MXR MC-401 CAE Booster/Line Driver - no clean gain.

[SilentBob]

I have built this but its not acting as a clean gain boost, clipping on everything but unity gain.

RC4558 around 4.3 volts on all pins but vcc+ 8.6v vcc- 0.
Checked values and placement, knife traces, re-soldered. still clipping. Any thoughts?

[induction]

I recommend using a signal probe to figure out where the clipping occurs.

[SilentBob]

Thanks, I will try that but I have now built this 3 times and swapped parts and it still has massive gain and distorts very badly. I suspect biasing or negative feedback issues but I have very limited knowledge. Frustration is leading me to  suspect that perhaps the diagram is wrong somehow and maybe others have assumed it's meant to do this?

[ξεναγος νεκροπολης]

you could upload clear high res photos of both sides here.
no. the layout is just fine. and your voltages are good. so there must be something else.
good luck!

[induction]

Are you sure the pedal is distorting, rather than pushing your amp or another pedal into distortion?

This is why I recommended the audio probe. If we know where the distortion is being generated, we can focus our investigation more appropriately.

For example, if there is no distortion at the output of the pedal, then the problem is more likely a low-headroom issue in your amp or pedal chain.

If there is distortion at the pedal output, then tracing the signal path with the audio probe can tell you where it's coming from, which will let us know where the build error or damaged component is.