The Slacktave, CMOS octave down fun

[earthtonesaudio]

If you're going down the multiply up route, you could try the waveshaper from the PICsynth http://picsynth.000space.com/.
I'm not sure how successful the upper octaves will be though, I think the pulse width might get too narrow to hear. It would probably still work to drive a divider though.
I have another idea along these lines using a CD4046 to multiply the signal up about 8 or 16 times then divide it back down. In theory you would then have enough outputs to make a digital sine wave, or triangle at different octaves. From there you can get saws and squares. You could even go really crazy and make a vastly simplified version of Ian Fritz's DoubleDeka VCO, where you could actually draw the waveform you want.
It will probably have to wait until the winter though, I'm pretty busy with stuff most of the summer.

Agreed, 3 octaves up would be hard to hear in most situations.  Especially if you took the output from the XOR directly!  That's why I've tried to show the output being taken from the 4024, after 50% duty cycle has been restored.

That other stuff is crazy talk, way over my head!

[slacker]

Sorry, I didn't look at the schematic properly 

[earthtonesaudio]

I just found a decent sized enclosure for the monstrosity that my interpretation of the Slacktave is shaping up to be... and I realize I have room for MORE FEATURES!!!  Mwa-hahaha!

So I'm thinking a sequencer to step through the octaves would be nice.  Does anyone know of a sequencer that can invert its outputs, or would it make more sense to go with a serial/parallel shift register a/la TheToneGod's Vanishing Point 1.0?

Also, envelope control over something.  Perhaps pulse width, before the signal goes through the waveshaper, for Uglyface-ish tones.

And tap-tempo, of course.

[gigimarga]

Hello,

Can i use another 4070 for the +2 octave up?

Thx!

[earthtonesaudio]

Hello,

Can i use another 4070 for the +2 octave up?

Thx!

Short answer: yes.


Long answer:
Anytime you put a square wave into one input of an XOR, and a slightly delayed (by the r-c network) version of the same square wave into the other input, you get a High output when only one input is high, which happens be twice the input frequency.

If the RC delay is 1/4 the period of the input frequency, the output will be a square wave (50% duty cycle).  For other input frequencies, the fixed RC delay will cause the output will be more or less than 50%, which in subjective terms results in a thinner or reedier tone.


Getting back to your question, stacking RC-delayed XOR networks (just like I drew in the schematic in reply #56) will result in doubling the frequency each time, but the tone will become much thinner, over a broader range of input frequencies. 

This is why I put the output of the 4th XOR into the clock input of the 4024.  The Q₀ output is now one octave lower than the clock frequency, but the flip-flop circuit makes the duty cycle exactly 50%, and the output's timbre is independent of input frequency.  I chose this because I was worried the XOR output would be such a narrow pulse that it would be completely inaudible, not because I think it would necessarily sound better.  Having an output which changes dynamically per the frequency will probably sound more interesting, but that's up to your ear to decide.

I'm assuming you've also checked out the Slacktave MKII, correct?  There are many ways of putting this thing together.

[rousejeremy]

I just built the Slacktave on vero.
I have to hit the strings REALLY hard (Stratocaster) in order for the Octave effect to happen, and the effect dies quickly, leaving just the clean guitar signal.

[Microscope]

Maybe this is a dumb question but I don't see an "out" marked on the veroboard layout.

[jacobyjd]

Maybe this is a dumb question but I don't see an "out" marked on the veroboard layout.

Not a dumb question

Vol lug 2 (the middle one) is where you take the output from.

[Microscope]

Thanks.

[rexindigo]

Hello, im new to this forum and just wanted to say "hi evrybody, great forum you have here!"
and ask a question about the slacktave which I just built:
The two diodes in the  output section, are they just the usual clipping diodes of a fuzz circuit?
Can they be omitted in order to get clean guitar + binary counter sound?
(btw: what a great sounding unit the slacktave is, thanx for sharing!)
thx for your reply

[earthtonesaudio]

They are limiting the signal like in a fuzz, but in this circuit the signal going into that section is fuzzy already.  So they don't really add much distortion, but rather their main purpose is to limit the output volume and keep the op-amp itself from clipping.

[rexindigo]

I will keep the diodes then, the sound is nice anyway,
thank you.

[Fuzz Aldryn]

Yeah, definiitely keep them in. They are limiting the output signal to about 0,7V. Without them the voltage would jump from 0 to 9V in a squarewave manner as far as I did understand the circhuit.

Cheers
Helge

[John Lyons]

Yeah, been a while. 
Anyone have the Slacktave MKII schematic?

[duck_arse]

[John Lyons]

Thank you kind sir!