Silver alligator build.... problem.

[sergio]

Does anyone found problem with the Silver Alligator schematic about the point to connect the vibrato circuit?
Here is what I found: when connect the 50k modulation pot, to 1Mohm volume pot, the entire volume go down a lot.
Has anyone made this model before and found the same problem as me?

[Bombacaototal]

This is correct, same happens in fender amps with that circuit. It's because you have a low resistance to ground and hence bleeding a lot of signal

Which schematic did you use?

[sergio]

This one

[Aaron]

Hi Sergio,

That was a guesstimate from the photo copies. Rafael did a great schematic after more info was available.

The one I built worked out fine, I built another version and it was a nightmare. Couldn’t get the right balance volume wise and had a horrible thumping sound. Went completely different trem circuit using optocouplers.

Thanks,
Aaron

[Richard1001]

This is correct, same happens in fender amps with that circuit. It's because you have a low resistance to ground and hence bleeding a lot of signal

Which schematic did you use?

It looks to me that in a Feñder amp, the LdR and 50k pot connect to the other side of the 220k resistor.

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[ChopSauce]

They do seem to connect right after the coupling cap of the preceding stage in both cases, though...

[Bombacaototal]

Hi Sergio,

That was a guesstimate from the photo copies. Rafael did a great schematic after more info was available.

The one I built worked out fine, I built another version and it was a nightmare. Couldn’t get the right balance volume wise and had a horrible thumping sound. Went completely different trem circuit using optocouplers.

Thanks,
Aaron

Thanks Aaron, hope you are well, it's been a while!

Indeed below in this thread you can find my schematic

https://ampgarage.com/forum/viewtopic.p ... &start=150

[Richard1001]

They do seem to connect right after the coupling cap of the preceding stage in both cases, though...

Sure, basicly the coupling cap and 220k resistor should switch places and the 50k pot should connect between them to make it work the same as the Fender AB763 schematic.

In the Fender schematic the 220k resistors are there for mixing the two channels (normal and vibrato) together and are therefore last in the signal chain before the next stage. Placing the 220k resistor before the 50k pot, like it is drawn in the aligator schematic, results in a voltagedevider with more then 80% signal drop.

[sergio]

I think placing 220k res after 50KA pot the final volume is gained, but the vibrato effect will be hardly noticeable!
I'll do a test with 220k res.
Thanks
Sergio

[sergio]

with 220k res after 50kA modulation pot, the vibrato has no effect , so I decided to change the method to mix the vibrato effect with a dry signal.
I'll tweak the mixer stage.
Thanks all for the helps

Sergio