No announcement yet.

Modified MBB results

  • Filter
  • Time
  • Show
Clear All
new posts

  • Modified MBB results

    So, I got a general guitar gadgets marshall bluesbreaker a while ago. I had some MA856 diodes from a few years ago that I held on to, and I used them.

    I've heard on the internet and therefore cannot back up with any actual facts or what have you, that the KoT is based on the bluesbreaker.

    This blog had a guy modding a vintage one to KoT specs (supposedly) - at any rate the schematics I used were on that page.

    The interesting thing is how close the GGG MBB circuit is to the KoT circuit (with the exception of the additional clipping stages) - you change R2, R3, add a resistor to the gain pot to change the sweep, swap out R9 (it's something like R6 on the KoT page but R9 is the one you want to replace with a carbon comp in the GGG MBB), and you change the tone control capacitor from a 47 pf to a 100 pf, and C10 (this is what I have in my notes at least) to a 1uf (from a .1uf)

    That's it! I'm not even sure how necessary it is to change the diodes (IMO 1n4148s sound close enough to the ma856 that it isn't worth the search unless you're a masochist), and you're there.

    The only thing is, I left c10 alone because I forgot to order a 1uf replacement capacitor. So it's kind of an in-between now. I'm leaving it as is because I'm afraid it will make it a better stand alone boost - my goal is to use it with an EP boost kind of pedal that (with many thanks to midwayfair at madbean) will run a transistor that's a work-alike to the one found in the original echoplex, at a voltage (~23-24v) that's closer to the original EP than a lot of contemporary pedals.

    It's late right now, but when I get around to recording some samples I'll upload them to sound cloud. Initial impressions are:

    - More distortion
    - Sweeter sounding
    - Tone control still not super useful above noon

    The changes have been very subtle. I imagine it's that one cap - c10 - that makes a huge difference. Right now, it's like the GGG MBB pedal, with just this little something extra. Maybe not as dry sounding, I don't know. But, If I was still on the market for a DIY boost/OD pedal, I'd strongly consider picking up the MBB and getting a few extra components from mouser for the conversion. It's very good.
    Originally posted by ImmortalSix
    I wouldn't pay more than $300 for a BJ.