Mbox 2 Mini High Pitched Hum Problem

[riz78]

Hey ya'll,

Been having a 'humming' problem with my Mbox 2 Mini and after hours of research I still can't seem to find an exact match in this forum for a solution.

Quick info on my system: PC (duo core), Windows XP Pro (Sp3), Mbox 2 mini, ESI Maya 44 pci soundcard (running Cubase on another partition & OS), behringer xenyx 1204 mixer, yamaha hs80m monitors, and I am running all this through a power regulator.

The set up: I have two separate partitions with two OS's. One to run Pro-Tools only and the other running Cubase only. The two softwares never mix, hence, to each its own realm. I usually run my condenser mic thru the mixer using its pre-amp, send it out via alt3-4 into the soundcard (either mbox or esi, depending what I'm working on), and then have the signal return back into the mixer via tape in (so as not to clash with anything).

It's worked fine for a while, until recently of course.

So I've been through a process of elimination and here's what I've found out so far:

1. Like most cases, there'll be a high pitch hum when PTLE (7.4) has fully loaded, and ONLY when it is running.

However, what is peculiar is that when PTLE is not running there still exist a low-level static-like 'noise' if you crank up the volume loud enough. This 'noise' however strangely does not exist when I load the other partition/OS, despite it running the exact same hardware and drivers. Strange, I know.

2. The headphone output from the Mbox is fine and is not effected (unless you hook up the mixer out to the mbox input - but this is just simple logic).

3. Thinking that it might be a clash of sound cards I disabled and uninstalled the drivers for the ESI (used for non-DAW stuff) but it made no difference. Still humming.

4. Read in this forum about ground loop so I completely disconnected all forms of connections from the ESI soundcard to the mixer (literally pulled out all the wires!). Didnt' help though.

5. Changed USB ports. Still humming. I did however get a 'dae-1155' error on one of the ports though, which made things just ever so slightly more annoying.

6. Kept the Mbox as far away from other peripherals. I read in one of the threads that someone fixed his problem by separating his mbox from his ext hdd). It didn't work for me though.

So, that said, I wouldn't mind trying other suggestions. It would be much appreciated

Cheers!

[RiF]

I had the same problem (high pitched noise) with my MBox 2 Mini. The high pitched noise disappeared almost completely when I used balanced TRS cables to connect the MBox's monitor outs with my mixing console (which has balanced inputs). It's a bit weird, because the MBox 2 Mini does not have balanced outs, but it works (for others as well).
The high pitched tone seems to interact with my M-Audio Delta 1010LT which is connected to my console as well. The noise changed (=reduced) after disconnecting the 1010LT from the console which is connected with unbalanced cables.

[TOM@METRO]

From the general troubleshooting thread:

If you're experiencing noise from the Mbox II, there are several things to try:

- Make sure you're using balanced cables on all balanced inputs and outputs. Remember that the Mbox 2 outputs are unbalanced, and should use unbalanced connections.
- Try using a power conditioner for all your electronic gear (Furman, Monster).
- Run your outputs directly to shielded monitors and not through a mixer to see if the noise goes away.
- Some noise complaints arise from noisy power supply units inside computers - try installing and running on another computer (or if you're using a laptop, unplug the power supply and run off of batteries to see if noise goes away). Moving the Mbox II in relation to your monitor, computer or speakers may also lessen the noise.
- Unplug and turn off all unnecessary gear and run only the computer, the Mbox II, and monitors.
- Listen through headphones to determine if the noise is isolated to a particular output.
- Make sure you're not running through a USB hub or other device - the Mbox II always needs to be plugged directly into the computer.
- Try all USB ports on the computer to see if the noise lessens.
- Trace your cable path for long cable runs, and isolate your cables from possible interference (other gear, florescent lighting, CRT monitors, etc).

Lastly, if you feel a repair is necessary, please contact Digidesign Tech Support to set up an RA.

[riz78]

RIF: You took the opposite direction of the advice Tom gave and used balanced cables instead and it worked?? Haha. That is rather unconventional but really glad it worked out for you

As mentioned I too disconnected my ESI from my console, but unfortunately it didn't help at all in my case.

TOM: Thanks for the suggestions. I've already tried 7 out of the 9 possibilities however, so will let you know soon what happens on the last 2.

Cheers guys. Wish me luck.

[RiF]

Originally Posted by riz78

RIF: You took the opposite direction of the advice Tom gave and used balanced cables instead and it worked?? Haha. That is rather unconventional but really glad it worked out for you

Did you try this? Other have reported a cure by using balanced cables. I even found an explanation why this helps even if the outputs are unbalanced (I did not understand it, but I don't care, coz it works for me).
Make sure to UNPLUG all cables from your MBox INPUT. Why this? I had TWO high-pitched-noise-sources: 1. the inputs, 2. the outputs. Both seem to need different treatment (balanced cables on the inputs did not help, so I am still searching...), so make sure you solve each issue one by one and don't mix it.

[riz78]

RiF: No I haven't tried it as I don't have any balanced cables lying around atm but it might be just the advice I need...

One of Tom's advice worked: I connected my monitors direct from the Mbox's output and the hum disappeared completely. So now I've come to the conclusion that either there is something wrong with the cables that I'm using from the Mbox output to the mixer (hence I should try ur balanced cables approach) OR that there exist a ground loop issue happening somewhere (which then becomes more complicated).

Whichever it is, I must get to the source of the problem as I don't intend to keep my set-up this way - It's quite difficult to work without fully utilising my mixer, particularly when I run two types of DAW.

That said however, I seem to have come across a bigger problem now. My USB ports have all stopped working. It might have something to do with the "dae-1155' error I received after re-installing PTLE (consequently also an upgrade from PTLE 7.3 to 7.4). I then moved to another port, and it worked fine yesterday, but has gone haywire today - Multiple 'balloons' keep popping up telling me that one or more USB ports have malfunctioned... Hmmm.

Gonna try to re-install PTLE now (perhaps back to 7.3 as that worked better for me) but if that doesn't work, I think I might have to resort to re-installing windows instead as it looks like it's been corrupted due to all the 'testing' I've been doing...

Wish me luck.

Btw, as for your 'input' problem, perhaps my suspicion on my system (i.e. a ground loop problem - most likely due to the connections into the mixer) relates to yours? Have you tried not running anything through your console at all? Perhaps if you directly connect your monitors & mic ONLY through your Mbox, the hum might go away? If so, then we're most likely on the same boat

[RiF]

Originally Posted by riz78

Wish me luck.

I do.

Originally Posted by riz78

Btw, as for your 'input' problem, perhaps my suspicion on my system (i.e. a ground loop problem - most likely due to the connections into the mixer) relates to yours? Have you tried not running anything through your console at all? Perhaps if you directly connect your monitors & mic ONLY through your Mbox, the hum might go away?

There's a weird ("weird" like in "I don't know much about electronic engineering...") interaction between other sources connected to my mixer and the MBox-humming. One of them is: It hums, then I move the fader of my M-Audio Delta 1010LT (unbalanced connections) from the usual 3/4 to full and the humming almost disappears. I can control the hum of my MBox with the fader of my 1010LT.

Originally Posted by riz78

If so, then we're most likely on the same boat

Yes, I am pretty sure we are in the same boat. It might not help, but feels better not to be alone...
It is not an option for me to directly connect the output (or inputs) from my MBox to the monitors or whereever, because I NEED my mixer and can't live without it (same as you). The mixer is a 32/16/2-Soundtracs Megas. It is old but and a bit noisy but in very good shape and is far more professional than this little MBox stuff, so it is not the problem.

What drives me mad is that whereever the problem lies (maybe OUTSIDE the MBox), I don't have this problem with any other gear. It only appears with the MBox. I am very close to completely ditching the whole Pro Tools thing, because it starts to drive me mad. Everytime I fix one problem, another one come up...

[riz78]

There's a weird ("weird" like in "I don't know much about electronic engineering...") interaction between other sources connected to my mixer and the MBox-humming. One of them is: It hums, then I move the fader of my M-Audio Delta 1010LT (unbalanced connections) from the usual 3/4 to full and the humming almost disappears. I can control the hum of my MBox with the fader of my 1010LT.

That is VERY weird. I don't know much about electronics either, but (like you) my logic is simple - If it works for the other sound card, why not the Mbox? Grrr

Anyways, I've fixed the USB problem (that was more of a PC issue) so now I'm back to square one (i.e. Hum). I've given up doing personal tests and am gonna leave it this way until the local pro-tools technician (luckily a friend of mine) comes over this Friday to check it out. Hopefully he'll figure it out and, if so, will let you know of the solution. Perhaps it'll work for you too, provided of course he fixes it.

[RiF]

Originally Posted by riz78

That is VERY weird. I don't know much about electronics either, but (like you) my logic is simple - If it works for the other sound card, why not the Mbox? Grrr

Double-Grrr

Originally Posted by riz78

Hopefully he'll figure it out and, if so, will let you know of the solution. Perhaps it'll work for you too, provided of course he fixes it.

Yes, pleeeezzz!

[RiF]

I can eliminate humming by:
- Using balanced cables from the MBox into my mixing desk.
- Disconnect my M-Audio Delta 1010LT (unbalanced cables) completely from my mixing desk.
- Use balanced cables for everything else that is connected to the mixing desk.
- Do NOT connect anything to the MBox's inputs (which makes it half useless).

I can NOT eliminate humming when I connect anything on one of the MBox'
s inputs. It does not matter if I use balanced or unbalanced cables here.

I bought an active (powered) USB-hub, but did not notice any difference.

If it stays like this, I have no choice and have to dump the whole MBox/PT thingy. At the moment, I am not willing to shell out EUR 1000 for a 003 just to get rid of some humming...

EDIT: I re-cabled everything, all balanced cables into the mixer, unbalanced out of a mixer's bus and into the MBox. I am using a powered USB-hub also. Delta 1010LT still disconnected from the mixer. Now the high pitched humming is almost gone. It's still there and very far from a professional recording signal, but it's not as annoying as before. I give up trying to find out what the problem actually is...