Anyone have built succesfully the R. Barnett's Guitar Synth?

[gigimarga]

Hello,

I've just finished the R. Barnett's Guitar Synth using the layout from http://geocities.com/worthekik/guitarsynth.html.
The only thing that i got from it it's a strong oscillation, which i can modify using the "VCO" and "Frequency" pots 
Searching, I found some topics with the same problem, but all have no conclusion.

So, have anyone succesfully built it or not?

Thx a lot all!

[RickL]

That looks familiar. I think I built one with some minor amount of success. I'll try to dig through my box of finished-but-not-boxed projects and see if I can give you a better reply.

[gigimarga]

Thx a lot RickL!

[Radamus]

Is that monophonic? I'm assuming it is or every other "How do I make a guitar synth" topic would lead here.

[frequencycentral]

Looks monophonic to me. The 4046 is a PLL/VCO chip. Square waves only. I would be interested to hear it!

[StephenGiles]

Is there a circuit diagram for this - I have huge doubts over it!

[R.G.]

It's an interesting snippet of a circuit. It is monophonic, and relies for good sound on the two gates in front of the PLL to shape the signal into square waves. It will work best with a neck pickup, and notes near the 12th fret, to keep the harmonic content down.

The circuit is one of several guitar note trackers using the CD4046 I've seen. The most elaborate was the E&MM Harmony Generator that's available from Mark Hammer's site, hammer.ampage.org.

The 4046 VCO can be adjusted for an output of zero Hz (i.e. off) for an input of 0V, which is what this one relies on to turn off the VCO between notes. It's one of those side effects that works mostly. If I were doing this in earnest, I'd arrange some kind of gating to keep the output at zero whatever the PLL is doing unless there is a note present. The Harmony generator does this an interesting way. It makes an envelope of the original guitar sound, then uses the PLL signal to operate a CMOS switch, chopping the envelope at the PLL frequency. This is then taken as the output. That trick makes sure that whatever the PLL is doing, the output is zero if the signal is zero.

As a side effect, it includes multipliers/dividers to play an octave up, down, and thirds, fifths, etc. Take a look at it.

[sean k]

I was at a gig the other night an a guy was making a really kind of neat straight sine wave sound with his guitar. Turned out that it was not fx - just little lumps of blue tack on the strings. Little fishing weights would work as well and the sound really is harmonic free.

Might help to get those things tracking properly.

[R.G.]

I was at a gig the other night an a guy was making a really kind of neat straight sine wave sound with his guitar. Turned out that it was not fx - just little lumps of blue tack on the strings. Little fishing weights would work as well and the sound really is harmonic free.
Might help to get those things tracking properly.

Neat trick! I'm guessing that lead weights would change the tuning too much; the string would be heavier and therefore have to be tighter to hit the same note, but worse, the lead weight would not be distributed, so it would change the frequency of the string more as you fretted the string on higher frets - hard to compensate for that.

But if it was what I envision "blue tack" as, the mass would be low and would give less change in the tuning, while still soaking up the harmonics. Just a guess.

I've been through an amazing number of string-to-sine converter attempts. The one which I think has the best chance of success (other than the blue tack, that is!) is a bank of bandpass filters, maybe six per octave, with output detectors and a gate on each one, with logic to select only the lowest-frequency filter with output to be passed through. This should be sine-ish, and with six filters per octave, it would even separate out intervals as low as a third... I think. So it wouldn't matter if you played monophonic or not, it would all come out as the lowest-frequency sine wave. Lessee here, three octaves on a guitar fretboard, six filters per octave, that's eighteen copies of filter, envelope detector, gate, and a net of logic to sense and run the gates.

It's probably easier to build a combo organ than to get that mess running!

Blue tack seems like genius from here.

[puretube]

Latest E-H "Voice-Box" pedal (a.o.: Vocoder) sports 256 bands... 

[RickL]

Sorry, I can't find it. I thought it would be near the top but I dug about halfway through my box and couldn't find it. Maybe it ended up somewhere else. If I find it in the next little while I'll report.

Rick

[puretube]

Is there a circuit diagram for this - I have huge doubts over it!

"schemo"... 

[alanlan]

The only thing that i got from it it's a strong oscillation, which i can modify using the "VCO" and "Frequency" pots 

Sounds like your input signal isn't getting through to the phase comparator input, otherwise you would hear some signal on the VCO output.

[e45tg4t3]

may somebody should try to lower the ouput voltage from the 2 amp stages...  i readed somewhere that the 4046 doesn´t support signals which amplitudes are going rail to rail... so just lower the inut voltage (i.e. trimpot 100k , like a volumecontrol) before it runs into the 4046... maybe it works but just a guess..

Benny

[gigimarga]

Thx a lot all!!!
I was out og town for two days, so i will try all the suggestions and i will post the results.

You're wonderful!

[StephenGiles]

Is there a circuit diagram for this - I have huge doubts over it!

"schemo"... 

Useless really, for the 100th time what's wrong with the EH Guitar Synth fundamental generator? You get a pure sinewave at the output.

[gigimarga]

I don't know yet EH Guitar Synth...