Anyone else building an analogue synthesizer here? - Page 1
Forum section: electronics / projects

author: LektroiD
author_rank: Frequent Contributor
timestamp: September 04, 2014, 07:13:37 am
content: I've been building this behemoth for the past few years, I just wondered if there's any other synth buffs on here?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 04, 2014, 07:36:11 am
content: Um, technically, on a far more humble scale; my Theremin is always evolving, and currently uses about 50 transistors (no ICs*).By building, do you mean buying modules, or...actually building every freaking one of those things?!Tim

author: LektroiD
author_rank: Frequent Contributor
timestamp: September 04, 2014, 07:53:33 am
content: Quote from: T3sl4co1l on September 04, 2014, 07:36:11 amAwesome! I cheated and bought a Moog Theremin Plus, mainly for the CV outs to control the modular. I would love to build my own though. Did you design it yourself?QuoteI made a point of not buying any production modules...Built myself, mostly through hole, but a few SMD's here and there. Some boards are home etched, others were blank manufactured double sided PCBs. The panels in the top (5U) section are all home drilled and handwritten, in the lower (3U) section, they are factory printed. There's a few interesting parts inside, like vactrol opto's for nice bouncy CV control & tempco's to stabilise the oscillators. Not all discrete components like your Theremin though, there's quite a few CMOS chips & op-amps lurking inside...

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 04, 2014, 09:21:03 am
content: Quote from: LektroiD on September 04, 2014, 07:53:33 amYes. This documents the basic build:http://seventransistorlabs.com/Theremin/I built a few of those, with minor changes between them. The most developed of which I keep on hand, and modify periodically.Right now, it includes:- Discrete transistors (approx. 50 total, mostly 2N3904 and 2N3906)- Pitch, Volume, and Local Oscillators: Hartley, ~2MHz, Buffered, Adjustable (via varactors)- Pitch and Volume Mixers: single balanced (single ended output coupling)- Level Control Mixer: single balanced (balanced current mirror output coupling)- Volume IF ~10kHz; slope detector- Riser board: all important signals and control voltages are available on an expansion connector- Audio output: max. 0.1W power amplifier, 1/4" phono jack output- Power supply: 9V wall wart (primary source), onboard converter supplying regulated 6.3 and 120V DC (9 transistors, discrete except for the TL431, an acceptable sacrifice)Currently, the riser board includes a timbre circuit (primarily a single common-emitter amplifier stage with variable input and bias levels to vary distortion and clipping), and a PLL which implements an auto-tune-and-hold feature, allowing instantaneous adjustment (no fiddling with trimmer capacitors or antenna position!).Future plans: the switching converter was designed to provide the perfect voltages for vacuum tubes, with enough current capacity to power one or two 9-pin miniature types. These will be added to a new riser board, or a second level stacked on top, to provide "That Tube Sound". It should also be possible to add a PLL to the volume control section, for automatic tuning of that section as well.(this was mostly copy-and-pasted from another document)The PLL I don't think I've heard mention of before, which is odd because tuning these things is a bitch. Any slight change in the environment (imagine setting it up on a metal music stand or something) or temperature (I haven't matched tempcos yet, so it drifts quite a bit) makes for a lot of tedious adjustment.The circuit, I've posted before:The mixer output (as mentioned above) has a DC coupled resistive load, so when the beat is zero frequency, it's zero as in DC, so it's a fine phase detector. Comparing that with a fixed threshold (depends on mixer bias, but since that's set with resistor dividers, a fixed resistor divider should be fine here as well) gets a phase error signal, which goes right into the pitch oscillator's varactor. The only funny part about this, I think, is the amp itself serves as the sample-and-hold: the 2N3904/6s have low enough leakage (and the MOSFET follower, basically none), that the 0.01uF compensation capacitor stays quite nicely at whatever operating point it stabilized to. No need for suboptimal building blocks (namely, an op-amp, analog switch and JFET op-amp follower), which would consume loads more current (not that power is in short supply here) and suffer from capture transient problems (while disconnected, an always-on error amp will wander off into la-la land and saturate, guaranteeing a worst-case frequency spike every time the analog switch is closed -- it might not even re-lock phase anymore).QuoteAn insane amount of work for a few years, in my opinion! I'm not very musically obsessed though, which would surely count for a lot.Doing stuff like OTAs, S&H, VCOs, timers -- not terrible to do discrete, but for the most part, yeah, even I would be piling the chips on, no problem there.Add in things like switched capacitor filters, sequencers, muxes and so forth, and you're counting a lot of CMOS alone, that would've been just a royal pain back in the day (early 60s or earlier, I guess?).Tim

author: German_EE
author_rank: Super Contributor
timestamp: September 04, 2014, 03:20:50 pm
content: Not now but in the 1980's I built my own version of the Mini Moog. The keyboard drove some logic that let me generate three note chords with one VCO per note. I managed to cure every problem apart from drift which meant that I gave up in the end.If I was building a synth now I would make it all digital. A memory mapped keyboard driving DDS based oscillators takes care of sound generation and a DSP can do the work of the filter and envelope generation stages.

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: September 04, 2014, 03:32:37 pm
content: Wow, that is a very impressive project! I built one of these from a kit a long time ago.http://www.paia.com/fatman.aspBefore too long I realised I had a lot more talent with electronics than music!

author: LektroiD
author_rank: Frequent Contributor
timestamp: September 04, 2014, 03:41:58 pm
content: Quote from: German_EE on September 04, 2014, 03:20:50 pmThere's a few digital modules in my build, but not filters, filters always sound better in the analogue domain. That's the only thing I would not cut corners on, if I were to build a digital synth

author: Len
author_rank: Frequent Contributor
timestamp: September 04, 2014, 04:17:06 pm
content: Quote from: German_EE on September 04, 2014, 03:20:50 pmIf you fixed the drift it wouldn't be a Mini Moog any more!

author: RobertoLG
author_rank: Frequent Contributor
timestamp: September 04, 2014, 04:28:59 pm
content: not exactly on topic but related, you may like it, enjoyhttp://youtu.be/69Wjc6QYuKIand these guys too:http://youtu.be/vSg2pfn-T7g

author: electrophiliate
author_rank: Regular Contributor
timestamp: September 06, 2014, 02:37:32 am
content: @ LektroiD. Cool project. A friend of mine used to be really into analogue synthesizers but has since moved onto Native Instrument's Reaktor software for the PC. After having a go at some classic equipment like the Roland 101 synthesizer I wondered about building individual hardware modules but never really got into it. Good to see that other people are into it though!

author: Alex30
author_rank: Regular Contributor
timestamp: September 06, 2014, 02:21:37 pm
content: Wow this is impressive, would love to hear any music you have produced with this bad boy

author: Yago
author_rank: Frequent Contributor
timestamp: September 06, 2014, 03:30:07 pm
content: That is a synth indeed!I too would like to hear some sonic rippage from that beast.

author: LektroiD
author_rank: Frequent Contributor
timestamp: October 30, 2014, 03:29:20 pm
content: Thanks for the comments, I generally use all my hardware to make music (not just the DIY stuff). Here's my latest effort, I use the big synth for various percussion and bass, clocked through MIDI from the computer, meaning I can keep the other instruments clocked from the same source.For the more refined stuff, check out the link in my signature...

author: dentaku
author_rank: Frequent Contributor
timestamp: October 30, 2014, 04:52:49 pm
content: Synths are pretty much the reason why I have any interest in electronic hardware.When I first started looking into how synths work I found it interesting how all the terms we use in synth programming even today with VSTs turn out to come from the early days of electronics. I like that synth manufacturers didn't try to rename everything to make them more musical sounding.I find analogue sound sources to be interesting but not really practical allot of the time but I do believe that filters are still best left analogue.Lately I've been looking into exponential converters and I'd love to find a very simple VCO/Expo converter combination that is good for experimenting with on breadboards just as a learning experience.The best thing I've built lately is the Hip Bass Drum by Craig Anderton.http://electro-music.com/wiki/pmwiki.php?n=Schematics.HipBassDrumByCraigAndertonThe next step would be to build a step sequencer with maybe some 4000 series counters and multiplexers or maybe a shift register of some sort.

author: Yago
author_rank: Frequent Contributor
timestamp: October 30, 2014, 05:13:35 pm
content: Quote from: LektroiD on October 30, 2014, 03:29:20 pmTried a listen of your track, and could hear nothing from the massive 1inch computer speaker... intro in the bass I guess!Looks like I'll have to finish repairs on soundcard to hear it properly, argg inspired into work by EEVBlog again!I always thought keys are another of life's nodes that attracts geeks, or turns the geek upon them!Have always been a geek really, played keys and piano for decades now, but some years in a band kind half turned me back towards the normal side. Like Blade, a halfbreed of normal and geek, (a nork? :p).Still have digital electric piano and Korg T3, and that old guitar amp I should repair (eek valves!).Will tune in to your threads more Lektoid, if my feeble memory holds out!

author: Kjelt
author_rank: Super Contributor
timestamp: October 30, 2014, 09:47:05 pm
content: Very impressive. I love the analogue synth sounds but would not know where to start building one. Friend of mine had a yamaha cs80 he had to tune each few hours and change some cmos chips twice a year, not very practical. Loved the sound though but unable to build it due to the custom asicsWill you show some schematics and explanations?

author: RobertoLG
author_rank: Frequent Contributor
timestamp: October 30, 2014, 10:11:03 pm
content: Quote from: LektroiD on October 30, 2014, 03:29:20 pmheh, do you like Vomito Negro???http://youtu.be/o6009QG4XNkhttp://youtu.be/rvnA6lwdeg4http://youtu.be/UZjbAA1GCzkcool stuff

author: MasterBuilder
author_rank: Regular Contributor
timestamp: October 30, 2014, 11:01:11 pm
content: Very nice big modular you have.Im currently building a few modular bits, my plan is to include:Mutable Instruments AnushriA montoron delay in modular formatA Meeblip in modular formatDIY mixer, power supplies and Midid thruThis is a great resource for inspiration for DIY modular:http://cgs.synth.net/

author: Yago
author_rank: Frequent Contributor
timestamp: October 30, 2014, 11:14:12 pm
content: Aha, I had a listen to "Darktones", nice(and my sound card works yet again!)Much prefer electronic to be a little slower, go for the swing/groove before tempo anyday. ( too old to dance and 1988 is just corrupted data now:P )A bit of influence from Planet Rock and Tour De France in there, will listen to some more I think.

author: miguelvp
author_rank: Super Contributor
timestamp: October 31, 2014, 06:20:56 am
content: This was posted on another thread a while back:http://www.ucapps.de/I'm not into this but my son is, that's why I kept the link.

author: 22swg
author_rank: Frequent Contributor
timestamp: October 31, 2014, 09:24:31 am
content: Lecktroid... Just to say , great work where is the keyboardEdit Um I watched the vid...

author: dentaku
author_rank: Frequent Contributor
timestamp: October 31, 2014, 11:58:19 am
content: Quote from: MasterBuilder on October 30, 2014, 11:01:11 pmOlivier Gilet from Mutable Instruments would be a good guest for Chris and Dave to have on The Amp Hour sometime when he has time. He's quite busy right now trying to fill orders and finish new projects.

author: LektroiD
author_rank: Frequent Contributor
timestamp: November 02, 2014, 12:00:19 pm
content: Quote from: Yago on October 30, 2014, 11:14:12 pmHow aboutthisone?

author: calexanian
author_rank: Super Contributor
timestamp: November 02, 2014, 10:20:54 pm
content: Very nice. I have played with building envelope circuits and just straight analog keyboards, but never that large. I have always had some kind of small do everything keyboard around to fill my need for bleeps and farts. I also have an Arp Omni 2 that is at a friends studio. Once I got that all feeling of need to build a synth went away, and every year I visit with Eric Barbor from Metasonix and get my analog synth jargin fix.

author: Yago
author_rank: Frequent Contributor
timestamp: November 04, 2014, 10:21:39 am
content: Quote from: LektroiD on November 02, 2014, 12:00:19 pmNice!Quite a few different "textures" mixing in there that normally don't sit together.No soon as it starts, it goes through JMJ, The Who, several others and finally settling on something akin to old OMD with an updated sound!Electronica is not really my "go to" music (to rip a USA "tool time" expression), but you certainly have talent and write nice material.I am half tempted to start plugging some stuff together... must fight the urge, have to finish the lab first...

author: Andytechman
author_rank: Newbie
timestamp: November 04, 2014, 01:35:38 pm
content: Here's a pic of my analogue modular. All hand built over the last 12 years.

author: LektroiD
author_rank: Frequent Contributor
timestamp: November 04, 2014, 02:51:53 pm
content: Nice system!Quote from: Yago on November 04, 2014, 10:21:39 amThanks, I had no intent to sound like anyone else, although, it's always easier to identify with something akin to something familiar, I just create what feels good at the time.I highly recommend building something once your lab is ready. I did it the other way around, built the lab around my synth DIY hobby.

author: Yago
author_rank: Frequent Contributor
timestamp: November 04, 2014, 03:11:30 pm
content: Indeed, it's hard to talk about music without a reference of some kind.I was hamming up the adjectives earlier, sort of a Jazz Club style "NIIIICCCCEEE".Still have Korg T3 and a Casio Privia(great budget piano action controller), some odds and sounds of recording equipment, so not to hard to step back into it.In DIY terms, Always fancied have a crack at throttling the life out of freak oscillator circuits to create some weird sonic crucifixion wrangler.Fek all use for music probably though!:PSomething akin to what the husband and wife team did creating the soundtrack for the 1950's film "Forbidden Planet"@AnytechmanThat looks lovely piece of work, any shots of the internals of some of these babies?Three octave keyboard!?!

author: Andytechman
author_rank: Newbie
timestamp: November 04, 2014, 08:19:59 pm
content: Quote from: Yago on November 04, 2014, 03:11:30 pmWell, my website hasn't been updated for 5 years, but it does show some of the modules:Www.techman.synth.net

author: Yago
author_rank: Frequent Contributor
timestamp: November 04, 2014, 08:34:08 pm
content: Your site looks very familiar, are you a member of GearSlutz?

author: Andytechman
author_rank: Newbie
timestamp: November 04, 2014, 08:59:45 pm
content: Quote from: Yago on November 04, 2014, 08:34:08 pmNope

author: Yago
author_rank: Frequent Contributor
timestamp: November 04, 2014, 09:18:15 pm
content: I must have found it reading about synth DIY sometime, it is rather a memorable set-up!Certainty wins a Jazz Club nniiiiccceeeFired up the T3 today, though Alternative Ulster on piano doesn't qualify I fear

author: JohnS_AZ
author_rank: Frequent Contributor
timestamp: November 05, 2014, 04:39:45 am
content: Back in high school (about '74) I built a Paia 2700 kit synth. Lost the thing in a move a few decades ago.Just recently I've sort of been bitten by the bug again. I plan on designing a number of my own modules, but decided to build a known platform first. Toward that end I've bought a set of PCBs from MFOS; a VCO, VCF, VCA, ADSR, and keyboard interface. I've also bought a small mountain of components from several distributors to populate the boards. Nothing to show in pictures yet, but I guess I could take one of a box with a couple thousand components in it. :-)I have designed and built the two power supplies and some power distribution boards which you can see here:https://plus.google.com/102867471209152798204/posts/haWMaUr1aSwNow that I'm out of the Hackaday Prize contest, I hope to devote more time to it.@JohnS_AZ