Separate ps for Khadas Tone Board ?


2004-09-27 2:35 pm
after reading some nice reviews about Khadas Tone Board i will order one and try as one usb dac with Pi 4. GPIO connection with Pi is not possible, only usb.

I would like to power the "Tone Board" separately at GPIO pins, not with usb 3 connection from Pi 4.

My question - what will be the best way to disable the dac usb power from Pi ? I need only usb data from pi. Just cut the "+5V" cable inside the usb cable ?

I'm running a RPi4 and a KTB since a couple of months.

The RPi 4 finally improved great times on its USB and ethernet part. I wouldn't have switched
back to USB Audio without this development. All older RPi or RPi based streamers or USB
bridges suffer that shared USB/network bus, sharing a single USB2.0 towards the CPU.
No matter what you attach to these old RPi based solutions you'll always face this IMO serious limitation.

The powering is done via Allo Shanti.
With shortened cables and relays on the output to eliminate the nasty turn on- and off problems
that come with Shanti and to be able to switch (remotely) both rails separately)

The main issue is that the KTB still needs buspower.

I feed the 3A-out of the Shanti to the KTB GPIO.
For my special RPi4 setup using the 1A Shanti output is OK.
But that won't work for everybody out there. You can just switch the rails. It'll also work.

Overall I do think the KDB works nicely with a RPi4. All my HATs (Katana, Audiophonics, IANs Fifo, etc, etc.)
are settling dust now. Pretty amazing. And I paid 89€ only for the KDB.

Watch out though.
We'll see a new brand popping up soon. It's called Soncoz. The KDB designer opened his own company.
By end of February he promised the evolution of the KDB. Now with a nice case, dual mono Sabre,
NO ESS-HUMP flaw, at around 199$. You'll find an early review incl measurements on AudioScienceReview.

That low-cost DAC area gets more and more crowded with IMO excellent devices. Great times.


PS: Since I am running the USB DAC now I can use a quite effective passive cooling case for the RPi4.
The RPi4 generates seriously more heat then its predecessors.
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