[PLUGIN] SerialAmpController - Control Amplifiers with Serial Interface from Volumio (e.g. ROTEL A12/A11/A14)

Sound is just fine from usb, I only got problems and distortions the first time I used it, then everything went fine.

New rs cable is coming in few days :wink:

unfortunately it does not work even with the new adapter, must be something boroken in my preamplifier…

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I‘d say that it’s rather unlikely. Normally those interfaces are quite robust these days and do not break easily. I‘ll try a few things over the weekend and if you are willing to spend some time to get it working, we‘ll figure it out. Will come back with instructions. It also took me some time to get it working, maybe I forgot something important.
Btw: did lsusb -v return anything?

No problem I will do what you’ll ask me to do!

The command gave me back quite the same instructions it gave to you

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Ok, that means that the RPi is talking to your RS232 interface.
I also found the reason why the cat command is not working. I installed everything on a fresh RPi and found out, that you need to first configure the communication. On my development system that was not necessary, need to check why. Sorry that I did not remember that - but I started the plugin 2 years ago and it works for more than a year…

You can try again:

  • log into your RPi via ssh
  • issue stty -F /dev/ttyUSB0 115200 raw -echo -echoe -echok -echoctl -echok
  • issue cat /dev/ttyUSB0
  • turn the volume dial and change the input on the amp front-panel or via remote control and see if there is any output on the terminal (I assume it should work now)
  • Next, try to issue echo -e -n volume_15! > /dev/ttyUSB0(you may need to try twice) this should change the volume to 15
  • Try also echo -e -n volume_up! > /dev/ttyUSB0 and echo -e -n volume_down! > /dev/ttyUSB0
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yes, that worked, I have every command mirrored on the terminal now.
But if move volume in the app it does not change on the rotel amp still.
Only “Switch input at play” has given me some results. If I’m on Phono, for example, and push play in volumio, the amp switches correctly to the Pc-USB

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dunno if it is 'cause of one of these options…

mmmmh… that could really be it. I did not think about that earlier - sorry.
When you set the hardware mixer to enabled, Volumio is using the volume control of the RPi.
Can you set “Mixer Type” (Tipo Di Mixer) to “disabled” and try again? It might be a good idea, to restart Volumio once, because I am not 100% sure, my plugin will recognize a change of the Mixer Type setting.
I’ll try to include a check routine in the next update of the plugin, that will check if there is any hardware mixer enabled and at least issue a warning.

At least what we learned so far, is that your serial interface works and the communication from the amp works, too. In case the Mixer Type setting does not help, the next thing would be to try out the communication from RPi to Amp.
In case above proposal still does not help you could issue
echo -e -n volume_15! > /dev/ttyUSB0
That should set the volume of the amp to 15.
echo -e -n volume_up! > /dev/ttyUSB0
Should increase volume by 1.
echo -e -n volume_down! > /dev/ttyUSB0
Should decrease volume by 1.

Disabling volume mixer the volume control on the client’s interface disappears completely


So no way to rise and lower it no more in volumio.

If I enable the software mixer it only enables me to control the volume of volumio output (i can lower and rise, and it actually goes down, but not on Rotel amp, just the output)

Those commands you sent me (volume15! - up - down) work just fine

If the commands work ok, then it is only a matter of finding the issue now.
I played a little with the settings of my system. If I set the Mixer type to “none” and save, it puts the volume control to 100 and I cannot use it anymore.
But if I then switch off and on the plugin, it works just fine and the volume control is usable again and controls the amp.
Can you please try that? If it still does not work, you should leave it on “Mixer Type: none” and make a log again. Make sure, that the log starts with enabling the plugin and do not only try to use the volume dial in volumio, but also use the volume knob on the amp. This way, we should be seeing commands from the amp or the computer.
In principle all the communication works, so it can only be a rather small thing related to the differences between the amps, if it does not work yet.

Hi there!

the point here is this, If I put the “mixer type” on “none” the volume bar keeps disappearing, also if turn off and on the plug-in it reamins invisible. The only time it got back visible was when I switched from iOS Volumio app to Win11 browser (dunno why) it auto reenabled the Hardware mixer… but if i go back to “none” it stays invisible…

btw, here’s the log, I’ve tried to rise and lower the volume from the amp (nothing happened) then I switched source to Phono and pushed Play in volumio, it changed souce back to PC-USB and started playing the song. It’s the only command that seems to work!

serial amp contr log.txt (17.1 KB)

What surprises me the most is that only one command works…

The log looks good now. We are getting closer. The messages from the amp are coming in and are partly recognized. However, there is also an error message, where the plug-in had a fault. Currently I am too busy with other stuff but toward the weekend I can investigate and try to make a fix. If we are lucky, it may work after that.
One remark: If you are using the iOS app, I cannot really comment that one. I am only using browser based devices. Disabling mixer hardware just fixes the control in the Browser interface and the plug-in then takes over. The app may be programmed to hide the control if it is fixed. Not sure, if I can prevent that, would need to revisit the Volumio code.
Will report back as soon as I have a fix. Have to ask for some patience.

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Thanks for your great work! I will wait for news from you. Keep up the good work!
ciao for now

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Surprisingly had some spare time tonight, so I looked into the issue and found the sources of your issues:

  1. Your amp always sends a terminating ! after messages, except for the message about the amp-type. Unfortunately, the plugin did not correctly handle that. I fixed it be just not requesting that info from the amp - thus it should not be an issue anymore. It caused an unhandled error - maybe that blocked the remaining stuff.
  2. Installed the iOS app and played a little - the issue with the vanishing volume control was actually a small bug in the plugin, that did not cause any issue in the browser - it works now with the app as well

Thanks for reporting it and the patience to help me get down to the bug.
You can try v2.0.5 from the plugin store. Let me know, if it works… at least this was a big step forward. Maybe we need a few more tweaks, but some of the basic issues are now solved.

THAT WAS A GR8 STEP FORWARD!

From iOS I still get a vanishing volume bar, but if I go up and down with the volume (remote or knob) the bar comes back and moves accordingly to input. Unfortunately as soon as I touch it, it disappears again. The other functions work: If change input on the preamp Volumio pauses, when I hit mute is stops and so on…

Tomorrow I will test from pc

(Can you make it recognise the play, stop, pause, forward and backwards commands from the Remote control too?)

sadly gotta confirm that volume bar vanishes now also in chrome pc browser

Hmmm. You really give me a hard time :wink:… Got me an old USB cable from the basement and connected my RPi to the PC-USB input. Could find one more bug that might be at the heart of the problem. On my system the Amp is listed in Volumio as the fourth item in an array but it get’s the ID=5. My code tries to read the 5th item from the array and crashes, because there are only 4 items. I fixed that now - did not know, that IDs could skip one digit, because I never observed that.
You can try to download 2.0.6.
Below my settings for reference. I had to first set the hardware in General Playback options and then set the plugin - else the volume was quite low.

removed images - most recent settings below

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Regarding the question of the remote control: I suppose you mean from the IR-control? I think those commands are just interpreted by the Rotel CD-players. The amp ignores them or only passes them to the CD-Player via their own communication interface.
The amp does not send any notification via the RS232 when it receives a FFWD/RWD/STOP/START command from the IR - so there is no way that we can interpret it, because we get no notification.
(you can verify with the cat /dev/ttyUSB0 command)

hi there, unfortunately, after this last update,Volumio is not working anymore, I can’t even access from rasp ip, it only shows the loading circle…

I’ve also formatted and reinstalled volumio on the sd, dowloaded the new plugin beta again, but all I get is the loading circle :frowning: this only happens when I select PC-USB as VOLUMIO_INPUT

SSH still works (and I’ve checked what you told me aboud FFWD/RWD… commands too