user01 Posted January 9, 2023 Share Posted January 9, 2023 (edited) Some of Logic's distortion plugins seem to alias at least a bit - it's obvious when running a sine sweep through them. It can be heard and seen on the spectrum analyzer. That happens when the movements are captured at points that still have a meaning to us - only it looks like it's moving backwards now because we happen to capture those exact moments out of order but a specific out of order, that is. Problematic plugins that I found causing aliasing problems Vintage EQ collection Drive and PHAT FX Analog modeling Filters, We can see this in ANalyzer when we open a test oscillator and send Sweep on 1 khz Sinewave between 20-20khz. I think it would be great if a solid HQ oversampling MOD was added to these plugins to eliminate aliasing problems. Edited January 9, 2023 by user01 1 Quote Link to comment Share on other sites More sharing options...
roverlogic Posted January 21, 2023 Share Posted January 21, 2023 That doesn't look anything like aliasing. It appears to be normal harmonics (not extending up to Nyquist as would be the case with aliasing). Try setting your project to 96k and testing again. This should make the aliasing go away, if that is what you're hearing. Quote Link to comment Share on other sites More sharing options...
user01 Posted January 21, 2023 Author Share Posted January 21, 2023 I can't see any aliasing in the flat and moving signal at 96 khz, the results are below human sense, so at -110 db Quote Link to comment Share on other sites More sharing options...
roverlogic Posted January 21, 2023 Share Posted January 21, 2023 That is just a tone with no added harmonics. To test for aliasing you need to add harmonics using one of those vintage plugins you mentioned. Harmonics are like mini tones based on multiples of the fundamental (the lowest frequency tone). So if you see tiny spikes ascending up from the fundamental, those are harmonics. If you see those spikes bounce off the nyquist frequenxy at the rightmost side of your analyzer and reflect back to the left - that is aliasing. Quote Link to comment Share on other sites More sharing options...
roverlogic Posted January 21, 2023 Share Posted January 21, 2023 I agree that plugin oversampling would be great though. But it’s often better if the plugin makers implement this inside their plugins so they can intelligently filter out the aliasing artifacts. Quote Link to comment Share on other sites More sharing options...
des99 Posted January 21, 2023 Share Posted January 21, 2023 I know you have a lot of suggestions to Apple for improvements or changes to Logic - just to make sure - you are sending these to Apple, via their feedback mechanism, right? Rather than just posting them here? Quote Link to comment Share on other sites More sharing options...
user01 Posted January 21, 2023 Author Share Posted January 21, 2023 right , already Simulation of analog sound like saturation from transformers, compressors, tape, EQs,... makes the creation of harmonics necessary.If harmonics are created by plugins, frequencies within the plugin are created which easily could exceed the current Nyquist frequency of the project.What caught my attention from here is that EQ and other Stock plugins don't have such problems without the need for oversampling.For example smashing hihats or cymbals (which have significant amplitudes in the 10 kHz range) with a compressor and/or tape saturation, means - for example - the 3rd harmonics of the 10 kHz already appear @30 kHz.That means, if the DAW runs @44 kHz (Nyquist = 22 kHz) and the plugin developer does not care abut that problem, that 3rd harmonics created in the plugin will appear below Nyquist in the audible treble range at 14 kHz.example 4th harmonics of 10 kHz = 40 kHz -> that inaudible 4th harmonics of 10k reappears at 4 kHz in the audible range... So an aliased 14 kHz / 4 kHz signal is added to the cymbals track (ofcourse not only these two frequencies, because the cymbals are not only @10 kHz, but all harmonic multiples of the frequencies in the original signal above Nyquist are folded down into the audible range). In contrast any recorded analog gear would be free of these aliasing "signals". What makes things worse: the aliased, downfolded, unwanted frequencies add unwanted signal energy to the frequency range they appear in. They add "treble" energy by adding garbage. They increase signal energy in the mids, If a SNR of 65 dB is assumed as technically acceptable minimum between the signal and any unwanted "noise" (aliasing frequencies technically are not noise, but are unwanted garbage just like noise), the anti-alias filtering taking place in the plugin should keep any harmonics below that level. What caught my attention from here is that EQ and other Stock plugins don't have such problems without the need for oversampling. Quote Link to comment Share on other sites More sharing options...
des99 Posted January 21, 2023 Share Posted January 21, 2023 There are many techniques for avoiding aliasing - the most common being to bandlimit the range of frequencies to below Nyquist. So not every plugin needs, or benefits from oversampling. The ones that need it, often incorporate it in the design, and so don't have options to turn it on or off. This is mostly up to the plugin DSP designer as to how they implement this. 1 Quote Link to comment Share on other sites More sharing options...
user01 Posted January 21, 2023 Author Share Posted January 21, 2023 6 minutes ago, des99 said: Logic'teki iyileştirmeler veya değişiklikler için Apple'a pek çok öneriniz olduğunu biliyorum - sadece emin olmak için - bunları geri bildirim mekanizması aracılığıyla Apple'a gönderiyorsunuz, değil mi? Onları burada yayınlamak yerine? yes 🙏 1 Quote Link to comment Share on other sites More sharing options...
des99 Posted January 21, 2023 Share Posted January 21, 2023 Just now, user01 said: yes 🙏 Great! 👍 Quote Link to comment Share on other sites More sharing options...
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