Zendrive pcb: how to get more gain….

[Anonymous]

I just built the latest guitar pcb Zendrive… I remember the old original one I had having more gain.. which I liked… it mentions just putting a jumper in place of the LED in the instructions… will this increase gain? Any other ideas to get it closer to the higher gain original Zendrive?

[Barry]

Please post clear pictures of the top of the PCB that shows resistor band colors.

[Anonymous]

[Anonymous]

Barry, this is the only picture I have… I built it and gave it to someone…. Can you see what’s going on?

[Barry]

I wanted to double-check a few things before making a suggestion.

The resistor values look good, so there’s nothing to adjust there.

If you swap the Gain pot for a B1M, you’ll get more available gain. However, keep in mind that maxing everything out could introduce some noise or potential squealing.

 

 

[Anonymous]

Thanks, Barry! What’s would omitting the LED do and just bridging there…would it affect gain?

[Barry]

The LED is a clipping Diode. In this case providing asymmetrical clipping. So between the LED and the assymetrical clipping the idea is that it provides a more “Tube Amp” like clipping tone.

The B1M Gain pot will affect the Gain.

[Anonymous]

I’ll give the 1M gain pot a try and see how it goes! Thanks, Barry

[Chuck]

I’ve tried different ICs in the Zendrive in the past. While they don’t actually increase the gain, they may add a bit of color that gives the impression of a bit more gain. I’ve got a TL082 and a OPA2134 in different builds as well as the TL072.

Chuck

[Billy]

This version is exactly the same apart from changing the reverse polarity protection diode to a series 1N5817 which obviously wouldn’t affect gain

The gain of the op amp is provided by resistance in the negative feedback loop increasing that would increase gain as Barry says

The only thing I can’t clearly see is your LED orientation It’s difficult to tell whether you have the cathode flat side going to the flat side of the silkscreen

I’d also double check you have the correct value for the gain pot it’s easy enough to mix them up

 

[Anonymous]

Thanks for all your help!! I have another kit coming… I’ll dig in soon…

[Author]

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