Audible distortion when trying to record above 96kHz
 

I am having a continuing issue with audible distortion being heard and recorded when trying to use a sample rate above 96kHz. It sounds like a clocking issue. I have tried restarting the entire system, hardware and software. I have verified that all software and all drivers are up to date. I am unable to find a solution. If I monitor the audio directly off of the headphone output on my interface, the audio sounds great, no distortion. When monitoring in PT there is audible distortion, sounds like a clocking glitch. The distortion is recorded on the track. Track count does not make a difference.

system set up:
iMac 2017 w/ 16GB RAM OS 10.10.5
Avid C24
Universal Audio Apollo 8 Thunderbolt
Universal Audio Apollo 16 Thunderbolt
Universal Audio UAD 2 Satellite [ 2 each] Thunderbolt
ProTools 2018.4

Re: Audible distortion when trying to record above 96kHz
 

Outside of the obvious question of why would you need 192 K operation you may want to move up a level or two on your OSX install. Your version of PT wants to see a minimum of OSX 10.11.6 (aka El Crapitan) per this chart: http://avid.force.com/pkb/articles/e...tibility-Chart

If I understand you right if you monitor through the UAD console the audio is clear but when listening to audio coming from PT there is distortion? And you say it's recorded? Have you checked your levels that you're not overloading things somewheres in the recording chain?

Re: Audible distortion when trying to record above 96kHz
 

I definitely do not have a clipping issue in ProTools. Everything is in the green.
Will try OS update.

Could this be an issue with Thunderbolt? Currently all 4 UA units are “daisy chained “ to a single port on the iMac.

Re: Audible distortion when trying to record above 96kHz
 

I doubt it's because of the daisy chaining itself; according to the Apple spec one can have up to 6 devices in a chain. Maybe try changing the order of devices in the chain and make sure all devices are powered up at the same time.

Re: Audible distortion when trying to record above 96kHz
 

I think first thing I'd do is take this down to a single interface and see if I can get solid connectivity at 192k there. Then start adding devices.

Re: Audible distortion when trying to record above 96kHz
 

Just a quick follow up. The issue is solved. It was with the daisy chain of Thunderbolt devices. Yes, you can have 6 things on 1 chain, but not at 192kHz, or 96kHz. By splitting my devices to 2 different ports I am able to run a full 192kHz session no issues.

To answer the other question why 192kHz...

1. Future proof recordings. True, formats and tech are racing forward and the end listener will soon have easy access to HD audio and will want it. The gaming industry is driving this forward.

2. The most important reason is sound quality. It simply sounds much, much better. The science is out there about all of this, study up and give it try; it is worth the effort.

Re: Audible distortion when trying to record above 96kHz
 

The REAL science isn't out there at all. The fake science would have you believe that Nyquist's perfect 40 kHz. sampling with infinite slope/infinite length (latency) low-pass filters is readily available. It simply isn't in the real world. What you hear can always be measured. You just need to know what to measure!

Re: Audible distortion when trying to record above 96kHz
 

^^^ thanks Bob.

Re: Audible distortion when trying to record above 96kHz
 

Unless your interface records up to 40kHz at 96k all it does is move nonlinearities of a realworld system to higher frequencies that are cut off later. In which case going from 96 to 192 only has a placebo effect. Different story if recording via your interface actually stores frequencies up to 80kHz when recording 192k

Again if it sounds better for you just go for it. I can tell that most interfaces benefit from 96k recording (and the src to 48k for mixing) but 192k is just overkill if the track ks limited to 20kHz frequencies. IMO of course

Re: Audible distortion when trying to record above 96kHz
 

The reason the major labels archive to 192 is to preserve the tape bias signal that can be used to remove wow and flutter.

You don't want filters that allow flat response to 40 or 80k You want gentle filters that start rolling off at 20 k with minimal ringing. The point is to reduce distortion including filter ringing. People having hearing damage such as guitar shredders are far more sensitive to ringing than people with pristine hearing. Most of us pro recordist types are somewhere in between.