Building a MJM London Fuzz... Any suggestions?

[Starcaster75]

I tried to order a London Fuzz, but it was out of stock, and there is no info on when it will be available again. So I did a search for the schematics and it seems like a very simple Fuzz Face circuit with a few mods. I would save a good bit of cash by building it myself. But can anyone tell me what has been changed from this page?

http://revolutiondeux.blogspot.com/2...-gutshots.html

I will use it with a 5E3 that has been modded to play clean and has a black face filter on the bright channel. With a weber 1265 ceramic speaker. This is a bright amp so the fuzz needs to be darkish and from clips on youtube etc. the London Fuzz seems very nice.

I have built a SHO on vero board before so I have a good bit of board left over. Would it be simple enough to build this pedal on vero board?
Thanks for the help everyone,
Claus

[JohnnyCrash]

Shouldn't be too hard.

Two germanium transistors... it's essentially an old school Fuzz circuit. Easy to tweak to taste (if you want it dark, that should be as easy as a cap swap).

Should be small enough to fit on a single square of perfboard (probably even less). I imagine you could cut a pretty small piece of vero to fit it on.

[Starcaster75]

Great! Thanks JC! How do you go about getting the germanium transistors? I hope this not too newbie a question, but this will be my first fuzz build ;)
Thanks,
Claus

[Blue Whale]

Howdy Starcaster75

The MJM London Fuzz that you are liking the tone of so much is a silicon transistor fuzz built around 2x BC108 transistors, a 70s fuzz tone.

http://www.mjmguitarfx.com/london2.htm

It's worth reading this paper/article "The technology of the Fuzzface": http://www.geofex.com/Article_Folder...ace/fftech.htm

It will explain a little about the differences between germanium and silicon transistors and also the PNP NPN differences. It's a very low power consumption circuit so I prefer to stick to the traditional battery only approach, and if using PNP types stick with +ve earth/ground.

Also there's enough here to help you, the build instructions have info & layouts: http://www.generalguitargadgets.com/...t/view/101/26/

Further the the text in link that you posted seems to have the caps reversed, I would suspect that the MJM London Fuzz has the 4.7uF on the input and the 0.047uF on the output #:o) also they are using a 10uF cap to bias the fuzz. So if you use those values you should capture their tone. They are still using a 100K feedback resistor, the other resistors used will depend on what transistors you use and how you want the run the transistors, follow the links above for that.

I hope that helps get you under way.

[Starcaster75]

Thanks for the reply Blue Whale!
Sorry if I got it wrong in the link I posted. MJM have two versions of the London Fuzz (I and II). The one I liked best in clips etc. was version one which seems to have germaniums... or am I wrong? Thanks for the links. I will go ahead and order the bits.
Claus

[Blue Whale]

I was looking at the wrong MJM London Fuzz, and had in my mind that a London sound was more "silicon".

I like germanium, a very organic fuzz tone, silicon is great in it's own way, a harder tone.

With making a germanium fuzz get the very best transistors that you can, that's where the sound is, and just keep the build nice'n'tidy.

It's a great circuit that belies it's simplicity.

All the best with the build.

[danroy]

bout to build this, myself.

in my opinion (!) sure you can tweak a simple circuit like the fuzz face till your face turns blue. but what makes a botique or well designed fuzz face sound good is a combination of very specific and usually more than two or three small tweaks. so copying these designs might pay dividends to the discriminating builder and tone hound. and yes of course getting good germaniums (no noise, not too much leakage, ideal gain "buckets") is quite a task! buying from Small Bear or certain eBay tested/matched sellers is obviously the best bet for a beginner like the original poster. You'll save time, effort, and probably money, plus they offer hard to find pieces that you really just can't find anymore, if you're into that sort of thing.

I have fun buying batches and testing them myself, though, using RG Keen's testing machine you can build as described in the link above

fuzz faces are so much fun and the differences can be subtle but relevant. I've built so far a Sun Face, '69 ish clone, and a Lunar Module, and they are all wonderful in different ways (the lunar module being very different from a regular fuzz face). no, I'm not done yet. Next up: London, JH-F1, and possibly a '70 or joe bonamassa. probably not that many though

oops, I'm a pirate! I don't feel too bad because I'm building them for myself though, and not to sell, doing all the work, and not as counterfeits

anyway, what a fun hobby. good luck with it!

next time check in with freestomboxes.org or diystompboxes.com for a community specifically designed around this subject

[danroy]

sorry the input and output capacitors should be reversed on that schematic.

.47 uF input cap, .047 output cap

waiting for my pots to come in to finish my build! Man I love fuzz faces!

[DOGMA Dunn]

Great info. That picture is like a seizure magnet.