Easyvibe mods - stereo?

[psiico]

I breadboarded an Easyvibe.   http://www.hollis.co.uk/john/easyvibe.jpg





Hell of a mess, ain't it?  I have holes drilled in that aluminum piece at the bottom for mounting pots, I don't know why I never use them.  Too lazy to put the switches into that plate too.   I didn't get real careful with the LED's pointing at the LDR's for this, it works just fine as is for testing purposes, especially with the film cap over them.

I added another 2 LED's next to the 4 that blink so I could see the rate outside the box, I'll only have one showing.  I tried using one but it didn't blink the same way as with two in series.  The extra LED's are on their own resistor.

I also changed the 0.1uf cap in the LFO section to a 2n7, I was experimenting and discovered it made the top speed faster, something that I wanted anyway.

I also changed the 47k resistor on the first opamp section (the one for the sound signal that doesn't have an LDR on it) to a 100k, I noticed this increased the overall volum, I then added a 500k pot (I used that value just because it was the first one I grabbed) to the input to set the volume.  Now I can have it quieter or louder then the clean signal.

Those mods were done knowing nothing about electronics, they were a trial and error thing so if I did something really stupid there that's why.


Next I added a rotary switch, I guess you'd call it a 4P3T.  The first throw is normal mode, the second is the phaser mode (0.01uf caps) mentioned here (http://www.hollis.co.uk/john/easyvibe.html) and for the third I used 0.1uf caps.

Now for my first question.  For that third throw, can anyone suggest an interesting combination of caps?  The 0.1uf caps don't sound much different from the 0.01uf caps.  Since I have that throw I may as well use it for something.  I have a 6PDT that I can use if I can't come up with something useful.  See below for one idea I had for it.

Next, what about a stereo mode?  I was thinking to make basically two of the same pedal in one box but just one input section, have 2 phase shift networks and 2 LFO's.  Only the first channel would have the switchable caps.  The point would be to be able to set the second channel to different depth/speed settings, would this sound terrible you think? 

How about this, would reversing the order of the caps in the phase shift network make any difference?  What I mean is have channel one use 15nf, 220nf, 470pf and then 4n7 and have the second channel use a 4n7 first, then 470pf, 220nf and lastly 15nf.  I could use the third throw on that rotary switch for these cap values.  Would this cause some sort of weird phasing effect or do you think it would it be unoticable?

I've been thinking why have 2 channels, well, there's the obvious having left and right speakers tremolo at different times/speeds/depths or I could use a mixer pedal and blend the two outputs into a single signal hopefully getting some sort of cool sounding effect or I could use the second channel to drive the envelope follower of a phuncgnosis.

I'd just build it and see what it sounds like but as you can see my breadboard is full, I'd have to buy another first.  I'm also out of 10k resistors, I had to use 4.7ks in series in a couple of places and I'd need more LDR's.  So I'm asking about the stereo mod to see if it's worth the effort to go out and buy the parts to build it.

[psiico]

I more or less somewhat answered my own question.  A friend of mine has Guitar Rig 2 so I went over to his place today and setup two tremolos with an A/B splitter.  Experimented with different depths and rates then I tried driving an envelope filter with one channel.  Everything worked the way I imagined it would, turns out there's some neat sounds in there.  There was no way for me to try different caps though obviously so I still don't have an answer to that question.

So it looks like I'll be building a stereo Easyvibe.  It'll have to wait a couple of weeks until i get the chance to go downtown for more parts.

[lovric]

hi,

i only have a small stone and i have tried something easier. instead of adding vib/chorus switch i have broken the line between the exits for straight an phased signal lines. i than just sent phased signal to one amp and straight signal to another. it sounded really nice.

maybe you could use the third position in your switch with all 4 same value caps and introduce feedback into phasing line? but just the switch might not be enough to do it.

i was also wandering is there any change in sound when you use green leds in led/ldr pairs??

regards, marin

[psiico]

I don't think different color LED's would affect the sound since they don't have anything to do with the sound, they only drive the resistance of the LDR's.  If their brightness was different it would affect the LDR's resistance but not the tone.