Voodoo vibe, pangea

[Marshall Arts]

Another solution might (!) be to lower the resistance of the first LDR (e.g. with a parallel resistor or by using another LDR). It would alter the "taper" and overall feel of the tremolo and probably also the other modes (chorus, trem).

And before I forget it: Big "thank you" to brenja for the board, which is awesome!

[Marshall Arts]

I tried a booster (AMZ mini booster), this works, but adds a bit noise to the tremolo.

Another, much more simple solution is attached and SHOULD work (I will test it over the weekend). With about 70k in parallel to LDR1, I get unity gain (volume max, bias min) in tremolo mode but loose a bit of the "helicopter tremolo" (there is still enough Fender-esque tremolo on tap). If I want a stuttering tremolo, I have the little blue switch to disable the parallel resistor arrangement on the vero (but than don't get unity gain). With everything attached to the rotary, the parallel resistor will only be active in tremolo mode, so the other modes remain unchanged.

[Marshall Arts]

I just built the above mod - works!

[Manc]

Great! I will give it a shot 
I'm just waiting for ONE gl5516 (well, a pack of four, but I need the one).

[Marshall Arts]

After some more testing, I am pretty sure, that the volume drop is a result of the chosen LED/LDR combination. All four LEDs should be the same brand/supplier (they are arranged in parallel, so if one is different, it will likely lead to an unbalanced current flow). In tremolo mode, only the first LED/LDR is used, and this might lead to less volume in tremolo mode. To increase the LED brightness (rather than lower the LDR resistance), you can also add a resistor parrallel to R20(1M2), which will only be "active" in tremolo mode (see attachment). I like this slightly better than the LDR-mod suggested above.

To the ones who built this already: On my build, the symmetry pot changes the symmetry slightly in the first 3/4. Symmetry changes more in the last 1/4, but also the speed of the pulse goes down. Is this the same with your builds?

[brejna]

After some more testing, I am pretty sure, that the volume drop is a result of the chosen LED/LDR combination. All four LEDs should be the same brand/supplier (they are arranged in parallel, so if one is different, it will likely lead to an unbalanced current flow). In tremolo mode, only the first LED/LDR is used, and this might lead to less volume in tremolo mode. To increase the LED brightness (rather than lower the LDR resistance), you can also add a resistor parrallel to R20(1M2), which will only be "active" in tremolo mode (see attachment). I like this slightly better than the LDR-mod suggested above.

To the ones who built this already: On my build, the symmetry pot changes the symmetry slightly in the first 3/4. Symmetry changes more in the last 1/4, but also the speed of the pulse goes down. Is this the same with your builds?

About symmetry, that is normal behavior. 
Thanks again on your input.

[Marshall Arts]

I tested the whole circuit with other LEDs (clear red ones) yesterday and achieved unity gain in tremolo mode without any of the above mods yesterday. I ordered yellow LEDs from Tayda as well (brenja said he used those). Brightness is the key, those have 2000-3000 mcd, the ones I had in had only 20 mcd.

[Adam_DIY]

That looks mega really really great.

[gitaar0]

I tested the whole circuit with other LEDs (clear red ones) yesterday and achieved unity gain in tremolo mode without any of the above mods yesterday. I ordered yellow LEDs from Tayda as well (brenja said he used those). Brightness is the key, those have 2000-3000 mcd, the ones I had in had only 20 mcd.

Hi Mfunky,

I followed your endavours on the unity gain aspect. Did not have time to work on it myself.

The trick with the led's is something I might want to try. What is the effect of the changed led's on the vibe and chorus mode?

Slacker on DIYS suggested changing R40 (larger) as it is part of a voltage divider for the tremelo level, but I have not had the chance to try that.
There is a post somewhere on the web that RM himself suggested to the one who posted that, that he had a simple solution like that. Never found what that solution was.

[Marshall Arts]

The other modes sound slightly changed, but nevertheless equally great. The Bias control reacts different, so you can dial in the deemed for sounds ;-)

Slacker on DIYS suggested changing R40 (larger) as it is part of a voltage divider for the tremelo level, but I have not had the chance to try that.

I tried that a couple of days ago and desoldered R40 - it did not change too much.

There is a post somewhere on the web that RM himself suggested to the one who posted that, that he had a simple solution like that. Never found what that solution was.

If you find it, make sure to post it here :-). If not, the LED-Mod is the most simple and effective choice, as it provides the best range from smoth tremolo to (almost) stuttering tremolo. It requires desoldering under the pots, though. For future builders, I recommend to socket the LEDs (and use the recommended LDRs).

I also had a question about the external speed control resistance (and taper), but I found an answer here: http://www.roger-mayer.co.uk/vibe+speed.pdf

[gitaar0]

Did the change of the leds not just raise all the levels? Meaning the the tremolo is now at unity but still lower in level compared to the vibe and chorus?

[Marshall Arts]

No, it's all more or less even :-)


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[gitaar0]

The other modes sound slightly changed, but nevertheless equally great. The Bias control reacts different, so you can dial in the deemed for sounds ;-)

Slacker on DIYS suggested changing R40 (larger) as it is part of a voltage divider for the tremelo level, but I have not had the chance to try that.

I tried that a couple of days ago and desoldered R40 - it did not change too much.

There is a post somewhere on the web that RM himself suggested to the one who posted that, that he had a simple solution like that. Never found what that solution was.

If you find it, make sure to post it here :-). If not, the LED-Mod is the most simple and effective choice, as it provides the best range from smoth tremolo to (almost) stuttering tremolo. It requires desoldering under the pots, though. For future builders, I recommend to socket the LEDs (and use the recommended LDRs).

I also had a question about the external speed control resistance (and taper), but I found an answer here: http://www.roger-mayer.co.uk/vibe+speed.pdf

I am trying to find the leds to try your mod. It seems hard to find yellow diffuse leds 2000-3000mcd here in the Netherlands. How important is the color and them being diffuse?

[Marshall Arts]

I am trying to find the leds to try your mod. It seems hard to find yellow diffuse leds 2000-3000mcd here in the Netherlands. How important is the color and them being diffuse?
[/quote]

The yellow LED's from Tayda worked the best for me. They should deliver to the netherlands

[brejna]

I am trying to find the leds to try your mod. It seems hard to find yellow diffuse leds 2000-3000mcd here in the Netherlands. How important is the color and them being diffuse?

I had best results with Tayda LEDs too.