Bad Bob Boost

SillyOctpuss

Well-known member
I know it's based on an AMZ mini booster but I don't know the component values to turn a mini booster into a bad bob and I'd love a tidy little PCB to build it on. I've searched for a bad bob schematic and keep seeing people asking for it on FSB, tagboard and Madbean etc and getting the same answer so I know I'm not the only one who wants it.
 
I can't see the value of the silver mica and electrolytic cap, but otherwise it looks like a stock mini booster...

1 x 1K
3 x 1M
1 x 47n
1 x 220n
2 x JFETs (J201?)


1625343998477.png
 
Lol I've been doing the same thing with this image because you can see the traces. It actually looks like a straight up amz mini booster minus the 100r resistor and 100uf electro to ground for 9v. I'm assuming the mica is 10pf like the mini booster because the other resistors and caps match up exactly. The only thing I can't see is the value of the electrolytic between the source and gate of q1. I can't tell if it's the original 3.3uf or if he changed it- to be fair I don't actually know what difference it would make to change that cap to a 1uf or 2U.

one of the other gut shots for that pedal show the jfets are 2n5457.

I'm about to throw it together using Mark's layout from tagboard. I'll socket the electro to find out what changing the value will do.

Screenshot_20210628-130109_Brave.jpg
 
I was looking to build my own Bad Bob boost, but couldn't find any details regarding differences from the AMZ boost, so that is what I built. It's one of my own etchings, the FETs are on the other side, it looks like I've used MMBF5457, but my schematic says J201, so I might have changed them after the build, but made no note as to why... which I appreciate isn't much help.
I should really box it up and give it a go, the fact that I haven't suggest I was underwhelmed!
 

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Well I built the stock amz mini booster using the tagboard layout and hooked it up to my test box. I plugged into my princeton and lost myself for over an hour playing with the amz booster, a madbean Aquaboy and some harmonic trem.

Sounds great and I'll be boxing it up tomorrow night in a recycled enclosure. I could have done it tonight but had entirely too much fun playing and lost track of time.
 
I was looking to build my own Bad Bob boost, but couldn't find any details regarding differences from the AMZ boost, so that is what I built. It's one of my own etchings, the FETs are on the other side, it looks like I've used MMBF5457, but my schematic says J201, so I might have changed them after the build, but made no note as to why... which I appreciate isn't much help.
I should really box it up and give it a go, the fact that I haven't suggest I was underwhelmed!
I love your board. It looks a lot better than my vero build.
 
I dug through my archives for my trace

following the amz schematic http://www.muzique.com/amz/miniboo.gif
R1: 1M
R2: 1M
R3 1M
R4: jumper (analogman eventually added this 100R back in the mini form-factor pcb)
R5: 1K
R6: 100KA

C1: 47n film
C2: 1uf
C3: 220nf
C4: omit (analogman eventually added this 100uf back in the mini form-factor pcb)
C5: 10pf mica (seen screenshots of it being ceramic as well)
C6: omit

Q1, Q2: 2N5457


When I built mine I found it pretty necessary to add the power filtering (r4/c4) when not using pristine power sources ... I added a charge pump because there's a fair amount of grit with humbuckers when running at 9v ... and I eventually added the Q3 buffer (see amz pcbs and premade modules) because I found an impedance mismatch with a few amps I used at the time.
 
some additional reading material from my stash re: the mini booster
https://web.archive.org/web/20170407165719/http://www.muzique.com/tech/minib1.htm (can't hide from the wayback machine)
http://www.geofex.com/Article_Folders/modmuamp/modmuamp.htm

digging through all that stuff has me wanting to revisit this circuit
Fantastic article. I never have much luck with the waybackmachine. It never seems to have archived what I'm looking for. The last time I tried to use it was when I was searching for that "looking for klonfirmation" blog mentioned on the madbean forum but no dice
 
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