backwhenIwascool wrote:Ok elaborating.
So, to me vactrols/photocell expression (IMO) is/are for noise. And that is the farthest thing from what I want to make with this pedal. I want tweakable soaring ambience on crstal seas of heavenly bliss. Not warbley quirks of dissonant noiseyness. Photocells are completely random and they never work the same in any environment (which I am sure people will say "That's why I like it"). I think photocells work great with Fuzz pedals, circuit bent devices and feedback loopers, but not with pretty yum yum reverb! (IMO) All this, of course, is my opinion - didn't mean to offend, but I think everything ELSE that we have mentioned for the RRR v.2 is totally necessary and practical (well maybe not practical

).
Again, I know that tons of people are going to chime in and say "I want the crazy...." and "I want the noise...." or "I like the random...." but not me. I apologize for any offense, I really should have been a little more humble with my initial statement, but I guess I am zealous for my dream reverb!

Alex, I figured you were thinking something crazy about photo-cells! *smile* (no offense intended there)
Photocells are awesome and they get used a lot as control elements. It's just a special kind of resistor that the value of changes depending on the light shining on it. It's a really useful analog hack actually, a great way to either modulate a resistance or isolate a resistance.. they're one of those things that you can keep coming up with uses for if you just keep thinking about it.
I use a photocell in the SDD and the Tremolessence, much like Jack describes. In the SDD the photocell modulates the resistance to ground that sets the delay time for the delay chip, providing the warble sound. In the Tremolessence the photocell's varying resistance is what provides the tremolo effect.
In the RRRv2, one photocell is being used just like in the SDD, modulating a resistance that sets a timing signal. That's how I get global modulation of the reverb patches, by using a triangle waveform to raise and lower the voltage to the LED which raises and lowers the resistance of the photocell and thus raises and lowers the digital timing signal... and voila, modulated reverb.
The other 4 photocells are for stereo mix. Stereo mix with expression control is kind of an annoying problem... it would be easy to use a dual ganged pot for stereo mix control, but there's no dual ganged expression pedals that can take over that job. I set up a mix control using 2 LM13700 OTAs as voltage controlled amps, one for each channel, and it worked well with a single pot and a wide variety of expression pedals but I felt that running the audio signals through the OTAs really compromised their tone and added a lot of noise.
So I went with a really simple solution, vactrols... 2 vactrols per channel provide for stereo mix with a single potentiometer, it's easy breezy and only requires the vactrols, a pot, and a resistor to power.
The negatives are definitely what Jack said, the vactrols aren't cheap and they aren't small and they aren't low power, but shoot, the RRRv2 ain't gonna be cheap or small or low power. *smile* I think they're a great solution and they aren't unpredictable or of random values, they're actually really predictable and well behaved. I've measured lots of the Vactec ones I'm using in the RRRv2 and the results have been really consistent, which is really important.
Jack would have done the RRRv2 stereo mix in a different way I betcha.. using a micro and digital pots maybe? But he's got cleverer tricks up his sleeve than me! For me the vactrols are simple and powerful, they do exactly what I need done and they do it well within my realm of comfort.
gururyan wrote:Ok, so two things just hit me. First, I don't see a short/long toggle on the RRRv2. Is that because now one pot can take the entire range? You're going to have to excuse my ignorance under the hood, I just drive cars, I don't work on them. Secondly, I guess adding the brick (or some custom made variant) for spring reverb was dropped sometime ago?
Decay control on a knob has always been something I wanted to do with the RRRv2 and I've got a system working well on the breadboard using a neat little CMOS square wave oscillator running from 5MHz to 12MHz. It covers a little more range than the toggle switch of the miniberators or the old RRRs. I also have yet to test this system in a boxed up pedal... it has some touchiness details on the breadboard that I'm hoping will go away with a proper and well ground planed pcb.
As for the Belton brick, I did experiment with them.. and I experimented with my own spring reverb simulation using digital delay chips, but I just didn't love the results with either. Plus the addition to the circuit in terms of component count and complexity with either method was more than I thought was reasonable. I decided it was best to let the RRR shine at what it was good at and deck it out with features that made it more powerful/versatile.