MP 1,1-5,1 SPDIF pop / delay & HDMI ground loop hum

[citizenkhan]

I'm trying to diagnose an annoying issue in my AV system.

Currently audio is routed from the Mac Pro via SPDIF to a Harmon/Kardon AVR 254. It's an old receiver rife beset by a number of widely reported issues, so I suspect it's the culprit.

Video is output through HDMI on an RX 580. Unfortunately I can't use audio over HDMI due to what sounds like ground loop hum.

During playback the quality is OK - I can live with hiss. Not ideal, but not obnoxious. However, during periods of silence or relative silence, the signal cuts out completely with an audible pop. Additionally, it takes the system about one second to send the signal after playback begins, which makes it impossible to use SPDIF when editing in FCPX. In that case I must switch to analog output.

Does anyone else have this problem with their Mac Pro? Or a solution to the RX 580 HDMI ground loop?

 

[defjam]

I'm trying to diagnose an annoying issue in my AV system.

Currently audio is routed from the Mac Pro via SPDIF to a Harmon/Kardon AVR 254. It's an old receiver rife beset by a number of widely reported issues, so I suspect it's the culprit.

Video is output through HDMI on an RX 580. Unfortunately I can't use audio over HDMI due to what sounds like ground loop hum.

During playback the quality is OK - I can live with hiss. Not ideal, but not obnoxious. However, during periods of silence or relative silence, the signal cuts out completely with an audible pop. Additionally, it takes the system about one second to send the signal after playback begins, which makes it impossible to use SPDIF when editing in FCPX. In that case I must switch to analog output.

Does anyone else have this problem with their Mac Pro? Or a solution to the RX 580 HDMI ground loop?

I assume the SPDIF connection is coaxial and not fiber? Easy way to test for ground loop issues is to put a cheater plug on the suspect equipment. If it goes away it's definitely a ground loop. Unfortunately that doesn't help fix the issue which would require internal service of the equipment.

 

[citizenkhan]

I assume the SPDIF connection is coaxial and not fiber? Easy way to test for ground loop issues is to put a cheater plug on the suspect equipment. If it goes away it's definitely a ground loop. Unfortunately that doesn't help fix the issue which would require internal service of the equipment.

Thanks for you rapid response. I tried a bunch of power options in the mean time before I remembered that I had a spare flatscreen with built-in speakers. Connected the Mac directly to it an POOF - problem gone. I've always hated this receiver anyway. Finally have a good reason to ditch it.

Again, thanks!