J.Hollis EasyVibe, there's something strange

[nooneknows]

I've finished my Easyvibe, it took me a bit of time to build it but I'm not completely satisfied with it.
I made it because I wanted to substitute my rotovibe in the pedalboard but I've noticed it doesn't sound as expected.
I suspect it's a matter of biasing point: I tried tweaking with the IK trimmer but I'm not able to find the right sound, it becomes too much nasal or too much glassy, comparing it with the bypassed signal.
Is there any standard trick to find the sweet spot?
Is it possible I made any mistake?

Any help is appreciated, thank you.

Marcello

[oldrocker]

Sounds like you might have an error in your build.  I don't think it should sound like that.  Check your cap values possably a misread.  I did a mod trying to bring it out of the vibe sound and make it a more of a classic phaser by replacing the vibe caps with all 0.01uf.  I don't think it sounds classic but it's more of a useful phaser for me now.

[nooneknows]

Well, actually I double checked the caps a thousand times and everything seems correct.
I mean, it sounds like a vibe indeed, but it's not, how can I say? Liquid as I expected. That's why I think it's just a matter o biasing.
How does the 1K trim works?

thank you

[oldrocker]

I believe the trim adjust brightness of the pulsing LED's.  This is so if you have used some other LED's and or LDR's with different specs you'd still be able to tweak it in.  How does the vibrato part sound on yours?  Not that it matters much, I was just curious.  The Easyvibe is a great vibrato pedal IMHO.   It might be that you expected more out of it than it was designed to do.  You could do the mod I did with all 0.01uf caps since this will increase the phaser effect but wouldn't be considered a univibe anymore.

[ncc]

Hi,
The first time I tested mine, it didn't work as well as I expected either.
But in my case, all I had to do is to turn off the light in th eroom, and it changed
the sound totally. The lamp above my workbench affected the amount
of light detected by the circuit and it messed up the effect.

It's probably not your problem but I thought of sharing the story anyway.
It might help someone else.

Norm

[nooneknows]

This is so if you have used some other LED's and or LDR's with different specs

I used the original LED and LDR of the project

How does the vibrato part sound on yours? 

Mine is good and the sound is not as coloured as the vibed one.

It might be that you expected more out of it than it was designed to do. 

I already worked around this putting a 100K resistor in place of the 47K in the first opamp feedback, the level is ok now.

You could do the mod I did with all 0.01uf caps

I prefer to stick to the original cap, I was looking for that Hendrixy underwater vibe

But in my case, all I had to do is to turn off the light in th eroom, and it changed
the sound totally. The lamp above my workbench affected the amount
of light detected by the circuit and it messed up the effect.

The LDR/LED combos are inside heatshrinked tube and the bias LED are covered

thank you,
ciao

[nordine]

noone knows, i've experimented a bit with the 'vibe and got two conclusions (not hard brainer ones, but useful nonetheless):

a) "mix" section matters
b) position of the LEDS regarding the LDRs matters a lot

one way to attach LEDS to LDR's is to face then at their heads.. other is putting they on some distance (5mm), other is doing it a-la univibe ..one led (or two) and LDRs facing the sky so they pick light  laterally

in regard to the mix section, sometimes 10k - 10k is not always the best choice (tolerance values, etc) ...i trim these values to the point the vibe comes diaphanous, and liquid