Audio Artefacts

[dhankotb]

Hi guys,

I'm having an issue that seems to be isolated to connecting to a DAW via USB and concerning pc speakers, and plugging an XLR into an interface with headphones as its output source, but not plugging headphones directly into the FM3 or using it with a power amp & cab.

The audio seems fine at first, but after about 20 seconds a start hearing crackles that get about 40% worse over the next few seconds and then just plateau.

I was thinking it was something to do with the driver, since when I change the sample rate then set it back to where it was, it acts to reset the signal chain and the audio is fine, and then after another 20 seconds or so it will start to degrade again.

A similar thing is happening with the interface, however, where if I switch between using the 48V button it will reset the audio and it clears up again, only to degrade again over the next few seconds.


I can use headphones directly into the unit, or into a power amp/cab with no issues, but I would prefer to get it working with my PC since it means I can share the headphones between all PC audio, play songs on youtube while playing along etc

Any help is appreciated
Thanks

 

[DLC86]

I had a similar problem a while ago and after a lot of troubleshooting I found out the NVidia driver was the culprit, but I don't remember how I fixed it (maybe by disabling the nvidia audio driver?).
From time to time it happens again, usually when more than one app tries to take control of the audio device (e.g. chrome open while the daw is running), but usually a reboot of the Fractal fixes it.

Anyway, I suggest installing LatencyMon to get some hint on what might be the cause.

PS: and obviously check your asio buffer, if it's set too low that's inevitable.
Btw, if you don't need to hear plugins in real-time, there's really no point in setting it at lower values, you can leave it at 2048 samples, that will give you the most cpu headroom on your daw.

 

[dhankotb]

That’s a good shout in LatencyMon.

What I’m wondering is that the same happens when headphones are plugged into the interface which, as I understand it, bypasses the pc as a processing stage altogether. I can use the interface without the DAW so I don’t think the pc itself is involved over with the issue, unless using fm3-edit with the unit plugged in somehow slows things. I’m out right now but will check if the issue persists even while the pc is taken out of the fm3 > interface chain.

 

[DLC86]

That’s a good shout in LatencyMon.

What I’m wondering is that the same happens when headphones are plugged into the interface which, as I understand it, bypasses the pc as a processing stage altogether. I can use the interface without the DAW so I don’t think the pc itself is involved over with the issue, unless using fm3-edit with the unit plugged in somehow slows things. I’m out right now but will check if the issue persists even while the pc is taken out of the fm3 > interface chain.

If the fm3 is connected via usb, even if you don't hear what goes thru the pc via headphones, dpc latency might still throw off the fm3 clock which is what produces the crackles. I for sure heard it when monitoring via spdif, not 100% sure that's valid for analog outputs as well though

 

[dhankotb]

about 20 seconds a start hearing crackles that

this is so Yorkshire that I used a instead of I

 

[dhankotb]

If the fm3 is connected via usb, even if you don't hear what goes thru the pc via headphones, dpc latency might still throw off the fm3 clock which is what produces the crackles. I for sure heard it when monitoring via spdif, not 100% sure that's valid for analog outputs as well though

That seems weird since the unit > pc chain is isolated and not involved with the output audio but will check tomorrow if not today since it's 2am

 

[dhankotb]

Think you might have been right about the Nvidia/DPC thing. Does this look like it's within reasonable tolerences?

 

[DLC86]

Think you might have been right about the Nvidia/DPC thing. Does this look like it's within reasonable tolerences?

View attachment 141276

Not the best but, as the app itself says, it should work fine... What's your asio buffer set to?

That seems weird since the unit > pc chain is isolated and not involved with the output audio but will check tomorrow if not today since it's 2am

The audio chain is not really isolated since the clock always syncs with what it's connected to (usb and/or spdif)

 

[dhankotb]

Not the best but, as the app itself says, it should work fine... What's your asio buffer set to?

I have it at 256/512 between in/out for about 12m/s latency. Anything more than that i.e. 1024 samples between both and the latency gets to like 28m/s and it's pretty close to unplayable.

The issue isn't the same as audio degradation with too low a sample rate, which is consistently bad. It'll start clear then after about 20s start to crap up.

The audio chain is not really isolated since the clock always syncs with what it's connected to (usb and/or spdif)

When you say clock, what exactly do you mean by that? Just out of interest.
I'm guessing the processer does something to sync speeds so tasks are completed within the same interval?

 

[DLC86]

I have it at 256/512 between in/out for about 12m/s latency. Anything more than that i.e. 1024 samples between both and the latency gets to like 28m/s and it's pretty close to unplayable.

The issue isn't the same as audio degradation with too low a sample rate, which is consistently bad. It'll start clear then after about 20s start to crap up.

Hmm I think there's something wrong in your setup, you shouldn't hear any added latency while playing your guitar cuz, if you have headphones or speakers connected directly to your fm3, that is directly monitored via the fm3 output. If you hear latency it means you're listening to the PC output instead.

When you say clock, what exactly do you mean by that? Just out of interest.
I'm guessing the processer does something to sync speeds so tasks are completed within the same interval?

Audio clock, the one that dictates the sample rate. When the fm3 is connected via usb or spdif it needs to sync its own clock to the PC or to the external audio interface clock.

 

[dhankotb]

Hmm I think there's something wrong in your setup, you shouldn't hear any added latency while playing your guitar cuz, if you have headphones or speakers connected directly to your fm3, that is directly monitored via the fm3 output. If you hear latency it means you're listening to the PC output instead.

I thought buffer rate doesn't apply when using headphones with the interface, because no values seem to make a difference to the audio. I meant while using ASIO in a DAW

Audio clock, the one that dictates the sample rate. When the fm3 is connected via usb or spdif it needs to sync its own clock to the PC or to the external audio interface clock.

Wouldn't that also affect the sound coming out of the cab or headphones while the unit > pc via usb?

 

[DLC86]

I thought buffer rate doesn't apply when using headphones with the interface, because no values seem to make a difference to the audio. I meant while using ASIO in a DAW

Oh ok, maybe I misread your previous comment... That's normal then, I can go as low as 32 samples if the project doesn't have lots of plugin loaded, but that depends mainly on your cpu and on its load.

Wouldn't that also affect the sound coming out of the cab or headphones while the unit > pc via usb?

Not really, it's just the cycles of the clock that sync up.

You can see some effects of that sync though. For example if you set your daw to a sample rate of 44.1 kHz you'll see that the fm3 tuner shows wrong notes

 

[dhankotb]

Think it might have just been the Nvidia driver. I've been using this for the last minutes or two and the quality hasn't started dropping yet.

 

[dhankotb]

Oh ok, maybe I misread your previous comment... That's normal then, I can go as low as 32 samples if the project doesn't have lots of plugin loaded, but that depends mainly on your cpu and on its load.



Not really, it's just the cycles of the clock that sync up.

You can see some effects of that sync though. For example if you set your daw to a sample rate of 44.1 kHz you'll see that the fm3 tuner shows wrong notes

That's interesting. I have an 8700k OC'd to 4.5ghz but could never get anything below 12ms before deleting the driver. I guess a higher sample rate means more cpu loud but ableton shows it rarely going above 4% and I'm not noticing any audio issues with the above set up.