That MG15 pre-amp looks similar to the Guv'nor pedal also produced by Marshall. Guess the sound could be similar. But a believe there are two important differences that could make the distortion sound different;
- Guv'nor uses two red LEDs to produce (symmetrical) clipping, with one green an one red LED, which the MG15 pre-amp uses, the clipping should be asymmetrical if I get this right?
- Instead of connecting the diodes to the ground like the Guv'nor, the diodes is at the feedback (not sure about the thermology here so feel free to correct me if I'm wrong) of the op-amp. This usually produce a softer clipping than putting them between the signal and ground. But the MJ4558 use in the MG15 is described as an "high gain op-amp" in the data-sheet (Guv'nor uses the old familiar TL072). So I don't know, I guess it can clip quite hard anyway.
I'm also looking for a good metal pre-amp and this one really looks interesting. One that sounds like the ProCo Rat (best metal distortion ever IMO) would probably be better, but maybe this one can work.
- Guv'nor uses two red LEDs to produce (symmetrical) clipping, with one green an one red LED, which the MG15 pre-amp uses, the clipping should be asymmetrical if I get this right?
- Instead of connecting the diodes to the ground like the Guv'nor, the diodes is at the feedback (not sure about the thermology here so feel free to correct me if I'm wrong) of the op-amp. This usually produce a softer clipping than putting them between the signal and ground. But the MJ4558 use in the MG15 is described as an "high gain op-amp" in the data-sheet (Guv'nor uses the old familiar TL072). So I don't know, I guess it can clip quite hard anyway.
I'm also looking for a good metal pre-amp and this one really looks interesting. One that sounds like the ProCo Rat (best metal distortion ever IMO) would probably be better, but maybe this one can work.