Turn a Drive Master into a Blues Breaker?

[Madjong]

Hi!

I have had this Marshall Drive Master since I was a kid. But it doesn't come to use for My blues playing because of the out of control gain knob.

I know very little about modifying pedals. But can I somehow add resistors and caps in the gain section and make it a lower gain? Closer to the Blues Breaker? But still have even more options with the tone stack of the Drive Master.

Thanks

[mysteriousj]

Just did a quick google for the schematic... See the 3k3 resistor by the first op amp. That's what you should change, to get less gain you need to remove that resistor and replace it with a something higher. 6k6 for example will give you half the gain range of what you had before. If you notice a change in tone the .1uF cap you should replace that with 0.047uF but I'd just see how it sounds first.

Another option now I think about it... might be easiest to just stick a 100k in parallel with the gain knob. Will give you about half the gain, and save you messing around desoldering stuff. It will mess with the taper though, which could be good or bad thing I can't really tell off the top of my head.

[Madjong]

OK, thanks alot! =)
Thats exactly want I wanted to hear. I wasn't sure, because I am a complete noob at this. I feared it would change things further down the chain. But now I am in for a try. Hopefully it will turn into a Blues Master. =P

[Madjong]

Starting to think twice about this modification already. I found this page:
http://gmarts.org/index.php?go=217
And according to it, the Drive Master uses LED's instead of the Blues Breakers silicon diodes to shape the soft overdrive. I wanted a clone, more or less. But I don't think it will turn out anywhere near the same?

[KaosCill8r]

You could add a switch and switch between led and silicon. You might make something versatile and unique even if it doesn't sound like a Blues Breaker.

[Jero]

Starting to think twice about this modification already. I found this page:
http://gmarts.org/index.php?go=217
And according to it, the Drive Master uses LED's instead of the Blues Breakers silicon diodes to shape the soft overdrive. I wanted a clone, more or less. But I don't think it will turn out anywhere near the same?

The Blues Breaker has soft clipping in the opamp with 4 silicon diodes, which will probably be smoother and less crunchy than the hard clipping setup of the Leds to ground in the Drive Master. It's a doable mod, but just changing the diodes, without changing the placement of said diodes, will prob not get you where you want. A combination of the mod for lowering gain mysterious j posted, plus swapping the leds for something else, might get you close though.