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Khadas Tone Board

tomek

tomek

pfm Member
Hi,
after reading some nice reviews about Khadas Tone Board

https://www.khadas.com/tone

i will order one and try as a 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.

it is very well documented

https://docs.khadas.com/toneboard/HardwareDocs.html

My question to pfm diyers - 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 ?

Tomek :)
 
You can put a small piece of insulation tape over the power pin in each end of the usb cable as a non-invasive test. Fiddly, but I've done it here ok.
 
Maybe Ian's pi conditioner might do the job, it's a hatboard that feeds the pi rails from above. Detail on diy audio,com in the power supply section.
 
So i have one Tone Board. Already connected with usb to PI4 running picoreplyer sounds very good. With one linear ps based on lt1083 sounds better.
The sound quality for this price is incredible.
 
I tried different ps with Tone Board:

1. Official raspbery pi 4 ps connected to pins 1 and 21 - better sound, than getting usb power only from pi 4
2. Standard LM317 built with good parts - much better sound, than with 1.
3. Absolutely phantastic sound with ps based on TPS7A4700 set at 5.2V

https://www.ldovr.com/product-p/tps7a4700-spsu.htm

Also tried different ps for pi. Impact on the sound is very small, but noticable - official raspberry pi 4 ps with shortened cable and buffered with bigger caps just before Pi (1x 10000uF/25V+ small oscon) sounds better, than big linear ps build around LT1083CP. I have to try ifi power for pi.
 
Let me know your thoughts Tomek please, also interested in one for a streamer I plan. Thanks :)
 
This is actual test setup:

20200221-000139.jpg

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Khadas on the left powered with https://www.ldovr.com/product-p/tps7a4700-spsu.htm, on the right side Pi 4 with picoreplayer powered with official raspberry pi 4 ps and buffered with some extra caps.
 
Last edited:
The mezzanine board is a nice upgrade...I killed a Pi trying to remove the DC/DC converter though. Second attempt was successful.
 
brumjam said:
The mezzanine board is a nice upgrade...I killed a Pi trying to remove the DC/DC converter though. Second attempt was successful.
Click to expand...

More detail please :) Was converter removal to allow the use of a mezzanine provided 3.3v line?
 
A nice clean 5v feed is good especially if otherwise youd be introducing a smps into a system without one. If your dac doesnt take power from the pi then its unlikely to affect the sound. I think Allo showed a 1.5db Improvement in thd+n for their best psu,
 
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