Duo-Vibe: a prototype --- DEMO ADDED

[Scruffie]

Ahhh that ol' chestnut, the volume drop can be gotten around but it isn't always necessary to completely remove the dry for something pleasing. Sounds like the cap swap does the job you want anyway.

It's not just a volume drop. It really sounds like the effect "depth" is gutted if dry is killed completely. I can't explain it, but that's what my ears hear.

I just went with Lune LFO as lots of people seem to favour it  yeah that could be a bit hard on off for vibe... can't see the parts you'd have used in the shot but did you go with something sinusoidal?

It's still somewhat choppy, even when on the "smoothest" setting. It's a bit lopsided, as is usual with LED/LDR. The LDRs just don't turn on/off linearly. But I tweaked the Depth control a bit to help smooth out the wave a little on less deep settings. It's got some trem-like character, for sure.

Have a think about why it might sound like depth is going with dry signal removed... just your wet path...

Have you tried 'clipping' the wave? And adding some extra capacitance at the output to smooth the wave? I don't know if you want it overly smooth though, that choppyness is probably a bit of the charm with just 2 stages.

[culturejam]

Added a demo clip to the first post.

[nzCdog]

It's certainly got some great sounds man, nice work.

[ch1naski]

I got queasy at the 1:30 mark. I like that it's very present in the slower speeds.....I could almost hear the opening notes to "shine on you crazy diamond"......

Sent from my Nexus 7 using Tapatalk HD

[Guitarmageddon]

That's really cool Forrest. Of course it looks beautiful, but I've been waiting on the clip.
I really like the square wave sound and especially the phased trem effect at about 2:37
Sweet!

[culturejam]

Thanks for the kind words, guys. 

Have a think about why it might sound like depth is going with dry signal removed... just your wet path...

I guess phrased it wrong. I'm not really completely wiping out dry. It's impossible to do so in this circuit. When the LED is dark, the signal is going through is basically dry. When the LED is lit, the signal is out of phase with the input. In between those extremes is where things sound interesting, as there is a mix of in-phase and out-of-phase sounds as they cross over. Adding the cap-coupled feedback path (or is it feedforward?) essentially gives a constant in-phase signal path from input to output, which makes the phase oscillation sound more pronounced at certain points in the sweep. At least I think that's what's happening.  

[midwayfair]

Sounds awesome. The vibrato mode is really much better than the magnavibe by itself, and I really like the mild phaser sound on this.

I note from looking at the layout that the switch is a SPST. If you really wanted to get fancy, a DPDT on-off-on could make a third vibe mode, one without pitch shifting but also without the "wah"-ish sound of the phaser mode. It'll sound really watery. All you do is take two resistors of the same value as the emitter resistors and put them in parallel with the fixed emitter resistors to ground. When you switch them in, they half the value of the emitter resistors and you get very little pitch shift. (This is the voicing I used in the blue warbler.) You only need one pole because they're both connecting to ground. Plus it would be really easy to just use a cheaper SPST still, by only using one side of the switch pads ...

or you could build a third effect on the same board and have an extra product but tell everyone it's a completely different amp and totally NOT the same pedal they've already bought twice ...

[culturejam]

I note from looking at the layout that the switch is a SPST. If you really wanted to get fancy, a DPDT on-off-on could make a third vibe mode, one without pitch shifting but also without the "wah"-ish sound of the phaser mode. It'll sound really watery. All you do is take two resistors of the same value as the emitter resistors and put them in parallel with the fixed emitter resistors to ground. When you switch them in, they half the value of the emitter resistors and you get very little pitch shift. (This is the voicing I used in the blue warbler.)

I'll have to check that out. Sounds like a neat bit of bias trickery you've outlined. Does halving the emitter resistance cause a volume bump? Seems like it would, at least for the in-phase collector output signal.

[midwayfair]

Does halving the emitter resistance cause a volume bump? Seems like it would, at least for the in-phase collector output signal.

Well, without deciphering your emitter/collector values on the board, you're probably at 10K on both the emitter and collector, right? What's the actual volume difference in a transistor stage when you go from 10K to 4.7K? It's almost imperceptible -- it might be a couple decibels at most on the treble side of the wave swing only. Whereas the emitter will always be at unity volume unless the biasing is just wrong or the emitter resistor becomes much smaller, like <1K.

I find that I'm less sensitive to small volume changes than many people, though, so obviously: YMMV.

[neiloler]

Very cool finish, and I dig the sounds. Even in the extreme setting, I still felt like it maintained its musicality.

[culturejam]

Well, without deciphering your emitter/collector values on the board, you're probably at 10K on both the emitter and collector, right? What's the actual volume difference in a transistor stage when you go from 10K to 4.7K? It's almost imperceptible -- it might be a couple decibels at most on the treble side of the wave swing only. Whereas the emitter will always be at unity volume unless the biasing is just wrong or the emitter resistor becomes much smaller, like <1K.

Good point. 

[culturejam]

Just tried this bad boy with some fuzz. Sounds pretty damn good *in front* of dirt. Not so much with a dirt box in front of the vibe. But like everything else tone related, some folks may like the dirt first.

[TreeSlayer]

hey, Bruh! PLEASE send me the docs on this!!! it's WAY cool!!!

Layton

[culturejam]

PM me your email and I'll get you the schematic and whatever else I have for that version of the board.