Plugin detune issue in Logic Pro X

Dear all,

I have a detune issue with AU plugin inside Logic Pro X for certain sample rates.

So when playing with 44.1k sample rate and all other multiples of that sample rate then there are no issues with plugin being detuned - playing note C3 is correctly produced as C3.

If I change sample rate to 48.0k then playing note C3 produces C#3 - half step detune.

Now this only happens with AU build on the plugin inside Logic Pro X.

I have tested with REAPER and Live and no issues at all - for both AU or VST3 builds.

Any ideas what might be the issue here?

Thank you

I am using JUCE 4.3.1 and it seems that issue is fixed with this commit below for version > 5.1.

Am I right?

This fix above didn’t help

Are you checking for sample rate changes in prepareToPlay or in the processBlock method. The sample rate can change.
A good test maybe is to change the sample rate in reaper and see if your plugin still have the right pitch. Really hope this isn’t a JUCE bug. What version of JUCE are you using?

Hi @kunz , thanks for feedback.

Yes, I am checking sample rate changes and JUCE version is 4.3.1.

I have already commented that I have tested in REAPER and LIVE and no detune issues for both AU and VST builds no matter what is the sample rate - pitch is correct. So only when I am using AU build with Logic Pro X and having sample rate 48k or multiple of that (96k etc) I am having detune issue - half step pitch deviation.

If you take 44.1kHz and 48kHz, transpose them into audible range[1] and convert to note names, you get:

44.1kHz -> 11025Hz = F9 minus 23 cents
48kHz -> 12kHz = F#9 plus 23 cents

Roughly a semitone difference.

[1] (for note names) repeatedly dividing by 2 until 27.5Hz > X > 14.08kHz

I think no one can help if you are running such an old JUCE version. The best would be to update your project to version 5 or even 6 and verify if the problem still exists.