactly the same? :-(

I got these as previously linked: http://www.amazon.co.uk/gp/product/B...=AYTOIPMDVLT36

Something that might be of help, theres a low freq noise when i turn the main mix knob up, while I just have the pc on but, when i load up Logic Pro, THAT is when i start getting the low and hi freq noises form turning the stereo level knobs up...

So what's that about!?

[deevey]

Hey.

Balanced cables arrived, noise is still happening exactly the same? :-(

I got these as previously linked: http://www.amazon.co.uk/gp/product/B...=AYTOIPMDVLT36

Something that might be of help, theres a low freq noise when i turn the main mix knob up, while I just have the pc on but, when i load up Logic Pro, THAT is when i start getting the low and hi freq noises form turning the stereo level knobs up...

So what's that about!?

Aha!

Do you get the same hum during playback, or through any other applications e.g. audiactity / itunes etc ...

Start there.

Secondly, do you have any record switched punched in on unused channels ?

Thirdly, check it when running the laptop on batteries.

I think you need to start eliminating things from the setup that could be causing the problem.

If you plug in your synths WITHOUT connecting to the computer and see if there is still noise through the desk.

If you move the mixer around when plugged in, does the hum "change"

If you move the cables around when plugged in, does the hum "change"

If you use a USB hub, is the hum still present

If you try it on a Laptop (if you have one) without plugging in the charger - is the hum present.

Remove any other USB devices from your PC and plug in your Soundcard directly (no hub) - is there noise

Move the PC to a location on its own not close to anything and plug in the mixer, You may have to play around with placement of the PC / mixer, check if the USB cables are shielded.

It might be as simple as a power socket is not grounded or a power cable is touching a USB or as difficult as an internal grounding issue in the PC or simply that the USB cables are too long or not shielded.

[deevey]

For reference ... and might be of use

http://www.soundonsound.com/sos/nov0...erproblems.htm