Synthbox

[liquids]

I love synthy-sounding pedals, and I've been messing with the Shocktave to that end, on and off for a while now.  This is a souped up and tweaked version based on Joe Davisson's super cool Shocktave circuit, to achieve that kind of sound.   I came back to a simple version I had build a while ago that I recently felt I could improve, and developed this.  It's nothing drastic, but I think I've tweaked it as much as I'm currently capable of, so I thought I'd offer it here for others to try, and dare I say, for others to continue to improve....

Here's a link to a schematic: http://sites.google.com/site/teaandfiction/_/rsrc/1247755172710/Home/synthboxschem/Synthbox.jpg

It's tweaked to work with bridge pickup without a tone roll off, as there's 3 stages of identical filtering built-in post-buffer.  It's uses the bleepy, sqare-ish octave down and shapes it a bit to get a sound I find like a modern and 'aggressive' synth sound.

It tracks fairly well, but is of course is not perfect.  As always, picking technique (both pickstroke and rest) should be even, timbre should still be as warm-toned as possible (fingers or with picks near neck pickup) for best results.  Glitchy playing = glitchy octave.     Playing more in the middle of the neck on up is favored, as first five frets are most likely to cause it to 'skip' an octave up after a few seconds, but that can be mitigated for the most part.  Lower strings will always sustain more than high strings, but you should be able to play notes solidly, even above the 12th fret E string, with a fair amount of sustain time.  The decay on the octave side of the shocktave, to me, was fairly odd and glitchy; I think I've improved it, but it still fades a bit oddly on occasion though less so, and more so just 'gates out' if you try and hold a note endlessly.  It loves bends and staccato playing... 

Careful on the schematic around the 1N4148--the program I used is limited and made it difficult to draw that and the flip flop section; do reference the original shocktave for more visual clarity on the schematic.

Matching' transistors as closely as possible, and using the .22uF/220nF caps really seemed to help the tracking significantly, though .1uF could be used (or put in parallel) if thats all you have.  The resistor and cap feeding that section seems to make the 'octave' ultra dry, and removes  remnants of the 'straight' signal that comes through.  The value of that cap affected the decay quite a bit; 68nF seemed optimal, though 100nF works too, though maybe not as well to my ears.... 

While using electrolytics is not ideal for most, but it seems the cumulative affect of using smaller(even .1uF) caps was more than tonal--it affected tracking a bit.  Use whatever reasonably sized electrolytics you have around for the caps labeled as 2.2uF - I'm using random values that I rarely use otherwise. Do avoid going below 2.2uF for best tracking, to my ears.  The 'bass' DPDT at the end then gives you the option to for huge low end or filtering through  the .01 which is still HUGE-sounding, but may 'cut' better live, especially with already bass-heavy rigs.

Most importantly, this thing is tons of fun with some reverb and/or a little echo!  Enjoy!

[Derringer]

nice work

any chance of some clips?

[liquids]

My "recording rig" is really awful -- an old $5 computer mic into my generic soundcard...but I'll see if I can manage something over the weekend as I imagine more people will be interested once I do.   

[liquids]

The schematic had some errors and a thing or two missing, so I updated it:

http://sites.google.com/site/liquidselectronics/synthbox

I found that the first link only goes to the original version, which will be removed.  This link should stay updated to whatever is the most recent version, if I ever do work on the schematic.  Once you're there, clicking on the image should isolate the page to view the image only, and make it clearer.

I did record a long sound sample as per Derringer's request, but I need to whittle it down a bit; that should be coming soon, for those who are interested!   

[liquids]

Sound sample montage is here:  http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+Demo.mp3.html

I recorded a bunch of stuff and chopped it down to what I though was most useful for a sound sample.  Most of it has a fair amount of reverb, and a tad of delay right into the amp. Here's a play by play of what is happening...

Phrase played cleanly :00-:04
Phrase played through my Foxrox Octron for comparison; octave down only :04-:08
Phrase played though Synthbox with 'shape' knob up, showing range of notes low to high :20-:30
Synthbox improv with tone knob up  :08-:20
Phrases with shape knob down :30-:48
Phrases with 'shape' knob down demonstrating sustain and decay characteristics, no reverb :48-1:00
Improv with 'shape' knob down and a little extra delay for a little nintendo 'lead' sound  1:00-1:10

[Top Top]

Sounds really good! Much more synth-like than most octave effects I have heard.

[earthtonesaudio]

Cool!

[liquids]

Sounds really good! Much more synth-like than most octave effects I have heard.

Yeah, I thought so too.  As you can hear, it's not synth-like in that that it's a satisfying moog copy.  Nothing ever will be, in my opinion, though it's fun trying and getting close.  There is no filter here on purpose, which is a key aspect of 'convincing' synth sounds, though you could add one and it's fun.  More so this sounds 'synthesized' to me, something 'from outer space,' yet the feel when playing it is controllable enough to have fun playing through it.  I've tried a fair number of 'synth-like' pedal configurations (boss synth pedals over the years, multi octaves+various filters, good digital, etc, etc).   I have an EH microsynth, which is amazing, and to me a pinnacle of analog synth imitations and non-guitar sounds with straight guitar.  It's huge, and I love it, but like the rest, it's more borders on a fun toy than something to put in the average guitar rig.  I want(ed) to be able to cop even one moog-like synth sound, but in the end, live, I always ended up saying that if I need a true synth sound, we should get a real one!   

I liked this because it made single notes sound rather unlike a guitar, but is relatively consistent; it can have an aggressive tone that cuts for leads.  For example, the concept of a 'clean octave up' is interesting, but what makes octavia sounds cool is that they can cut through a mix, since they're clipped and squared, to some degree, and fairly aggressive about it.  This one likewise has a unique tonal quality I like a lot, but happens to be a very fat octave down.  So like an octavia it is less something that is trying to imitate a sound, more so the interest factor is that it makes a sound that you hear and say, "what the heck IS that!" 

I love the escobedo Simple Square Wave Shaper Made Simpler and the PWM, and I have tweaked those out a bit to similar effect.  They have counterpoint tonal qualities worth exploring, though they don't octave. Those have gone on the back burner for me like this one did, and I ended up coming back to this one first and being satisfied with the result.  I still need to do a vero layout, though!   

[cpnyc23]

Was this clip made with the Synthbox on breadboard or have you created some kind of layout?   I noticed you said that you still need to do a vero layout... just wondering if you've created one on other formats.

Brilliant work - I love a to see a quest for the holy grail take a substantial step forward!

-chris

[mantella]

yes, vero layout please.

really cool modifications to an already fun circuit.

[earthtonesaudio]

Almost saxophone-like at the end there... 

[liquids]

Was this clip made with the Synthbox on breadboard or have you created some kind of layout?   I noticed you said that you still need to do a vero layout... just wondering if you've created one on other formats.

Yeah, that was with my breadboard 'rig.' 

yes, vero layout please.   really cool modifications to an already fun circuit.

Thanks!  I'm painfully slow with creating vero layouts.  I tend to make ones that are fairly tight and not so pretty as the spacious layouts I've seen in the gallery, with all the pot wiring coming off the end of strips, etc.   Lots of people on here are fast with them, though, so maybe one will show up soon.  When I finish one I'll post it, but hopefully someone will beat me to it. 

[liveloveshare]

That sounds great.

[Top Top]

I would build this right away if there was a layout... even a breadboard layout.

It sounds very synth-like - sounds like a raw synth waveform sound before the filter.

Would be cool to combine this with some filters and PWM effect.

[flo]

[EDIT: sorry, removed comment about schematic link not working]

[thereverend]

i've been looking for a new project to do. i think i just found it. this thing sounds right up my alley.

[SpencerPedals]

That sounds great...nice work

[Joe]

Awesome soundclip.

Found an error, the output seems to be taken from 9v instead of the emitter. Also looks like one side of the shape control is not connected?

[liquids]

Your right that it should be from the emitter side.  Good catch   

The shape pot is just a variable resistance, a tone control like a rat, but after a buffer so that is correct.  The 'tracking' trimmer is wired the same way, though I should state that you can make that any value you want, within reason.  I tried it with a brighter guitar and found that a little more range is not bad, though too much and you lose the highest notes on the guitar.

The tone pot with only two terminals wired up as a variable resistor and in conjunction with the buffer stage means it can go from having no audible effect on the tone, to cutting off some amount of the highest highs.  It, at most, adds about 11k resistance on the output if you leave it stock, so it's fairly minimal.  'The third terminal' should not be connected to ground.  It could be connected to the same point as the second terminal.

Realistically, that whole part could be omitted and you could tap straight off a cap (or via the DPDT switch) from the emitter if you prefer the sound of the 'earlier' clips where it is more aggressive, rather than the smoother sounds with the 'shape' knob down.  You could also wire it as a SWTC, if you prefer, I imagine.

[edd29]

The schematic had some errors and a thing or two missing, so I updated it:

http://sites.google.com/site/liquidselectronics/synthbox

I found that the first link only goes to the original version, which will be removed.  This link should stay updated to whatever is the most recent version, if I ever do work on the schematic.  Once you're there, clicking on the image should isolate the page to view the image only, and make it clearer.

I did record a long sound sample as per Derringer's request, but I need to whittle it down a bit; that should be coming soon, for those who are interested!   

is this verified shematic? http://sites.google.com/site/liquidselectronics/synthbox