Behringer DCX no like digital

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I wonder if anybody else has encountered this problem:

I have tried to include a diy isobarkik sub with my kef's 104/2.
Crossing over via the dcx at 50Hz, i feed the dcx via aes/ebu from the deq 2496, who in return gets the signal from a src 2496, also via aes/ebu. I had no problems driving an "activated" kef calinda, but when I swiched to the current set-up the digital signal gets horribly noisy, with scratching, clicks etc.

I have analyzed using a test cd, and all frequencies above 500Hz result in this digital noise. I have tried to attenuate the deq output, only at a level of -15dB the noise vanishes for frequencies up to 10kHz, but above that - no matter how low the output - the noise persists.

Switching to analogue out/in - no problem.

This problem in the digital domain ocurred suddenly (I am using 100 ohm cable) after I used the dcx for a DIY setup for several years.
Before I could drive the dcx without ill effects right to the red indicator. Not anymore.
Any idea what might be the problem?

PS.: the problem could be also related to the digital path in the deq - but cannot test this not having a second dcx (I have another one that refuses to accept digital input at all).
 
Yes, checked everything in the menu. And the cables. Before the problem occured - the dcx was always mounted in the rack, not moving at all.
Problem occured after testing the setup with a kef speaker, then for a few days switching the dcx off, taking the analogue from the deq to my amp and feeding the kef 104. When reintroducing the dcx to drive a sub in sum mode - then the ...hit the fan.

SRC can't be the problem, otherwise the analogue out of the deq would be affected - which it isn't.

What I forgot to mention - the problem does not occur when feeding an analogue signal to the chain, starting with the src as the adc.
Only the signal digital signal from the pioneer dv 59 avi shows this noise - but only when the sign al is fed through digitally right to the dcx. Taking the analogue signal off at the deq - no problem.
 
How much EQ are you applying with the DEQ?

The problem you will have with feeding SRC->DEQ is that if you boost the signal in the DEQ you can achieve "digital clipping" which sounds exactly as you described.

The way to work around this is to look at your GEQ settings and PEQ settings and adjust the overall level to just avoid the clipping. For example if you have +9db boost in the highest GEQ band and a couple of 3-6db boosts, you would need to set your overall level to output atleast -12db.

You can do this directly on the GEQ screen by hitting the uppermost small knob. The freq band box will show "full". You can no adjust the entire level of the GEQ +/- 12db...

You can test if this is digital clipping by driving the SRC with an analog signal in A->D mode. Adjust the analog gain on the SRC to see if the problem goes away. This way the DEQ is still all digital and the settings are the same only the digital signal level into the DEQ is being adjusted by the SRC.

HTH

--Chris
 
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