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No sound at all on double-checked superbasic distortion circuit...

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bob91343:
I don't think a well designed circuit is intended.  Whoever invented this probably cobbled together the parts he had and then published it without regard for parameter spread or temperature stability.

With that in mind, perhaps adjusting the 2.2 Meg resistor over a wide range might locate a satisfactory operating point with, of course, the desired distortion.  Try values from around 100k up to 10 megohms to see what works.  You want about a tenth of a volt on the emitter.

John B:
But this goes back to what the circuit is actually supposed to do. What is the input voltage range? What should the output look like? Is it supposed to add some 2nd order distortion "overdrive" or is it a total tone crushing circuit?

bob91343:
As I said, the chances are that it wasn't designed.  It was just cobbled together and fussed with until it worked.  That kind of circuit doesn't lend itself to precision design.  And it's likely that it doesn't keep working as it warms up.

If you want distortion, you need to decide what sort of response to look for.  Usually it's clipping that people want.  So a signal needs amplification to the point where it can be clipped by, say, some diodes with a reverse bias.  And you need gain controls on both input and output in order to have decent control over the setup.

SiliconWizard:

--- Quote from: John B on May 26, 2020, 01:22:16 am ---But this goes back to what the circuit is actually supposed to do. What is the input voltage range? What should the output look like? Is it supposed to add some 2nd order distortion "overdrive" or is it a total tone crushing circuit?

--- End quote ---

Assuming biasing is properly adjusted - which likely will need manual trimming here - it won't be anything more than some kind of crude "fuzz" distortion - the typical hard clipping, which sounds really awful, but was popular at some point. You may like it. Playing with biasing will also allow to get somewhat asymetric clipping, which may introduce interesting variations in the distortion effect, but again don't expect much from it.

TheUnnamedNewbie:

--- Quote from: SiliconWizard on May 26, 2020, 02:33:45 pm ---
--- Quote from: John B on May 26, 2020, 01:22:16 am ---But this goes back to what the circuit is actually supposed to do. What is the input voltage range? What should the output look like? Is it supposed to add some 2nd order distortion "overdrive" or is it a total tone crushing circuit?

--- End quote ---

Assuming biasing is properly adjusted - which likely will need manual trimming here - it won't be anything more than some kind of crude "fuzz" distortion - the typical hard clipping, which sounds really awful, but was popular at some point. You may like it. Playing with biasing will also allow to get somewhat asymetric clipping, which may introduce interesting variations in the distortion effect, but again don't expect much from it.


--- End quote ---

I imagine this circuit came out of some 'playful simple pedal circuits' type book. I suspect nobody makes it expecting the most amazing tone ever, but it is just fun to play around with.

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