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KTB DAC - music stuttering and DPC Latency issues while using resource intensive applications

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#1
Hello,

I have Khadas Tone Board as my DAC which is connected to my 'high-end' workstation PC using high bandwidth/power USB-C port on my motherboard. For an AMP I am using JDS Labs Atom connected to my Tone Board.
Recently I noticed my music stutters for example if I am listening to music and in the same time Android Emulator is booting up. After emulator boots up, stutter is gone and the music plays nicely.

Here is my video so you can see exactly what I am talking about. While emulator is booting, DPC latency starts to increase
 

odyo

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#2
What is a good latency value here ? My pc stays between 150-200. Also noise coming from my pc when i start the latency mon measurement. Interesting. While it's consistently between 150-200, if i use the render test in gpu-z it's consistently between 50-60. After closing the gpu-z pcie render test it start constantly jumping between 50-60 to 150-200. I guess there is a pcie or gpu related issue.
Highest values comes from DirectX Graphics Kernel and Nvidia Windows Kernel Mode Driver.
I have SBX AE5 soundcard installed to pcie btw.

Edit: This must be some kind of pcie power saving related issue. I will check my bios to see if there is any option like this.
Edit2: But why latency mon makes noise similiar to coil whine while measuring ?
Edit3: Google Chrome increases the latency a lot in my machine. It's like 5-10 when chrome off, 150-200 when chrome on, 50-60 when both chrome and gpu stress test on.
 
Last edited:

Crane

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#3
Hello,

I have Khadas Tone Board as my DAC which is connected to my 'high-end' workstation PC using high bandwidth/power USB-C port on my motherboard. For an AMP I am using JDS Labs Atom connected to my Tone Board.
Recently I noticed my music stutters for example if I am listening to music and in the same time Android Emulator is booting up. After emulator boots up, stutter is gone and the music plays nicely.

Here is my video so you can see exactly what I am talking about. While emulator is booting, DPC latency starts to increase
It is likely something on your PC causing the issue rather than the dac/amp combo. It may just be the program itself or something in the background causing processing.
 
OP
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Thread Starter #4
In my case also highest values comes from DirectX and Nvidia. During the emulator boot process, it probably requires gpu resources and this is reflected in DPC latency. I'm not sure why GPU activity reflects so much on an external DAC device/usb ports.
 

A800

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#5
DPC latency is, apart from other things, highly dependent on CPU usage.
 
OP
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Thread Starter #6
DPC latency is, apart from other things, highly dependent on CPU usage.
I have 12cores/ 24threads so CPU usage in this case is about 2-3% at max and there is no peak on single core etc.
 

A800

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#7
Process Explorer is more accurate to determine CPU usage.
 

Crane

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#9
Typically not an issue but RAM overload, maybe you need to update firmware? What processor are you using wouldnt happen to be an AMD Ryzen 3900x?
 

A800

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#10
Then it's probably the nvidia driver.
They are known to cause high DPC latency.
 
OP
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Thread Starter #11
Typically not an issue but RAM overload, maybe you need to update firmware? What processor are you using wouldnt happen to be an AMD Ryzen 3900x?
Yes, it is 3900X and I have 32GB of RAM memory. Latest version of Bios is already flashed on the motherboard.
 

Crane

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#12
yea play a video on your pc and see if you notice stuttering when you see this issue. Many people including myself have complained about the issue you most likely wont notice unless a video or sound is being played. i haven't done much music or anything my PC to notice this issue in that regards, but i definitely see it with watching videos.

i can for sure tell you that the KTB and atoms together don't have any issues, you can always connect to your phone and run it through there.
 
OP
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Thread Starter #13
Yup, same thing if video is playing at the same time when emulator is booting up I can hear sound crackling and popping.
 
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#14
I had this issue with a new K5 Pro recently and resorted to using SPDIF; however, I came back to troubleshoot and it looked like the RAM speed was impacting USB performance. Anything over 2400mhz would make the USB DAC pop when the PC was under load, and I had my RAM running at 2666. Pushing it to 2800 made the usb audio almost unusable and it would completely drop out under load, so I was sure it was related to this. What fixed it for me was increasing PCH voltage (part of the chipset that controls SATA/PCI-E/USB devices). With enough overvoltage, the popping was completely eliminated even under extreme prime95+furmark loads. I'd try PCH overvolting and/or reducing RAM speed to see if you're having similar issues. By the way, only LatencyMon works fine with Windows 10, DPC Latency Checker can't read W10 values properly.

(If you have an AMD CPU, I'm not sure if the PCH is still called the PCH - try searching for equivalent terms if you don't see this option in UEFI)
 
OP
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Thread Starter #15
I had this issue with a new K5 Pro recently and resorted to using SPDIF; however, I came back to troubleshoot and it looked like the RAM speed was impacting USB performance. Anything over 2400mhz would make the USB DAC pop when the PC was under load, and I had my RAM running at 2666. Pushing it to 2800 made the usb audio almost unusable and it would completely drop out under load, so I was sure it was related to this. What fixed it for me was increasing PCH voltage (part of the chipset that controls SATA/PCI-E/USB devices). With enough overvoltage, the popping was completely eliminated even under extreme prime95+furmark loads. I'd try PCH overvolting and/or reducing RAM speed to see if you're having similar issues. By the way, only LatencyMon works fine with Windows 10, DPC Latency Checker can't read W10 values properly.

(If you have an AMD CPU, I'm not sure if the PCH is still called the PCH - try searching for equivalent terms if you don't see this option in UEFI)
Thank you. On AMD platform that is called SOC voltage. I will check that

Just checked SOC voltage. Even after overvolting that value the issue is still there. Resetting bios to factory defaults did not help either
 
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#16
I had this issue with a new K5 Pro recently and resorted to using SPDIF; however, I came back to troubleshoot and it looked like the RAM speed was impacting USB performance. Anything over 2400mhz would make the USB DAC pop when the PC was under load, and I had my RAM running at 2666. Pushing it to 2800 made the usb audio almost unusable and it would completely drop out under load, so I was sure it was related to this. What fixed it for me was increasing PCH voltage (part of the chipset that controls SATA/PCI-E/USB devices). With enough overvoltage, the popping was completely eliminated even under extreme prime95+furmark loads. I'd try PCH overvolting and/or reducing RAM speed to see if you're having similar issues. By the way, only LatencyMon works fine with Windows 10, DPC Latency Checker can't read W10 values properly.

(If you have an AMD CPU, I'm not sure if the PCH is still called the PCH - try searching for equivalent terms if you don't see this option in UEFI)
This worked for me. I have been trying to fix this issue for several months by updating, uninstall and disabling various drivers and devices.
The audio always stutter when the CPU is running intensive programs such as opening Photoshop.

I tried increasing the my RAM voltage from 1.35v to 1.40v and viola everything is now smooth, no more clicks or stutters. Seems to be a problem with only Ryzen CPUs as I am runing the 3600 with 3200mhz RAM.

Thank you for the solution!
 
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#17
I've had DPC latency issues in the past. its nothing to do with your audio equipment (almost certainly). Really bad DPC latency issues happen when you have a device on the bus with a bad driver, or more rarely an issue with the bus itself e.g. overclocking or underpower. wifi USB devices are particularly guilty of this but of course most are fine.
 

digitalfrost

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#18
In my case also highest values comes from DirectX and Nvidia. During the emulator boot process, it probably requires gpu resources and this is reflected in DPC latency. I'm not sure why GPU activity reflects so much on an external DAC device/usb ports.
Nvidia drivers had a known issue with DPC latency some years ago. Which driver version are you using? Have you tried updating to the latest?
 

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