Neovibe idea....

[obblitt]

I did a search to find out if anybody had built a Neovibe and if they were satisfied, and then I got distracted  .

I had the idea (sparked by one of the threads that came up in the search) of using a two color LED for the bulb/photoresistor section. I was wondering if the photoresistor would be sensitive enough to pick up and be affected by two different wave lengths (like red and blue), and if it would affect the effect  .

On a related note, since I got distracted, who wants to tell me about their Neovibe? I have a Danelectro Cool Cat Vibe right now, and it sounds pretty awesome, but the circuit is all funky in mine, and the tapers on the controls are all out of whack. The two extremes of the mix control are the same - which is off - and the intensity control is all over the board. It's really freaking annoying, because it offers only a VERY limited vibe sound that is actually discernible. Basically the only parameter I can change currently is the speed  ...

I bought the three pack off musiciansfriend, and was planning on rehousing the Vibe and the Trem into the same enclosure, but I don't like the Trem (and it keeps shorting out), and the Vibe is all weird, which is why I'm asking about the Neovibe.

...

[R.G.]

I did a search to find out if anybody had built a Neovibe and if they were satisfied, and then I got distracted 

Hundreds if not thousands of people have built the Neovibe over the years (the PCB layout predates the rise of the web)

I had the idea (sparked by one of the threads that came up in the search) of using a two color LED for the bulb/photoresistor section. I was wondering if the photoresistor would be sensitive enough to pick up and be affected by two different wave lengths (like red and blue), and if it would affect the effect 

That's a solid "maybe, a little". The photoresistors do have a varying spectral response curve, which means that they are most sensitive to green light, and their response falls off to both the red and blue sides of that. "Sensitive" means the amount of resistance change per unit of light brightness. Small amounts of green light can cause big changes in resistance. Bigger amounts of red or blue light are needed to get the same changes in resistance.

The important part to remember is that all that changes is the resistance. They don't distort more or less, have treble/bass changes, or anything else that would affect the sound; only the amount of resistance change is modified.

So yes, changing the color (=frequency) of the light on the cells does change things: it changes the depth of modulation, and that's about all.

On a related note, since I got distracted, who wants to tell me about their Neovibe?

There are lots of Neovibe sound posts in the forum.

[earthtonesaudio]

...but but but: isn't there a difference in response time of the photocell to different wavelengths of light?  I think I read somewhere (here we go...) that CdS photocells respond more quickly to the blue end of the spectrum versus the red end...

I'm not trying to imply that a change in response time on the order of microseconds has anything at all to do with how it would sound in a Neovibe LFO, just a general curiosity thing.

[R.G.]

...but but but: isn't there a difference in response time of the photocell to different wavelengths of light?  I think I read somewhere (here we go...) that CdS photocells respond more quickly to the blue end of the spectrum versus the red end...

Could be, I guess. The blue end of the spectrum has more energy per photon, certainly. I don't really know.

I'm not trying to imply that a change in response time on the order of microseconds has anything at all to do with how it would sound in a Neovibe LFO, just a general curiosity thing.

Yeah, the LDRs have light response times in the tens of milliseconds and up. But as I said, I don't know. All of the LDR lit I've read has just talked about the spectrum senstivity in one section, and speed of response in another, the speed being a function of the LDR composition and light history.  But they certainly didn't say that there was not a speed difference to different parts of the spectrum.