Built the MXR Microamp...seems to work but is this normal ?

[Incubus]

It's the one from tonepad with the 4558.

At high pot settings above 75%, with my pickup using both coils, it gets a nasty distortion...not the good kind but one that is kind of crackly. If I turn down the gain a little (on the MXR), it goes away. I checked with a cro and whats happening is that the signal is being clipped, more in the positive direction than the negative.

So I tried a TL 072, and the clipping still occurs (with the pickup using both coils)at roughly the same gain setting, but on the cro it's more even (top and bottom of the waveform), but still sounds like garbage. If I backoff the gain, it's ok though. When I turn one of the coils off on my pickup, I can set the gain on the MXR to full, and it will not distort at all.

I'm just wondering if it's normal to get distortion of the signal on an actual MXR Microamp ?

I've never played thru one so I don't have a clue.......inspected the board and all seems correct.

Any help much appreciated.

[Fret Wire]

Assuming everything is wired and soldered correctly, yes that's normal. Usually at around 3:00 pot rotation, the unit starts adding it's own distortion. And no, it's not very musical.

I usually get all the boost I need before I hit that point. You're not getting enough? Double check your IC voltages and wiring. A proper running unit will have good boost and then start to distort around 3 oclock. If there is a ground or other problem, it still may behave the same way, but have alot less gain, making you push it into the 3 o'clock territory.

[Incubus]

Thanks......

I'm getting alot of boost, all that I need in fact, but I just wasn't sure if the original MXR unit went into distortion at any point.

Since mine does, it seems to be working as you've described.

I guess all is well....thanks for the response !

[Fret Wire]

You're Welcome. Nice little booster, ain't it?

[petemoore]

There should be alot of output, that amount could easily drive whatever comes after it into 'not normal' sounding distortions.