Fulltone 2B - Great Boost with limiter

[cjonesplay]

Exactly - this is what I’m talking about with the switch;)

[fx-fidden]

So, the layout should be ok, we have to remember the output cap is still reversed.
I'll correct it and label it as verified just in case cjonesplay can try it with a more traditional amp or another guy build it succesfully, too. This could be me. Who knows?

[cjonesplay]

Sorry for the delayed response. I finally built my TPA3118 amp (which is awesome, btw) and had a chance to check the 2B with the amp. I can verify that there is no volume boost when the level knob is full CCW, so you can build this if you’d like a nice boost with an attack knob:) thanks again for the layout!

[fx-fidden]

Thanks to you for verified the layout!

[kragg]

Hello,
Thank you for this layout!
To make it suitable for bass, should we just increase the 100nF cap?

In the end, did the 2nd layout posted on the first page (which is said "verified") really ok (with the right capacitor orientation), or should we reverse the output cap (like written in the post above)?

[fx-fidden]

The second layout is totally correct.

I think it works great with bass guitar, too, with any loss of low end.
Input cap 100nF and output cap 10uF are so large that is useless increase them.

[kragg]

Hello,
Perfect, thank you :)

fx-fidden wrote

The second layout is totally correct.

This is what I realized after looking at the schematic, but I wasn't unsure after reading the comments.

fx-fidden wrote

I think it works great with bass guitar, too, with any loss of low end.
Input cap 100nF and output cap 10uF are so large that is useless increase them.

Ok : I will be building it this week, thank you!

[kragg]

Hi,

Am I right assuming that, if i want the booster always, on, i could :
- get rid of the switch;
- remove the cut at A8;
- move the jumper (row 9, line A to B) to row 1, line B to D?

[fx-fidden]

If I understand, if you want the booster always on, as if it didn't have a switch, it's enough to leave out the switch, because is the connection of the pin 2 and pin 6 of the op-amp thanks the switch that make the circuit a buffer, bypassing all the gain part.

So without footswitch you have the booster always on, with no other mods of the layout.

[kragg]

Yes, that's it :)
Perfect, thank you!

Is it the GAIN pot value which defines the amount of volume boost? If I don't need 20dB of boost, should I try with a smaller pot value?

[fx-fidden]

Yes, it's exactly as you said.
So you could reduce the Gain pot at 50k to get 15db or at 25k to get 11db, but probably it will have effect to the sound and the clipping. It's like to set the original Gain pot lower.
If you like the sound of the whole range of the Gain pot I advice to don't replace that 100k pot, but you could replace the 100R resistor in the end with a 100k, getting around 14db. If it's still too much replace the 100k in the end to the ground with a 47k to get 11db. If it's still too much... well, this is the trick: higher value for the 100R and smaller for the 100k.

It was better if you could add a resistor between the 10uF and the 100k in the original layout instead to replace the 100R, but I think it's a bit hard to find a spot. Replacing the 100R, in the end, I guess it's not so different.

[kragg]

Thank you very much, FX Hidden.
I plan to use it on drum machines, with an already good volume, so i don't need a 20dB boost. 6 to 12dB will be more than enough :)
With all the information you provided, I have everything to experiment and tweak to taste.

If I understand correctly, if I remove the switch, I can get rid of the row #8 cut and row #9 jumper, right?

[fx-fidden]

Yes, without the switch that cut track and that jumper are useless.