I've got an extensive music background and have been infatuated with synthesizers since I was young. I had dreamed of going into an EE program to make my dream a reality, but I couldn't afford school (long story).

Basically, I'd like to build a 3 oscillator analog synthesizer, but I have zero experience building boards. I know basic signal flow and process and have a strong design sense, but I really lack the knowledge otherwise to get started.

I think starting simple with a 1 oscillator and building upwards would be an awesome learning experience, and I would love to get to the level that some of you are at and actually make a fully usable synthesizer.

My question is, for audio-oriented electronics, where can I get started for this full analog synthesizer? Am I reaching too far? What will I need to make this happen?

  • 1
    If you've always dreamed of doing this, I'd say you're reaching just far enough. – Joel B Jul 24 '12 at 20:46
up vote 8 down vote accepted

There is plenty of interesting info at the Music From Outer Space website. Including circuit schematics accompanied by detailed explanations of the designs. As well as a range of advice and links relevant to building synthesizers.

You'd be better off first gaining experience with some simpler audio electronics projects, and building up the skills and equipment that a major project like this would require. Then you'd be in a better position to evaluate how/whether to proceed further.

Another place to start is the TB303 schematics! the machine that started it all :) http://machines.hyperreal.org/manufacturers/Roland/TB-303/schematics/

Start off by understanding a portion of the circuit and go ahead and design something based on it on small piece of breadboard, and build up from there.

Once you have a few of the elements working, try designing your own pcb with ground planes (this will improve the noise levels) or check out some kits as Rob has already linked to.

I'd also recommend they synth DIY pages at http://www.yusynth.net. That's a great resource I've used for my synth projects.

EDIT: Sound Synthesis: Analog and Digital Techniques by Terence Thomas. Awesome book. First chapter starts with how to build a variable output power supply, then moves into a "test box" which is basically a speaker, a couple pots and a breadboard so you can test before soldering.

Copious schematics and foil diagrams throughout, and an excellent explanation of why certain components are placed where they are to achieve particular results. HIGHLY recommended!

I would suggest that even if you want to use analogue filtering stages (they can give sound a warmth that can be hard to achieve via other means) it may be a good idea to generate the starting waveforms digitally. Many Williams' Electronics arcade machines in the 1980's generates sound using a board that contained a 6800 microprocessor, a small amount of RAM and ROM, and a little bit of I/O including a DAC. All of the sound effects were generated using tight program loops which generated samples and fed them to the DAC. Since the processor was used for nothing but sound generation, loop execution speed could be used for timing.

In practice, even the simplest microcontrollers have some sort of timer resource, which could be helpful if you want to be able to change the audio parameters while playing sounds. Using something like 6805 code, one would start by writing a poll routine for each voice; for speed these routines would live in RAM--something like:

        brclr TMR_CONTROL,TMR_READY,poll ; Wait for start of next 'tick'
FRQ1L:  lda #PATCH
PH1L:   add #PATCH
        sta PH1L+1 ; Patch value for LSB of phase
FRQ1M:  lda #PATCH
PH1M:   add #PATCH
        sta PH1M+1 ; Patch code
FRQ1H:  lda #PATCH
PH1H:   add #PATCH
        sta PH1H+1 ; Patch code
        sta FETCH+2 ; Patch LSB of target
FETCH:  lda TABLE_BASE ; 16-bit address
        clr DAC_ENABLES
        sta DAC_OUTPUT
        lda #ENABLE_1
        sta DAC_ENABLES

Next, one would have a main loop which would repeatedly call the poll routine for each voice in sequence and, between calls, perform whatever other logic needed to be done (e.g. seeing if any voice parameters needed to be updated). Using this approach, it's possible to update a fair number of voices with a high sample rate.

While it's possible to do the initial wave generation entirely using analogue circuitry, it's difficult to have multiple independent analog generators whose frequency characteristics are absolutely identical within a fraction of a percent. The human ear is very sensitive to variations in pitch--far more so than to variations in amplitude--so whatever is used for signal generation must be very consistent. Using a simple microcontroller as a starting point is a good way to get such consistency, even if one then feeds the generated signal through analog shaping circuitry.

In addition to the excellent reading sources already suggested - in particular Terence Thomas's Sound Synthesis: Analog and Digital Techniques - I would like to add the following two books:

  • The late Ray Wilson's Make: Analogue Synthesisers, May 2013.

    Ray is the brains behind Music From Outer space (MFOS) as described in Rob Kam's answer. It describes the basics of synthesisers and providing the essential electronic theory behind sound generating circuits as well as explaining VCO, VCF and VCA.

    In addition, it also details the construction of the Noise Toaster, which is a nice synth starter project.

  • Barry Klein's Electronic Music Circuits, 1982

    It is this book that I would recommend to someone starting out to build modular synths, if they wanted just one book.

    As Barry notes himself, the original publication contained a number of errors,

    Electronic Music Circuits

    This is a complete copy of the original book (published by Sams in 1982). It contains circuits for most every type of module you would want to make for a modular analog synthesizer. Some circuits are my own, some slightly modified from the Digisound series, many Electronotes circuits. There were a few errors in the original printing and I have made the corrections in this copy. Also, this copy is enlarged up to 8 1/2" x 11" - lots easier to read! I include a 32 page update booklet that suggests alternative approaches, parts substitutions, an updated source list, etc. There are no new circuits (in case you have the original book already). Many of the circuits use CEM/SSM chips that are no longer available, but these circuits may serve as examples for repairing analog synths using these IC's. There are discrete examples of VCO's, VCF's, envelope generators, etc. many of which you have seen discussed on this list. Page count is around 335 pages.

    He is selling a corrected version, if you contact him directly. See http://www.abacom.com/~ivanohe/synth/books.txt

    There is also a sister publication:

    Electronic Music IC Databook

    This is a collection of all SSM and Curtis Electromusic (CEM) IC datasheets as well as volume 1 and 2 of the Curtis Synthesource shortlived newsletter/ applications bulletin. As the majority of these IC's are no longer manufactured, this manual serves as a one source reference databook for all of them. The written material in these datasheets is surprisingly detailed as to how the IC's work internally, and how they should be applied. The Synthesource material is especially cool. I also include some material from Linear Integrated Systems, a source for matched transistor pairs.
    Page count is around 300 pages (8 1/2" x 11").

    If you want to get hold of the book, it might be worth reading this thread (which does not provide the PDF), Barry Klein Book. Link to PDF.

Note that I am not affiliated in any way with either of these authors, but I just think that their books are great.

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