TOPIC:

I have received my boards (MiniDSP, MiniDIGI and MiniAMP). I will do a three step implementation.

Step one: MiniDSP alone: Fairly simpel, no questions
Step two: MiniDSP + MiniDIGI - Is MiniDSP slave clock and MiniDIGI Slave?
Step three: MiniDSP + MiniDIGI + MiniAMP: In the manual for MiniDSP it seems that all three boards should be slave? Is that correct? In the MiniAMP manual it's described as MCLK ext. jumper should be in place - i guess that is the same as jumper in Slave position as mentioned in the MiniDSP manual?

Basically what I read in the different manuals are that all clocks should be in slave position, when MiniDSP and MiniDIGI are stacked.

Hello,

Glad that you're asking this question as I've realized lately that indeed it could lead to a bit of confusion. We'll have to update the user manuals to make sure that it make it clear.. The confusion being that although they say Master/Slave, they are not for the same purpose.

Basically, your configuration is correct, but a bit of explanation of how MCLK and I2S works would certainly help you: (or confuse you..
- MCLK (stands for Master Clock) is the equivalent of the word clock, synchronizing all units in a stack to a same clock.
- I2S also has clock lines ( LRCLK/SCLK) which need to be in "sync" with Mclk.
The trick is that MCLK and SCLK do not have to come from the same IC/board. They however need to be "synchronous". I2S also work as a Master/Slave when basically you can only have 1 master in your system.Anyway, down to the thing you need to know.

miniDSP doesn't have a way to output an MCLK to other boards AND miniDSP will always work as a master I2S in the current plug-ins we have. This means that if you want to stack a miniDIGI on top of a miniDSP, you'll need to place the miniDSP on "External MCLK"(previously incorrectly labeled Slave MCLK). That's because you'll want to have the miniDIGI on board MCLK(oscillator) to provide the MCLK to the miniDIGI. The miniDIGI will however stay I2S slave, since no matter what, the miniDIGI will

miniAMP is a different breed in the sense that this module is always behaving as an I2S slave(no jumper required) AND doesn't need any MCLK. So if you stack miniDSP + miniAMP, no need to change anything on the default configuration of a miniDSP, it will still get its MCLK locally on the miniDSP board, as previously labelled: Master MCLK, i.e. MCLK derived locally.

How about miniDSP + miniDIGI + miniAMP: you got it right again. The module will need:
- miniDSP is Slave MCLK, miniDIGI is Slave I2S, miniAMP doesn't require anything since it's by default a i2S slave

Anyway, long story short:
- miniDSP jumper is for MCLK Master/Slave, and if there is a miniDIGI board stacked on top of a miniDSP, you need Slave. Otherwise, all other configurations work in Master
- miniDIGI jumper is for I2S Master/Slave.

So maybe a quiz for you to see if I made things clear:
How would you think you could configure a miniDIGI + miniAMP with the explanation I just tried to make?

Take care,

Thanks, that cleared up some questions. I have been reeding a lot to figure this out, at only reading all manuals and tech notes gave me the answer. Maybe som more close op pictures showing, what you are writing might help.

As promised I will make some macro shots. But I'll wait until I have it all up and running.

I have now tried to connect the MiniDIGI board as described above. MiniDSP jumper on the middle of the board are in slave position, and jumper settings on MiniDIGI is as described in de userguide for stacking theses two boards. I have sound, but it distorts heavily. Signal in/out is not clipping.

Master/slave on MiniDIGI (middle of the board) is out, and MCLK on the I2S header is in.

Hmm! Maybe this is it. The MiniDIGI should be slave on both Master/slave jumper and I2S MCLK, so this jumper also have to be removed?

Hopefully my last edit to this post

MiniDSP is always Master MCLK (can only be slave by software update), so MiniDIGI have to be slave.

Hello,

This is odd that you're getting distortion and most likely due to an incorrectly configured jumper somewhere.. Reading your thread, I see that you removed the jumper for miniDIGI. As per the manua (p5):

"I2S slave, in which the board is receiving clock from a master - Jumper in place"

So actually, on the miniDIGI, the jumper in the center should be in place. Did you see some conflicting information in our documentation somewhere? Thanks for letting us know if that's the case.

As for the I2S_MCLK (jumper on the side), leave it closed since it's required for the board. to work.

Once the jumpers configured correctly (do it power off), reboot the board and see if you're still having the issue. If you do, send an email to our support team @ This email address is being protected from spambots. You need JavaScript enabled to view it. so that we can communicate easily on troubleshooting the issue. (pics and stuff).

Thanks.

Your userguides says there can only be one I2S master, it also says that MiniDSP only can be I2S slave by software upgrade.

MiniDSP is then I2S master, but the jumper in the middle should be slave - right?

MiniDIGI should be I2S slave, but jumper MCLK should be closed - right (your document also shows closed jumper)? and jumper on the middle of the board should also be closed? mine is open now.

Yes - that is very confusing, and not very clear in your documentation.

I'm sorry to hear that it's confusing, we always try to clarify our documentation, and will look into simpler, more graphical explanations. The main confusion as I tried my best to explain it in the previous post is that:
- Master/Slave jumper in the middle of miniDIGI is for I2S Master Slave.
- Master/Slave jumper in the middle of miniDSP is for MCLK Master/Slave.

I'm not sure if you fully got that part, but let's use point form and rules:
- There can only be a single I2S master and a single MCLK master
- MiniDSP is always an I2S Master, but can be configured as MCLK master/slave, depending on center jumper configuration
- miniDIGI can be configured as master/slave for both MCLK(side jumper) and I2S (center jumper)
- If stacking a miniDIGI board what needs to happen?
1) miniDIGI should be configured as an I2S slave (with center jumper CLOSED, in place)
2) miniDIGI will be a MCLK master, with jumper closed on MCLK jumper on the right
3) miniDSP will be a MCLK slave, with jumper on slave position.

Does this make a bit more sense?

One final thing to realize is that while we do try to provide plug-&play, the extensive flexibility in hardware configuration makes it quite hard for us to clarify all these concepts in a simple point form. Three user manuals, a wide array of combination, and customers each trying their own configuration makes the documentation hard to combine. Believe me... This being said, I'm certainly not trying to find an excuse, always room for improvement..

If you have some ideas on improvement and maybe letting us know which part of our documentation confused you (e.g. putting miniDIGI in Master), we're certainly open to suggestions! When you've been working on a product for so long, explaining it isn't so easy because everything is second nature and makes sense to us.

Now I see where I got confuesed. You say in the MiniDIGI manual that all MiniDSP kits configures as I2S master. I have misunderstood this and thought that all bards (incl. MiniDIGI) was configures as master, and I therefor opend the jumper to configure it as slave.

In the manual it also says, that master is with jumper in position, but then i thought it was the other jumper (MCLK).

You do a lot to make us understand I2S and MCLK etc. But, for me that is tech talk, and don't really help me. Diagrams, pictures with short text is much better. Page 6 in MiniDIGI manual is what I would like to have more of. I'm trying to make the first configuration. If you add two more drawings, showing the two jumpers on MiniDSP and MiniDIGI, then even I could have figured it out.

"A picture is worth a thousand words!"

We'll take your word and put together more of these diagrams since you feel that it helps.
I agree with you that as engineers, we always try to explain and aren't always the best at getting down to a simple explanation in few words... Thanks for your patience!

So down to the question: Is the problem now solved?

Don't tell anyone, but I'm at work. I will get back with feedback when I'm home again.

lol... Ok, I won't fly to Europe now to tell anybody...

Keep us updated if you still have questions.

It worked

The quite low background hiss from the analog inputs have now disappeared. The hiss on analog inputs are expected, and actually very low, but with spdif input it's naturally gone.

But, I now have som other noise on the analog output. It was not present, when I used the MiniDSP anlone. It's not background white noise hiss like before, but a specific frequency. I use USB to power the two boards, could it be noise from here?

Glad to hear that your setup is now working. Got you involved in understanding a bit more what's going on when you deal with digital audio, and like anything new there is a learning curve. If it was a plug & play device, it wouldn't be fun or wouldn't be called DIY DSP!

As for the noise you're getting on the outputs, I'm not sure where that could come from to be honest since we can't reproduce it here in the lab... One quick test would indeed be to see if powering the device from a simple USB phone charge (e.g. simple iphone charger or USB supply) would still display the same symptoms or not. What is the miniDSP connected to? I'm wondering if you have a ground issue with 2 devices (miniDSP and Amps) powered from 2 different supplies (PC I'm guessing?) and amp from a different source? So potentially a ground loop going on somewhere..
Anyway, have a try with a USB supply to see if that solves the problem.

I have just stacked all boards, and saw that the clock on MiniDSP was not slave but master. Now with all jumpers correct, I have the most silent system ever.

Thanks for the very intuitive new application note.