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DIY Stompboxes => Building your own stompbox => Topic started by: black mariah on December 01, 2004, 09:48:08 AM

Title: What actually makes the distortion...
Post by: black mariah on December 01, 2004, 09:48:08 AM
...as far as components go? I still don't understand exactly what each component does as far as augmenting the signal. I know what individual components do and how they work, but not how they change the sound. :?
Title: What actually makes the distortion...
Post by: MartyMart on December 01, 2004, 09:59:28 AM
Please forgive me if i'm getting this wrong, but lets say you use the inverted side of an op-amp,  stick a pair of diodes over it, are you not just making the sound "break up"  by sending a little too much voltage through them, ie: lower rated diodes like 1n4148 will "break up" more readily than LED's, who's voltage rating is higher ??

Thats how I understand it in that situation, I'm sure there's a much better technical explination, but I like "stupid laymans" terms myself !!

Cheers,
Marty. :)
Title: What actually makes the distortion...
Post by: RDV on December 01, 2004, 10:00:32 AM
http://www.geofex.com/effxfaq/distn101.htm

RDV
Title: What actually makes the distortion...
Post by: RedHouse on December 01, 2004, 10:06:29 AM
This doesn't answer your question but it's hard to visualize these things without an Oscilloscope, surf e-bay, you can get a used dual trace for under $100 that is well good enough for audio work.

With an O'scope you can see exactly what/where/when you get distortion (and many other things) by applying a sine wave to the circuit input and monitoring it with one trace, then using the other to probe to move along through the circuit comparing the two traces you can see where the signal changes and how it changes.

Once you get into using an O'scope, you'll hardly ever use anything else in debugging. I avoided buying an O'scope for years, but then after I did, I kicked myself for not buying one years ago, once you get one you can trace things through your circuit and learn/fix things that were beyond your grasp before.
Title: What actually makes the distortion...
Post by: black mariah on December 01, 2004, 10:17:35 AM
I should be clearer. I know that distortion is caused by the signal being clipped.... but HOW is it clipped at the component level? How is it that a transistor set up one way is a clean boost, but add a cap here and there and it becomes a fuzz? It makes my brain hurt... :lol:
Title: ..
Post by: petemoore on December 01, 2004, 10:40:12 AM
The transistor can only swing pos and neg so far, using 9v. When it tries to make an accurate amplified replication of a wave, and runs out of room at the top or bottom of the wave to swing that far, it clips the peak of the _ or + wave, causeing a distortion of the wave shape.
  If resistors are used to set the gain of a tranny lower than what would cause it to clip, cleaner boosts are available. If input is attenuated enough to cause the transistor to run within its clipping threshold, cleaner boost is available.
  Reads around the area here [links etc] explain it much better than this, excuse if I miswrote...something.
Title: What actually makes the distortion...
Post by: RDV on December 01, 2004, 11:22:54 AM
Here I'll try again. This is simpler.
http://users.chariot.net.au/~gmarts/ampovdrv.htm

RDV
Title: ..
Post by: petemoore on December 01, 2004, 11:41:07 AM
Thanks RDV, my memory is too selective, I can remember the useful content of info, [in my own 'Petespeak'  :P  as someone put it] not always the sources.
  For someone building and forming questions like these, it probably is behouving to read through alot of useful [and deemed at that time useless] other stuff to find the particular answer you desire, often times the answer entails alot more than the specific question adresses.
  Looking for a simple answer often raises new, more complex questions.
 Simplest answer I can muster...transistors distort by clipping the peaks of a signal when they run out of room to amplify in their linear range.
Title: What actually makes the distortion...
Post by: niftydog on December 01, 2004, 06:58:10 PM
Quote
but HOW is it clipped at the component level?


a diode only conducts in one direction. ie; a diode will pass a positive voltage from anode to cathode, but not a negative voltage.

A transistor is similar to a diode in construction.

The other way is to simply overload an amplifier. Say your amp runs from a 9VDC battery and you're asking it to produce an output signal of 12V peak to peak. Well, it can't, obviously, because it doesn't have enough voltage to work with, so the signal goes up and up until it hits the 9V threshold and then it clips.