anyone built a synth?

[choklitlove]

just curious, because i've been considering it.  many of the components are the same.  there's a pretty simple project that i've been considering here: http://www.musicfromouterspace.com/analogsynth/YOUR_FIRST_SYNTH/YOUR_FIRST_SYNTH.html
sounds really cool, and seems like a good learning project.

then there's also the more advanced: http://www.musicfromouterspace.com/analogsynth/SOUNDLABMINISYNTH/soundlab.html
and there's a guitar-effect mod for it here: http://www.musicfromouterspace.com/analogsynth/SOUNDLABMINISYNTH/guitar_trigger.html

it all sounds very cool to me.  has anyone built any of these or anything like them?

[Tim Escobedo]

Yes. I have built several minimal "synths" from mostly CMOS chips. One is a bit similar to "YOUR FIRST SYNTH", but a bit simpler and without the filter. Really, remember that the Schmitt Trigger is your friend and be creative. I've had on my to do list a little web page showing a few ideas for making simple noisemakers like these.

[Wild Zebra]

 Â Yep, Both of em.  The Weird Sound Generator is pretty simple.  Stripboard and Pcb layouts availiable.  Its pretty cool.  The soundlab is great.  Alot bigger build, but all the info is straight forward.  Heres a forum with lots of discussion of both.
http://electro-music.com/forum/index.php?f=99&sid=2adde4c9850d5c58fa73edaf028da196  here is pdf of the WSG alredy sized just pick no page scaling http://files.electro-music.com/phpbb-files/wsg.pdf  Good luck have fun.  See you over a www.electro-music.com

[choklitlove]

Yes. I have built several minimal "synths" from mostly CMOS chips. One is a bit similar to "YOUR FIRST SYNTH", but a bit simpler and without the filter. Really, remember that the Schmitt Trigger is your friend and be creative. I've had on my to do list a little web page showing a few ideas for making simple noisemakers like these.

it's cool to know that there are others in the diy community (even though i'm new), that are interested in effects and synths.  i think that page is an awesome idea.  that's the best thing about this community: everyone wants to learn, and everyone wants to help.

[choklitlove]

i was going to try the wsg without the filter (kind of like tim), but then i saw that board and everything that lorenzo made (the one that wild zebra posted), and i figured that'd be easier.  i've been looking over lorenzo's layout, and did he use something other than spst switches?  i know he used angle mount switches, but they seem more like dpdt's.  i thought spst's had only 3 terminals.  know what i mean?

[Wild Zebra]

  Yeh Lorenzo has it set up for PCB mount Pots, Switches, and Jacks, but you can use whatever.  Just use the schem for reference or just look at the PCB some of the pads don't go anywhere(so not used) Merry X-mas.  You can always P.M. with any other ?'s

[choklitlove]

i know they're pcb mount switches, but my question is if they're really spst's.  i thought spst's had 3 terminals, when the ones he used and what his layout calls for have 6 terminals like an spdt or dpdt.

[Tim Escobedo]

I won't be posting any PCBs or layouts. Just ideas.

In my mind, any sound generating circuit should have at least one control: being able to turn the sound on and off. In my mind, a free running oscillator without that control is pointless. Next is pitch and/or timbre control. Those criteria are easily accomodated in the simplest of circuits using as little as a single Schmitt trigger gate and a couple of capacitors.

[choklitlove]

i agree totally with those points.  when i get the parts and all that junk, i'll more than likely start a thread at electro-music.com in the diy synth forum for the help i'd need to figure those things out.  i'd really like to figure out the way to make keys for automatically setting the pitch.   a lot like this guy did: http://www.musicfromouterspace.com/analogsynth/photogallery/Ricardo_Del_PooLP_3.JPG

do you have any idea of what kind of switches lorenzo used?  i know they are angle mount switches, but are they spst, spdt, or dpdt's?

[DiyFreaque]

Thanks for the Electro-Music tip, Wild Zebra.  I signed up yesterday - I posted to the Introductions forum.

Choklitolove - You might consider getting a CGS10 pedalboard/keyboard PCB from Ken Stone (CGS10):

http://www.cgs.synth.net/modules/cgs10_pedal.html

This looks to be an easy way to get a pretty decent little keyboard going.  Of course, you'd still have to wire up a matrix board (or alternatively buy one of those phone keypads all of the surplus places seem to have).  For my home-built synth, I took an el-cheapo minikeyboard, hacked a matrix out of it, and used a circuit from Thomas Henry's "Build a Better Music Synthesizer".  It's a great 5 octave CV/Gate/Trigger keyboard, but a bit more complicated than Ken's little keyboard here, which would probably be more suited to the SoundLab.  Ken's little board could be sandwiched in there, and Voila!

I've had a SoundLab board for over a year now - I've just got too many projects lined up to even get near it yet.

Cheers,
Scott

[DiyFreaque]

BTW, Ken's circuit looks like it's built for +/-15V or +/-12V, but I have an idea it could be forced to work at +/-9V.  Guess one would have to look at the 74C922 datasheet.  It's a CMOS IC, so it should work with a Vdd of +9V. 

BTW, for those Soundlabbites out there, Electronic Goldmine has a +/-12V wallwart that would power the Soundlab nicely.  It's a low current wart, but the Soundlab is very miserly on its current requirements (Ray's told me it would work as well).  Myself, I'd regulate it down to +/-9V internally just to give it some stability.  Soundlab itself would have no problem running at +/-12V.

[choklitlove]

that little keyboard circuit sounds like a good way to go.  i have a question (probably a stupid one): is that circuit capable of producing sound by itself?  or does it need an additional circuit that it controls to make the sounds?  if it's the ladder, could you give me some guidance on how to combine that circuit with the weird sound generator?  thanks for all of you help and patience with a newcomer to this stuff.

[DiyFreaque]

Well, the keyboard could be interfaced to the Soundlab fairly easily, but I don't think it would be practical to control the weird sound generator with it.  That design is pretty much dependent on pots set up as variable resistors for controlling the parameters.  One could get some level of voltage control over it by replacing the pots with LDR's or strapping them across the pots.  A keyboard wouldn't give you anything approaching pitch control because this really isn't a V/Oct arrangement per se.  This contraption falls more into the noise maker kingdom.

The Soundlab, though I think Ray originally envisioned it as rather a noise maker too, albeit more synth-like, is quite a bit more sophisticated and therefore falls more squarely into the synth phylum.  IE, it has voltage control, the classic VCO/VCF/VCA arrangement, and is configurable to different routings either through patching or switches.  I say that he originally thought of it as a synth/noisemaker, because when he first released it, it had no tempco control over pitch stability.  Actually, even before the addition of the tempco, it probably tracked no worse, and most likely better, than some of the more famous original analog synths (the VCS3, for example).  Later he added the pitch stability. 

As for the CGS keyboard:  the circuit itself produces only control voltage and a gate signal.  The cool thing about synths is that just about everything can be controlled by voltage.  The main use for a keyboard CV is to control the VCO and oftentimes the filter itself.  Ray's VCO is a volt per octave type VCO, so each volt will move the oscillator in frequency one whole octave.  The keyboard itself will step the voltage in 0.083V increments, which corresponds to a half step for each key.  The filter also responds to V/Oct.  One common application is to patch the keyboard voltage to both the VCO and the filter, so that the filter tracks the VCO's pitch.  Oftentimes synthesizers will provide a switch to cut this voltage in half so the filter pitch doesn't raise linearly with the VCO pitch - this is handy for different instruments and/or further defining the sound you are programming - the higher notes will not be as bright as the lower notes.  You could even 'play' the filter itself by patching in noise or a static tone and play the keyboard - the filter cutoff freq will form the notes.

The other signal the circuit puts out is a gate signal - this is for controlling the envelope generator.  A lot of keyboards put out both a gate and a trigger, this circuit does not.  However, it would be easy to derive a *simple* trigger from the gate signal. 

A gate is used to provide a 'sustain' signal to an envelope generator.  In other words, if you hold down the key, the gate stays high, and the EG puts out a voltage that keeps the filter and VCA open so the note can be held.  If the EG has a trigger input, the trigger will pulse each time you press the key.  The attack and decay parameters of the EG then determine how long the note lasts - no matter if you hold down the key or just tap it quickly, the note will always have the same length.  A lot of keyboards keep the gate high as long as you hold down at least one key and pressing another key while the other key is held down will keep the gate high, so you can play legato.  This differs from a trigger in that a trigger will fire each time you press a different key, no matter if another key is held down (of course it depends on what type of note priority the keyboard has - for example, if it is low note priority, pressing a higher key while holding a key down will not produce a trigger).  This is one function that may be a bit difficult to get out of this keyboard - I haven't really looked at it that closely.

There are other options - there are MIDI to CV converters that will put out a CV, Gate and Trigger from any MIDI equipped keyboard (PAiA has one - I have one from Midwest Analog that I still haven't put together).

If you're planning on building the weird sound generator instead of the soundlab,  you may even consider some other type of controller such as a joystick.  Here's a very versatile design:

http://home.comcast.net/~sbernardi/elec/og2/og3_joystick.html

You derive two voltages from the joystick; so you can control two parameters with one stick.  Say side to side you patch to pitch, and up and down you patch to filter cutoff or amplitude or whatever you want. 

Another option would be to make a touchpad controller, but that may or may not be fairly complicated for a first go at a synth.  Google for 'Arpad Benares' (this is Serge Tcherepnin's nom-de-plume).  He wrote an article long ago about building a touchpad controller that appeared in Synapse magazine.  This design put out a gate and trigger for each note, and also provided a *pressure* output voltage.  The more pressure on a key, the more voltage.  So, wiggling your finger on a touchpad will produce a nice little vibrato (or something else, depending on where you have the voltage patched).

Then of course there are a plethora of other goodies you could rig up.  A step sequencer might not be a bad thing to throw in there, for example.  Then you could program a rhythm and jam along on your guitar.

I should warn you that once you start, you may never stop.  Then you'll have the synth monkey keeping company with the stompbox monkey that's already riding on your back 

Have fun!
Scott

[choklitlove]

thanks for all this extremely useful info.  all of it almost makes sense to me, and i'm sure it will over time.  for now, i think the best route for beginning would be to make the wsg without any mods.  that will give me some experience, insight, and hopefully some confidence to make some more complicated stuff that would be more useful to me.  i still haven't even had a chance to make a stompbox.  i was all ready to go with the big muff pi, but then i got one for xmas.  anyway, i think i'm gonna tackle the wsg.  thanks again!

[choklitlove]

oh yeah, and look out for me on the electro-music forum.  same screen name.  i'm sure i'll have many more wonderful questions.

[Wild Zebra]

  You should go on ahead with the WSG.  It's a fun little noisemaker.  The PCB is kind of large so it makes it a little of a pain etching.  Just need a bigger tupperware or whatever.  It's pretty simple and there is alot of info in the Sound Lab section of the ELECTRO-MUSIC forum.
Its under the Instruments section.  http://electro-music.com/forum/viewtopic.php?t=6532 Have fun and don't be afraid to ask more questions.

[choklitlove]

zebra- thanks for the help in the pm.  i read that whole thread, and it helped.  believe me, i won't be afraid to ask questions.  thanks for everyone's help!  i'll get back to you sooner or later in the process.  maybe even in a few minutes.

[choklitlove]

sure enough, i'm back.  i'm getting ready to order all of the parts.  i want to order as many as possible from small bear.  then i'll go to mouser for the remainder.  (1)first, do those "ceramic capacitors" have to be ceramic?  small bear doesn't seem to have ceramic, but instead, "Low Voltage Poly Film".  would those work?  (2)also, do those "electrolytic capacitors" need to be axial or radial?  (3)last one for now: is there any specifics on an LED?  edit: another- (4)can't find Non polarized capacitors.  i thought the other ones were nonpolarized.  ?  thanks!

[choklitlove]

okay, does anyone have the time to develop a list of mouser part #'s?  it's probably better if someone does it that knows what they're doing.  if not, pointt me in the right direction (see last post).  thanks!

[Wild Zebra]

 

(1)first, do those "ceramic capacitors" have to be ceramic?  small bear doesn't seem to have ceramic, but instead, "Low Voltage Poly Film".  would those work? 

No, polyester are fine.

(2)also, do those "electrolytic capacitors" need to be axial or radial?

Doesn't matter, but most people use radial (I believe) it just seems PCB's are usually made to accept these (stand up) type caps.

(3)last one for now: is there any specifics on an LED?

Not that I know of.  Any standard led should work. Especially if you order from smallbear.