Connecting a Raspberry Pi 3 model B+ to the Khadas Tone Board


#1

Dear Khadas community,

I recently purchased a Khadas Tone Board, General Version, and I was wondering how to connect the Tone board to my Raspberry PI 3 model B+. When I look at the GPIO (40 pins) layout of my Raspberry they don’t match with the GPIO (40 pins) on the Tone Board from Khadas. I was wondering how to connect these two devices with the GPIO? (So apart from the USB C to USB connecting).

With kind regards,

Thomas


#2

:yum: …lol…interesting. I was looking at the schematic too and they don’t match to any pins of any PI version. The statement on their web site below seem like you need connect USB cable to usb on PI so it would detect, not the 40 pins compatible.

" No driver is required on almost all O/S include Windows, macOS, Linux. And the Tone Board also works pefertly on Raspberry Pi and other SBCs."


#3

Yes, it seems like the only way to propperly connect the Pi to the Tone Board is with the USB cable. Perhaps you can connect it via GPIO if you connect the correct pins with external wiring, I will look after that because I want to leave the USB C inlet free and feed the Tone Board with power and data using the GPIO of the Tone Board…


#4

Do you know which pins? Not sure if I am label correctly. If correct, we can run 4 wires jumpers which it’s pretty easy.

The Raspberry Pi Model B+
Pin 2: 5.VDC
Pin 6: Ground
Pin 8: TxD
Pin 10 RxD

Khadas Tone Board
Pin 1: 5 VDC
Pin 21: Ground
Pin 18: Rx
Ptin 19: Tx


#5

I don’t know which pins to use, I’d have to look that up. How do you know pin 8 and pin 10 on the Pi are for TxD and RxD? I can’t find that anywhere.

I would assume you can feed the Tone Board with those pins you mentioned, as with thd USB you also have only four pins: 5V, Ground, Data + and Data -. Which match the pins you mentioned.


#6

I am thinking to get either PI B+ or VIM2. Not sure what I want yet

Click on the PI model that you have for 40 pins schematic

http://pi4j.com/pin-numbering-scheme.html


#7

What would be the main purpose of the Pi/VIM? For me it is streaming Spotify and music from USB.

Thanks for the link


#8

The Tone Board accepts only two ways of input:

  1. the USB-C connector
  2. USB connection on pins 3 and 4 of the GPIO header

You cannot use I2S nor the serial UART (RxD/TxD) for sound. And RaspberryPi has no USB connection available on its GPIO header.

You could connect USB from your PI’s USB port to the pins 3 and 4 on your Tone Board if you want to avoid external USB cord on your Tone Borad for aesthetic reasons. But there won’t be any other use for the USB-C port of the ToneBoard anyway.


#9

Thank you for your information!


#10

My plan is to build the tube preamp then incooporate the PI B+/Tone board inside the preamp box and solder the RCA ports from the tone board directly to the preamp without running cable outside. I will look into that later to see what options I have.


#11

I also was thinking of doing that, I have a cheap tube preamp (FX-Audio Tube-01). My main plan is to build a HiFi stand Alone Dac with Spotify Connect option useing a Raspberry PI 3 Model B+. But I might change my plans to build a tube dac powered by the Tone Board, my preamp and the Raspberry Pi. I could make a dac with the option to have two pre outputs, one which goes straight from the DAC and one which goes via the tube pre amplifier.

First I will test the dac with usb c and ofcourse with the Rpi itself before I make my final decision and make a solid case for them.


#12

As I just checked the GPIO layout of the Tone Board, what you said is right. I am guessis if I use pin 2 and 5 for the power and pin 3 and 4 for data, that would be the correct way to feed the dac with power and data via the GPIO of the Dac?

I could simply strip a usb cable and solder that onto the board and connect the male usb connector onto the usb in/outputs of the Rpi.


#13

I have bought all the parts for Aikido Octal (6SN7) but don’t have time to build yet. Since I don’t plan to have any input so it would be better to solder the Tone board to the preamp. Still have couple old laptops around so maybe I would go for it instead of PI to eliminate out 1 problem.

As wanthalf mentioned above, pin 3 and 4 would work. I don’t have ohm meter around to check the pins yet.

What is tube dac? If you have tube dac, why need Tone board? Are they both DACs? How would that work out?


#14

Hi @Alashikita,

No what I meant was this. The tube preamp I have is a simple rca in and rca out pre amp powered by two 6J1 tubes. I have tuberolled the tubes with JAN-GE 5654w NOS tubes for a better sound.

Since my receiver has not have the greatest dac build inside of it, I want to build my own dac using the Khadas Tone Board, feed with data and power via the Raspberry Pi 3 Model B+. Since I really love the sound my little tube pre amp brings me I might change my plans for building a DAC and build a Tube DAC, using my tube pre amp AND the Khadas Tone Board.

I don’t want to solder the output of the Tone Board onto the input of my Tube preamp because that would mean I’d always have to listen to both the DAC and the tube pre amp. So if I would intergrade my tube pre amp onto my dac I would like to have two pre outputs comming out of my DAC: One which is simply straight from the DAC output and One output from the Tube amplifier.

I will add a picture of the Tube preamp so you could check it out yourself. I hope this answers your questions.


#15

That means, you have 1 input which it’s from tube preamp, then 1 output of tube preamp and 1 output from the Tone board.

1 input = tube preamp
–Vinyl goes in here

1 output = tube preamp
–Vinyl has to go out here which can’t go out to the tone board

1 output = tone board

SPDIF/USB tone board = input

So the only way to use with the Tone DAC is you must connect DAC Output to the preamp Input

Tube DAC is really expensive and doesn’t have high bit rate, Why would you want that? You’re looking for something is not under $300.

Actually, you want to make a short connection between preamp and tone board so you don’t lose the signal or hum.

Have you checked they DIY about the this kind of preamp? I heard there is a hum on certain boards of this design.

https://www.diyaudio.com/forums/tubes-valves/309876-6j1-china-preamp.html


#16

I made A quick schema. I inserted it as an attachment.
hope you understand what I meant with it, it was made in just a few minutes using Word. My final schematic will be drawn with a professional program.

the lines coming in above the squares are meant as input(s) and lines coming out underneath the squares are meant as output(s).


#17

You have another receiver that you want to swap the Khadas between FX and other receiver? I think it would be nice for FX as the main output but require to have amplifier. That’s my intention of having 6SN7 tube preamp as the main output to the amplifier which it’s exactly as your layout.

:yum: I bought two Tone DACs which one goes to the tube preamp and built-in everything includes a router to control the PI/VIM, Another will swap around with other receivers.


#18

Nope only one reveivery, but with multiple rca inputs, I want to use one input on my receiver wired straight to the dac and another input wired to the output of the tube pre amp. So that I can swap between dac or tubed dac on my receiver.

I am very curious on your project, would love to here more of it and see some pictures if you want to!!


#19

Sure will, I got all the parts but haven’t done anything yet. May take couple months.

The preamp is from here. The problem of delay is the manual doesn’t have everything to complete the project. All parts are general which the designer allow DIY to play around. It’s pretty hard without oscilloscope.

http://glass-ware.stores.yahoo.net/octalallinone.html


#20

Yes I could imagine that. What about the prescripted parts? As mentioned on the pcb?