PreSonus VSL44 60hz hum in headphones

For some reason, I'm now getting a pretty bad 60 Hz hum in my headphones connected to my VSL44. The hum is consistent and fairly loud, and is proportional to the Gain/Volume setting.

My DP (Casio PX-850) is connected to my AudioBox VSL44 via line out to the Mic - Line ports. The headphones are connected to the VSL44 headphone jack. Notes:

- The hum is not present when the headphones are connected directly to the DP.
- The 48V button is NOT pressed.

Any ideas of what may cause this? Defective AudioBox? Improper grounding between DP and Audiobox?

Thanks,

Dan.

So you know it's not the piano . . . it sounds like a grounding problem, or a "ground loop" problem.

This is the kind of problem that "DI boxes" are built to solve. Try buying a pair (one for each channel, if the piano output is stereo) and using the "lift" switch to disconnect the piano ground from the soundcard ground.

. Charles

I'm not familiar with the AudioBox VSL44, but have you really connected DP line out to a Mic in port? Other than that, ground loop.

Got a USB/MIDI cable connecting DP to 'puter in addition to audio connections? If so, try disconnecting USB cable and see if hum problem goes away.

As Charles suggested, fix by using a DI (e.g., Radial ProD2) for audio connections. Or, just don't connect MIDI and line-outs at the same time

Ben

I would recommend checking your cable.

Gentlemen,

Thanks for the suggestions.

The Casio midi USB was connected to the computer and then to the Audiobox, and the Casio line out was connected to the Audiobox line in. When I disconnected the line out all was well, except the I can't figure out how to get the Casio midi to the Audiobox phones.

Midi is perplexing to me. I'd simply like to route Casio midi to the computer and listen to the result on headphones connected to the Audiobox.

Regards,

Dan.

Dan,

I'm a little bit confused--not sure exactly what you mean by "get the Casio midi to the Audiobox phones."

We know that MIDI is a protocol for sending control information, not audio signals. So I take it you are using the PX-850's MIDI output to control a software piano on your computer? And you want to listen to the resulting sounds through the 44VSL's headphone output, correct?

Then you basically need 2 USB connections. The first USB cable (from DP to computer) sends MIDI control information to the software piano. The second USB cable (from computer to 44VSL) sends digital audio to the 44VSL, which performs the D/A conversion. You turn the 44VSL's Mixer knob all the way CW to the VSL position, and adjust its Phones volume control to taste.

As long as the software piano is configured to recognize the Casio as a valid MIDI input device and your computer is configured with the 44VSL as its selected USB audio output device, you should be golden.

You can leave the Casio's line outs disconnected unless you want to listen to its internal sounds, in which case you should temporarily disconnect the Casio's USB/MIDI cable to keep from creating a ground loop. Also, remember to turn the 44VSL's Mixer control back to Inputs when listening to the Casio's line outs.

If you want to leave the audio cables connected all the time, you can install a humbucker (like the Ebtech HE-2) or a DI box (like the Radial ProD2) in the signal path between the Casio's line-outs and the 44VSL's line-ins. Either of those devices will kill the 60 Hz ground loop by using passive transformers to buffer the 44VSL's analog inputs from the Casio's path to ground.

Does this all make sense, or am I missing something?

Ben

Ben,

Good morning and thanks for the feedback. Yesterday was a tough 14, hour day. My apologies for not being clear. Comments inline below...

Thanks,

Dan.



Absolutely correct.


This is my exact configuration.



I tried using Sibelius First, Home Concert Extreme, and Synthesia. None generate any sound in the headphones connected to the 44VSL.

Since the sound works fine when the Casio is hooked up using the Casio Line Out (or headphone out) to the 44VSL's line in, the 44VSL's preamp seems to be working fine.


I tried this and it appears to work fine.


I'd like to get MIDI-only working, but it would be great to have the flexibility. Assuming the sound is the same, I'll probably get the Ebtech HE-2.


Definitely makes sense. It looks like I'm missing something subtle with the MIDI connection or signal path.

Dan,

If you can hear the software instruments on your PC's analog headphone output but not through the 44VSL, I would suspect a configuration problem in the PreSonus software that you may have installed when you first set up your 44VSL.

Did you install the VirtualStudioLive or StudioOne applications when you set up the system for the first time? If so, you may have to go through the docs for those to examine their default audio I/O setups.

I think both apps basically interpose a layer of software mixing/routing between the operating system and the AudioBox hardware, which may be preventing you from monitoring the software pianos via the 44VSL. In the case of StudioOne, IIRC, you may have to open up a dummy project, make the I/O setup selections, and then store them as default settings for new projects.

That's where I'd start looking, anyway, if the software piano sounds are currently audible on the PC's native audio outputs but not through the 44VSL.

Ben

If the hum disappears when USB MIDI from the Privia is removed then it is most likely a ground loop. This is a problem with a USB MIDI in general. Dave Smith refers to the issue in this video:

http://www.youtube.com/watch?v=SFIZc7IMzyA

I have this problem with a laptop when used in combination with some keyboards hooked up over USB and a particular firewire audio interface. Different computer, everything else the same no problem.

This same issue is talked about here along with a solution which involves cutting the ground on your USB cable. I keep a couple USB cables that I've modified this way handy.

http://www.theworshipguitarist.com/blog/...ise-eliminated/

As Slowtraveller indicated, 2 connections only are required 1. Keyboard to computer 2. computer to Audiobox. That's it. I have the identical config RD700NX to iMac, iMac to Audiobox 44VSL. Headphones plugged into the Audiobox. All good. There would be no technical reason for a 3rd connection Keyboard to Audiobox, what purpose could it serve, other than cause problems?

Ben, Mike, and Peter,

First, thanks for the excellent feedback and please accept my apologies for the late reply.

I bought an Ebtech Hum Eliminator eliminator and that solved the hum problem completely. That's the good news.

The bad news is that a major underlying problem appears to be with Audiobox itself. As I mentioned above, a major reason for connecting the Casio Line Out to the AudioBox Line In was to hear the audio. After spending about two hours messing with the AudioBox, reinstalling drivers, reconnecting USB and audio cables, restarting the computer, blah, blah, blah... My "BS Meter" hit the red zone and I bought a Steinberg UR22 Audio/MIDI Interface.

Immediately after installing the UR22 Thursday evening, things improved tremendously. Now I get sound from my headphones plugged into the UR22 with ONLY the USB cable plugged in to the DP via the PC. Sibelius 7 First, HCX, Reaper, and all of my other music software started working. And my demo copy of PianoTeq works perfectly.

So it looks like they underlying problem is a defective AudioBox 44VSL. For all it's nice features, mine doesn't work properly. I'm returning it today.

Again, thanks for your help.

Regards,

Dan.

Edit: I spoke too soon. It looks like I can't return it because it's outside of the return window. Oh well, maybe I can use if for a plant stand or book end.

Peter,

As I mentioed above, I resolved my connection issues. That said, one possible reason to connect from my DP to the audio interface with audio cables is to play along with some music software which does not allow that feature.

HCX does allows play along well. It's not clear if Sibelius will allow that.

Regards,

Dan.

Hi Dan, I just purchased a Krome 61 last week and am now considering a audio interface and the UR22 is one I am considering. How are you finding it so far? By any chance are you using the Cubase software?

I spent a lot of time doing research today and have narrowed it down to the Steinberg or the Akai EIE (16bit) which uses Pro Tools Express.