Trouble Connecting Preamp to Mbox 2 Mini

[Big C Dub]

Hello all,

I'm new to the forum and new to recording in general. I have a Mbox 2 Mini that I'm trying to pair with a PreSonus Eureka preamp but, I'm having issues with noise. I've tried connecting the preamp to the DI in Line 2 using a XLR to TRS cable, a balanced TRS cable, and an unbalanced TRS cable but, each configuration gives me noise in my monitors (even with all gains on both pieces turned down and not in record enabled).

I've hooked up the preamp to the Mini using a XLR cable into Input 1 which reduced the noise levels dramatically but, I've been warned that pairing the hardware this way may cause me to burn up either my preamp or my Mini. Any advice is much appreciated.

Thank you.

Big C

[sw rec]

Preamp output goes to the LINE level input.

[Big C Dub]

I tried the Line input but, it still has noise. Any other ideas?

[LincolnT]

Originally Posted by Big C Dub

I tried the Line input but, it still has noise. Any other ideas?

Have you tried toggling the pad and mic/di buttons?

Ok, I actually have an idea:
My experience is with an MBox 2 Pro being fed a balanced line level from a Roland stage piano. I had lots of noise until I grounded the MBox chasis to the chasis of the electric piano. That eliminated almost all of the noise. Try making tiny jumper cables to ground the equipment together.

Also, it seems like the ground issue could actually be a monitor problem. What kind of monitors do you have? Try grounding the monitors to the MBox to the preamp.

[Big C Dub]

Thanks Lincoln, I was thinking along the ground issue lines too. I will try to isolate the piece that is causing problems by systematically plugging into my power conditioner. My real concern is that the Eureka and the Mbox 2 Mini won't get along because its going from balanced (Eureka) to unbalanced (Mbox) connections. I hope I don't have to drop more coin to upgrade my interface but, it may aslo fix some MIDI issues I'm having (but that's another post).

Thanks again.

Big C

My Setup:
Dell Inspiron 545: Intel Core 2 Duo 2.8 GHz, 3.25 GB RAM, dedicated internal recording drive
Digidesign: Mbox 2 Mini with Pro Tools LE 8.0.1
PreSonus: Eureka preamp
Furman: PL-BC power conditioner
Tascam: VLA5 Monitors
Casio: Privia PX-320 piano

[getz76]

Are you sure there isn't something wrong with either unit? Try plugging another line level device into the Mbox 2 Mini....

[Big C Dub]

I tried to isolate the source of the noise by unplugging everything from the power conditioner (plugging into a regular surge protector) and this helped eliminate that as a source. I then plugged in our electic piano directly to the Line/DI Inputs 1 and 2 and, no noise. When i plugged in the preamp into a regular surge protected and tried balanced and unbalanced lines into both the Line/DI inputs 1 and 2 the noise got worse. So, I think it is either the preamp or the preamp and the Mini are just not compatible.

[Big C Dub]

Well, I learned that the Mini and my preamp weren’t destined to get along. After checking with the folks at Digidesign I learned that the Mbox 2 Mini had balanced input sockets installed but, they were not wired balanced. So, I upgraded to an Mbox 2 and ran an XLR to TRS line into the TRS Input on channel 2 and bada bing, no more noise. I wish I would have known this before I bought the Mini, now I have to try and sell it. I guess that's part of being a newbie.

Thanks for the responses; I can see I will be spending a lot of time here in the future.

Thanks,
Big C