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Old 07-09-2011, 09:55 AM
BJosephs BJosephs is offline
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Default Latency Compensation on Hardware Inserts

I've searched quite a bit on this topic, and done a bunch of experiments myself, but like most of the others that have posted on this topic there seams to be something not quite right.

I am trying to patch analog hardware devices as inserts on tracks and I get phasing issues when monitoring side by side with a duplicate track.

I am running PT 9.0.3 on Mac OS 10.6.8 (Dual Quad, 8 gigs). My hardware is RME HDSPe AIO - some testing was done with it's built in ADA converters and some done through it's ADAT port to a Tango 24.

Here are the circumstances and the results:

One source track with a file, no inserts -> duplicated to a second track. When played back the sound obviously is louder, and no phasing. If I put a hardware insert on either track there is a phase issue (The delay view on the fader indicates 149 samples of latency). This does not change with ADC turned on and if I plug numbers into the I/O "HW insert w/ delay" page the latency gets reported longer and I never achieve phase correlation. I tried plugging in the values RME reports for latency (AD=.84ms + DA =.65ms) and also the latency that may arise from the software buffer (32 samples = .72ms) - no combination works. I played this game with with both the internal ADA and through ADAT.

What is interesting to me is that if I use a bus send from the original track and monitor in record mode on a new track (Obviously no latency here yet) and put a HW insert on like above I still get identical figures for latency - but I can print this track and the result is phase coherent! ADC on, ADC off, delay figures or not there is no problem. Both Internal ADA and ADAT port.

It seams that PT has the facilities to account for recording delay automatically independent of ADC. Obviously, I would like to enjoy phase coherence while monitoring as well. Any thoughts on what I might be doing wrong or am I expecting too much here?

Thanks,
Brian
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  #2  
Old 07-09-2011, 01:36 PM
ROBB007 ROBB007 is offline
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Default Re: Latency Compensation on Hardware Inserts

I have the same problem with a RME Raydat card and Pro Tools 9.0.3 and RME adi-8ds converters LATENCY???What can you do to fix this.
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Old 07-10-2011, 10:28 AM
BJosephs BJosephs is offline
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Default Re: Latency Compensation on Hardware Inserts

Quote:
I have the same problem with a RME Raydat card and Pro Tools 9.0.3 and RME adi-8ds converters LATENCY???What can you do to fix this.
Do you experience the latency only while monitoring? Is it gone after printing the track?
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  #4  
Old 07-10-2011, 12:16 PM
therecordinghouse therecordinghouse is offline
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Default Re: Latency Compensation on Hardware Inserts

hmm, my Raydat card seems to be working fine. 9.0.2, and using Apogee Ensemble in standalone mode.
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Lynn Graber
Studio and Mobile Recording, Fort Wayne, IN.
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Old 07-10-2011, 12:20 PM
therecordinghouse therecordinghouse is offline
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Default Re: Latency Compensation on Hardware Inserts

just out of curiosity, have you tried higher buffer settings? I am at 256.

also, have you tried actually measuring the latency and using those numbers? you can do this by recording a bit of click to an audio track, duplicate it, put a hardware insert on one, bus them both to a new track and measure the difference in samples.

by doing the above, i found my hardware inserts took an extra 31 samples, which is 65ms at 48k. this is what i put in the field in the IO setup.
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Old 07-10-2011, 07:29 PM
BJosephs BJosephs is offline
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Default Re: Latency Compensation on Hardware Inserts

Great suggestion, thank you. I was suspecting a test like this was necessary but I wasn't sure which way to approach it as there are a few variables.

With ADC on I measured 68 and 64 samples of latency for the RME interface and Tango 24 respectively. Without ADC they are off by a mile (I was running this session at 1024). At 48k this works out to 1.416 and 1.330 milliseconds - slightly higher than the specs would suggest. These values lead to phase coherence while monitoring as long as ADC is on.

Obviously the true delay changes with software buffer settings - another reason why I think ADC needs to stay on when I play this game to prevent needing to know 12 latencies per sample rate - but at the very least I have phase coherence while monitoring.

Thanks again
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Old 07-11-2011, 06:45 AM
therecordinghouse therecordinghouse is offline
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Default Re: Latency Compensation on Hardware Inserts

glad it is sorted.
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