Mosfet and Sparkle Boost Build Report

[80k]

Just wanted to thank Dragonfly, AMZ/Orman, and Torchy for the designs and layouts... Excellent boosts, and my guitar and amp has never sounded better!

I built the two circuits into the same box, Mosfet going into the Sparkle Boost, both footswitchable.  They sound excellent together.  Haven't had a chance to crank it yet (i always finish these pedals too late in the night, and don't want to bother neighbors!).

I noticed that the Mosfet Boost seems to be right around unity gain with the gain knob all the way down (is this right?)... The overdrive as i start to crank it sounds excellent.  

With the Sparkle Boost, i had a real hell of a time getting the drain to 4.5 Volts... That 100k trimpot was really hard to tweak, hehe... The best I could do is 4.6 Volts (i was afraid to touch it after that )  Does that 10th of a volt make a difference?

These are both excellent circuits, and I can't wait to play around with it some more tomorrow!

Here are the pics




BTW, that's a violet and a white LED... not sure why it came out both blue in the picture.

[mojotron]

Great job, you know on those trimmer pots, I just tweak it until it sounds loudest - I have no idea what the voltage ends up at the drain.

[80k]

Great job, you know on those trimmer pots, I just tweak it until it sounds loudest - I have no idea what the voltage ends up at the drain.

cool i should give that a try  
I adjusted it with my multimeter before i even plugged my guitar in

BTW, i just did a great test... connected 5 true bypass pedals together using the longest cables I had.  Probably had a good 75' of cable total between my guitar and amp.  Wow, the tone was horrible, and then i kicked in the Mosfet boost, and all the high end sparkle of my Strat and duncan pickups came right back to life  I can't believe how long i have been playing without a dedicated boost/buffer in the front!

[mojotron]

Ya, the other cool thing is to put a Fetzer/sparkle/MB boost circuit infront of an overdrive circuit with a BJT front end... So I have been re-implementing a lot of my overdrive projects, replacing the input stage with a J201 with a 5k resistor on the source along with a 1-10uF cap on a 5k pot, 1uF input cap, and trimpot on the drain. In every case so far this has made an improvement where the original circuit was not an emitter follower. It's easy enough to do and makes a world of differece on a strat, but more than a mod - it changes the nature of some pedals into something related, but very different.

I'll post some schematics/layouts in a couple of weeks when I have some of the tone shaping issues worked out.

[barret77]

Have you sanded the box? It looks nice.

[80k]

mojotron, cool, i'll be interested to see how you progress on that idea.  Sounds great!

barret77, yep, i wet sanded the box with just regular sandpaper, and then put some clearcoat matte finish on it afterwards.  I have been trying that out (did it with a recent muffmaster boost), and this one came out the best, since i was more patient and spent more time sanding this time

[Connoisseur of Distortion]

nice looking box, and very clever layout for the inside. 2 boards, 2 jacks, 3 pots, 2 switches, AND the battery, all in a b enclosure?  

[Mark Hammer]

Actually, those boxes are a bit bigger than 1590B's along all dimensions.  Not sure where 80k got his/hers from, but I bought some at Circuit Specialists.  The internal ribbing may not be "for your pleasure", but it sure is for your convenience.  For example, one could easily divide a circuit up into two boards (howzabout a Ropez/Ross with 8 phase-shift stages?) and slide them into the slots provided as both spacers and mounting hardware, with a few short jumper wires connecting the boards.

This particular chassis is a very nice alternative to 1590BB boxes in terms of usable space without being bizarrely shaped or sized.

[80k]

yep, i got mine from SmallBear.  CircuitSpecialists certainly has the best deal though... i think if you buy ten, you can get them at 4 bucks each.  (i'll probably do that someday).

Yea, i have been using 1590B's for years, and this was my first 125B box i've ever used, and the extra space felt like such a luxury