Fallstaff OD, or "Fat Mastered" from Jon Patton. It's a modern take on Rangemaster with a few quite cool features. I replaced 8K2 resistor from Q2 base to ground with a 20K trimmer for easier biasing.
From Jon: The Fallstaff overdrive (or "Fat Mastered boost") is a variation on the Rangemaster, but with a buffered input stage and a color knob to fatten the sound in a way that offers a nice change from the usual input cap mods. It can be tweaked to sound a lot like a traditional rangemaster, as a full range boost with sparkly top end, or as a dark mids boost. The extra input stage makes the pedal behave the same whether it's before or after another pedal. It provides a 20db of boost or more depending on the gain of the transistors you use. Unity volume on my prototype was about 10:00.
For Q2, values as low as 35hfe were acceptable with proper biasing, but gain ranges around 50-60 are ideal for the values shown. I got decent results with values as high as 120hfe. NPN Si transistors in that range will work, too. R5 and R6 bias Q2, like a rangemaster, to ~7v on the collector. Use sockets or trim pots or breadboard before building if your transistors aren't pretested! Q1 can also be a JFET. I used 2N2925 instead because it sounded really good and I didn't have to twist the leads to get it in the sockets in my layout.
Here's a collection of vero (stripboard) and tagboard guitar and bass effect layouts that we have put together covering many classic and popular effects in growing numbers. Many of these have been posted on freestompboxes.org, so check that site out for great discussions on building your own effect pedals. Enjoy the builds and please also visit us on Facebook and Twitter
Hey, sorry about this, but I made a mistake in the schem a long time ago, and kept copying it over until recently. That 1M resistor should be 22K. (At some point I had a default value of 1M and missed it until I was building the BOM.) Here's a link to the build doc with the current schematic for reference: https://docs.google.com/document/d/1033QEzKtTQJ0B3pTqJyp3mo-y4V7ErbM35hi3phTJLI/edit
ReplyDeleteThe trim is a good idea. I probably should have used one on my PCB, but I was (maybe overly) concerned about noise.
Sorry for any inconvenience this might have caused anyone. The 1M won't break the pedal, but it will keep the diodes from doing anything. :)
-Jon
Thanks Jon! I'll fix the value on the layout.
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Made this and boxed it - nice thanks.
ReplyDeleteAnd one more.. :)
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Nice one David, you've been on fire!
Delete14x11 not 15x11
ReplyDelete