solving mbox ground noise

[queemacarthur]

Hi There

I have used an mbox2 for several years now and still have not found a complete solution to the noise it creates in certain situations.

When used on it's own with a mic or jack plugged in, no noise, no problem.

As soon as I use any external preamp or DI connected to ground,
a lot of noise appears in the signal. I have managed to reduce this by various combinations of ground lifting, until there is only one route to ground, I've changed the usb cable but these changes only reduce the noise and do not eliminate it completely.

I can only conclude that there is something else going on, it's not just a ground hum or plain hiss, it sounds like there is something from the computers generating the noise.

The equipment and computers I have used are in perfect working order.
I also use a digi002, same equipment, no noise, before that I used a 001, no problems.

I realize that this has been discussed before, and several other people have had the same problem with different mboxes, but I have not heard a definitive solution.

I would particularly like to hear a solution from digidesign as this is a serious design flaw in the mbox that they must surely be aware of.

Can anyone give me a solution apart form not using the mbox?

[DigiTechSupt]

It is not a design flaw.

See the list of suggestions in the General Troubleshooting thread, as they've solved a vast majority of these reports.

[queemacarthur]

Thanks for the reply.
There are some useful suggestions in the troubleshooting thread. I have been using the following one for a long time now. "Run your outputs directly to shielded monitors and not through a mixer to see if the noise goes away"
Not using my mixer means a lot of re-patching and is not really a permanent solution.
The mbox2 FAQ suggests using balanced cables on the output, which contradicts the troubleshooting thread which states that the outputs are unbalanced. Which is correct?
I have ordered a monster ultimate performance USB cable as suggested by the FAQ.
This would suggest that the cable provided with the mbox is not up to the job, which is a bit disappointing.
I would guess that the 002 does not suffer from the same problem in the same situation as it is externally powered so there is no direct connection to the computer's power supply, which must be the source of the noise.

Originally Posted by DigiTechSupt

It is not a design flaw.

See the list of suggestions in the General Troubleshooting thread, as they've solved a vast majority of these reports.

[Mark Angus]

Hey,

I've been having the exact same problems - having just upgraded to PT LE 8, and now using my Mbox again instead of my Edirol that I was using for Logic output.

There is a noticeable amount of hum and whine on the Mbox, even in its headphone output when not connected on to any amp.

I've read the troubleshoot guide, and tried:

- the "nap" fix. Didn't make any difference
- buying an expensive Monster USB cable. Minimal reduction in the amount of noise, but it's still there.
- Ground Loop isolator. This worked for my Edirol, cleaned it up completely, but for the Mbox it makes no difference

I want to run the Mbox directly into an amp, which doesn't have balanced inputs, only phonos, so I can't try the balanced cables option.

Has anyone tried the Behringer Hum Destroyer - I'm up for buying one, but having splashed out on an expensive USB cable for no benefit, I'm a little wary now.

Any other suggestions? I've got it down to a level that means I can work, but mastering music and fine EQing of bass frequencies will be practically impossible with this ongoing hum.

[queemacarthur]

I use an unbalanced output to an amp.
I found that the monster ultimate performance cable did help but it sounds like you have a ground loop.
It would be worth testing using only balanced inputs on the mbox.
Perhaps you could borrow some transformer based DI boxes with a ground lift to use on line inputs. Another solution is only having one piece of your equipment connected to ground. You have to be very careful with this (avoiding electric shock) so I would do a search about preventing ground loops and read up about it.

[bilco]

I have given up trying to solve this for now. As long as I use the Mbox running off battery power of my ibook and a mic or bass plugged directly into the Mbox 1, it is really quiet. If I add any other external AC powered device to the chain like a preamp, headphone amplifier-distributor or even plug the ibook into AC power, I get ground noise to one degree or another.

I notice the whining noise also comes and goes infrequently, even with a replacement USB cable from Digi, but it seems to only be in the monitoring output to the headphones or monitors. It is never actually recorded.

If I want to do really serious tracking (and I am NOT a pro!), I use the Great River patched into my Digi002 Rack.

To capture songs in a hurry or for ultimate mobility to record someone else on an overdub, I just use the Mbox/ibook on battery power with 1 set of headphones for the person recording only, just like a Portastudio.

It is what it is.....

bilco

[queemacarthur]

It would be a shame not to use your Great River preamp. Try using the preamp connected with just XLR to the mbox and the computer running on batteries. That should work. Next, try using a headphone amp with a balanced input with a trs jack from the mbox output.

On a positive note, I've had some excellent results recording into the mbox 2 with a demeter tube direct box so it is worth persevering with it

[Mark Angus]

Originally Posted by queemacarthur

I use an unbalanced output to an amp.
I found that the monster ultimate performance cable did help but it sounds like you have a ground loop.
It would be worth testing using only balanced inputs on the mbox.
Perhaps you could borrow some transformer based DI boxes with a ground lift to use on line inputs. Another solution is only having one piece of your equipment connected to ground. You have to be very careful with this (avoiding electric shock) so I would do a search about preventing ground loops and read up about it.

Cheers MacArthur. I think it IS a ground loop problem, but yet my ground loop isolator (in the signal path to the amp) won't clean it. Furthermore, the hum is audible even listening directly to the Mbox's headphone socket, so although using balanced outputs to a mixer might clean the monitoring signal, it's not actually where the problem is. Plus, I'll have to buy a mixer

I guess the Mbox series aren't properly grounded internally.

[eidschun]

I am responding to DigiTechSupt, in reference to the inherent noise of the Line/DI circuit that DigiDesign has acknowledged, which is present for me and many others, even with the knobs and push buttons set as DigiDesign prescribes, as discussed by DigiDesign here:

http://www.digidesign.com/index.cfm?...34&nStartAt=21

I point out that the additional measures suggested by DigiDesign to solve this problem are unnecessary for clean audio output from other equipment, including DigiDesign's own. Therefore, it is DigiDesign's Mbox that is outside of this norm, and so it is DigiDesign's responsibility to modify the Mbox's design. Denying that this is a design flaw is simply refusing to recognize this responsibility.

Furthermore, modifying its design accordingly is well within DigiDesign's means, as it can largely copy the design of its products that produce clean audio output even under very poor electrical conditions, grounding or otherwise.

However, if DigiDesign is not going to modify its design, then it should at least acknowledge that it needs to be changed and apologize, rather than continue to exhibit its contempt for all those who justifiably complain, which includes myself, among many others.

DigiDesign, with its continued denials and displays of disrespect, should be ashamed of itself.

[vocalvoodoo]

Agreed! It's beyond me that they just don't admit that it's a design flaw.

The only way I've been able to get most of the noise to go away is using external converters for connecting monitors and extrernal pre's. (I've tried all their other suggestions) As soon as I plug in "BALANCED" or unbalanced cables into the monitor outs of my MBox2, the noise appears.

Originally Posted by eidschun

I am responding to DigiTechSupt, in reference to the inherent noise of the Line/DI circuit that DigiDesign has acknowledged, which is present for me and many others, even with the knobs and push buttons set as DigiDesign prescribes, as discussed by DigiDesign here:

http://www.digidesign.com/index.cfm?...34&nStartAt=21

I point out that the additional measures suggested by DigiDesign to solve this problem are unnecessary for clean audio output from other equipment, including DigiDesign's own. Therefore, it is DigiDesign's Mbox that is outside of this norm, and so it is DigiDesign's responsibility to modify the Mbox's design. Denying that this is a design flaw is simply refusing to recognize this responsibility.

Furthermore, modifying its design accordingly is well within DigiDesign's means, as it can largely copy the design of its products that produce clean audio output even under very poor electrical conditions, grounding or otherwise.

However, if DigiDesign is not going to modify its design, then it should at least acknowledge that it needs to be changed and apologize, rather than continue to exhibit its contempt for all those who justifiably complain, which includes myself, among many others.

DigiDesign, with its continued denials and displays of disrespect, should be ashamed of itself.