Cygnus X-2 issue

Posted: Tue Mar 18, 2008 11:03 am

Hi there, I bought a Cygnus x-2 about 3 weeks ago. I seem to be having some issues with interference and/or grounding that may or may not be related to to X-2... so I thought I'd post here for some advice.

Here's my situation:
I have a Firepod (which will soon be replaced regardless) that I feed balanced outputs (xlr to trs) of the x-2 into via the line inputs on the back of the Firepod. From the Firepod to signal is sent to a mixer, then to a pair of active speakers.

Minus the x-2 the signal path was surprisingly quiet. With the x-2 it's obnoxiously noisy. Now, I'm not saying it's the x-2, keep reading please...

So I've isolated all the new noise to the Firepod and the X-2. Without the x-2 the Firepod is really quiet. If I run the x-2 balanced or unbalanced into the mixer it's really quiet, unless the firepod is on. To clarify, by quiet, I mean the lack of unwanted noise.

Also I should mention that the noise isn't typical 60 cycle hum. It may be a multiple of 60hz, but the noise fluctuates in amplitude at a steady rate and has almost a "dirty" sound to it. All gear is connected to power conditioners and UPSs.

So I'm curious if this noise is being introduced because the Firepod doens't haven't a ground power supply and the x-2 does. I noticed that all of Presonus's new products use grounded power supplies instead of my pod which, again, is two prong ungrounded into a transformer then into the pod.

Thanks in advance. Let me know if you need more info.

Posted: Tue Mar 18, 2008 1:55 pm

ebbnglo wrote:

All gear is connected to power conditioners and UPSs.

Just checking...are all the power conditioners and UPSs plugged into the same place? In other words, is all the power coming from the same outlet?

Posted: Tue Mar 18, 2008 4:36 pm

Thanks for checking.

In this case yes. I've tried moving outlets etc., without luck. But the firepod, preamp, workstation, mixer and speakers are all routed to the same power source, via multi-strip conditioners then into the same UPS.

Just remembered, though I'm not sure if it's relevant. The 2 gang outlet in question that the UPS is plugged into also serves as a light switch. Being the top outlet is for a lamp that's turned on/off from a fixed (not variable) switch, the bottom being where my UPS is plugged into. Though turning my LED lamps on/off don't affect the amount of noise I'm hearing. I'm not an electrician by any means, so I'm not sure if that type of circuit would induce noise as variable one could.

With that said, I'm trying to track down another interface to test with. I'm certainly hoping the firepod is the culprit (I'm long overdue for an upgrade in that dept) since what I've heard of the x-2 is definately work keeping...and sending it back may be difficult since Sebatrons US dealers appear to only deal online.

Thanks again.

Posted: Tue Mar 18, 2008 6:23 pm

Sounds like you might have to lift the ground wire on the XLR to XLR cable.
I had a similar problem with my firepod and a DMP3 preamp.Neither was noisy by themselves but they produced an odd hum when I connected them together.I tried various different combinations of power outlets and I also tried power conditioners which didn't help.Then I read somewhere to disconnect the earth pin on the XLR cable running between the two.
So I opened the little XLR plug ( the end that went into the firepod ) and cut the earth wire whch is conected to the pin one on the XLR plug.The problem went away immediately.I since made up a set of leaads exactly for this purpose to use and they stay permanantly connected in my recording setup.
Hope this helps you.

Posted: Tue Mar 18, 2008 6:49 pm

Thanks for the reply. However, I'm bypassing the preamp of the firepod, using the xlr out on the x-2 to the trs line input on the back of the firepod. Another side note, even when I bypass the firepod completely (unbalanced ts to unbalanced ts to my mixer) the noise/interference is still audible unless I power off the firepod.

In your case it sounds like you are feeding your preamp to the firedpod via xlr. I haven't this yet since I'm trying to bypass their preamp altogether.
Or did you mod your firepod?

I also tried a ground lift with a DI between the x-2 and the pod, it helped a bit but it was still in no way acceptable for recording purposes...especially in my case as I do a lot of location recordings for jazz and classical musicians. Certainly it's not something I would want to be a permanent fix either (the DI in the signal chain).

I'll record some samples of the noise in the next few days and post a link here, in case that'll get some gears turning.

Keep the suggestions coming! Every bit helps!

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