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Delay in Signal Path?


mgoslett1

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Hi All

Another bazar one I can't wrap my head around. For context, I'm running a Lewit LTC 640 into a Focusrite 2i2. In Logic these go into a standard channel strip and straight out to the stereo bus. I'm not running any FX at this point and for the purpose of troubleshooting I've disabled all plugins and aux's. In preferences I'm not running any recording delay and my Mac is a bit of a beast so I know I'm not troubling the CPU, as can be verified by the metres. Input monitoring is on.

 

Issue:

When I play/sing, there is about a quarter of a second delay before the audio reaches the channel strip both audibly and visibly. I'm sure this is further down stream of the Focusrite because with direct monitoring on, and input monitoring off, there is no issue. I can also visibly see the gain meters react instantly on the FR. I've tried the good old off n on trick, I'm running I/O buffer at 64ms at 8.6ms roundtrip, processing threads are automatic but has 20 at its disposal. I've reset the core audio, unplugged the FR, and changed to and from various I/O rates to see if anything jolts it back to where it should be. At this point I'm imagining I've clicked a button I didn't know existed.

 

Ant thoughts?

 

Many thanks

Mark

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So you send audio into your interface with the mic, and see the meters on the interface immediately, but on the *channel strip you are recording through*, you don't see meter activity until about 250ms later?

 

You have the Focusrite selected as the audio input and output device? Do you have any other audio utilities running, like Loopback, Audio Hijack, Soundflower, a screen recorder utility or anything else that might be hijacking the audio signal?

 

This also happens in a new, empty project with no plugins inserted at all?

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So you send audio into your interface with the mic, and see the meters on the interface immediately, but on the *channel strip you are recording through*, you don't see meter activity until about 250ms later?

 

You have the Focusrite selected as the audio input and output device? Do you have any other audio utilities running, like Loopback, Audio Hijack, Soundflower, a screen recorder utility or anything else that might be hijacking the audio signal?

 

This also happens in a new, empty project with no plugins inserted at all?

 

Correct. I'm not running any other programs or utilities, just Logic via the FR as the only I/O device. I know that Screenflow for example can cause a massive latency but it doesn't usually trouble my system anyway. The issue seems to be specific to this particular session. It was running perfectly well yesterday. I'd saved the session but it remained open and on overnight. Today... weird things are happening. It's like the recording delay has been set to maximum samples.

 

Thanks

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The issue seems to be specific to this particular session.

 

Then we know it's not a driver or audio interface issue.

 

It's like the recording delay has been set to maximum samples.

 

No, recording delay simply *places* the recorded audio at earlier or later positions - it doesn't affect the reception of incoming audio.

 

If it's just happening in this project, I'm still inclined to think it's plugin related.

 

As a test, open the project, and remove all the plugins completely (as a test) and try it again. Do you get the same behaviour?

Have you placed any plugins on input objects?

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The issue seems to be specific to this particular session.

 

Then we know it's not a driver or audio interface issue.

 

It's like the recording delay has been set to maximum samples.

 

No, recording delay simply *places* the recorded audio at earlier or later positions - it doesn't affect the reception of incoming audio.

 

If it's just happening in this project, I'm still inclined to think it's plugin related.

 

As a test, open the project, and remove all the plugins completely (as a test) and try it again. Do you get the same behaviour?

Have you placed any plugins on input objects?

 

I definitely know it's not a driver issue. It's all worked swimmingly well for the last year and a half. I'll give the plugin removal another try in the morning. It's past my bedtime :)

 

Thanks for your persistence.

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The issue seems to be specific to this particular session. It was running perfectly well yesterday. I'd saved the session but it remained open and on overnight. Today... weird things are happening.

 

This.

Don't leave a project open for hours or overnight. Shut down Logic. Weird things can happen as you experienced.

Your project probably got corrupted.

 

Open a new one and use the Import function from the Project Browser to get everything on it.

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The issue seems to be specific to this particular session. It was running perfectly well yesterday. I'd saved the session but it remained open and on overnight. Today... weird things are happening.

 

This.

Don't leave a project open for hours or overnight. Shut down Logic. Weird things can happen as you experienced.

Your project probably got corrupted.

 

Open a new one and use the Import function from the Project Browser to get everything on it.

 

Yeah, you're probably right, and this is next on my troubleshooting list. Thanks!

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UPDATE: after trying a few more things, including both your suggestions the problem seems to be resolved after importing the files into a new session. I don't think that this was a latency issue introduced by plugins as I wasn't running many, or anything that was introducing that much latency. Even when removing all of them completely the issue persisted. All I can put it down to at this point was a bug that creeped its way in to the session over night.

 

Thanks for your suggestions and persistence. This is a great community.

 

Mark

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