Ktb becomes silent 10 times per day

i bought a ktb in december 2019 ( on the Khadas SBC amazon shop ), and i always had issues with it.

With driver 224, it disconnects from the pc ( foobar stops playing, and ktb is absent from the popup which list the devices, and from the list of devices in the sound systray).

With driver 4.86 eval, it’s a little bit different:
foobar continues to play, and the ktb is still in the list of devices, but there is no sound.
The oscilloscope is still moving, i can change track, stop/play, close foobar and reopen it.
ktb is still listed in the systray, but there is no sound.
Exactly like if i had activated the mute in windows.

I believe i’ve tried all the drivers, all the usb port of my mother board ( aorus x470 ultra gaming ).
I also tried to rise the tension of the “dac usb port of the mb” to 1.1V ( and even 1.2V )

The issue appear independently of the application i use ( winamp/foobar/youtube/ vlc).

Other issue, if i power off the pair of active speakers ( mackies mr524) plugged on the ktb, and i turn them on again => ktb is silent, but not disconnected. ( Every time/ every driver )

In each case, the sound comes back when i unplug and replug the ktb.

The issue occurs about 10 times per day.

Date written on the ktb is 44 19.
I have the black cable ( the new one )
Windows 10 x64 pro (version 19041.572)
Is the issue located on my pc or on the ktb?

x470 aorus ultra gaming. (bios version: F31)
1080TI aorus gigabyte
seasonic prime titanium 750W

Hi @bug_lee

You use the driver from our webiste, right?

Can you help to check the configuration of the foobar2k? As if the KTB still absent and list from Win10 popup menu, it should be still connectted.

Or can you just try with another player and check if another player still work for Tone1 with existing driver when this happens again.

BTW, we will release new driver for Tone1 recently.

May I know where you get this driver? We didn’t release this eval driver :slight_smile:

hi, thx for replying ^^
Yes the 224 driver i used comes from your site. “Thesycon-Stereo-USB-Audio-Driver-V224”
I have reinstalled it, and trying it with foobar2k ( it can take 1h, but less than 2h for the issue to occur).
I’ll check if ktb still appear in the systray list.

But in ALL cases, there is a constant: ktb NEVER plays any sound (whatever the application i try ) after the bug occurs. I have to unplug /replug it to ear something again.

I found “Khadas_UsbAudio_v4.86.0_eval_2020-09-07_setup” on your forum.

Is it normal that if i turn off the speakers while playing sound, the sound doesn t come back when i turn speaker back on? ( have to replug ktb )
If i m not playing sound, i can turn off speakers, then turn them on, play a sound and i will work.

Surely, it’s abnormal. Need to do further confirmation one by one:

The device you power off and turn on is speaker, not the KTB right?

What you un/repluged? RCA cable or USB-C cable?

Maybe you can take photo or explain more details to show the connections you set up including:

  • KTB
  • PC
  • Active Speaker
  • RCA Cables

Right i only turn off the speakers, not the ktb.
If i do that while ktb plays sound ( music/ movie ), then this will trigger the bug.

I unplug only the usb-c cable.

After the bug occurs, ktb is still visible on the win10 systray pop up menu. But no sound.
And i can launch winamp which will read the music, but ktb won’t make any sound.

Fun fact, sound doesn t come back even if i reboot the pc ==> Ktb’s usb-c NEEDS to be unpluged/repluged for the sound to come back.

Nothing fancy in the connections:
-ktb is connected to the pc with the usb-c cable. ( the one i disconnect reconnect 10 times a day )
-active speakers (metallic blue and red plug ) are connected to the appropriate slots on the ktb.

Ps: to simplify i have removed the jds lab atom ( it s a headphone speaker and pre amp.)

So you have both Active speaker and JDS LAB ATOM Headphone Amp, right?

Did you try if the issue also happen with JDS Lab ATOM? (From the information you provided it’s active speaker with this issue)

Start from the time you recevied the device? It’s wired and it’s 1st time I heard with thus issue. Maybe we just let our sales support team to contact for a quick after service?

BTW, interesting BOX :slight_smile:

(Metallic rcas are the speakers.
The aluminium box is there because i was thinking that the heat was maybe the cause why the ktb becomes mute in the middle of a movie/music/yt video.)

Yes, the issue also happens when jds atom is in the chain.

I can turn on and off the atom ( b ) without issue.
But if i turn off (a) or (b), WHILE a sound application is “active” i’ll HAVE TO disconnect/reconnect usb-c of the ktb. By active, i mean like winamp in pause or stop mode.

No issue if i kill all the software involved with sound before opening (a) or (c ).
No issue if i turn off the speakers with the on/off button on their back.

(i have a earth loop if i connect the speakers to earth, that’s why they are on a non earthed wall plug).

The more annoying bug is the ktb becoming mute while playing sounds. 10 times per day is unbearable.

Yes, i agree with that.


Hello All,…

No more informations about this issue ?

Not yet.
I sent back the ktb to the tech support. They told me it has arrived on the 6 november 2020.
I’ll have news when analyst will be done.
Wait & see

1 Like

I believed I encountered a similar issue where I had to reboot the pc to get it detected. It was caused by multiple things: firmware, driver, built-in sound card on pc, etc…I am not sure what the solution was since I did many thing that stopped the problem.

Old firmware:
-Flashed to 1.04 (whatever the latest one was)
-Updated FW, then installed, and deleted all the Eval. drivers.
-Installed the official driver
-Disabled built-in sound card on PC/LT

The evaluation driver will stop the tone1 every 15mins/30mins with a buzz noise. Sometimes had to reboot the PC/LT to get it worked again. I didn’t check what the cause was since everything was working without problem.

I have flashed FW to version 2.0 and new driver that has been released a few days ago and haven’t seen any problem yet.

If there is a problem on your pc, it may be the built-in sound card. Otherwise, windows OS 7 or 10 shouldn’t be a problem. If you have another pc or laptop, you can test to see if it occurs the same problem or not. Make sure DO NOT use evaluation driver, uninstall and remove after flashing the FW. For FW version 2.0, you don’t have to worry. Good luck for waiting to get the Tone back.


Problem solved with the replacement unit Khadas sent to me.
Tried it for one week, and not a single mute.
Perfect, thanks :slight_smile:


Congratulations! it is very important when the problem does not stand aside.

1 Like

My apologies.
I’ve found the real issue: ktb NEED to be plugged on a “power supplied” usb port, (not a port of the motherboard).

If connected to any usb port of the motherboard ( gigabyte AORUS X470 ULTRA GAMING), my replacement ktb becomes silent after a while.

To avoid this, i have to plug ktb on any usb port of my display. This solve the issue.