Alternative microsynth

[Maneco]

...the generator section is the super octaver from Mark Hammer's site...
the envelope generator from the "Royal VCF" posted here by Stephen Gilles some time ago...
The filter: MXR envelope pwm filter,it can be converted to voltage control...

Sounds good?

[Ben N]

I'd start with the Rocktave; add the pre-octave filtering from GFR's site; add a CMOS-based octave-up circuit and a ring mod in parallel to the fuzz and octave down sections; add envelope switching to the expander half of the compander a la the EA Fuzz; put a state-variable filter or other eq on the "clean" side-chain.  Haven't given any thought to filtering.

[Paul Perry (Frostwave)]

The problem with a project like this is knowing when to stop.
I'd stay with the original suggestion (but, I think a MS20 style filter better than a MXR PWM for ease of construction and use, the PWM has not enough range).
If you do put a ringmodulator in, make its oscillator volotage controlled, then you have the option to drive it from an envelope.
And, although fets look like cheap and convenient elements, the amount of trouble that comes from the wide spread in characteristics, means that one should think twice before using them in circuits that others might build (except as amplifiers and buffers) in my opinion.

[Jaicen_solo]

I think it sounds like a great idea, though try and keep it low parts count!
I agree with paul regarding the Jfets, i'd much rather use OP-amps where current is not a problem, though I prefer mosfets as gain stages where possible.
I think the addition of a voltage controlled ring-mod would be excellent, as would clean octave up (perhaps using R.G Keens CMOS design??).
Perhaps you should add some LFO modulation as an option (using a buffered effects loop would probably do the  trick just as well though).
I'd be interested to see what you come up with, keep us posted.

*Jaicen

[Ben N]

Paul, since I have no intention of building any such thing, I can speculate all I want on Maneco's idea, without the least concern for practicality .  And on that note, is there any simple way to get different wave shapes than square and sine--say, sawtooth or triangle--without a VCO?
Ben

[Paul Perry (Frostwave)]

is there any simple way to get different wave shapes than square and sine--say, sawtooth or triangle--without a VCO?
Ben

I'm not sure what you mean here. Do you mean to generate them, or are you trying to convert the guitar signal into an unusual waveform?
In any case, suppose you have a squared waveform (from an octave down first stage, say) then you can distort it by slew limiter circuits, or you could run it into an integrator to make it triangular, but the exact result would be frequency dependent.

[Maneco]

you can clearly see the different aproaches in the guitar synth by eh versus the microsynth...the first extracts cv information to drive vco's ,so the different waveformsa are possible,while the microsynth works like an octaver...i supose running those square waves through waveshapers would give interesting results...there's a synth pedal project in the japanese electronic book at Colin's site that uses an lm2907 ,f to v,to run a 4046 as a vco,but that vco  is only square wave capable...

[zachary vex]

...the generator section is the super octaver from Mark Hammer's site...
the envelope generator from the "Royal VCF" posted here by Stephen Gilles some time ago...
The filter: MXR envelope pwm filter,it can be converted to voltage control...

Sounds good?

i didn't know that MXR made an envelope PWM filter!  where can i see one of those?

[puretube]

free information sucks...

[Mark Hammer]

Zach,

It's not a PWM filter in the sense of varying the duty-cycle of the audio signal.  Rather, it uses PWM as a means of envelope control.  Relative on/off time of a switch ganged to a resistor sets RC constant for filter frequency.  Quite clever, actually, and very flexible.

Check the A-Gua layout at Tonepad or any of the Envelope Filter schems posted around.

[Maneco]

...it has become my favourite state variable vcf now...no fets or ota's...there are some original schematics somewhere,i think in PISOTONES.COM,that add some useful information...this filter does not self oscillate,though,due to the auto limiting of cmos gates as opamps...but is really interesting

[zachary vex]

...
I hope your question doesn`t arouse new suspicions,
that a Pro might clone the clone of a fellow-DIYer...  :lol:

yeah, i know.  8^)  those clones of clones can be dangerous... you start seeing genetic mutations creep in... if the first cloner plants a marker in their design, it's pretty easy to trace later on.  8^P

[GFR]

A "synth" project that appeared in a Brazilian magazine lots of time ago:

http://www.gfrhpg.hpg.ig.com.br/CCDB/ccdb.html

Text in Portuguese only.

Some things are obvious copies like the sustainer and the phaser, but you may find some nice (new?) stuff like the octave up and the more synth like stuff like the VCF, modulation mixer, noise generator, etc.

If someone has mp3s of the Sergio Dias (ex-Mutantes) LP where he used it that's something I'd like to hear. (The author of the articles is his brother Claudio)

[Mark Hammer]

What kindof file is a chm file?  Not sure if I'm able to read any of these.

[DiyFreaque]

How about a CMOS filter?  There's a design for one at Rene Schmitz's site for a state variable filter and VCA based off of a 4007, quad op amp, a few caps and some resistors.  

Low parts count, no FET's to match, no OTA's or exotic parts.  Fairly uncomplicated.

I haven't tried it myself, but Rene's circuits generally rock....

http://www.uni-bonn.de/~uzs159/

Click on 'Filter' then on '4007 based filter'.

Cheers,
Scott

[GFR]

What kindof file is a chm file?  Not sure if I'm able to read any of these.

Compiled HTML Help. I think you need Windows 98 or newer, IE6 or newer.

[Mark Hammer]

If you like that, check out Osamu Hoshuyama's website.  Just for the hell of it, while he was visiting here in 02-03, made a completely CMOS synth.  Many of the circuits, including those in his "lunchbox" synth (http://www5b.biglobe.ne.jp/%7Ehoushu/synth/MOSular01.JPG) are listed.

Thanks for the tip about chm files.  Viewing them fine now, and saving them as 4-bit gifs.

[DiyFreaque]

Oh, yeah!  Sam's famous 'tupperware synth'.  There's some good circuits in there.

So, did you meet him, Mark?

Cheers,
Scott

[Maneco]

i think there's an error in part2 of the brazilian synth...hey ,i have the printed nova electronica that contains part 3! one of my first references was that article,back in 1985! bought that magazine second hand in a flea market,along with some uruguayan electronic magazines...yes,we had an electronic industry here during the eighties  ...

I tried building the 4007 vcf some weeks ago,with not god results,but i'll make a second attempt...i think the 4007 and cmos tricks in general are quite useful in the stompbox world,and somehow forgotten...there's  a lot of territory to explore...the mxr envelope filter is an amazing example....
another incredible cmos progie is the wasp synth and it's succesor,the pixie...i can{t believe what can be done on just 5v...

[Mark Hammer]

Yeah.  Sam was here as a visiting scientist at Carleton University from May 02 to May 03, and we were sorry to see him go.  As sweet and decent a man as you're likely to find anywhere.  Though his family was back in Tokyo and he missed them dearly, he finally had a basement and workbench of his own to work in while he was here and he was immensely productive, completing not only the "lunchbox synth" but the entire PAiA 9700 series synth and other projects.  The bunch of us in this region and beyond had several wonderful get-togethers and gadget-fests.  One shown here ( http://www.physicsenterprises.andrews.edu/diy_archive/synth_diy.html#canadians ) had myself, Mike Irwin, and Peter Snow over to my basement.  Another, had Harry Bissell and his wife Dana up from Detroit and Gilles Caron in from Québec City.  One of the truly seminal days in gadgeteering.  My younger son learned to play theremin.  Sam visited Mike's world of wonders outside Ottawa several times.  He was back in the neighbourhood in May for a conference, but both Pete and I had separate out-of-town family functions we couldn't get out of, so Sam spent the day at Mike's.

I have to say that meeting up with folks from the forum has always been an immensely enjoyable experience.  Brian Duguay and I hooked up at one of his band's shows and chatted (Aharon Colman was supposed to be in on it too but we couldn't find each other in the crowd).  J.C. Maillet was in town during a cross-country trip and dropped by for a wonderful afternoon.  I've met with Gilles Caron in Quebec and had the honour of being his host here, and was happy to drop in on Rick Lawrence out in Victoria this summer.  Mike Irwin and Peter Snow are "locals" of a sort, and we see each other from time to time.  Tim Larwill, who makes Retrosonic pedals (http://www.musictoyz.com/guitar/pedals/retro.php) also lives not too far away and we get together form time to time.  I tell you, it's a charmed life.  One of these days, maybe Steve Giles and RG and I will be able to touch base.  Aron too.  And although beer is not my taste, I'd be happy to hoist one with Ton on his turf or mine.  Hell, I'd even pay for it!