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How to set up I/O plugin in Logic X so hardware processed signal is time-aligned?

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How to set up I/O plugin in Logic X so hardware processed signal is time-aligned?

Postby samuk » Sat Feb 22, 2020 10:16 pm

I am using Logic X’s I/O plugin to send audio out via my interface (Apogee Duet 2) for processing with external outboard equipment.

I am able to send out a mono audio track (e.g. a vocal) out of the Duet’s Left Speaker Output, route it through an external outboard device (I’m using guitar pedals and rack units such as the EQP-WA) for processing, then record the processed signal to a new audio track in Logic.

However - the processed audio is slightly out of time with the original.

How can I set this up in Logic X - and perhaps using Apogee’s Maestro 2 software - so that they are in time and aligned with each other? Further, if this is not possible is there a reliable workaround? I tried doing it by ear then by eye but I wasn’t able to exactly align them.


I initially tried to use the ‘Ping’ function in the I/O plugin. My understanding of this is that it reports back the amount of samples that the interface’s driver is under-reporting its latency by. I was getting ‘+16’ samples when I used ping, so I inverted the number of samples and manually set the recording delay to ‘-16’ samples, thinking this would compensate for the delay. But the processed audio was still misaligned.


I don’t think its plugin-latency causing this - this occurs even without any plugins except the I/O plugin on the original, unprocessed audio track, and no plugins on the stereo buss nor the processed audio track, nor on any other track.

It also occurs when I have the buffer set as low as it can be at 32 samples.

It’s a very frustrating issue but hopefully one with a fix - I’d be extremely grateful for any help.

My setup:
Logic X v.10.4.1 running on a 2018 MacBook Pro.
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Re: How to set up I/O plugin in Logic X so hardware processed signal is time-aligned?

Postby desmond » Sun Feb 23, 2020 3:55 pm

Are you using the I/O utility on an audio track, or an aux channel?

If the former, try changing your mixer configuration so you are routing to your external effect via the I/O on an aux channel (as described here: https://help.apple.com/logicpro/mac/10. ... cef2d8c7d2), rather than on the audio track, and see whether this works better for you.
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Re: How to set up I/O plugin in Logic X so hardware processed signal is time-aligned?

Postby samuk » Mon Feb 24, 2020 12:37 am

Hi Desmond,

Thanks so much for this! :D :D :clap: :clap:

I was using the I/O utility on an audio track - when I used it on an aux channel it seemed to work. The waveforms don’t look exactly in time but are much closer in time. More importantly, they sound in time and I can’t hear any of the phasing I was getting before with a delay between them.

I’m still not sure as to why Logic doesn’t compensate the delay properly when the I/O plugin is on an audio track rather than using a bus. Perhaps it’s something to do with Logic calculating the delay compensation differently on a bus track?

I’m away from my studio this week but I’m going to be testing this a lot more when I get back.

Thanks so much again Desmond - I was getting pretty defeated by this!
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Re: How to set up I/O plugin in Logic X so hardware processed signal is time-aligned?

Postby desmond » Mon Feb 24, 2020 12:57 am

That's good, thanks for the follow up.

I haven't used it myself for ages (and can't test at the moment) but I just remember someone coming across this and saying the ping latency for some reason (likely a bug) isn't compensated on audio channels, but works OK on aux channels, which is why I suggested to try it.

To be fair, the manual only talks about using the I/O on aux channels, but it *should* work on audio channels I would think...
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