Audio stops / interrupts and comes back after some seconds

[Eule]

Update:
I have switched the SD cards and now I was using the normal Pi Os and the CPU temperature doesn’t exceed 41°C.
I did some diagnostics and all seems normal. Temperature is stable between 39 to 41°C max.
I think, that Zynthian is somehow very demanding of my Pi and I thought I have a rather good one.
Raspberry Pi 4 Model B Rev 1.4
Plenty of RAM is available as you can see in my previous screenshots.
To me, this is a mystery about what’s going on.

Can someone please let me know if my Pi is not good enough for a Zynthian?
I am aware it is not the newest model, but with ARM technology and enough RAM this machine seems pretty capable with its 4 cores

[jofemodo]

@Eule

Right now the Pi is back in its case with the little fan (not inside the Zynthian case) and I booted Zynthian and do nothing. No music plays… Now the temperature is at about 42°C constantly.

And you can still reproduce the issue? If yes, please, send a smapshot.

regards,

[riban]

Hi @Eule

You show a list of presets but I haven’t seen what synth engines and processors you are using. It sounds from your description that the quiescent temperature is 40C which seems fine but it shoots up to 70C when playing. With no cooling and high CPU usage, e.g. resource hungry synthase being played heavily you are going to push the temperature up. With good cooling, i.e. effective heatsink attached to chips this will improve dramatically. Heatsinks transfer the heart away from the active components but will only work if the ambient air temperature is significantly lower hence the need to vent the hot air away from the heatsink. I wonder whether the heatsinks you have attached are fixed with thermally conductive compound and whether they are make of a good thermal conductor like aluminium. A heatsink with large surface area is more effective (which is why they often have fins).

It does sound like your issue is related to hear dissipation (or lack of).

[Eule]

Hi @riban

The ZynAddSubFX is the synth engine I use. First in the list and there I selected the synths in the list.
The Pi has heatsinks and a built-in little cooler, as you can see in the photos above.
I guess this is the standard Pi package. I bought it like this with that plastic house, ventilator and heatsinks installed already.
Last night I put in the raspberry OS SD card and ran diagnostics, rand reaper and stuff to see how it behaves and all was normal at around 40°C with a max of 41°C.
So, no issues under those conditions.
I will take it out of that house and mount it directly in my case and I will add air holes to the case, for better air circulation.
After I have done this I will run excessive tests again and see what happens.
@jofemodo explained how he runs it in a metal housing without vent and it doesn’t run hot, so mine should behave the same.
I have the suspicion that the synths I am running are CPU demanding and that might cause that steep rise of heat. I am not using simple mono synths or so, because I have real mono synth machines in my setup and I want to use the zynthian for pads and with multiple chains running to create nice layering.
I like the new Zynthian firmware with the audio mixer and I can handle the BPM as it is right now. at least I can adjust by cent and when I use the DAW to trigger the MIDI channels the timing comes from the DAW anyways. I would not be able to use sync-demanding effects like a delay, but that is ok.
Not so essential. Still, I think having a SLAVE function for the Zynthian should be an upgrade target for you guys in the near future, so it can be implemented nicely.
The ambient air temperature is not very high. I like working in a rather cool environment and I also ran the Zynthian with the case open, so enough air circulation is provided.
I will look into purchasing other heatsinks. The ones installed seem pretty small and maybe they are just standard heatsinks. I have never researched special cooling upgrades for the Pi.
I think the Pi itself is pretty capable and a more efficient cooling system makes sense for sure.

Thanks everyone for the input. I am on the case and will update here when I have new results.

[Eule]

Here is a closeup photo of the Pi with its heatsink and vent.

[Eule]

Finally, another screenshot of the temperature when Zynthian is running, but not playing anything.

[Doug]

Looks to me like throttling since the temp shows close to 80c, BUT the ‘-p 256’ option on the jackd command may be too small a buffer for your interface. Try changing this to -p 512 and see if this fixes the problem. Latency will suffer tho.

Ssh in and use ‘man jackd’ to review the options.

[Eule]

@riban & @jofemodo so, I bought a very good passive cooling case for the Pi and ran it now for about 10 minutes with the exact same 5 tracks in a loop as before. The case is ice cold since it was just delivered by Amazon and still feels cold to the touch.
The only external device connected is the NI Audio 2 soundcard via USB 3.0 and the max. temp I measured goes up to 53.5°C when another audio dropout happened.
After some seconds the sound comes back and the temp went down that time about 5°C.
The cooling case is the best I could find online, which is fanless.
The case is called Armor Case V2.0 / 52Pi. Of course, I added the temperature transport pats on each IC with the provided pats in the package.
I am at the end of my options now.
I also increased the buffer to -p 512 as @Doug suggested in his comment.
The NI Audio 2 MK2 soundcard I also used with Ableton DAW to check if I can reproduce any dropouts and it can handle many more tracks running than the 5 synths I added to the Zynthian.
So, I don’t think the audio interface is the cause of the issue.
Right now I have no other USB audio interface I could test on the Pi, because my studio soundcard is a RME Fireface 800 with firewire. The MK2 soundcard is very capable of handling these 5 tracks and it never caused any dropout whenever I used it while DJing or when I tested it with the DAW.
I was also reading online, that external USB devices could cause an increase in temperature when they draw too much ampere from the Pi, so nothing is connected.
The only other device connected is the 7-inch touchscreen. That’s it.
In the past week, I also switched the SD cards and ran the Raspberry OS, even watched some videos to see if I could reproduce any dropout situation and various benchmark tests didn’t show anything wrong with the Pi.
So, do we have any other ideas on how to get to the bottom of this issue?

The last option I see is to buy a new Pi and I don’t really want to invest and maybe have then the same issue.

Would you guys have any analytics scripts I could maybe run on the Zynthian, which could show more details under the hood when these dropouts happen?
Are there any log files I could maybe export to share here, which would give more insight?
I also activated the CPU usage indicator at the Zynthian on the top right and it seems that the CPU is barely busy. Unfortunately, there is no CPU usage number visible on the home screen of Zynthian. Only memory and sd card usage and the temperature.

[Eule]

That is the passive cooler I bought.

[Eule]

[Eule]

Well… temperature keeps going up now after running about 20 minutes with those 5 tracks in a loop.

The room here is cool and I can’t understand why it would get that hot again.
The last option would be to find a power supply for the NI MK2. It has the option to add a power adaptor, but it didn’t come with one originally. I gonna check which specs it has and maybe I have one to see if it might use too much ampere from the Pi, which could cause the rise in temperature.

[Eule]

researched now for a power supply for the MK2.
It has a surprisingly high voltage of 15 V DC with 1.2 A
I am not sure if this little thing draws really 18 W. I never used it ever with a power supply and always just run it on the USB plug on my MacBook Pro, the Mac mini and now on the Pi.
I did order a UMC 1820 Behringer, which runs on USB. So, gonna wait for it to arrive and will test it again with that interface, which has its own power supply.
Ordered the UMC as a backup card for live performance, because I don’t wanna use my RME anymore live on stage. The UMC has good reviews, even though it is a rather cheap interface.
I saw you have the UMC in the audio interface list of the Zynthian, so I see this as my last chance.

[riban]

Hi @Eule! It sounds like you are having quite an ordeal with this. It does look like the Pi is having some temperature management issue. I wouldn’t expect a Pi with such a good heatsink to rise in temperature like that but it may point to other issues like how much the CPU is being stressed. Also, it may not only be heat related. (That has been our main focus due to some unusual behaviour you reported earlier.) 62C isn’t bad when hammering the CPU - you are running 5 instances of ZynAddSubFX which is a powerful synth and depending on the patch/preset can ramp up CPU usage.

It is really important that the power supplier is able to deliver the required current without the voltage collapsing. This means the PSU must be capable of supplying 5V at 3A and have a good quality cable and connector. Thicker cables will generally provide lower impedance and hence be more capable of delivering the current without voltage drop across the cable. Also avoid any switches inline with the 5V supply. This adds resistance and has been identified as a common issue. By far the most frequent issue with Zynthian performance has been with substandard PSU or cabling.

Your NI interface does sound like it needs substantial power which will limit the performance of the Pi. Even with the best PSU, there will be a limit to the current that can be delivered to and through the Pi. You could try a powered hub to supply the NI MK2 with its power. The UMC 1820 is a nice interface. I have one. It has its own PSU so reduces the load on the Pi. I really like my UMC 1820. It turns the Zynthian into an audio mixing desk as well as synth. The mic preamps are fairly good and you have options for digital I/O if that’s your bag.

In the past, USB audio interfaces have required 3 buffers. This requirement has mostly been reduced / removed with changes in the drivers but it may be worth changing this setting to see if it improves your problem (It will improve because there will be more buffer space so onset will be delayed but it may be significant improvement.) In the jackd options, change -n 2 to -n 3. Don’t increase further - it won’t solve anything and will increase latency.

[Eule]

@riban sooooo… I have news.
Now I made a single track with fluidsynth/ensamble/slowstrings and it was playing a single standing note for about 1 hour now. I regularly checked the temperature and the maximum it reached is 47°C.
And, it just dropped out again at 47°C, which is for sure not too much heat.
Something else is going on.
Obviously, the single track and probably less demanding synth is much lighter on the Pi, but still, it drops out. CPU load is near nothing - a slim green line at the display. barely noticeable.

I did change the jackd -n 3 setting as you suggested.

What I will do now is plug out the NI MK2, activate the internal Pi soundcard and see how that behaves.

[Eule]

Same story with the internal RBPi soundcard. Right now I am only using the headphone output.
CPU Temperature was still up between 47 and 48°C and just again a dropout happened.
There is only LAN, headphone jack, power supply and display connected.
These dropouts happened since I used Zynthian for the first time in the end of 2020.

I can’t think of a more minimal setup to not get a dropout.
Bought this cooling case and obviously, the temperature is much lower now than it was with the old acrylic case and I don’t seem to see any change in those dropouts.

I am really at the end of ideas now on how to solve this.
The newest stable Zynthian version is installed, CPU load is near nothing with only one audio track running in a loop. Dropouts with both - external USB and internal Pi soundcard.

It would be really nice to somehow have analytics to know what actually causes the dropout.

The symptom of a dropout appears as follows:
Audio stops, volume level meters freeze at their position, as if the entire system freezes for a moment and after some seconds sound comes back and level meters work again.
When the system comes back I can observe a short peak in CPU load, which has to do with resuming the sound and animation.

I am giving up for today. I also don’t believe anymore that another soundcard would fix that problem.
I mean, at this minimal load I am running it right now with only one simple audio track and no effects on it, any soundcard should playback this without any trouble.

The Pi shows no such symptoms when I switch from the Zynthian system to the Pi OS.
It just works fine, doesn’t run hot either.

I have the feeling this is the end of my zynthian experience. It is useless like this.
I would have loved to include this little machine at my live sets. I wanted it to do nice pad drones, in sync and in the correct master tuning. You guys provide the master tuning and tempo setting, but those dropouts I had since the beginning and it seems hard to figure out what causes it.

This took a lot of my time and I enjoy fixing stuff and making it work, but I lost confidence in this.
Unless you guys have another idea, I guess I am out of the zynthian world.

[riban]

Hi @Eule! I understand your frustration. You just want to make music! The behaviour you describe is very unusual. I don’t recall hearing of anyone suffering the same symptoms. If the CPU is struggling then you may get xruns with associated clicks on audio but not a complete UI freeze.

FYI the internal soundcard is poor and uses a lot of processing. It should be avoided if possible.

You haven’t described your power supply. This could be contributing. It is a common cause of problems.

It is plausible that the Pi is affected by other things. Try disconnecting the network in case there is a grounding issue or hf oscillation. These can cause severe current drain.

Also post a screenshot of the whole webconf dashboard. There may be clues.

It would be a shame to lose you but your frustration is understandable. It’s a shame you are experiencing unusual behaviour.

[Eule]

Good Morning @riban

I have used the zynthian at various locations and everywhere is good electricity.
Obviously, I have overseen the power supply question.
What I have is the original power supply, which came with the Pi.
Here are the specs:
It is a 5V DC, 3A power supply.

Last night I decided to let the Zynthian run in a loop for the entire night and this morning the case was slightly warm to the touch. So, rather cool. The internal soundcard didn’t cause it to get that hot.
I think we are on to something now.

I remember now, that you wrote something about not having a switch on the power supply, which mine has. I have a good USB-C cable and a strong power supply. So, I will now run another test with this setup and see if anything changes. It would be great if this is the cause because this is an easy-to-solve issue.

Is there a recommended power supply for the Zynthian?

I will get back to you after another day of testing.

[jofemodo]

Hi @Eule !

The recommended power supply for zynthian is the RBPi’s official one. It’s the best i’ve tested. Some months ago i decided to make a comparison and tested several power supplies, measuring the voltage and current ripple with an oscilloscope. The result was clear: the more stable, with the lowest voltage dropout and ripple was the RBPi’s official power supply.

For doing the measurement, i had to cut the wire and it was quite obvious that RBPi’s PSU has the thicker one, almost doubling AWG (American Wire Gauge) than the rest of PSUs i tested. This is very important when driving 3 Amps.

Anyway, your problem doesn’t seem related to PSU and i’m starting to think it could be a faulty RBPi. I mean, what if the temperature sensor is not working properly? I would encourage you to test with a different RBPi board.

BTW, how is your zynthian connected to the network? Ethernet? Could be something bizarre on your network connection? Perhaps POE?

Really strange issue you have …

[Eule]

I am using a rather short LAN cable connected to my Mac mini.
In the past at different locations, I also connected the Pi to my MacBook Pro and to an iMac.
Different computers and different locations make sure the LAN can not be the issue.
To exclude this possibility I will also run the Pi without LAN, so I will not be able to monitor the temperature, but I will hear when the sound drops out.
I was expecting my power supply to be the original since it came with the Pi, but I will look up the original and get one. I hope it isn’t the sensor you suggest.
So, while I am typing here the Pi is running with the other power supply and I just noticed a dropout and the temp is at 43°C.
I will disconnect the LAN cable now and keep it running.
Another thought I just had was the SD card. What if there is a moment when the Pi needs to load something during the performance and the SD card doesn’t work as it should?
I am using a ScanDisk Ultra. I think I saw this as the recommended one at some point.

[jofemodo]

As @riban commented above, we never saw the behaviour you describe. It doesn’t fit any of the common patterns most of people have when testing zynthian. This kind of UI-blocking is really strange, it seems like the RBPi totally stop working for a while. Perhaps you could check from the terminal how deep this “lapsus” is. I mean, could you check if network is also interrupted? What if you run something like this from the terminal:

top -1 -d 0.1

Does it get frozen too?

Regards,