When my Dad retired in 2011, he bought himself a Roland HP503 electric piano to relearn how to play - the first big thing I can ever remember him buying for himself.
The sound quality (specifically the internal synth) has deteriorated significantly over the past couple of years, and I’m noticing he is starting to play it less.
We’ve done a few experiments using the aux in, and shown the internal amp and speakers seem just fine. Equally, the USB MIDI out seems just fine too - it’s just the internal synth that’s gone bad.
So, I have a Pisound and a Raspberry Pi 4B, and I’m working on bypassing the internal synth.
As a prototype, it works just fine - although I’m testing it here with an AKAI LPK25, not with the Roland HP503.
But I am having to do a few things manually on each boot - and that is where I need some help.
I want to make this setup as bulletproof as possible.
Currently, when I boot, I have to:
Stop jackd
Kill fluidsynth (started as /lib/systemd/user/fluidsynth.service)
Jack would be preferred, as it has decent performance, and has more flexibility when you multiple audio programs & effects in your signal chain.
sudo systemctl disable --now jack
If you want to run Fluid Synth, why not simply run MODEP and make use of the Fluid plugins. It can run automatically on startup, but also you can edit the pedalboards remotely.
With some MIDI utilities on the pedalboard, you might be able to reroute the instrument making use of some existing controls on the keyboard, but I haven’t looked into what is actually available, just sharing some further development ideas.
It’s a great question - and there are people on this discussion board much more qualified to speculate then me, but since I’ve spent a number of hours chatting this through with my Dad, this is my best guess:
A common failure for electronics from 2010’s is leaky capacitors. (Something todo with switching production from Japan to China)
This is from the service manual from an older model Roland HP electric piano:
It pre-dates USB, but it’s my best guess at roughly what’s inside the electronics of the HP503.
There is a circuit path via IC13 (Tone Generator) → IC5 (‘Data’) → Panel L (Volume and brilliance) → IC9 (Mix) which has dozens of capacitors as potential points of failure, independent of the midi Out and Mic board.
So that is my working theory. Bypass the internal Tone Generator path.
Given that the piano has sentimental value and is 90% functioning, my Dad wasn’t keen on investigating the internals more, if we could come up with an external workaround.
Just wanted to say thanks for the help and suggestions (and of course the great work done on PiSound and Patchbox OS).
We have a working system in place now, and my Dad can get back to practicing.
Few tweaks we can make still, but getting something going was the priority.
That’s great! Your dad looks very happy with your work!
Is the audio generated by Fluid Synth?
My guess would be degraded power supply, causing sort of digital audio artifacts. Or it could be the flash ROM itself, that has a limited lifespan, causing audio processing & logic issues, unless it is overwritten occasionally. It would have been interesting to hear the sample audio that the original misbehaving digital circuit was producing, but no need to spend effort on this, this is just a general curiosity, as you’ve already made the decision to bypass the generator externally.
Yes, the audio is from Fluid Synth, connected to the Aux in on the Roland.
We tried a few sounds fonts before picking this as the default.
My Dad is happy. He thinks the PiSound possible sounds better than the Roland ever did.
And just for interest, here is a link to an audio recording of the Roland being playing in Oct 2024:
