Hey all, after half a decade of running sound “professionally”, I’ve wound up here at the Allen & Heath forums from an issue that’s left me completely stumped.
A summary of the issue: There is distinct, audible distortion on my SQ-5 Aux Mixes when the volume gets loud enough despite NO CLIPPING anywhere in the signal chain.
An overview of the signal flow (bear with me):
- DiGiCo SD-RACK for I/O
- Fiber connection from SD-RACK to DiGiCo SD10 at FOH
- BNC connection between SD10 and DiGiGrid MGB (all audio sent to the MGB is using DiGiCo’s “copy audio” feature)
- DiGiGrid MGB is connected to an isolated SoundGrid network over RJ45
- Waves LV1 pulls audio from the MGB on the SoundGrid network for a dedicated broadcast mix
- SQ-5 with a Waves I/O Card pulls audio from the SoundGrid network (routed in LV1) for monitoring
- PSM1000s receive 6 stereo mixes from the SQ-5
As for clocking
- A Black Lion Micro Clock MK2 syncs all of our consoles to 48k. Master and slave assignments are set primarily in LV1 with SOE.
The Issue, again: There is audible distortion on my SQ-5 aux mixes when it’s loud enough. There is no clipping happening at the DiGiCo, LV1, OR the SQ-5. On the SQ-5, there is no clipping at any input or on the auxes themselves. This distortion on Aux Mixes is audible on the solo bus going directly out of the console, completely bypassing the PSMs, leading me to believe that the issue is local to the SQ-5 and needs to be fixed there. This invisible distortion is not happening at any other console either, my inputs and mixes all sound clear except for on the SQ-5.
The only way I’ve been able to stop this from happening is just by turning down the master volume of a distorting mix and cranking the P10R receiver pack, but this leaves users with no headroom and inadequate volume for their in-ears. It’s not an adequate solution to my problem.
I’d appreciate any input or advice on how to troubleshoot this problem.