Oversampling oddities

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Re: Oversampling oddities

Post by blinddrew »

Ah, thank you. I thought it was an abbreviation rather than a company.
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Re: Oversampling oddities

Post by Martin Walker »

Tomás Mulcahy wrote: Mon May 16, 2022 8:40 am Yes I think it’s better to test each plug-in for aliasing. DDMF has an app to do it. It’s quicker than doing blind AB listening tests and it’s definitive. I’d consider using something other than saturation to achieve certain sounds. Because that’s the hardest effect to do with minimal aliasing.

I've now done SO many aliasing tests at 44.1kHz sample rate that I've adopted a standard test tone: 15kHz sinewave at a level of -18dB (most common default input level for non-linear plug-ins).

1. I can't hear this 15kHz tone at my age ;)

2. With a 44.1kHz sample rate and a suitable saturation plug-in, the 2nd harmonic of this test tone will be at 30kHz, and its folded back aliasing tone at 14.1kHz (again inaudible to my ears).

3. However, the 3rd (typically the strongest harmonic for symmetrically modified waveforms) will be at 45kHz, with aliasing tone at a very audible 900Hz.

So, as soon as I start to create presets for any saturator/preamp etc., I pop in my 15kHz test tone, and if I can hear any 900Hz tone the it's time to turn on oversampling. More extreme saturation settings will typically require greater oversampling multiples, but there's no point in piling on ever-greater oversampling if you can't hear any aliasing.

Tomás Mulcahy wrote: Mon May 16, 2022 8:40 am By the way, the TDR plugins are incredibly good.

Agreed - that's why I rely on their internal oversampling. I generally leave them on the 'precise' quality, but switch to 'insane' before rendering, as I can just hear the improvement.

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Re: Oversampling oddities

Post by Tomás Mulcahy »

:D:clap:
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Re: Oversampling oddities

Post by Matt Houghton »

Worth noting that Acustica Audio specifically recommend *not* using external oversampling option for their plug-ins, and especially not going higher than 96kHz, which they say can cause problems. (Their plug-ins typically work very differently from most others).
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Re: Oversampling oddities

Post by Martin Walker »

Matt Houghton wrote: Tue May 17, 2022 10:42 am (Their plug-ins typically work very differently from most others).

You can say that again! ;)
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Re: Oversampling oddities

Post by RichardT »

Martin, I notice that reverbs sound clearer at 96kHz. Have you ever looked to see if they create aliases at 44kHz?
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Re: Oversampling oddities

Post by Martin Walker »

RichardT wrote: Tue May 17, 2022 1:05 pm Martin, I notice that reverbs sound clearer at 96kHz. Have you ever looked to see if they create aliases at 44kHz?

Great question Rich!

No, they don't create aliases per se (reverbs aren't essentially 'non-linear' devices that create harmonics). However, since a reverb is creating hundreds of spaced copies of the original sound, it stands to reason that doubling or quadrupling the computing power you give the reverb would improve the clarity and transient detail of reverb-ed sounds, as well as improving any filter and EQ responses.

I too have tried out Reaper per-FX oversampling on my reverbs and have definitely heard this extra clarity on my 44.1kHz when the reverbs are running at 96kHz. Some reverbs even have integral oversampling options (such as my favourite 2C-Audio Aether, which even offers real-time and offline options, so you can further improve your reverb sound at render time).

It's well worth experimenting and using your ears to see what sounds best to you, but I'm sticking with per-fx oversampling rather than running my entire projects at 96kHz (or greater).

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Re: Oversampling oddities

Post by Spells »

I am always dubious of having different real-time VS render over-sampling options set on plugins because I prefer to hear exactly what it is that I'll end up with.

Aside from that, I'm noticing a trend for people working at 48k now... with no relation to TV / video. I have made the same switch as working at 96k, on massive productions brought in issues but also, I found that on SOME material, lower sample rates kind of suited the music more. 96k on a stripped down acoustic piece is a great option, but I found on testing with modern pop type stuff, the lower sample rates sounded more 'right' somehow.
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Re: Oversampling oddities

Post by Martin Walker »

Hi Spells, and welcome to the SOS Forums! 8-)

I totally agree about hearing exactly what's going to be rendered, except that some 'insane' real-time oversampling settings would cause my projects to stagger to a halt within a second or two ;)

I also agree that recording at lower sample rates can sound perfectly good with lots of material (I still use 44.1kHz all the time) but if recording acoustic instruments like acoustic guitar I'd be tempted to go for 96kHz, just in case.

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Re: Oversampling oddities

Post by Spells »

Thanks for the welcome!

Yes, seems we're in agreement. I found on really dense (high track count) songs, that the improved detail on all of the reverb tails wasn't actually a desirable sonic aesthetic, in and amongst all that was going on.
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