Understanding Aliasing

OMG...were Dan and Shadowk the same person?

Does anyone remember if Dan ever went into detail on his plugin chains? I'd love to know how many plugins he was using per session. A lot of plugins have a lot of problems and it will definitely pile up if you're using dozens of things that are introducing stuff like aliasing and phase issues. 

I guess I’ve never been clear what exactly I am supposed to be listening for when it comes to aliasing. And how obvious is it in a real world application as opposed to a sine sweep. My ears are old at this point so I’m sure there are fairly attenuated highs, and the low end in one ear is also messed up. So, I suppose in theory I should be somewhat aware of it and where it might most make its presence known, but in practice I dunno.

Cheers,
Geoff

I think all compression and saturation plugins alias to some degree. Evan Kelvin on “pristine” mode. It only becomes a problem if it creeps into the audible range. If the aliasing is 100dB below your peaks it’s pretty inconsequential. It also matters a lot more on harmonic instruments than it does on drums, since drums are already mostly blasts of inharmonic noise.

From other people’s tests I can tell you Soundtoys stuff is pretty bad, and benefits a lot from oversampling.

Bonus post

This is much like gain-staging your pre-amps for desired (or undesired) harmonic content. But what about how much harmonic content you are getting out of your microphone? (most relevant to tube mics) Do you move it further back from the source to purposefully achieve less distortion? Abbey Road used to use noise-guns on their microphones to inform this decision making



Also,

there is a mega thread on gearspace regarding plugin analysis - particularly aliasing. It's is called "Lets do it: The Ultimate Plugin Analysis Thread" and worth a skim through if interested in this sort of thing

Never, in a way, all his comments/criticisms were abstractions. I’m not saying invalid, but at least I post shit from time to time.

If all this isn’t actually about trying to improve our recording chops: what the fuck are we doing here ?

I'm still confused a bit. Lets say I wanted to just have HP and LP filters on the first insert of every channel. I roll them at 35hz and say 15khz. Does that plugin need to be oversampled? Or does the hi cut make that moot? Then - when you add any other plugs - they should all be oversampled...or do they not need to be because the top is high passed?

For the HP and LP filters - no. Most EQ plugins are clean. But let's say they were not clean eqs - well the low pass filter is already attenuating any frequencies that would extend past Nyquist, so the aliasing is virtually gone

Note every single plugin in a chain can alias. Ideally, plugins that create harmonic material should either allow for oversampling (pushing the Nyquist frequency way up, so that any harmonics then do not reflect off the original Nyquist, or if they do, then are very low in amplitude), or should have a low pass filter built into them (which attenuates the frequencies that would reflect)

This is one reason why I work at 96k. I can use plugins that have steep low pass filters up near 48kHz, which screws with the phase up there, but then my final product is 44.1kHz, and I just cut all that bent phase material out

Let's take a bad case for aliasing: plugin one is driven hard and creates harmonics and also creates aliased material. Then plugin two is driven hard creates harmonics and aliased material, which includes harmonics of plugin one's aliased material, and aliases of plugin one's aliased material. Plugin three compounds this further, and so on. This could end up as mush, creating heaps of signal that is actually unrelated to the original sound

A picture or a sound example here would make it a lot clearer than words

This.

I used to care so much about how everything worked.  I absolutely believed that knowing it would allow me to make the right choices and jump over my peers in my work.  

The truth is, that it consumed me and my time to the point where I'd spend more time dicking around with settings, parts, A/B tests and whatever else instead of just working.  I'm dead serious.  I'd spend a day in the studio messing around with all this stuff instead of actually doing something like mixing the song.  Then I'd be so spent that I couldn't hear it straight anymore.

Honestly, one day I was watching mixing videos and there was a Q&A where the mixer was asked about choosing this plugin over that plugin and he simply said "I don't care, I just used this because I had it and now I know it so well that I'm not going to change" and that was a lightbulb moment for me and reset my whole studio world.  

They didn't really care about the under-the-hood stuff at all.  They wanted an effect/affect and some plugin or piece of gear supplied it and that was that.  Just slap it on and keep going.  No achingly detailed testing or consulting the internet..  Just put it on, adjust it and keep going. 

It's like a weight has been lifted and I feel like I'm doing the best work I've ever done. 

All of pro audio is just my procrastination from writing songs.