Joined: Dec 23, 2005 Posts: 4127 Location: Mount Hope, KS USA
Audio files: 96
Posted: Mon Mar 30, 2009 10:27 am Post subject:
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Five stage quintature/decature oscillator. Sinusoidal at large damping, chaotic at low. (See clip 1 discussion.)
Wow - should have know.
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Also note: On the bridechamber.com panel, there is an output jack for the HF pulses from the core. This was Scott's idea -- he thought folks might have another use for it.
So you could make an auxiliary board/panel for any kind of waveshaper you want!
Well, badda-bim, badda bam! That would make it really easy. Heck, I'd start with mixing using the resistor values on the SH1000/SH2000 (they have slightly different choices in footages and waveforms). That would make a cool companion module, indeed, and still preserve the original Dekka funcitonality. Good thinking, Scott!
Heck, there might be enough divisions there to put in an octave switch!
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so i got this up on the breadboard!
Cool, Loss!
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Puts my little experiments to shame.
Not from what I've seen of your experiment.
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Sinewaves... they don't get much cred among DIYers here and I understand why... but a pure sine is a beauty to hear.. a sinewave harmonic modulator.. even nicer
Oh, I love a good sine wave - particularly for FM (obviously). The divided triangle just looked a bit punchy to me on the scope to make a really nice sine. Multiplying up might make sines a bit...errrm, non-pure as well (at least how I'm doing it).
I wonder if the output of the Double-Dekka driving a walking ring counter would make a good approximation of a sine? It would certainly have a different tone, even if it had some step in it, and might provide a way to get some PWM, too, if it's not too steppy.
i connected this up as the quasi ring mod per scotts instructions...it works pretty well if you get the negative pulse really skinny.
BUT the bleeddhtrough (through the jfet) makes it pretty unusable for any sound that isnt continuous
of course i suppose if you setup a system where AUDIO A created a gate which turned on and off the input to the comparator then you would have a unique ring mod.
but as it is it sounds pretty cool with 2 synth waves//
Joined: Dec 23, 2005 Posts: 4127 Location: Mount Hope, KS USA
Audio files: 96
Posted: Mon Mar 30, 2009 3:32 pm Post subject:
It will work with any width of waveform on the gate of the FET - as I mentioned before all the circuit does is invert the input signal if the gate of the FET is at 0V and does not invert if the gate of the FET is at -V. If there is no input to the op amp, it probably will have some sound on it if the FET is being gated, (hence the "poor man's" description), but will be quieter if the input of the op amp is grounded while the FET is gated. I'd put it in front of a VCA, all the same. _________________ My Site
so i finally tried it out with a scope (not the Ring Mod but the Wave divide)
i am getting a bit more of a glitch on the sawtooth than you were on your scope shots. granted I am running off of +/- 12volts . it is actually kind of cool though as if you turn the pot all the way you start getting weird shapes. this might be a cool thing to put under control of a vactrol.
I might try and replace the pot on the saw divider VR3 with a multi trimmer to see if it helps.
Of course the glitch does not seem to be effect the sound and as i built this on breadboard it is entirely possible i used the wrong value somewhere (i used a 50k instead of a 51k due to not having one,etc) or made some mistake.
Joined: Dec 23, 2005 Posts: 4127 Location: Mount Hope, KS USA
Audio files: 96
Posted: Tue Mar 31, 2009 11:43 am Post subject:
Yeah - you might try centering the sawtooth before it enters the circuit it would be a fine adjustment. Any offset is going to affect the points that "connect" after the inverter - after all, you're snipping two halves and sewing them back together, so if the two halves aren't equal, you'll get gaps, which manifest as glitches.
12V should work, though it will be putting things closer to the rail than 15V.
I think the 50k vs 51K resistor isn't going to make any difference. _________________ My Site
i will i will...actually one of the things i am trying to get going is a way to convert the guitar into a square into a saw so i can put it through this as a SAW....
anyway...once the baby goes to sleep i will head back to the lab
Posted: Wed Apr 01, 2009 7:46 am Post subject:
some samples!!
OK
Here are a few samples
Two of em aref of the wavething being used for what it is supposed to do. I fed it with a saw, and mixed the TRI out and SAW out with my vco which was being fed with a sample and hold and put through a woggled ssm2044.
The other samples are of a somewhat successful, somewhat failed experiment. I wanted to put my guitar through it. So using a bunch of the audio ark tech,and a square to saw converter, as well as an inverter, I manged to get a sloppy saw wave out of my guitar (well really out of a bunch of dividers)...(boy are there a lot of breadboards on my bench)the problem is that the SAW has a tendency to DIE really quickly after the note rings, which makes a weird swoop. THis is probably due to the fact that by the time the guitar has become a SAW it has gone through SO MUCH circuitry.... (the real ark without all this other stuff tracks without all the problematic glitches)
anyway...in the HOLD mode of the ARK that wouldn't be a problem...another day....
so the guitar ends up going through scotts wavething and it gets a TRI and SAW octave down added to it ..makes for a very thick guitar sound...
Joined: Dec 23, 2005 Posts: 4127 Location: Mount Hope, KS USA
Audio files: 96
Posted: Wed Apr 22, 2009 9:48 am Post subject:
The circuit I used in that video multiplies the VCO sawtooth frequency X8, and I've been playing with shaping waveforms with diodes and resistors (like the SH-1000/2000). I'm pretty impressed how well the waveforms actually sound.
Multiplying up that far from a sawtooth is a painstaking thing - I had to do a considerable amount of calibration to get as much as I could of the harmonics out of the mulitplied signal - it's a real pain and would make an impractical module for any but the most obsessed. Plus, at very high frequencies, it's hard to get the divisions to behave. But, man, dividing down from a pulse wave that's already available would be a piece of cake - no calibration at all!
Using an ultrasonic VCO, specifically Ian's Double-Dekka, would be a much better solution. For any of you adventurous Double-Dekka owners, this would be a fun thing to play with on a rainy afternoon, and you may wind up with a powerful companion to your Double-Dekka.
This is what I'm doing: I'm dividing down with a CD4516, with an extra CD4013 on the bottom, so I have the fundamental, three octaves above and three octaves below.
For sawtooth I'm using: 100K, 220K, 390K, 820K, 1M5, 3M3. For the lowest sawtooth, I'm using 4M7 and 2M2 in series for that last value (I don't have a great variety of resistors up in that range). Obviously, the higher the octave, the fewer the resistors and hence more step in the slope, but even three resistors makes a much better audible approximation than I had anticipated - there's certainly a difference between a three resistor sawtooth and a pulse and square at that octave.
For pulse waves, I'm just diode mixing now. The carry-out of the CD4516 makes a dandy pulse wave one octave below the fundamental (in my setup).
It's extraordinarily easy to do - Ian mentioned that the Double-Dekka has an output that could be used as the divide down frequency. Use that signal to clock the 4516, 4013's, or whatever you choose to use as the divider. When you mix the divider signals together, either capacitively couple the output, or mix with a DC offset to center around zero.
I envision a panel much like the Double-Dekka - you could have sliders that would mix in the footage/waveform you wanted to add. You could also have separate outputs for the waveforms - run a suboctave saw through a Threeler and really thicken things up, for example. One would probably have to think a bit about which waveforms/footages one wanted, because there would be a lot to choose from; more than what a reasonably sized panel could offer.
When I get the pocket change, I'm going to have to get a Double-Dekka and try this out.
I'm tearing this circuit down to work on something else (unrelated) that I've been hankering to do for a while. I made few samples, here's one I pulled off the D8 this morning - it's a bit more aurally explanatory than that crap video I made.
Cheerios,
Scott
div_down1.mp3
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Multiply then dividing down and forming waves like in SH1000/SH2000
scott when you say you are tearing this down, does that mean the wavething series is over? i know you had mentioned the possibility of some other schematics in this series at one point so i am bit worried you have abandoned ship!
Joined: Dec 25, 2007 Posts: 251 Location: Sydney, Australia
Audio files: 27
Posted: Wed Apr 29, 2009 7:05 am Post subject:
For ARP's version of this kind of circuit, track down the Explorer I schematics and see the waveshaper. It provides 16", 8", 4" and 2" of tri or squares. It seems are real 1974 thing!
I'd like to build three instances of the circuit shown in the very first post of this thread. They'll be used individually, not for a sub-sub-sub-octave. I don't see anything about a PCB but does anybody have a layout they could share? That would save me a little time. I'll probably hand wire it on a piece of perf board. Thanks in advance.
Joined: Dec 25, 2007 Posts: 251 Location: Sydney, Australia
Audio files: 27
Posted: Wed Dec 30, 2009 2:28 am Post subject:
(I posted this on another thread too, but it relates to this one too.)
Richard Atkinson has posted a great page on the Roland SH-3A waveshaper including the schematic missing from the ZIPs and TIFFs floating around.
It turns out to do things a little different than expected. But it is still pretty small (about 8 components per footage selector giving square, pulse and saw each)
Joined: Feb 23, 2006 Posts: 111 Location: Chicago
Audio files: 2
Posted: Thu Dec 31, 2009 2:18 am Post subject:
cbm wrote:
Salamander Music System had something called the "Frequency Transmuter," which multiplied the input x2, x3, or x4 before dividing by 2, 3, 4, 5, 6, 7, and 8. A very useful module.
Looked at the block diagram and an idea popped into my head for frequency multiplication. Full wave rectify the triangle to get double the frequency. AC couple this output and put it through another FWR for X4 frequency. You'll have to adjust for desired offsets and gains. This is actually an idea I got from Electronotes in which an envelope follower design uses the two FWR approach. X3 stage I haven't cracked yet. Perhaps a mixing in of the original or something.
Mixing the X2, X4 and various suboctaves gives a nice organ-y effect.
I like.
Joined: Feb 22, 2008 Posts: 66 Location: Ua
Audio files: 1
Posted: Tue Oct 05, 2010 2:47 pm Post subject:
Sorry for necroposting, (and indirect off-topic). I'm for the waveshaper section (not the f/2, f/4 thing, which is beautiful, might be too much for the VHS-size modular)
Say, this circuit
amplified to +/-5V (10p-to-p) and fed into wavething's U1 and U4. I don't need octave division functionality and another sawwave, so i ommit the following: U1 with R1 ,U2, U3, Q1 and everything after R5. So i get these waves: saw(initial), triangle and pulse with modulation. Am i missing something? I'm thinking about using single quad opamp for saw amplification as well as waveshaping. Should i use inverting or non-inverting config for such task? I'm using MFOS calculators http://www.musicfromouterspace.com/analogsynth_new/ELECTRONICS/TOOLBOX/toolbox.html#NIOAGAINCALChttp://www.musicfromouterspace.com/analogsynth_new/ELECTRONICS/TOOLBOX/toolbox.html#INOAGAINCALC
Has there been any update on this schematic? This is a module that I'd love to have in my modular. I'd be willing to do a pcb layout when it's finished. _________________ Youtube! modular demos! Whacky tunes!
Awesome little circuit! I've tried it on a breadboard a few days ago, but ran into a little trouble. The MPF102's become more and more unobtainium, so I tried a BF545 instead (I had one in a SMD package). It works as well, except that I adds a nasty spike in the saw output at the switching point and I have a hard time understanding why. Is the slowness of the MPF102 somehow beneficial to this circuit? Or are there other crucial differences between these JFETs that I overlooked?
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Wow - should have know.
