Tube Screamer Clone Testing and Waveform Analysis

[aquitania]

Hi everyone, I'm new to the forum but I've been building effects (and amps) for several years now.

One of my first projects was a TS808 TubeScreamer Clone. I bought the PCB off tonepad, and all the parts from small bear and completely butchered my first try. It took me a while to get to point where I could plug my guitar in and they're still be noise coming out of the amp after I hit the bypass

So now, I'm at University I have access to an oscilloscope, a signal generator and screen capture software. So I decided to take a look at the clipping characteristics on a sine wave.

So here's my thing, I actually have no idea what it's supposed to look like!! I don't actually own a tubescreamer (and don't have any close friends with one) and haven't found any references online.

So here's my deal: can someone or somepeople answer me a few questions:

1. Do the waveforms look like they should (I want an accurate clone of a tube screamer)

2. I'm pretty sure my two diodes are the same (its pretty hard to tell without removing them), so why is the clipping asymmetic?

3. After some playing around I saw that the drive pot does virtually nothing to the waveform (or maybe I'm just expecting a more noticable effect), is this correct, or did I mess up my wiring/ have garbage connections or something.

hopefully someone can help me out or make some constructive feedback or point me in the right direction or point me to a person that I could ask.

So here's an album I made of a variety of simple tests. Each photo is named and the levels are a percentage out of 100. I would've stuck em in a gallery but I don't know how yet. If you start at the bottom you can see the input waveform and then moving upwards gives my testing sequence.

http://www.flickr.com/photos/89178988@N05/

The test setup is as follows:

Tektronix TDS 2001C Two Channel Digital Storage Oscilloscope 50MHz 500MS/s
Global Specialties ProtoBoard PB503
GW INSTEK SFG-20044 Synthesized Function Generator
TDS 2001C OpenChoice Desktop

Tube Screamer TS808 Clone
Voltage: 8.88v (under load)
Voltage: 9.01v (without load)
Function: 440Hz Sine


Thanks in advance!!