Tube screamer only works at max

[moeburn]

Hey everyone, I just finish building this tube screamer on a breadbord:
http://www.generalguitargadgets.com/diagrams/ts-808_sc.gif

A couple mods: I added a third silicon diode (i'm using all 3 silicon) for the asymmetrical effect, and i replaced C8 with a jumper, because it was just sounding awful with C8 (tried 3 different caps, different types, same value, all sounded awful).  The chip is an LM358 and the transistors are 2SC1815.

When I turn the tone to full treble and the drive to max distortion, the thing sounds awesome, exactly like it should.  But if I try and get a less harsh distortion by turning the drive or tone down alot, all i get is clean guitar with the exact same harsh distortion on the hard notes.  If i play quietly, 0% distorted, if i play slightly louder, 100% distorted.

Is this a problem with the design of the circuit, or my parts, or should I be looking for a different pedal alltogether?

[aron]

The chip is an LM386 and the transistors are 2SC1815.

Does it really work? The LM386 is the wrong chip. You need a dual op amp for that circuit. Like a JRC4558 or TL072.

[moeburn]

by LM386 i meant LM358.  I'll edit that.

[seanm]

Sounds like a bias problem. I would check that all points labeled Vr go to Vr, not to ground.