New Article: Scope Expose

[The Tone God]

I threw up a quick article with some scope pictures of the Big Muff Pi with different settings. Should be interesting for those who do not have a scope. It could also be handy for those with a scope trying to debug a BMP.

I hope I can turn this into a series with different effects as they become availible.

Enjoy.

The Tone God's Domain

Andrew

[aron]

rats.... exceeded allocation.

You just reminded me, I need to build my sine generator!

[will]

Hi Andrew,

Your scope pictures look great! Very interesting.

I was wondering about your statement
"Input signal: Sine wave, 440hz (Open A String), 500mV."

Is the open A string 440Hz? I thought it would be lower like 220Hz.

Keep it up great stuff.  

Regards,
Will

[Peter Snowberg]

Very cool!

Nice job!

For anybody who doesn't have a scope, Andrew's expose should be motivation enough to get one! Sometimes a picture is worth more than 1000 words.

It's interresting that most of the distortion is crossover distortion. I wasn't expecting that.

Take care,
-Peter

[Alex C]

Hey, thanks Andrew, I've never seen actual guitar effects on a scope.  Now I have an idea (sort of) of what's going on.  Thanks also for the detail with the knob settings.  Great stuff!

Alex

[WGTP]

Very cool article.  I think an open A is more like 110Hz.

440 is concert pitch :lol: for an orchestra, middle C?

[R.G.]

It's interresting that most of the distortion is crossover distortion. I wasn't expecting that.

You still shouldn't be.

What may look like crossover is the time splattering effect of the tone networks on a clipped waveform. The BMP is all class A stages with negative or zero feedback. Crossover distortion in the normal sense of the term can't exist there.

[ExpAnonColin]

Cool... I was doing the same thing the other day with my big muff, believe it or not.

-Colin

[The Tone God]

Thanks everyone for the comments.

I have to say that after my soldering irons and breadboards my signal generators and scopes are the most useful tools I have. I don't know how I could make new effects or work on things without them.

I think I'm going to do a wha pedal next. I have a stock Crybaby lying around. I may throw it through the spectrum analyzier as well.

For the record A4 is 440hz, A3 is 220hz, A2 is 110hz. Middle C is 261.63hz. Geez I thought there were some musicians here.

Andrew

[Phorhas]

I wanna scope too :!:

:cry:

[Sic]

OMG, thats awesome... totally makes me want to get a better understanding of how all this stuff works. I need to find some book at a goodwill or something. the internet is a great medium, and you can find most anything... but i think it would be more helpful to sit with a book and READ.


those pictures are nothing less of an inspriation...


The other day i figured out that taking an AC signal and putting diodes in there would make it DC... that just gave me chills...


must sound weird... but knowledge is  amazing.


Thanks andrew

[WGTP]

I'm not sure which is worse, my musicianship or my physics :shock:

Still it is really cool to "see" what is going on.  Spectrum analysis is cool to.

[Doug H]

Perfect examples of why I hate the BMP tone control.  

Seriously, though. That's pretty informative. Those smooth triangles that show up with the tone turned down look familiar. I've seen those in a lot of PSpice analyses I've done on high-gain circuits that are filtered to smooth them out. My ears associate the real sounds of those circuits pretty closely with the BMP with tone rolled off. So it's good to know Pspice doesn't seem -that- far off...

Thanks!

Doug

[Paul Marossy]

It is indeed very interesting to see what waveforms look like when you tweak the controls, and at different parts of the circuit. Most of the time, it is not anything like I am expecting to see!