Distortion Problems

#1
Hey guys,

This is a bit complex to try and explain so here I go:

I am using the ULN-8 with Logic 8. In one session (and one session only as far as I can tell) I am getting electrical sounding distortion coming from output "3". I am using analog 3-4 for my monitors right now. Strange thing is, when I switch to another output (like 5-6) the distortion goes away. I suspected it could be the cable, but why would output 3 work in another sessions with the exact same DSP settings?

So this leads me to believe that the output 3 in my unit is malfunctioning. The distortion gets REALLY bad when I enable the 12 band EQ on DAW 5-6 like the DSP is overloading or something. Its really strange and would like to know if there is anything I can do to trouble shoot this more? I am borrowing a breakout cable from a friend this weekend to test it some more to see if it is the cable. I am using I/O plugs for all these DAW inputs and FW outputs.

Here is the mixer config with DSP on it (from left to right):

DAW 5-6: Master Vocal Bus
DAW 7-8: Master Drum Bus
DAW 9: Kick
DAW 10: Snare
DAW 11: HH
DAW 12: Tom 1
DAW 13: Tom 2
DAW 14: Tom 3
DAW 15: Left Overhead
DAW 16: Right Overhead.
DAW 1-2: Master Bus

Here is where it gets REALLY strange (and only with this session, I have other sessions that have the same amount of DSP plugins that sound just fine). On the vocal bus in Logic, if I bypass the I/O plug, and still have the DSP enabled for the DAW 5-6 return in the Mio Mixer, the distortion still takes place. The more DSP I bypass, the less distortion I get. I have tried as much as I can to narrow this problem down, but it all comes down to Output Analog 3 is getting distortion noises with this DSP setup, and other analog outputs are not.

Any ideas?

Also, I tried to search how to figure out how much DSP processing I have left, but I just can't seem to locate that information on my unit, where do I go for that?

-Robb
 

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#2
Look in the lower left side of the MIO Console window; there's a DSP Usage meter. It would be helpful to know what sample rate you're working at. It sounds like you're overloading the dsp.

I'm about to go on vacation for a week, so if you don't get any suggestions here that help please get in touch with support and Jon will help you.

Allen
 
#3
I am working at 44.1 / 24 bit.

Let's say it is DSP overload, but why does the distortion dissapear with a different analog output? Also, when I switch to cans there is no distortion.

I checked my amp, my speakers, and cables (as far as I know).

Also, I am looking and I still can't find that usage meter, so you're saying it is supposed to be the bottom left side of the MIO Console, in the I/O Control Tab? When I goto the +DSP tab the meter in there doesn't show any DSP being used...

-Robb.
 
#4
Sorry this is an old thread but I'm wondering if this was ever resolved? Because I'm experiencing a problem which sounds exactly the same as what you described here with a new ULN-8 and Macbook Pro which I've just set up. I'm currently only using analog outputs 1-2 for monitoring, and I get the electrical distortion just on channel 1 after working in Logic 9 or just playing system audio for a while.

If I know how you resolved it perhaps I can try the same thing? I'm already in discussions with the support team over email, but I think they are away for the weekend, and I really need to set up my surrounds on Monday. So any help or advice would be appreciated, thanks.
 
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