Catalinbread - Dirty Little Secret  [traced]

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EMG
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Post by EMG »

Hello friends! tell me please how to reduce the gain level in super lead mode? The minimum gain level in super lead mode is too high. lowering the 47k gain potentiometer resistor to ground just reduces the volume. how to reduce distortion only in super lead mode?

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Manfred
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Post by Manfred »

Try this with the trimpot in parallel with R20.
The lower the total resistance, the higher the input voltage of the stage can be before the output signal is distorted.
Catalinbread Dirty Little Secret SL-gain mod.jpg

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Lani
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Post by Lani »

Here is the build doc for V1, V1.5 and V2 if you are able to etch it yourself. I looked in my projects and don't have Gerber's for them but will start a PCB tonight when I get outta work
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EMG
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Post by EMG »

Manfred wrote: 06 Dec 2022, 11:54 Try this with the trimpot in parallel with R20.
The lower the total resistance, the higher the input voltage of the stage can be before the output signal is distorted.

Catalinbread Dirty Little Secret SL-gain mod.jpg
I made a jumper instead of a resistor.
this gave a slightly better result, but the gain is still too high. minimal gain in super lead mode is similar to AC/DC - Highway to hell. it's pretty high. Any ideas?

is it possible to put such a jumper instead of R15?

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Post by Manfred »

I made a jumper instead of a resistor.
this gave a slightly better result, but the gain is still too high. minimal gain in super lead mode is similar to AC/DC - Highway to hell. it's pretty high. Any ideas?
is it possible to put such a jumper instead of R15?
Yes, that is possible, the gain then goes down to about 60%, but that affects both modes.

Ok, then leave the modification of the second stage.

So it is needed to decrease the amplification of the first stage.
I have a solution for both modes, you can set the gain with trim potentiometers for each mode also for both, respectively.
I should know in which position of the SL/SB switch that corresponds in the schematic. Is the SL mode set when the toggle switch is in the normally closed position?

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EMG
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Post by EMG »

on the schematic, the switches are in Super bass mode, if I understand you correctly

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Post by Manfred »

Here is the modified circuit for both modes, the values were found with circuit simulation.
If there is an audible change in tone, then you need to select fixed values for the resistors and adjust the values of the capacitors that are connected in series to them.
Catalinbread Dirty Little Secret 1st Stage Gain Mod.jpg

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Post by EMG »

Manfred wrote: 07 Dec 2022, 09:16 Here is the modified circuit for both modes, the values were found with circuit simulation.
If there is an audible change in tone, then you need to select fixed values for the resistors and adjust the values of the capacitors that are connected in series to them.

Catalinbread Dirty Little Secret 1st Stage Gain Mod.jpg
Thanks Manfred! I'm sure it will work, but I have to check the board. I have found that when one of the terminals of capacitor C3 is disconnected, nothing happens. The sound does not change whether C3 is connected to the circuit or not. But it sounds really cool. Super bass mode works fine i think.

Tomorrow I will recheck the board and report the results.

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