psssst.... so, kid, wanna build your ow guitar synth?

[pinkjimiphoton]

my bud ethan strikes again


https://audioxpress.com/article/you-can-diy-building-a-guitar-controlled-synthesizer-lfo-and-adsr

[antonis]

I'd also use a film capacitor for C4 (Threshold), like the one for C5..
(you can never breath easy with those %$#& 555 timers..)

[ElectricDruid]

Nice. The use of FETs in the ADSR is unusual. Mostly you see simple diodes (which doesn't work brilliantly) or CMOS switches (which is pretty much what the FETs are doing).

I think Ethan needs to download a Potentiometer symbol for his LTSpice. It's a little thing, but it made my life much easier and my circuits much clearer.

He gets absolute bonus points from me for the heavily-notated schematics though - excellent stuff. It's all well laid out in nice clear demarcated blocks, with each block explained. You can really learn stuff from schematics like that.

Is there a VCF and VCA coming up soon?

[pinkjimiphoton]

i certainly hope so! ethan is a trip, really great guy with some cool spins on things.
hoping when all is said and done with the project he gets boards made

[StephenGiles]

Nice. The use of FETs in the ADSR is unusual. Mostly you see simple diodes (which doesn't work brilliantly) or CMOS switches (which is pretty much what the FETs are doing).

I think Ethan needs to download a Potentiometer symbol for his LTSpice. It's a little thing, but it made my life much easier and my circuits much clearer.

He gets absolute bonus points from me for the heavily-notated schematics though - excellent stuff. It's all well laid out in nice clear demarcated blocks, with each block explained. You can really learn stuff from schematics like that.

Is there a VCF and VCA coming up soon?

I printed everything to read during waits at hospital visits tomorrow - my wife's in the morning and mine for a chest Xray later in the afternoon, and I'm sure that I saw mention of a VCF and VCA in a later issue.

[StephenGiles]

Very difficult trying to read the notes wearing a mask!! I can no longer see any reference to VCA or VCF. Has the Pick Detector appeared yet?

Found it - "In this guitar synth a Pick Detector (not yet shown)" so it's to come!

[amptramp]

For a guitar-controlled synth, does the guitar have to be modified in any way?

I could see a guitar input featuring separate neck pickups for each string (and nothing other than a neck pickup) and possibly a fret detector as well as pick detection so there would be no wolf notes (sudden changes to an octave up like you can get in a viola) caused by second harmonics in the raw signal.  Using the neck pickup only would ensure the fundamental has a good chance of being the highest signal with harmonics being lower in amplitude.

Basically, this takes the guitar from being a standard instrument whose input is used to drive a synth to being a user interface capable of being operated by a guitar player.  The only difference the player would notice is the six-output cable and the lack of a whammy bar

It would be possible to create an in-between version with no fret detectors where the input signal determines the frequency and therefore allows the use for the whammy bar and the ability to tune strings directly rather than in software.

[pinkjimiphoton]

For a guitar-controlled synth, does the guitar have to be modified in any way?

I could see a guitar input featuring separate neck pickups for each string (and nothing other than a neck pickup) and possibly a fret detector as well as pick detection so there would be no wolf notes (sudden changes to an octave up like you can get in a viola) caused by second harmonics in the raw signal.  Using the neck pickup only would ensure the fundamental has a good chance of being the highest signal with harmonics being lower in amplitude.

Basically, this takes the guitar from being a standard instrument whose input is used to drive a synth to being a user interface capable of being operated by a guitar player.  The only difference the player would notice is the six-output cable and the lack of a whammy bar

It would be possible to create an in-between version with no fret detectors where the input signal determines the frequency and therefore allows the use for the whammy bar and the ability to tune strings directly rather than in software.

actually, a neck pickup would not work, too many harmonix. thats why hex pickups need to be as close to the bridge as possible, less harmonic content there.
all this is already done, bro, and has been for decades.
the whole point of this one tho is to make a stompbox that will work with a normal guitar input.
i doubt if it will work well polyphonically, if at all... for that, you need to enter the digital realm and need money.

but anyways, no, trying to get info from a neck pickup won't work well at all. i tried to add a gk2 up there when i was trying to figure out how to do 24 pin analog and 13 pin digital guitar synths to play together... ended up with the gk1 against the bridge and the gk2 just next to it.

in "normal" guitar synths like the roland stuff, it needs a full cycle to "capture" the pitch of the note... but with the yamaha, axxon and ibanez ones, it goes by attack transients so way less possible latency.

but to answer the question, does the guitar need to be modified in any way? depends on what ya hope to do with it. you'll get more control with a hex pickup, unless you go digital.

[Mark Hammer]

Not JUST the harmonics, but also the string-to-string bleedthrough.  Remember that the string is MOST compliant, and wiggles the widest at its midpoint, which is often not far from the neck pickup.  Regardless of where one happens to fret, a pickup either at, or very close to, the bridge, will provide the least string-to-string bleedthrough, which is why all sensible guitar synths stick their divided pickup there.

The old Guild Tri-Oct I have, and that Dino/digi2t reverse-engineered, employed a proprietary divided pickup that is about the size of a P90, which meant that you could only snuggle it up near the bridge if the guitar only had a neck pickup, or you could stick it between neck and bridge pickups.  Either way, the bleedthrough made tracking VERY inconsistent.  I imagine it was better if one used heavier-gauge flatwound strings, which were nice and stiff.  But a divided pickup anywhere OTHER than at the bridge, when using light gauge strings, was asking for trouble.

[ElectricDruid]

As far as the digital solutions to this problem go, I think they're only going to get better. After all, the six strings of a guitar each have specific ranges, and typically have different harmonic "fingerprints". So the initially-intractable problem of separating the signals out of a mixed guitar output is actually a fairly limited domain. Imagine trying to separate the different orchestral instruments from a stereo recording of a Hayden symphony in comparison!

All that said, the hex pickup still saves a lot of mucking about and improves response, since processing always takes time. Much simpler to not have to in the first place.

[PRR]

ethan is a trip, really great guy with some cool spins....

25+ years back I was working out of his QuickTools BASIC Toolbox. And chatting with him about the economics of book-writing (back when there were books... ).

[pinkjimiphoton]

part 4 is up

https://audioxpress.com/article/you-can-diy-building-a-guitar-controlled-synthesizer-input-section-pick-detector

[Rodgre]

pssssst..... always.

Thanks for the link!!

Roger

[Mark Hammer]

Not that it is better, but it did come first, many years before Winer's circuit, and seems a bit simpler, so I figured I'd post this.  Never built it myself, but I think I just might.   I retouched the image of Craig Anderton's AMS-100 trigger/envelope module, turning it into a single page, rather than the two it was originally.  I moved some stuff around, so it wasn't so spread out, and swapped out the original pin numbers of the unobtanium chips for more common chips (i.e., swapped 4739 for 4558, and 4136 for 324/TL074).  I hope it's useful to somebody.  Documentation of the circuit can be found here: https://hammer.ampage.org/files/Device1-1.PDF  Enjoy.

[StephenGiles]

Thanks Mark - saved me the trouble!!

[pinkjimiphoton]

finaL installment!!

https://audioxpress.com/article/you-can-diy-building-a-guitar-controlled-synthesizer-vca-vcf

[StephenGiles]

Many thanks for this.

[anotherjim]

All good stuff. I knew of Ethan's Real Traps venture and learned lots from his DIY acoustics articles. Didn't know he did much circuitry.
The link to Skull and Circuits in his resources thing at the end is worth a look. Lots of good ideas with ordinary components.