SOLVED Electrovibe biasing woes

[Locrian99]

Man, I feel like I’ve spent way too long messing with this thing at this point. The one mod I’ve done so far (figured I wanted to see how it sounded stock before going crazy) was the unity mod.

Perused just about every thread I could find, checked out dk pedals little snippet on jt (which I find his rough estimation of explaining the settings are about where I find mine is best). But I can’t help but think mine isn’t right.

So I’ve built a little light shield with a bottle cap some blue painters tape did some sharpee action but I also am just keeping the room as dim as possible and using a flash light to see when I move the trimmers.

Full intensity I feel pretty good at max speed that there’s a pretty decent range that sounds like what I’m after and I can kind of pick which sounds best to me. But as I lower the speed I feel like the effect really fades. I can at full intensity half speed feel like it’s a solid enough effect, but back off the intensity and I feel the effect is gone or for the most part. I keep twiddling with it, and just can’t find a spot where I feel like at half intensity half speed is the level of effect I should expect.

So I guess my question is, is the effect reallt subtle unless the intensity is maxed, or do I need to keep adjusting/look for another issue.

I’m using 9203 ldrs, currently I have them touching the bulb (I haven’t played with spacing much yet).

Thx

 

[ThePanda]

I think I got lucky with mine, but I can share my methodology. I was at the same place as you a week ago.

The GAIN trimmer controls how bright/power to the bulb. I found that when it was too bright the LDRs wouldn't wobble enough.
I think the BIAS trimmer controls the wobble/pulsing.

I figured it has to be dark under the cover and if you give it too much GAIN it won't wobble correctly. Because everything is too bright. Kind of like blowing the highlights in a photograph.

So I maxed out the GAIN and set my BIAS wobble (while playing to check the sounds). Then I backed off the GAIN bit by bit and adjusted the BIAS.
I don't remember what I set it as but it kind of sounded good and I just left it.

I maxed out the level so I can hear the slow wobble. As you expected the Rate is the speed and the Depth is the intensity. I played with those to help adjust.

Also checking out some youtube demo videos of vibes helped me out a lot. I never really had a vibe so I didn't really know what it was suppose to sound like.

I did back the LDRs off of the bulb, but more for aesthetic reasons. I don't thing it really matters too much.

Hopefully this helps out man.

 

[Locrian99]

I think I got lucky with mine, but I can share my methodology. I was at the same place as you a week ago.

The GAIN trimmer controls how bright/power to the bulb. I found that when it was too bright the LDRs wouldn't wobble enough.
I think the BIAS trimmer controls the wobble/pulsing.

I figured it has to be dark under the cover and if you give it too much GAIN it won't wobble correctly. Because everything is too bright. Kind of like blowing the highlights in a photograph.

So I maxed out the GAIN and set my BIAS wobble (while playing to check the sounds). Then I backed off the GAIN bit by bit and adjusted the BIAS.
I don't remember what I set it as but it kind of sounded good and I just left it.

I maxed out the level so I can hear the slow wobble. As you expected the Rate is the speed and the Depth is the intensity. I played with those to help adjust.

Also checking out some youtube demo videos of vibes helped me out a lot. I never really had a vibe so I didn't really know what it was suppose to sound like.

I did back the LDRs off of the bulb, but more for aesthetic reasons. I don't thing it really matters too much.

Hopefully this helps out man.

I am starting to think there is something uo
With my bulb, it doesn’t seem to light up as much as the bulb in the dk pedals at similar settings.

Mind if I ask where you sourced yours?

I ended up just grabbing some on Amazon

 

[ThePanda]

I am starting to think there is something uo
With my bulb, it doesn’t seem to light up as much as the bulb in the dk pedals at similar settings.

Mind if I ask where you sourced yours?

I ended up just grabbing some on Amazon

I got mine from mouser.

https://www.mouser.com/ProductDetail/560-7371

 

[Chuck D. Bones]

FYI: the bulb does not need to get very bright for this thing to work correctly. On the vibes I've built, The bulbs don't get brighter than a warm glow when everything is properly adjusted.

Are you testing it with the box closed? If the box is open, then you need to be testing in total darkness. Did you measure the light and dark resistance of the LDRs?

Don't assume it's bad parts. It's probably a workmanship problem. I'm not dissing you, it's just the most likely cause.

Wanna post some pix?

 

[Locrian99]

FYI: the bulb does not need to get very bright for this thing to work correctly. On the vibes I've built, The bulbs don't get brighter than a warm glow when everything is properly adjusted.

Are you testing it with the box closed? If the box is open, then you need to be testing in total darkness. Did you measure the light and dark resistance of the LDRs?

Don't assume it's bad parts. It's probably a workmanship problem. I'm not dissing you, it's just the most likely cause.

Wanna post some pix?

Sure I can post some pics.

The main reason I’m wondering about the bulb is just from watching the video where his setting as he is saying them are in the trimmers mine is in no where near the same brightness. I as I stated can get a vibe effect at faster speeds but at lower speeds I hear a little vibe effect at max intensity but not what I would expect. I am using a light shield in a dimly lit room as I am testing. I have a the depths clone and I haven’t been able to get near the same intensity. And it may be a bias issue but I’ve spent hours now and can’t see it I may have made an error somewhere.
I didn’t like how the speed switch was sitting on the board so I rewired it by hand using the info in the mod thread. And it is functioning fine.

 

[Erik S]

Did you double check that you’ve got the right value trimmers in there, and that there’re not swapped?

 

[Locrian99]

Did you double check that you’ve got the right value trimmers in there, and that there’re not swapped?

Yea I did actually one of the early things I thought of. Also double checked all values in the lamp driver portion. I’m wondering if it’s just more subtle than I expected. As said I can get a good vibe sound at max speed, just at slower speeds it seems to lose it.

 

[Erik S]

Yea I did actually one of the early things I thought of. Also double checked all values in the lamp driver portion. I’m wondering if it’s just more subtle than I expected. As said I can get a good vibe sound at max speed, just at slower speeds it seems to lose it.

500r right? Not 500k?

 

[Locrian99]

500 reads 501 250k reads 254

 

[Locrian99]

FYI: the bulb does not need to get very bright for this thing to work correctly. On the vibes I've built, The bulbs don't get brighter than a warm glow when everything is properly adjusted.

Are you testing it with the box closed? If the box is open, then you need to be testing in total darkness. Did you measure the light and dark resistance of the LDRs?

Don't assume it's bad parts. It's probably a workmanship problem. I'm not dissing you, it's just the most likely cause.

Wanna post some pix?

Tried to measure the light vs dark resistance I was getting while the pedal was going and I don’t think my dmm could keep up. I’m using one of the listed ones in the bom ordered from digikey 9203. If I just measure in a dark room the dark is beyond what my dmm will read (2M).

In fiddling with it I really feel like the only noticeable effect is in the last 10% of the speed. I have it set where I’m hearing the most pitch vibrato at max speed And at max intensity. I can hear some effect at slower speeds but it’s subtle far more than it should be I would think. I’m going to go through and double check all values, but I’m going to take a break from it for a bit and come back to it.

Should the window where I’m hearing the effect be pretty narrow?

 

[Chuck D. Bones]

That LFO is deliberately designed to have a lower amplitude at slower rates to compensate for the slow response of the incandescent bulb. You can improve the slow rate amplitude by increasing C8. C7 - C9 should be tantalum or film because aluminum caps are leaky and that could upset the LFO.

you can read about sinewave LFOs here.

 

[Locrian99]

That LFO is deliberately designed to have a lower amplitude at slower rates to compensate for the slow response of the incandescent bulb. You can improve the slow rate amplitude by increasing C8. C7 - C9 should be tantalum or film because aluminum caps are leaky and that could upset the LFO.

you can read about sinewave LFOs here.

Would mlcc be ok there? I’ll try changing that over I saw that mod listed on big monks page but I always prefer to have a working pedal before I start changing things lol.

 

[Chuck D. Bones]

MLCC is ok. Definitely better than aluminum.

I hear ya, but that mod C8 does no harm.

 

[Locrian99]

Well this is for sure the biggest leap forward I’ve had. Unfortunately I don’t have time to mess with fine tuning it, but a quick run through and it seems leaps and bounds better after changing c7 and c9 to 1u films and c8 to a 4u7 mlcc . Thanks

MLCC is ok. Definitely better than aluminum.

I hear ya, but that mod C8 does no harm.

I didn’t socket c8 in hindsight I probably should have. Would there be any reason I should avoid going 10u?

 

[Chuck D. Bones]

Diminishing returns. I found that 2.2uF was enough. Try 10uF and see what happens. At some point the cap overwhelms the diodes and then either the amplitude gets so large that the transistor starts limiting or it kills the oscillation altogether.

 

[Locrian99]

Continued tinkering, got my depths clone I made in strip board out and slower speeds it’s subtler than I remember. Though not as much as the Electrovibe. Starting to think the issue is with my expectations… I’m going to mark this solved as I think it’s functioning properly.

I did try some different mlcc’s, end up with 2u2 for c8. Didn’t notice much difference between 4u7 and 2u2, and the 2u2 was the last one in there so it stayed.

 

[fig]

My mini-vibe build is a pretty strong effect.

 

[Locrian99]

M

My mini-vibe build is a pretty strong effect.

Mine is strong but drops its strength at slower speeds. Max speed it too much.

 

[Chuck D. Bones]

It's not perfect, but we can always readjust the DEPTH knob. Like many pedals, not all combinations of knob settings are useful. I recommend that you dial-in the trimpots for the slowest SPEED and highest DEPTH settings you use.