Building musical synthesizers and keyboards

[PauloConstantino]

Hi there,

I've been VERY interested in building myself a synthesizer, sequencer + keyboard system!

I was building some sound circuits for my homemade 8bit cpu, and I got pretty interested in electronic sound generation, and then I went into the magic of synths. oh man what was I missing !! They're the most amazing thing!

So now I want to build one. I am very experienced with digital electronics but not much with analog, and I've been dwelving into analog these days more via textbooks to learn what I don't know.

So what do you guys advise as a place to start? I'd like to build an analog synth, because a digital one would really be too easy. I don't want to use a microcontroller. I want to do it via discrete analog components, and discrete logic for control as needed.


Do you guys know of a good book on designing synths? Maybe a website? Maybe some advice ?

Thanks a lot!

[Fungus]

a) It's not easy! A lot of the circuits/modules are quite complex - everything has to be voltage controlled.

b) Start with google: https://encrypted.google.com/search?q=building+analog+synths

c) Don't rule out microprocessors completely. They can save you a LOT of work for things like the keyboard input (which doesn't actually produce sound so a synth is still an analog synth even if the keyboard is digital). You can always remove them later if you're a purist.

d) Starting with an Arduino and simple function generator (or two) will let you get to work on the important units right away (ADSRs, LFOs, filters, etc.) and it will still be 'analog', technically speaking.

[AndreasF]

This might be helpful:

http://www.sdiy.info/w/Schematics_and_manuals

[Lee Leduc]

http://musicfromouterspace.com/

SYNTH-DIY section

[magetoo]

So what do you guys advise as a place to start? I'd like to build an analog synth, because a digital one would really be too easy.

Too easy?  It's pretty complicated if you want to do it right and not just half-ass a DSP or micro implementation.  Maybe I'm biased from having sketched out part of one in discrete logic...


But you wanted pointers for analog:

Video
Aaron Lanterman's "Electronics for Music Synthesis" lecture videos; see here for links.  Must see.

Books
Hal Chamberlin, "Musical Applications of Microprocessors" is recommended all the time.  Out of print.  No, it's not about digital synthesis.
Barry Klein, "Electronic Music Circuits" is another that gets mentioned.  I've seen a PDF of it somewhere.

The synth-diy mailing list is where the serious builders go.  Lots of information in the archives.

Some other places worth mentioning:
Muff Wiggler forum (mostly modulars and kit builders IIRC)
DIY section of the Electro-music forum

Ken Stone / CGS
Schmitzbits

You'll come across OTAs a lot, so might as well check out this article, "Understanding and using OTA op-amp ICs" by Ray Marston; part one, two (PDF), and perhaps this bit of "errata".

That should get you started, I hope it's not too much!

[Keicar]

The difficulty to achieving pitch stability in VCOs is temperature compensation of the exponential converter - here's a paper I found on the subject:

http://www.openmusiclabs.com/files/expotemp.pdf

[JanJansen]

If you can do digital you should use it, why logic control ?, because it is fun might be the reason for you, your circuit will be very big especially as first project.

[diyaudio]

Hi there,

I've been VERY interested in building myself a synthesizer, sequencer + keyboard system!

I was building some sound circuits for my homemade 8bit cpu, and I got pretty interested in electronic sound generation, and then I went into the magic of synths. oh man what was I missing !! They're the most amazing thing!

So now I want to build one. I am very experienced with digital electronics but not much with analog, and I've been dwelving into analog these days more via textbooks to learn what I don't know.

So what do you guys advise as a place to start? I'd like to build an analog synth, because a digital one would really be too easy. I don't want to use a microcontroller. I want to do it via discrete analog components, and discrete logic for control as needed.


Do you guys know of a good book on designing synths? Maybe a website? Maybe some advice ?

Thanks a lot!

If I were you, try to build an existing synth, like a Roland TB-303.. the schematics are all over the place , I designed a rudimentary TB-303 VST plugin for Cubase SX and even that was tough 2001, it was uncompleted and I spent a year trying to get the Accent, and Filter shapes correct. so good luck 

As tip look into this (if you change your mind about the DSP part) http://musicdsp.org/archive.php

[PauloConstantino]

Hi there,

I've been VERY interested in building myself a synthesizer, sequencer + keyboard system!

I was building some sound circuits for my homemade 8bit cpu, and I got pretty interested in electronic sound generation, and then I went into the magic of synths. oh man what was I missing !! They're the most amazing thing!

So now I want to build one. I am very experienced with digital electronics but not much with analog, and I've been dwelving into analog these days more via textbooks to learn what I don't know.

So what do you guys advise as a place to start? I'd like to build an analog synth, because a digital one would really be too easy. I don't want to use a microcontroller. I want to do it via discrete analog components, and discrete logic for control as needed.


Do you guys know of a good book on designing synths? Maybe a website? Maybe some advice ?

Thanks a lot!

If I were you, try to build an existing synth, like a Roland TB-303.. the schematics are all over the place , I designed a rudimentary TB-303 VST plugin for Cubase SX and even that was tough 2001, it was uncompleted and I spent a year trying to get the Accent, and Filter shapes correct. so good luck 

As tip look into this (if you change your mind about the DSP part) http://musicdsp.org/archive.php

You said it took you a year.... Why ? Did you lack knowledge of fourier series or what ? 

[diyaudio]

Hi there,

I've been VERY interested in building myself a synthesizer, sequencer + keyboard system!

I was building some sound circuits for my homemade 8bit cpu, and I got pretty interested in electronic sound generation, and then I went into the magic of synths. oh man what was I missing !! They're the most amazing thing!

So now I want to build one. I am very experienced with digital electronics but not much with analog, and I've been dwelving into analog these days more via textbooks to learn what I don't know.

So what do you guys advise as a place to start? I'd like to build an analog synth, because a digital one would really be too easy. I don't want to use a microcontroller. I want to do it via discrete analog components, and discrete logic for control as needed.


Do you guys know of a good book on designing synths? Maybe a website? Maybe some advice ?

Thanks a lot!

If I were you, try to build an existing synth, like a Roland TB-303.. the schematics are all over the place , I designed a rudimentary TB-303 VST plugin for Cubase SX and even that was tough 2001, it was uncompleted and I spent a year trying to get the Accent, and Filter shapes correct. so good luck 

As tip look into this (if you change your mind about the DSP part) http://musicdsp.org/archive.php

You said it took you a year.... Why ? Did you lack knowledge of fourier series or what ? 

at the time both . its 2017 today.

[PauloConstantino]

So what do you guys advise as a place to start? I'd like to build an analog synth, because a digital one would really be too easy.

Too easy?  It's pretty complicated if you want to do it right and not just half-ass a DSP or micro implementation.  Maybe I'm biased from having sketched out part of one in discrete logic...


But you wanted pointers for analog:

Video
Aaron Lanterman's "Electronics for Music Synthesis" lecture videos; see here for links.  Must see.

Books
Hal Chamberlin, "Musical Applications of Microprocessors" is recommended all the time.  Out of print.  No, it's not about digital synthesis.
Barry Klein, "Electronic Music Circuits" is another that gets mentioned.  I've seen a PDF of it somewhere.

The synth-diy mailing list is where the serious builders go.  Lots of information in the archives.

Some other places worth mentioning:
Muff Wiggler forum (mostly modulars and kit builders IIRC)
DIY section of the Electro-music forum

Ken Stone / CGS
Schmitzbits

You'll come across OTAs a lot, so might as well check out this article, "Understanding and using OTA op-amp ICs" by Ray Marston; part one, two (PDF), and perhaps this bit of "errata".

That should get you started, I hope it's not too much!

Damn. This is why this forum is the best in the internet no doubt. Always great replies. Thank you for all the resources. Seriously, lectures on designing synths... That's fascinating !!!!

Dude thank you so much! I'm going to study this in depth now!!

[pitagoras]

my link collection, copy paste from my evernote, you might need to dig a bit.

Dave Smith Instruments Prophet 6
Analyzed here http://polysynth.tumblr.com/post/134667237805/a-quick-tour-of-the-prophet-6-voice-card

http://electronics.stackexchange.com/questions/34970/design-for-an-analogue-oscillator-that-doesnt-drift-in-frequency

Micromoog service manual http://www.cyborgstudio.com/synthmp3s/moog/micromoog/manual/micromoogmultimoogservicemanual.pdf

Builders/Kits/DIY
http://musicfromouterspace.com/

 https://docs.google.com/file/d/0B3wD73e_RyWdbFlUbEpqeExRa0U/edit

Hybrid, polyphonic, discontinued: http://mutable-instruments.net/ambika

KIT MOOOG!!!!!
https://www.residentadvisor.net/reviews/16773


VCO
http://www.birthofasynth.com/Thomas_Henry/Pages/VCO-1.html
http://www.allaboutcircuits.com/projects/diy-synth-series-vco/
https://www.gearslutz.com/board/electronic-music-instruments-electronic-music-production/1111463-how-do-continuously-variable-oscillators-work.html

CIRCUITS

http://www.univertron.com/SAS/manuals/RSF/Kobol%20Expander%20Schematics/

continuously variable waveform

Continuously variable waveshape:

See Moog sub 37

https://www.gearslutz.com/board/electronic-music-instruments-electronic-music-production/800682-best-favorite-diy-analog-synth-kits.html

Electronic music & microprocessors book https://github.com/rabidaudio/synthesizer/blob/master/reference/Musical-Applications-of-Microprocessors-2ed-Chamberlin-H-1987.pdf


See also this: Moog 32 semi modular

PLL Based en http://www.birthofasynth.com/Thomas_Henry/Pages/X-4046.html
seems appreciated:
http://randomsource.net/modules
Someone did some modular: http://people.carleton.edu/~jellinge/mysynth.html


http://www.cgs.synth.net/modules/cgs92_ssg.html

[DaJMasta]

At least for the keyboard component, even if you're going to replace the guts with your own stuff.... get a commercial keyboard as your base.

Especially if you want weighted or velocity sensitive keys (which are quite important to regular piano playing, though often are less important to some kinds of synths), having a commercial product take care of the actuation, rigidity, and matching could be a huge improvement over homebrew input methods.

While full analog is an option, I wouldn't be so quick to shun the digital option... mainly because you still end up doing a fair amount of analog design for the inputs to your ADCs and outputs of your DACs, there's a lot of analog stuff to be learned there and it can be very, very helpful to use midi controls or interface with software - for debugging and interfacing, sure, but also to let you play around with effects before trying to build or program them into your hardware.  Going from a cool sound in a virtual synth pack to a basic DSP with a digital output is going to be a lot easier than trying to recreate it in analog, so if you want something other than the sound of established analog synth circuits, it could involve a whole lot of tweaking and adjustments.

[JanJansen]

get a commercial keyboard as your base.

Casio.

Going from a cool sound in a virtual synth pack to a basic DSP with a digital output is going to be a lot easier than trying to recreate it in analog

Until you find out that float dont works and all have to be integer math, no copy paste.

[Lee Leduc]

Thomas Henry has published many Synth Circuit Designs on the WEB. Many people consider is designs to be very good.
Do a google search for "Thomas Henry Synth" and you'll find some of his designs. You can find people posting YouTube videos of His circuits.

Here's a video of his 555 timer based VCO.

His "An Analog Synthesizer for the 21st Century" at is a good start for a basic Synth.
http://www.lulu.com/shop/thomas-henry/an-analog-synthesizer-for-the-21st-century/paperback/product-20192513.html

Here's a schematic he published of his 555 timer based VCO. http://electro-music.com/forum/viewtopic.php?t=54623

[Kjelt]

Analog ? To get in tune you have to tune the darn things every half hour.

Digital hell yeah! Use one microcontroller for sound generation per key, I have been thinking about that but a bit costly to use 32 bit micros , 8 bit could be done, modular and a big rack with big PSU.
Only the time........

[JanJansen]

Use one microcontroller for sound generation per key, I have been thinking about that but a bit costly to use 32 bit micros

I wanto do that one day, for every 2 voices use 1 DSPIC ( 16 bit stereo DAC ), all connected with SPI to a 40 pin 8 bit controller,
then have analog resonant filter + analog enveloppes + voltage controlled amplifier per voice,
phase modulation, phase distortion, or lookup-table synthesis thru analog circuits,
will be my biggest and most expensive synth ever build, 5 euro for each DSPIC.

Analog oscillators always sound better ofcourse, you need to tune them alot because tempco reistors are not available anymore ?,
with the correct tempco`s and a lot of testing it can be done ?, how would you solve that without the tempco`s.

[Lee Leduc]

Thermistors or NTC's can be used to temperature compensate VCO's. These are cheap, available at 1% tolerance from Digikey. I sandwiched one of these
between the two transistors of the exponential converter using epoxy.

https://www.digikey.com/product-detail/en/vishay-bc-components/NTCS0805E3472FMT/BC2576CT-ND/2237413

A tutorial on exponential convertors and temperature compensation at http://www.schmitzbits.de/expo_tutorial/ shows how.

Most NTC manufacturers have application notes describing how to linearize their response. I used this technique in a VCO I designed about 20 years ago.
It worked very well.

[Fungus]

Going from a cool sound in a virtual synth pack to a basic DSP with a digital output is going to be a lot easier than trying to recreate it in analog

Until you find out that float dont works and all have to be integer math, no copy paste.

Floating point DSPs have been reasonably cheap since the early 1990s.

This one is still in production:

http://www.analog.com/media/en/technical-documentation/data-sheets/ADSP-2101_2103_2105_2115.pdf?doc=AD7475_7495.pdf

 

[BrianHG]

Use one microcontroller for sound generation per key, I have been thinking about that but a bit costly to use 32 bit micros

I wanto do that one day, for every 2 voices use 1 DSPIC ( 16 bit stereo DAC ), all connected with SPI to a 40 pin 8 bit controller,
then have analog resonant filter + analog enveloppes + voltage controlled amplifier per voice,
phase modulation, phase distortion, or lookup-table synthesis thru analog circuits,
will be my biggest and most expensive synth ever build, 5 euro for each DSPIC.

Analog oscillators always sound better ofcourse, you need to tune them alot because tempco reistors are not available anymore ?,
with the correct tempco`s and a lot of testing it can be done ?, how would you solve that without the tempco`s.

At only 2 channels per DSPIC, with a very fast DAC, you have enough processing power to replicate an analog synth to the point where it would be indistinguishable from an analog synth.  You should be able to do 4 to 8 channels with a cheap CD audio grade DAC.

[Fungus]

At only 2 channels per DSPIC, with a very fast DAC, you have enough processing power to replicate an analog synth to the point where it would be indistinguishable from an analog synth.  You should be able to do 4 to 8 channels with a cheap CD audio grade DAC.

Yep, at some point the 'analog' part can be simulated so well you can't tell the difference. It's just a case of processing power. 192kHz simulation is probably enough for sound.

nb. You can still output at 48kHz, 16bit. 

[Kjelt]

You all know the story of the retired synth buidling expert from Roland who as hobby built a 8 bit synth that now went into production?

https://www.roland.com/global/promos/roland_boutique/interview_3/

Like to do something similar but then with a 8 bit uC for each key *if only I had the time , sigh*

[Fungus]

You all know the story of the retired synth buidling expert from Roland who as hobby built a 8 bit synth that now went into production?

I'm sure his "connections" had something to do with it going into production.

Like to do something similar but then with a 8 bit uC for each key *if only I had the time , sigh*

Why do you need one per key? You just need a bank of them and one other master uC reading the keyboard and telling them what to do.

[John B]

Nothing easy about digital synths. After reading stuff written DSP engineers at native instruments, building top notch sounding synths really does require top notch engineers. They've got the blend of scientific expertise and artistic streak too... Ive had a taste of it at the software level. Anyways.

Maybe expand on what you would like to do as an overall goal? If you're reinventing a keyboard for the sake of learning how they work, then cool. However creating interesting and unusual sound generating electronic devices with something other than a keyboard as a controller would make you quite popular with some university composition students who are dabbling in new/experimental written or improvised music. Even if what you do could be reproduced on a computer, there's a slight hipsterish aspect to having retro equipment generating sound. Its all part of the performance.

[Kjelt]

Why do you need one per key? You just need a bank of them and one other master uC reading the keyboard and telling them what to do.

Yeah but what do I then do with the reel of 200 pieces of 8 bit micros in my storage?