Bass fuzz sim

[Gus]

Here is a bass fuzz idea.  I have noted people have been posting about bass fuzzes
Sometime I simmed I did not build this.  I don't know what it will sound like but it did look interesting running the sim.  Might be noisy.

Rat type fuzz section NOTE it is inverting and has a clipping diode potentiometer control adjustment
SW1 A and B is to have more interaction with a passive bass and cable
R10 is the fuzz gain control
R13 is a 10K control for 0 to 10K ohm
R17 is a 100K tone control like the Rat
R22 is a 250K gain control
R5 and R14 are a 100K Mix control
R28 is a 10K volume control
Vref is buffered and offset from 1/2 the power supply voltage

First stage is inverting gain of 1 with adjustable interaction with a passive bass and cable think FF with the switch closed
signal then splits to an inverting rat like circuit U2 and a cleaner inverting lower gain stage U3 with adjusted input high pass C18/R4 and low pass (R7 and R22)/C2 in the feedback loop
Tone and diode clipper stage is buffered by U6
Both sided are combined by the U4 stage

IC is one I found in the LT Spice models use three good dual Jfet input opamps of your choice.

Nothing original kind of a cut and paste circuit with adjustments made with the help of LT Spice.  Buffer/gain split to a cleaner stage and distorted stage and mixed back together.
What is a little different is SW1 DPST and how it changes the interaction with the bass the other is making the distortion stage inverting.

Comments, feedback?

[Widows]

nice work!

[ggedamed]

Interesting ideas! I like the adjustable clipping circuit around R13.
What do you think will be the effect of choosing an asymetrical reference as opposed to the usual ±4.5V?

[Bill Mountain]

How does R13 effect the clipping?

[pinkjimiphoton]

i wish there was a program where you could hear what schematics sound like. somebody smarter than me needs to invent one!!

[Gus]

How does R13 effect the clipping?

D1 to D4 are a full wave bridge that would not conduct if R13(or some other device) was not there.  If you had a 0 ohm setting for the 10K it would act like a two diode drop clipper.  As you increase the resistance you get two diode drops plus the voltage drop across the resistor.

Adding a resistor(s) to a diode(s) drop has been done before, this is using a resistor at the "DC side" of a full wave bridge as a variable load

[Bill Mountain]

Would this be similar to putting it in series with the diodes?

[ashcat_lt]

i wish there was a program where you could hear what schematics sound like. somebody smarter than me needs to invent one!!

LTSpice does it.  Looks like that's what was used above.  It's only sort of useful using the sine wave generator shown, but there's a way to use a .wav in that spot and get a .wav output.  I haven't gotten around to trying it, so can't say how close it is to "real world".

[Bill Mountain]

i wish there was a program where you could hear what schematics sound like. somebody smarter than me needs to invent one!!

LTSpice does it.  Looks like that's what was used above.  It's only sort of useful using the sine wave generator shown, but there's a way to use a .wav in that spot and get a .wav output.  I haven't gotten around to trying it, so can't say how close it is to "real world".

I'd heard about that and then never heard of anyone doing it so I figured it wasn't useful.

[ashcat_lt]

LTSpice in general is not exactly "user friendly" in the sense of modern GUI tech.  The .wav output takes a long frickin time to generate, and I'm not sure how or if you can do component sweeps or whatever.

On top of that, there's the question of creating an appropriate input file.  It's kind of difficult to get a good read on how the input might interact with your guitar.  You'd probably want something that goes up and down the fretboard with both chords and single notes, or maybe a few different files representing these different aspects.

Anyway, you can probably breadboard the thing in the time it takes to render the output.

[Gus]

Would this be similar to putting it in series with the diodes?

The resistor is in series with two diodes

[GFR]

Here's an example of LTSpice processing a wav file, by studying the files and reading the help you can figure out how to use it. With fuzzes and amps you may want to run the output wav file through a speaker emulator plugin or at least some low pass filtering

http://www.piacenzacalcio.net/youtube_browser.php?do=show&vidid=63sqqas_JOU

As already mentioned, it takes very long to process just a few seconds of audio, even with low sampling rates. "CD quality" sampling rates are not practical at all.

[Bill Mountain]

Where did you come up with the values for your bass pickup sim?