Strange reamping latency issue

E

efx

Inspired
I have the axe fx set up as my soundcard so this is the only "outboard gear" in the chain. I'm recording in logic 9 and I decided to do some reamping.
The issue is this though that it seems that having a higher I/O Buffer size in logic will actually reamp with less lag than a low I/O buffer size and I'm not understanding why. Look at the picture below:
In it I have two tracks, they are essentially just the built in metronome of logic going through the axe fx and reamped into a reg. audio track. The lower of the two has the first hit closer to the beginning of the waveform than the top and yet the top one was reamped with the I/O buffer set to 32 and the lower 1024. Shouldn't that mean that with a lower roundtrip latency that the lower one should be behind the top one or am I not understanding this properly?
Sk%C3%A4rmavbild%202014-09-08%20kl.%2002.02.12.png

Very strange, I hope someone can help me figure this out :)

Thanks in advance!
 
efx said:
I have the axe fx set up as my soundcard so this is the only "outboard gear" in the chain. I'm recording in logic 9 and I decided to do some reamping.
The issue is this though that it seems that having a higher I/O Buffer size in logic will actually reamp with less lag than a low I/O buffer size and I'm not understanding why. Look at the picture below:
In it I have two tracks, they are essentially just the built in metronome of logic going through the axe fx and reamped into a reg. audio track. The lower of the two has the first hit closer to the beginning of the waveform than the top and yet the top one was reamped with the I/O buffer set to 32 and the lower 1024. Shouldn't that mean that with a lower roundtrip latency that the lower one should be behind the top one or am I not understanding this properly?
Sk%C3%A4rmavbild%202014-09-08%20kl.%2002.02.12.png

Very strange, I hope someone can help me figure this out :)

Thanks in advance!
Click to expand...

Go into the preferences of the Logic session, into AUDIO, and uncheck SOFTWARE MONITORING.
 
I run without software monitoring on at all tmes so that can't be it. Thanks for the input though :)
 
If your daw is playing nicely with your audio interface then you shouldn't be experiencing this behaviour. The ASIO drivers will report a latency for each buffer size but in my experience some software handles it wrong ex. in cakewalk sonar pre version 8.5 my layla 3g would have negative latency when recording and I had to manually offset every take forward to make it line up.

Try removing the axefx from the chain and just patching a cable from out to in and try at different buffer settings to see what happens. I don't know Cubase but some other daws have a manual offset setting so you correct problems such as yours automatically. Work out the sample offsets for each buffer size that you use and write them down.

Also the roundtrip latency introduced by the axefx will differ from patch to patch by up to around 3ms last time I tested it. Depends on the complexity.
 
Thanks for the input Glennski! I'm on a mac though so I'm not using ASIO drivers and I'm also just using the axe-fx as a soundcard as well so I can't remove it from the chain. Maybe it's something to do with using the axe-fx as the soundcard in all of this?
 
Interesting... I'm seeing the opposite - latency equal to just shy of 1/2 of the Axe-FX buffer size. The delay seems to be independent of the Logic Pro buffer size:

latency.jpg

I was seeing about 447 samples of latency with the Axe-FX set to a 1024 buffer size. You can measure the latency in the File View and compensate if you want with a negative "Recording Delay" in Preferences ... > Audio > General > Recording Delay.

This is with Software Monitoring off. Things get different with software monitoring on based on the plugins on your tracks, busses and output:

https://help.apple.com/logicpro/mac...al/index.html#chapter=41&section=3&tasks=true
 
As a comparison, if I go through a UA Apollo Quad using SPDIF Input/Output to the Axe-Fx I'm seeing 16 samples of latency with the same test.

I've been using USB for Axe-Edit and running all I/O through Apollo. That seems like an even better decision after this little experiment ;)
 
Wow, interesting stuff. I haven't messed with the usb axefx settings, maybe I should try it out. I'll see how it pans out and report back! Thanks so much for the input.
 
efx said:
Thanks for the input Glennski! I'm on a mac though so I'm not using ASIO drivers and I'm also just using the axe-fx as a soundcard as well so I can't remove it from the chain. Maybe it's something to do with using the axe-fx as the soundcard in all of this?
Click to expand...

Whoops, I'd better brush up on my reading skills :?

If you can afford a separate interface though your setup becomes much more flexible and it should solve your problem (hopefully!)
 
efx: I'm seeing this exact latency behavior with my Apogee Ensemble and Logic X. Software monitoring is off. When I change the buffer size to 1024 everything lines up correctly, but at 32 there is a serious lag.

Were you able to figure out why?
 
First I would try the test several times and see if it's consistent. You appear to be using Logic 9. Here is a guess. If you have an Axe FX with sound card then you probably have an editor to go with it. That might indicate you are on OS X Mavericks or Yosemite. If you are then all bets off on how Logic 9 functions with Yosemite. I have had a world of latency crap with that combo. Many times shutting down Logic 9 and reopening temporarily solve these latency issues, stutters and stammers.
 
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