Tutorial: Connect Mini/Pro to other I2S DACs

The company “Analog Devices” that developed the ADAU1701 dsp chips has it’s own community. You may ask there to help you with your problem. They have way more knowledge then me.

Sorry, but I’m still talking about the JAB5 Amplifier board. I don’t have the ADAU1701 DSP-Board. But the JAB5 has the same chip on board as I know. Perhaps the DSP-board can have more inputs but I have to deal with the inputs that are available on the JAB5, and this is only one I2S Input.
I don’t know enough about the technical details, I’m just frustrated, and try to find the source of the problem. If the Up2stream only sends 44kHz/16Bit I don’t understand why streaming over Wifi is not working but via Bluetooth or analog.
The solution to use the SPDIF conversion board as a bridge is ok if I don’t have any loss of quality. It’s not the philosophy of integration which I would reach, but if it works…
I will write some more infos if I took a look in the System with Sigma Studio.

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Yes, I know you are talking about the Jab5. But, the onboard bluetooth of the Jab5 supports Aptx-HD 24bit/48khz. When you use that too or connect another source to the SPDIF board, you can leave the settings in Sigma Studio to 24bit/48khz. That was what I tried to tell.
I can really understand that you are frustrated by now. I was suggesting the Analog Devices community, because these are pros that may can identify your problem.

Finally I fixed it with Sigma Studio. I had some issues before it works – combinations of drivers, switches, what to power on first. But at the end I got it.
The reason was not the sampling rate, it was the LRCLK polarity. After switching it it works. Don’t know why, but it works, also with bluetooth and USB.

Now the fun part. I have the four potentiometer connected to the JAB5, but I want just a 2.0 system. So I don’t need the crossover potis and also I want just one volume controller. My idea is to have

  • one poti for volume
  • one poti for balance
  • one poti for treble
  • one poti for bass
    The only concern is the volume controller. The Up2stream has also a volume controller. I recalculates the digital values.
    Can I deactivate the volume controller from Up2Stream?
    How to realize a IR remote volume controller?
    Any experiences or ideas?

Currently no, will consider to make a new command to use static volume for up2stream board, as it’s not a problem for DIYers :grin:

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Hi I’m back. Now I build up my complete setup. And I have still the issue with the distorted signal. But know I recognized that’s only in the right channel. Left channel works fine. In my first test I had only one speaker connected. And this is the reason why the problem disappears as soon as I switched the LRCLK.
With speakers connected to both channels channels the distortion can be switched from one channel to the other if I switch LRCLK. I also tried an other Up2Stream Pro without any changes in the setup. Same issue.
Definitely the I2S signal over Network connection creates distortion on the right channel.

I will start a new discussion, because this is not related to your original topic: Up2Stream I2S distorted right channel only via network


there is one thing i do not understand with using an external DAC / external amp with I2S connection:

When using an external DAC the volume control still seems to work, but with an I2S amplifier not. But both are feeded only over the same I2S data stream.

Has anyone an idea where is the difference?


Hi Stefan,
I’m not sure I can help you any further as all the DAC’s I have are connected to separate amplifiers. It sounds like you are feeding I2S into a digital amplifier, correct?


Hi Steve,

i will feed an external amp with analog input like you :slight_smile:

So my plan is to use a very good external I2S DAC and then use an amp behind with fixed gain. Of course an I2S amp would eliminate the D/A conversion, but what i have learned is that an I2S amp will loose the volume control (and i still don’t understand why).

Hi Stefan, what do you mean with »I2S Amp«? If you use a DAC with I2S input you can do the volume control at the analog Amplifier. You don’t need the digital volume control.
If you use something like Wondoms JAB5 you double the volume control. because the Up2Stream has a digital volume control and the JAB5 too.

Hmmm…Steve confirmed above that an I2S feeded dac has volume control over the app, so the I2S data stream is “manipulated” by the Up2stream board and the analog output if the dac is scaled e.g. 0…2V RMS, depending by the volume setting of the device. So there is no need to control the volume at the amp.

So you are right, with a JAB5 there would be double volume possible. When i am right, it should also be possible to run the JAB5 with I2S input and fixed volume setting (e.g.70%) and control the volume still over the Up2Stream digital I2S volume control.

The plan is to regulate the volume by the app/api/uart only without the need for a separate µC.

This should be possible with the use of a fixed gain amplifier without extra volume control, with direct I2S input (“software manipulated” from the Up2Stream module) or with an analog amplifier with an I2S DAC before.

So it is still unclear for me why in some other threads a loose of volume control in conjunction with an I2S feeded amp is observed. The JAB5 gets the same “manipulated” I2S stream as an external DAC and contains volume information.

Yes, the JAB5 can be used with a fixed volume setting. But it’s also manipulating the digital signal, because the volume is controlled by the DSP. In this case the digital information is recalculated twice.
I don’t know any »fixed gain amplifier with I2S input«. If you can send me product suggestions, I’m interested.

In my other project – DAC board packed on a Raspberry Pi and 3e Audio amplifier and Volumio – I know there exist two kind of volume controls on DAC boards. One recalculates the I2S signal – via software –, and the other ones have an array of resistors behind the DAC and manipulates the analog signal – they are called hardware controlled.

Thanks for the input.

For direct I2S amplifier, look at the TI’s TASxxxx range, e.g. TAS5760.

Dear j.eeken1,
can you confirm the connection between Mini/Pro v3 to the Wondom ADAU1701 board is tested and working fine?

On paper it doesn’t seem okay. Here’s why:
Take a look at the manual for the Mini/Pro v3

This is the digital audio output extension. For the IIS, BCLK is
2.8MHz, the LRCK is 44.1KHz, the MCLK is 11.288MHz, the
DOUT following the standard IIS data format and have 16 bits
depth. The system is running in master mode, you should make
sure the IIS port of connected device is running in slave mode.”

This means that the Mini/Pro is outputting the master clock, and the ADAU1701 should be set to slave.
In order to feed the MCLK signal from Mini/Pro to the ADAU1701 we should follow the instructions, given by Wondom - desolder the oscillator on the ADAU and feed the MCLK to the SMD pad, marked Y1.

@ j.eeken1
Looking at your earlier posts, other idea comes to my mind.
On the ACPWorkbench screenshots you provided, I see that maybe it would be possible to set the up2stream Mini/Pro as a slave and accept master directly from the MCLK pin on the ADAU1701 pcb. The MCLK of the Wondom pcb is 12.288Mhz, so in theory this is also a possible solution.


Unfortunately I don’t have neither the pcb, nor the software to check this myself.
I would really appreciate if you check this and confirm it is possible.

I am researching to build a setup, based on the Mini V3 and ADAU1701. The only draw-back which stops me from purchasing the modules is this little uncertainty. I don’t want to desolder any parts of the nice prefabricated boards, make them work.

Thank you in advance

Hi Stanislav,

I can confirm you that it is working properly. I’ve done it severel times but, I always use other dacs to output the sound and not tested with the internal dac of the dsp board itself. By the way don’t try it with the JAB3 boards. Don’t know why but they simply don’t work. Even with desoldering the oscillator.
I will look onto that with the internal dacs this weekend if you are not sure.
About the mini/pro in slave mode; I didn’t try that,because I didn’t need to. I will look into that too.


Thanks for the quick response, Jordy!
Looking forward to hear the result of your tests!

Don’t think it matters whether or not you are using an external DAC or the adau1701 DACS
As for the JAB3, I’m not planning to use it, I will use just the dsp kernel board and feed the signal to 3 channel class AB amp, for a 2.1 system (not a fan of class D). Just want to add some modern features like Bluetooth and streaming, and the DSP will handle the sub/high pass crossovers.

Kind regards,

I uploaded this video on Youtube. It’s the Up2stream pro in master mode and the oscillator still soldered on the Wondom board.