I wrote a software synth myself with the intention of running it on Raspbery Pi 3 / Zero 2. Those are actually quite capable processers; sound synthesis requires very little RAM, both code and for maintaining state, so everything fits in the rather tiny cache. But at the same time, while these Pis use "little" cores, the maximum throughput of NEON instructions is actually the same as for the corresponding "big" cores like the Cortex-A72. With four cores, you can do in the order of ~10 GFLOPS 32-bit FMA instructions. With a sample rate of 96 kHz and 32-note polyphony, you theoretically have a few thousand FMA instructions per note to spend.
To put this into perspective, five FMAs per sample is enough to implement a biquad filter. This is a very common DSP building block that can implement an idealized version of any of the 2nd-order filters that were ubiquitous in analog synths, e.g. high pass/low pass/band pass/notch/all pass. See the famous Audio EQ Cookbook for examples:
By chaining various combinations of EQ and non-linear distortion (lots of ways to implement this, probably involving more FMAs) and you can build very good simulations of common analog synth signal paths.
Note that gsliepen's example sample rate of 96 kHz is perfectly reasonable in this context; it's more than you need to exceed the limits of human hearing, but it's common to oversample your signal for processing to avoid problems with aliasing.
For more context, dsp chips historically were how you could get better better performance than was typical in the embedded space. At a time when you had sub 100Mhz typically in a chip that would be used in musical equipment dsp chips were super useful because they had many op codes that could be done in one cycle that might take many multiples of that in a general purpose chip. One prime example is add and accumulate. This meant that effectively, if you had an 80Mhz dsp doing calculations for you, you effectively had a 160-240mhz equivalent in your hotpath. This bump up in processing is necessary to meet hard realtime deadlines in audio processing at 48khz stereo processing.
Now, processors are so fast and cheap, that the need for dsp is way down. I personally ported the firmware for a popular pedal where the chip used was no longer available at quantity, and while it was tricky to get the same performance on a dual core 240mhz processor with floating point coprocessor, as the 96Mhz processor it was replacing, I just had so much compute, that I was able to port all but the gnarliest simultaneous effects on a chip that cost $6 cheaper but also came with enough ram to not need that $3 component either. And I can tell you, saving $9 dollars off a BOM means the product can retail at least $50 cheaper in an industry where volume matters a lot (no pun intended).
We have passed the inflection point where dsp chips are generally not worth the cost in most audio equipment. I’m not sure I’d use a raspberry pi, their reliability is not what I’d want in my products, but a similar single board computer? maybe. I’m not sure where linux realtime kernals are at the moment, ignoring the added complexity of a full linux running to process audio, audio requires hard deadlines. You will hear pops and other artifacts if you miss these deadlines, and buffering audio is also not something you can do for long, artists can feel delays in the ms. But, a single board computer running at ghz speed, gives an awful lot of compute so long as the OS can gaurantee your audio thread won’t get starved.
Max MSP has RNBO [0] which provides a Pi image, and a quick deploy path for patches. I've used it for a few art installations, and the versions from this year have been super nice. Basically, you can design and test audio on your regular dev machine and quickly deploy to the PI. You don't need to mess with any Linux audio nonsense.
I discovered by pure chance the vast ecosystem of iOS synths apps. And I was absolutely blown away. 90+% of the synths of the past century are available for ~5-20€ each. Connect that to a basic KORG MicroKeys Air [extra cheap, but includes Bluetooth]. And you are the next Jean-Michel Jarre.
[Note: and the amount of tutorial videos on YouTube is huge.]
I have a room full of synths from the 70's and 80's, two racks full of synths from the 90's, a veritable crap heap of soft synths on various Macs, and a Eurorack corner that threatens to implode my universe .. an as well - my Zynthian and Monome systems are chock full of great stuff, too.
It's not just iOS.
Zynthian and Monome provide an AMAZING ecosystem for audio exploration. If you haven't checked that out as well, here's the links:
That said - I could easily just get another iPad, throw away the room full of synths, wire up my iPads and the Zynthian and Monome systems, and be quite satisfied.
GarageBand is free on every iPhone and has a good selection of starter synths, with added DAW capabilities. Bluetooth midi controllers are supported (via bluetooth midi connect App). Using a pi or Arduino to build a midi controller can also be great fun.
This is the real competition. I'm not a Mac head but the one Mac in my house that will runs MacOS is connected to my Yamaha piano and runs Garageband. Is there any other software that works as simply as this, on any other platform?
For some synths like Blofeld, you're paying $10-20 for something that used to sell in a box for $300. And it's the exact same synth (100% digital) often with a better UI.
The iPad is a great choice for music - you get the variety of hardware synths with none of the annoying setup (power, midi, audio routing), at a cheaper price, but it still feels more immersive than sitting at a desktop PC and a daw.
But they are not the same, if you are a musician going to bars and practice spaces and the like that $300 Blofeld will handle the abuse and accidents much better than a laptop or tablet. No matter what you do and how careful you are, cords get snagged and stepped on, stuff gets knocked over, things get spilled etc etc etc. My Blofeld has taken far more abuse than any laptop or tablet will handle and still going strong 15 years later; three laptops and two tablets later.
There are things you can do to make computers more suitable for this stuff but it gets expensive fast and less convenient quickly. Toughbooks are tempting, but expensive, rackmount computer can be managed for not much and keeps the computer safe in its rack but now you more and bigger stuff to haul. Taking a disposable approach with rpi or the like is tempting but not exactly ideal. Computers/tablets are great and have their uses but are not a replacement for hardware yet.
The big problem for me with all things touch screen is that they get confused by water on the screen, which is an issue when it is hot and you are sweating or on a stage with bright lights cooking you. Not an issue if you just want to tap out beats but a serious headache if you want to adjust parameters. Connectors on tablets are also an issue, USB is not a very secure connection and the wireless options are not great. Give me a tablet with a plastic screen, 1/4" ins/outs, can run PureData and will not get confused by water on the screen and I will probably give up my hardware.
Building Blocks was a pack-in when I bought Syntorial in last years sale. It's technically different (web-based instead of a standalone app like Syntorial), and tries to do with music theory as a whole what Syntorial does with synthesis. Since it goes through the same 'theory, practice and create' cycle every time (eg. once for every chord type) I found it getting a bit tedious after a while.
I do the majority of my music composition on a desktop but it can definitely be nice to bring my 37-key midi controller + iPad for doing stuff on the go.
It's also not entirely uncommon for an App Store synth to offer both an iOS and a native Mac version so always check the store description to see if its universal. The ability to seamlessly bring your tracks over to a more full-fledged DAW on your Mac is really nice.
I'm not sure what it's like on iOS, but on Android the latency renders attempting anything "serious" impossible. There is a noticeable delay between pressing an on-screen key and getting sound out. I don't even want to imagine what a Bluetooth keybed introduce in the latency chain!
I notice no latency with my USB midi keyboard.
And the MicroKey Air I have is also real-time, in Bluetooth.
[the Bluetooth headphones on the contrary have a noticeable delay, so prefer the almighty jack 3.5 mm connection]
Yes! But, huge but, very huge but, you lose the affordance of the switches and the buttons and the knobs and the patch cables. And that is a terrible loss for fiddling and discovery.
True. But for going from zero to semi-hero, that’s definitely an option.
[the huge amount of presets in software synths is really an BIG added value, so you can learn how each given sound is built]
> Conversely, the likelihood of making it big just by making some good damn music was never lower than it is now.
Is that statement backed by any facts? Otherwise it sounds like a soundbite that sounds good, but I'm not sure how true it is. Maybe what "making it big" has changed more compared to how many people make their living making music, which for me would be enough to be considered "making it big".
How will that hobby fare against gen-AI prompt composing? Synths and samplers and sequencers were once removed from playing real instruments, softsynths and DAW twice removed and now there's genAI, thrice removed and arguably the biggest jump of them all. When softsyths appeared, real instruments weren't affected at all, but physical synths all but disappeared, just carried on by inertia, integration with real instruments and a bit of nostalgia. Will the same happen to soft synth now that there's an alternative thrice removed from real instruments?
I believe so: in an aging softsynth community I still mingle with occasionally, everybody who is still actively involved with music seems to have either moved on to genAI, or to soft-on-Rpi for better integration with real instruments (including synths of all kinds).
For some time now I've been supplying all my audio DSP plugins at airwindows.com pre-compiled on the Pi 400. (MIT open source, so it's not limited to that). The Pi version is included.
I mention this to make a point: you can't transform synths just by running some generic DSP code on a Pi and putting it in a box. Sound processing is also being transformed, and whether it's something like Hydrasynth generating poly aftertouch (but aliasing and not sounding that different from a VST) or Novation Peak/Summit receiving poly aftertouch (not generating :D ) but generating sound using custom hardware, sitting a VST on a Pi isn't going to get you a transformative synth.
Thing is, if you're able to dig into stuff like my DSP codebase that is actively under development AND plunk a VST synth onto a Pi AND do something interesting with the physical controls to direct the synth engine, that's starting to look transformative again. But just knowing about Pi isn't enough, you'll have to have a deep background in soundmaking and the ability to instrument-make in an interesting way.
If you have those things… game on. You can begin work FAR more cheaply than ever before, and that is how the Pi could be transforming synths.
I'm waiting for 24/96 audio hats to be common before I dig into this, even for stompboxes. I'm given to understand Electrosmith Daisy already has this, and that's a similar class of 'system on tiny board' that should be considered an audio Pi-like.
Little bit shallow article. Raspberry 3/4/5 are in a different league than RP2040. Newest Zynthian kits are updated for Pi5. There is also a big difference between using Linux (e.g. Zynthian) and running barebones (e.g. Minidexed, MT32-pi, probably some proprietary offerings).
I recently got a Daisy Pod (https://daisy.audio/product/Daisy-Pod/). It supports a few different runtimes, including a max/msp runtime and a Pure Data wrapper called Plug Data. It's a pretty neat little device, even though the documentation could use some work.
I've been working on building something using a Daisy Seed lately. Pretty amazing that I can have interesting sounds (and effects) generated in just ~200 lines of C++.
And you're absolutely right about the documentation.
I’ve actually been building a few synths based on the Pi over the years—it’s been a great way to “get rid” of the older boards as time goes on, although since I’ve never bought a Pi 5 I suspect that time has past.
You can use the Pi 2/3/3a/Zero 2 to build things like an mt32 or DX7 emulator almost trivially, and they make for great DAWless modules.
Readit News
https://www.w3.org/TR/audio-eq-cookbook/
By chaining various combinations of EQ and non-linear distortion (lots of ways to implement this, probably involving more FMAs) and you can build very good simulations of common analog synth signal paths.
Note that gsliepen's example sample rate of 96 kHz is perfectly reasonable in this context; it's more than you need to exceed the limits of human hearing, but it's common to oversample your signal for processing to avoid problems with aliasing.
Now, processors are so fast and cheap, that the need for dsp is way down. I personally ported the firmware for a popular pedal where the chip used was no longer available at quantity, and while it was tricky to get the same performance on a dual core 240mhz processor with floating point coprocessor, as the 96Mhz processor it was replacing, I just had so much compute, that I was able to port all but the gnarliest simultaneous effects on a chip that cost $6 cheaper but also came with enough ram to not need that $3 component either. And I can tell you, saving $9 dollars off a BOM means the product can retail at least $50 cheaper in an industry where volume matters a lot (no pun intended).
We have passed the inflection point where dsp chips are generally not worth the cost in most audio equipment. I’m not sure I’d use a raspberry pi, their reliability is not what I’d want in my products, but a similar single board computer? maybe. I’m not sure where linux realtime kernals are at the moment, ignoring the added complexity of a full linux running to process audio, audio requires hard deadlines. You will hear pops and other artifacts if you miss these deadlines, and buffering audio is also not something you can do for long, artists can feel delays in the ms. But, a single board computer running at ghz speed, gives an awful lot of compute so long as the OS can gaurantee your audio thread won’t get starved.
I work in the field and clunky, shit software is the norm. In particular, radiology information systems (RIS) just kill me. How are they so crap?
People also use this to make unique pedals.
[0]: https://rnbo.cycling74.com/
[Note: and the amount of tutorial videos on YouTube is huge.]
It's not just iOS.
Zynthian and Monome provide an AMAZING ecosystem for audio exploration. If you haven't checked that out as well, here's the links:
https://monome.org
https://zynthian.org
That said - I could easily just get another iPad, throw away the room full of synths, wire up my iPads and the Zynthian and Monome systems, and be quite satisfied.
The iPad is a great choice for music - you get the variety of hardware synths with none of the annoying setup (power, midi, audio routing), at a cheaper price, but it still feels more immersive than sitting at a desktop PC and a daw.
There are things you can do to make computers more suitable for this stuff but it gets expensive fast and less convenient quickly. Toughbooks are tempting, but expensive, rackmount computer can be managed for not much and keeps the computer safe in its rack but now you more and bigger stuff to haul. Taking a disposable approach with rpi or the like is tempting but not exactly ideal. Computers/tablets are great and have their uses but are not a replacement for hardware yet.
The big problem for me with all things touch screen is that they get confused by water on the screen, which is an issue when it is hot and you are sweating or on a stage with bright lights cooking you. Not an issue if you just want to tap out beats but a serious headache if you want to adjust parameters. Connectors on tablets are also an issue, USB is not a very secure connection and the wireless options are not great. Give me a tablet with a plastic screen, 1/4" ins/outs, can run PureData and will not get confused by water on the screen and I will probably give up my hardware.
It's also not entirely uncommon for an App Store synth to offer both an iOS and a native Mac version so always check the store description to see if its universal. The ability to seamlessly bring your tracks over to a more full-fledged DAW on your Mac is really nice.
Example: Minimoog Model D Synthesizer
https://apps.apple.com/us/app/minimoog-model-d-synthesizer/i...
Do iDevices not support hardware (USB) MIDI?
Now that I understand most of it, I am really considering buying a ARP 2600 replica.
So yes, the switch from software to hardware comes with time. But, at least for me, the first step is cheap apps on my already-owned tablet.
Experiences vary but sliding a slider on a screen is worth the benefits.
Conversely, the likelihood of making it big just by making some good damn music was never lower than it is now. Makes for a fine hobby though.
Is that statement backed by any facts? Otherwise it sounds like a soundbite that sounds good, but I'm not sure how true it is. Maybe what "making it big" has changed more compared to how many people make their living making music, which for me would be enough to be considered "making it big".
I believe so: in an aging softsynth community I still mingle with occasionally, everybody who is still actively involved with music seems to have either moved on to genAI, or to soft-on-Rpi for better integration with real instruments (including synths of all kinds).
I mention this to make a point: you can't transform synths just by running some generic DSP code on a Pi and putting it in a box. Sound processing is also being transformed, and whether it's something like Hydrasynth generating poly aftertouch (but aliasing and not sounding that different from a VST) or Novation Peak/Summit receiving poly aftertouch (not generating :D ) but generating sound using custom hardware, sitting a VST on a Pi isn't going to get you a transformative synth.
Thing is, if you're able to dig into stuff like my DSP codebase that is actively under development AND plunk a VST synth onto a Pi AND do something interesting with the physical controls to direct the synth engine, that's starting to look transformative again. But just knowing about Pi isn't enough, you'll have to have a deep background in soundmaking and the ability to instrument-make in an interesting way.
If you have those things… game on. You can begin work FAR more cheaply than ever before, and that is how the Pi could be transforming synths.
I'm waiting for 24/96 audio hats to be common before I dig into this, even for stompboxes. I'm given to understand Electrosmith Daisy already has this, and that's a similar class of 'system on tiny board' that should be considered an audio Pi-like.
https://shop.zynthian.org/
https://github.com/probonopd/MiniDexed
https://github.com/dwhinham/mt32-pi
And you're absolutely right about the documentation.
You can use the Pi 2/3/3a/Zero 2 to build things like an mt32 or DX7 emulator almost trivially, and they make for great DAWless modules.