Marshall MG15CD - Any mods??

[techno-rachit]

Hi,
    this is my first post in this forum and i find this forum really very interesting!
    I have a Marshall MG15CD and and i'm interested to do some tweaks in it.
    I want  some improvements in the overdrive section.Like a mod of increasing its gain. The clipping happens because of 2 LEDs (Red and Green) . Can the gain be increased by using 1N4148s or 1N914s instead of the LED's ??
If yes, then what are the other changes that i need to do??

Help is appreciated

Thanks and Regards

[J M Fahey]

The MG15 as-is is a very good amplifier, and probably has as much gain as what you can get from those parts.
Using regular silicon diodes would increase clipping, but at the same time lower the available signal, don't know if it's worth it.
In a way it's similar to what happens with classic Randalls.
Personally, I would build a simple distortion pedal (MXR Dist+) and use it as a booster.
The main distortion will still come from the Marshall.
You will have much less grounding and oscillation problems because it will be contained in its own metallic box (or a foil covered plastic one).

[joecool85]

I agree with Juan, modifying your Marshall to get more gain would likely be much more difficult than just changing the diodes.  And in that vein, I agree that building a distortion pedal to put in front of the amp makes more sense.

That said, changing the clipping diodes will affect the type of distortion (IE - how "sharp" it is etc).  If you are interested, it would make sense to pull the original LEDs and solder in some sockets so that you can try different diodes.  Then you can play with it as much as you like.  You very well might find that you like the sound of a clipping 1n914 over the LEDs.  Or you might try some other LEDs if you it turns out you like that sound.  Different color LEDs clip at different voltages.

Give it a go if you'd like and let us know how it works out!

**edit**

Also, Welcome to the board!

[techno-rachit]

Well!! thanks for the replies! Even i liked the idea about the distortion pedal....and i also liked the idea of putting sockets for checking the clipping level. I have a few queries. Will testing the marshall with other diodes harm the surrounding part of the op amp? And can i use 5mm leds instead of the 3mm ones??                                                                               Regards :-)

[joecool85]

No harm by trying new diodes.  You can use whatever size LED or regular diode you want - some might sound awful, but it won't hurt the amp at all.  You can also try mixing diodes (one LED and one 1n914 for instance) or even just using a single diode.

[techno-rachit]

Thanks a lot :-) i will turn back with the results within some days as soon as i get time to play with the amp!    Regards

[kin0]

I have a question about this amp that is not really connected to the thread. I hope you have no problem with me asking it. 
How is this amp in taking high gain pedals (I mean using the clean channel+pedal) compared to other amps (a small tube amp like black heart or a hifi chipamp)?