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Hi there people
So i use a DUAL STEREO buffalo DAC setup on my PA system, one for each of the CD players in a DJ type setup (with both DACS running into an analogue mixer)
We were running a festival for 3 days and on day 3 (note the system had been running perfectly continuously up until this time) ONE of the DACS started losing SPDIF lock. This meant a cut out in the sound from the PA so as you can imagine this was pretty high impact. the cut outs were brief (under 1 sec) and I tried a large number os things to try and resolve, and in the end we bypassed the DAC.
I can't recreate the fault here at home, so wanted to get some info as to what causes SPDIF lock to keep getting lost really intermittently. it would run for a few mins then bang -more cutouts. Note the OTHER DAC in the box kept working perfectly (i.e. the other CD player) , so it was just one of them in that's having the fault.
I tried:
- Unplugging all other devices from the power that was running the DAC
- A different CD player (SPDIF source)
- Moving the cables around
I have had this fault before but not this bad, so really keen to understand what causes SPDIF to lose lock. The CD Players have RCA SPDIF connectors and that is what I have put on the DAC, as I could buy standard RCA SPDIF cables.. i recently upgraded them and still having this issue.
Keen for thoughts, thanks in advance!
-David
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If you can't recreate the issue at home (e.g. there's no loose wires that need to be resoldered), then it was likely due to some spurious source of strong EMI at the venue. Strange that only one DAC was affected, but it could just be not as well shielded as the other.
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I agree with defterGoose - I could imagine that on that SPDIF signal there was too much jitter so it lost lock. You should try to set up everything at the original place again, with all lights on (switching devices, "bad" power supplies and so on) - perhaps then it will happen again. - That's my first thought!
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Just a bit of feedback on this one, i was poking around inside and discovered that on that DAC the Ground for the SPDIF connection had come loose (vibration mist likely). I put it back in and screwed it down.. could this have been the issue. I have been unable to recreate fault...
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Originally Posted by: biggsd  Just a bit of feedback on this one, i was poking around inside and discovered that on that DAC the Ground for the SPDIF connection had come loose (vibration mist likely). I put it back in and screwed it down.. could this have been the issue. I have been unable to recreate fault... Well, it will be easy to reproduce. Lift the gnd and see what happens. (I'll bet you, it will loose lock ;-)
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Ok so still got the issue grr!
Ran event a few weeks ago after fixing ground - all good no problems - note was just running rig at venue with just that on power line
Yesterday ran another gig same setup but with lights on same circuit as was small venue - both channels started dropping out - one worse than other.
Both different venues.
So I am starting to point at power - I see some discussion about dc spikeds causing this - has anyone tried putting an online ups in the chain to clean up the power? I can definitely recreate the fault and cause a drop out by plugging a light in to the same power as Dac - is this normal?
If a ups solves the issue all good - feedback?
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I can only suggest a power conditioner and maybe DC blockers.
You could also use a signal transformer at the SPDIF input to galvanically isolate it. I do that with anything that is going into a studio or live venue.
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