Some green bean questions

[midwayfair]

This is on the chopping block but not getting soldered until I know what parts to tinker with ...

First, what's my "required reading" on Tubescreamers?

Specific questions about the Green Bean:
1) Is the "Fat" switch just less bass cut, moving a high-pass shelf back further? I.e., messing with this and the bright mod section would produce more or less mid hump?

2) I was wondering if anything beyond the diode choice directly affects the amount of compression inherent in the circuit. C3 and R7 for instance. Will reducing R7 reduce the overall gain and thereby make it a little less compressed? Is C3 just the blocking capacitor?

3) Finally, I was wondering whether there's anything *really* offbeat (other than the obvious stuff like the OCD or altering the EQ) that can be done with the TS circuit. I don't need a ton of details, just want to know what's possible.

[irmcdermott]

First, what's my "required reading" on Tubescreamers?

His whole site is required reading, but here is R.G.'s TS article:

http://www.geofex.com/article_folders/TStech/tsxfram.htm

[jkokura]

The Geofex article on tubescreamers is like holy writ. http://www.geofex.com/article_folders/TStech/tsxfram.htm

1. I'm not sure, I haven't studied the schematic to be certain, but the concept sounds correct.

2. I think some people get confused by the word 'compression.' I see it thrown around a lot when it comes to guitar pedals and amps, and it's worse because some of our pedals are 'compression' pedals. Add in the concept of compressors from recording usage and you have an over used under defined word.

In this case, I think it's simpler to use the word 'clipping.' the diodes in the circuit 'clip' your signal, which introduces distortion on the sine wave. In that sense, it simulates compression from a tube amplifier, which in a sense is a form of compression.

The amount of clipping is directly related to the signal fed into it. Your suggestions about playing with C3 and R7 sound like fun, and you should try it on a breadboard before building if you're wanting to tweak.

3. I'm not sure about what you mean by 'really off.' Perhaps that's just terminology you're familiar with that you think we would be, but perhaps you should describe what you mean better?

Jacob

[midwayfair]

The Geofex article on tubescreamers is like holy writ. http://www.geofex.com/article_folders/TStech/tsxfram.htm

Thanks! I should have checked there first.

3. I'm not sure about what you mean by 'really off.' Perhaps that's just terminology you're familiar with that you think we would be, but perhaps you should describe what you mean better?

Woops, I meant to type "offbeat." Fixed that ...

[jkokura]

I dunno about the offbeat thing.

In some senses, you can do anything you want in circuitry, but then what you do ends up not being the thing you started with. So for instance, with the TS circuit as our example, as soon as you really start messing with it it's not really a tubescreamer at that point. That's why we have a glut of overdrive pedals available to us, because people start messing with the circuit and find something unique or special or quirky or whatever.

The typical things to do to a tubescreamer is to remove the input and output buffers, mess with tone stack and filters, and mess with the clipping diode and op amp choices. You can do other stuff, like add switches to select clipping diodes and such. I knew Dano at Beavis was working on an ultimate Tubescreamer to go along with his mega rat project. That involved switches for selecting op amps, others for clipping diodes, buffered and non buffered bypass, etc. If you wanna go all out, that's the joy of this hobby!

Jacob