Noise floor level changes depending on which app is in foreground

[Tony359]

OK, what is the digital path of Smaart to the Focusrite? The other DAW - you say running, also capturing? I do not see it capturing on your video. If capturing, what device and what digital path?

Digital path is USB-2, direct connection. Nothing else connected to the laptop.

The other DAW is not capturing, not doing anything. Just idle.

What are the audio connections you call irrelevant? When disconnected - that means Hi-Z inputs, susceptible to picking up the PC noise. When connected - to what? How is that device further connected? Example - the device could be a pre-amp with disconnected inputs, again picking up the PC noise with its hi-z inputs.

The audio connections I call irrelevant are the Focusrite Inputs and Outputs.
The video shows Smaart capturing the inputs of the 18i20 while connected to a sound processor set to AES input so to minimise the noise floor.

The first test - short the Focusrite inputs and test its real internal noise profile, without any external influence.

Thanks. Done, no change. Noise Floor is lower than when a device is connected of course but "bump" still shows up as described above.

 

[phofman]

Digital path is USB-2, direct connection. Nothing else connected to the laptop.

What direct connection - ASIO or Wasapi exclusive? What is the other DAW connected to (yet not capturing), what path? Is perhaps the other DAW outputtting something low-level?

Thanks. Done, no change. Noise Floor is lower than when a device is connected of course but "bump" still shows up as described above.

OK, how is the focusrite powered? Through USB? If not, it would be interesting to test a cable with USB V+ line disconnected, to completely avoid impact of the USB power from the PC (which certainly is affected by the other app running, that's normal). We are talking about -140dB change, that's basically nothing.

 

[RandomEar]

ASIO buffer already at maximum and I have tried with different settings

Good tests! Will try.

Discrete GPU is disabled via BIOS - the software implementation was hideous and causing all sort of issues with Windows.
CPU is AMD Ryzen 7 6800 so no efficiency cores.

OK. Some more ideas going into the latency and CPU priority direction:

• Set the Windows power plan to "Maximum Performance" even on battery - but I suspect you already tested it while charging and this would probably be the plan active in that case...
• Turn off USB selective suspend
• Turn off PCI Express Link State Power Management in the BIOS, if the Lenovo allows it
• Update the AMD CPU/chipset drivers from their page (not from Lenovo, those are guaranteed to work but often outdated)
• Install LatencyMon and check what it says while the bump is or isn't showing

 

[Tony359]

OK. Some more ideas going into the latency and CPU priority direction:

• Set the Windows power plan to "Maximum Performance" even on battery - but I suspect you already tested it while charging and this would probably be the plan active in that case...
• Turn off USB selective suspend
• Turn off PCI Express Link State Power Management in the BIOS, if the Lenovo allows it
• Update the AMD CPU/chipset drivers from their page (not from Lenovo, those are guaranteed to work but often outdated)
• Install LatencyMon and check what it says while the bump is or isn't showing

Thanks for the extra ideas.

No effect unfurtunately. I had already all the power saving disabled (I know Windows is bad with those), my AMD driver is already up to date (Lenovo's is from 2022 I think!). Changing priority in Task Manager also didn't have effect, VRR is disabled.
Apologies if I'm not going to test with the discrete GPU, I've recently removed the nVidia drivers for good and I don't feel like reinstall everything.

Latencymon shows the below result and doesn't change with or without the bump.

@phofman
Good question, I know they both use ASIO, how can I find out more to answer your question?
The other DAW is connected to the Focusrite as well. Please note that the bump is always present, even when only Smaart is running. When Audition/Ardour run, the bump go away so I doubt it's the other DAW's fault.

 

[phofman]

IMHO at those tiny levels you are measuring the tiny induced noise from the PC (via USB power or other ways - the power supply to the soundcard is still unknown...) . The power consumption profile is strong dependent on running apps - easy to see on ground loops effects when moving windows, even typing letters or just blinking cursor in a terminal are audible (i.e. levels 50+dB, 100dB higher that your effects). I suspect the graphics card to be the cause, any graphics change causes large supply current changes - in your case the modified windows structure on the screen + the different power consumption profile of the app on the foreground, for example.

I would not care about levels -140dB, it's way way below audibility.

 

[Tony359]

I don't care indeed - it's just that I'd like a reliable and repeatable noise floor for measurements purposes as mentioned.

I disagree with your analysis. If that was the case I'd be able to replicate the issue using different software, different windows layouts. It would come and go randomly. It does not. With only Smaart open, it's always there. Always. Never changes. Never reduces or increases.

Also, up to some weeks ago, I was ALWAYS able to remove the bump by power cycling the 18i20 and Smaart would NOT show the bump for as long as I wanted UNTIL Audition was opened. THEN, the bump would be visible until the 18i20 was power cycled (or the USB cable removed and plugged back in).

So no, I think the clues point to a different direction here.

 

[Tony359]

Just for the records, I bought an old MacBook Air M1 and plugged the Focusrite in it. The 18i20 gen1 is still supported - not the mixing app though but it's ok.

I don't see the issue on macOS, suggesting it's something with Windows and/or its drivers.

 

[Redacted]

Windows or any OS creates noise on a PC. Some PCs are worse than others. Apps that are backgrounded or foregrounded behave differently in terms of resources used, and a lot of stuff is on timers with relatively fixed cycles. The noise can come from all sorts of surprising sources, and there are quite a few "mini antennas"

 

[Tony359]

I disagree that the behaviour I’ve shown here comes from actual noise. I can run whatever I want on the PC, the noise doesn’t change. I can only change it when another DAW runs in the background and it’s in foreground or background. Besides those two scenarios, the noise floor of the focusrite doesn’t change. I can run graphic benchmarks, cpu benchmarks, any other software, it just doesn’t change.

Also, if I reinstall the driver from scratch and DO NOT open another DAW, the noise floor stays quiet, regardless of what I do.

Once another DAW opens, the noise floor will be slightly elevated - whether the DAW is running it not, even after a reboot.

 

[Redacted]

A new app launched and in being placed in the foreground certainly can have system interactions that do cause system interactions and noise that can be picked up. I can prove this easily on my laptop right here. Your specific issue is hard to determine though.

I don't see how a "raised noise floor" isn't noise as such.... There are things, as you know, that can be altered in settings when a app is closed, that are beyond user control, which can persist and affect how the overall system works. Many of the apps that you're using interact with a number of common subsystems, hardware and software - you know, like a bit flipped on something in a register or even in the registry can change things like interrupt rates and much more.

From your analysis, if the noise is more than just a curious or academic thing - to get your work done, I fear you may need different software or a different PC, but with latter, you could be in a frying pan/fire situation. We're all interested in you problem, and like speculating, but I doubt any of us have a magic bullet...

 

[Tony359]

I feel it's some sort of sampling issues, I remember I used to have that "bump" in the noise floor and I got rid of it by fiddling with the sample rate options around windows.

One day something happened and it came back - and I realised it would only come back AFTER another DAW was being run and I could get rid of it by unplugging and replugging the interface.

Then it became permanent (but only after a DAW was run - once. Then it would not go away even with a reboot).

I finally discovered that having another DAW running in the background REMOVED the bump - the opposite of what used to happen.

I see what you say but I must have spent 72 hours fiddling with this issue and I never had a feeling it was something induced by the laptop's own electromagnetic noise. I cannot be certain of course. As you say, it could be that register somewhere which is activating some XYZ HW which is being picked up by the Focusrite. Something totally unrelated to what I do.

But my guts feeling says this is some quirk introduced by software. No worries, I am not looking for magic bullets here, I just thought it was a polite thing to update the thread - in case someone one day has a similar issue and finds this weird discussion!

 

[audio_tony]

@Tony359 Just a thought - but have you checked CPU usage in task manager when the issue occurs?

 

[Redacted]

"I feel it's some sort of sampling issues, I remember I used to have that "bump" in the noise floor and I got rid of it by fiddling with the sample rate options around windows."

That sounds like dibbling in the windows mixer setup to me (as mentioned) - there's loads of incompatibly fun to be had there!
I don't do what you do, but when I play music to my USB DAC, or to the internal DAC on the PC, I use Foobar, but in the settings, I use exclusive mode and "event driven" to ensure bit perfect (AFAICT) goes out the DAC so nothing else gets to play sound. When I use VLC to play films, I let it play through the windows mixer, which up or down-scales sound to a common format for the mixer to work - so I also get windows ding sounds etc etc. I wonder if this has any connection to what your software apps may be doing when both are running.. Maybe this is teaching grandma to suck eggs! Sorry!

 

[Redacted]

@Tony359 Just a thought - but have you checked CPU usage in task manager when the issue occurs?

Good idea - if loads of DSPs are running, it might eat up lot of the available CPU(s) cycles (but usually only on older machines) especially if some apps are single-threaded.

 

[Tony359]

@Tony359 Just a thought - but have you checked CPU usage in task manager when the issue occurs?

Yes, there is really nothing going on. It's a modern-ish laptop (Ryzen 6800HS, 8 cores, 32GB RAM), it's not being pushed when just running an RTA. Nothing running in the background (I mean, there will be something of course but as you can imagine I've tried closing everything I can close as well).

there's loads of incompatibly fun to be had there!

Yes, that is basically what I am saying I am well aware of the steaming mess that Windows is when it comes to those control panels from different OS'.

What you say could be good but... I am recording, not playing. I did try all possible combinations of "allow apps to take exclusive control of this device", sample rate, bit rate, bit depth etc. I'm 99% this was the issue when I first discovered it: at some point I found the "sweet spot" and the noise bump disappeared. But that was quite some time ago and now it's changed its behaviour.

 

[Redacted]

I got that you were recording, but these apps can try to use outputs for live sound monitoring.

Do you keep full boot image backups? If behaviour has changed, image the current C drive (so you can get back to where you are now) and re-image C from a backup, if you have one. Painful, but if you can get back to a known state, you can add win updates and app updates to the point where the sweet spot changed....

 

[Tony359]

I don't keep images but I am planning to reinstall W11 at some point - I am waiting for some progress from Microsoft with "Project K2" where they promised they're going to fix all the issues ().

I'm reluctantly moving away from Microsoft, it's got to Windows Vista level now and I've recently been wasting way too much time trying to fix issues than using my computers.

For now, my workaround is to keep Ardour in the background running, silent - it's the free version, it cuts the outputs after 10m but that is somehow enough to keep my inputs "quiet" - oh well.

 

[Redacted]

If the same apps are available for other OSs (Linuxes, Mac or whatever), some of us would like to hear back from you to see if the issue goes away (or is different in a new annoying way).. Or even if a virgin Windows install makes a difference.

In any case, I recommend taking regular disk images (several usable products and some are free) rather that just backups of user files. I mess with things from time to time with things that trash windows, even getting boot sectors rubbished sometimes. I'm running again, freshly restored, in under 20 mins if the PC is trashed, or a disk in it fails. While Windows is less prone to become un-bootable these days, it's a habit I've had since 3.1!

 

[Tony359]

Oh yes, Windows can surprise you in unthinkable ways!

I am good at backing up the user data in multiple locations - I tried the whole disk backup but eventually decided not to go with a regular backup there, one day I'll regret for sure! My main machine is backed up though.

Sometimes it's just a matter of space and complexity. I am just losing track of things. Too many computers, too many backups, too many snapshots!

 

[Redacted]

It's why I have NAS/RAID units. It was never enough to back up only user files if I wanted to be safe from "no boot", but then, amazingly I found I could store all my audio and video media on it too, and play back on every device around the house. I never looked back, but as they say, "If you want to get to get to London, I wouldn't be starting from here", if you get me! (you would not want to sit and rip thousands of CDs on a wet Sunday afternoon!) - I digress from your issue though