BAJA Brighton Fuzz - (an updated silicon fuzz face variant)

bajaman · Post by **bajaman** » 05 Jun 2010, 10:01

Hi folks
It has been a while since I posted a new project - my apologies

I have a number of projects "on the go", but nothing ready to share as yet - when they are ready I will publish them right here for all members to enjoy.
Anyway - this project was inspired by mictester and aquataur

, who both got me thinking about the good old fuzz face once again.
WARNING: no mojo here, so if you get off on paper and oil capacitors or carbon composition noisy resistors etc., do not bother to read any further.

As suggested by the aforementioned fsb members this project uses a buffer at the input AND at the output of a fairly traditional silicon fuzz face. I have however made a few subtle changes to the circuit which in my opinion make it a far more user friendly device to use particularly with wah wahs and other pedals before and after it.
I chose low current drain op amps for the buffers - I know I could have used my favourite 2SK117 jfets but I chose to go with the opamps for a smaller parts count and more transparent sonic properties.
I have built a prototype of the Baja Brighton Fuzz (photos will follow when I get the box back from the powder coater

)
It works extremely well in my opinion and has become an unexpected and valuable addition to my pedal board.

Currently i am running it before one of my Baja Real Tube Drive pedals and the combination of the two is spectacular to say the least.
It is extremely quiet in operation, even at high gain settings and has the added convenience of being able to be run from a standard negative centre pin 2.1mm dc power supply too.
Do not omit the 100 ohm resistor and 220uf electrolytic capacitor in the fuzz face power supply line though - unless you want enormous hiss

Enough preamble - feel free to ask any questions - I may be able to answer them, if not someone here is bound to oblige

Here are the files - sorry no BOM - count the parts and make your own list

All files are 600dpi and the scale is in tenths of an inch for the Americans and for those of us brought up on veroboard, stripboard etc.
The metric size is of course 0.254mm

This project is designed to fit inside a Hammond 1590B or similar size generic enclosure.
Happy building - if you cannot etch your own board, just PM Brian (member madbean on this forum) - he may be able to supply a PCB for this project.
Hope this is okay with you Brian

cheers
bajaman

BC549 and BC550.pdf: (51.24 KiB) Downloaded 290 times

BD139.pdf: (41.32 KiB) Downloaded 294 times

lolbou · Post by **lolbou** » 05 Jun 2010, 10:22

as usual...

Thanks!

madbean · Post by **madbean** » 05 Jun 2010, 11:15

This looks very promising! I have some epitaxial transistors on hand, but not bd139. Similar hfe though. I'm looking forward to giving it a try. Thanks, Baja!

bajaman · Post by **bajaman** » 05 Jun 2010, 11:20

Hi madbean
They should work okay - a low hfe for the second transistor is important in this design - you could also try MPSA42 or MPSA43 ( observe the different pinouts though - EBC not ECB)
cheers
bajaman

fosnal1950 · Post by **fosnal1950** » 05 Jun 2010, 11:48

Good show , Bajaman !!
I'm defenitely going to try it .

Alf

MoonWatcher · Post by **MoonWatcher** » 05 Jun 2010, 11:50

madbean wrote:This looks very promising! I have some epitaxial transistors on hand, but not bd139. Similar hfe though.

The BD139 (and similar) is really a great tranny for this application.

Greg · Post by **Greg** » 05 Jun 2010, 11:59

madbean wrote:This looks very promising! I have some epitaxial transistors on hand, but not bd139. Similar hfe though. I'm looking forward to giving it a try. Thanks, Baja!

epitaxial is just the method of manufacture...
Hfe should be the key... do you have any numbers to shoot for bajaman ? (nice work BTW - thanks).

fosnal1950 · Post by **fosnal1950** » 05 Jun 2010, 13:39

Bajaman as you already mentioned a low Hfe is important for the BD139 . I noticed that there are 3 versions: the 6 / 10 and 16 all going up in Hfe . So I should take the 6 ? My supplier only has the 16 I believe.

Alf

JOHNO · Post by **JOHNO** » 05 Jun 2010, 17:02

This is just fantastic, Thank you very much Baja.

devastator · Post by **devastator** » 05 Jun 2010, 22:55

looks interesting but do we keep the possibility of controlling the gain with the guitar's volume pot ? (that's one of the things why I like this circuit)

mictester · Post by **mictester** » 05 Jun 2010, 23:11

bajaman wrote:Hi folks
It has been a while since I posted a new project - my apologies
I have a number of projects "on the go", but nothing ready to share as yet - when they are ready I will publish them right here for all members to enjoy.
Anyway - this project was inspired by mictester and aquataur , who both got me thinking about the good old fuzz face once again.
As suggested by the aforementioned fsb members this project uses a buffer at the input AND at the output of a fairly traditional silicon fuzz face. I have however made a few subtle changes to the circuit which in my opinion make it a far more user friendly device to use particularly with wah wahs and other pedals before and after it.
I chose low current drain op amps for the buffers - I know I could have used my favourite 2SK117 jfets but I chose to go with the opamps for a smaller parts count and more transparent sonic properties.
It works extremely well in my opinion and has become an unexpected and valuable addition to my pedal board.
Currently i am running it before one of my Baja Real Tube Drive pedals and the combination of the two is spectacular to say the least.
It is extremely quiet in operation, even at high gain settings and has the added convenience of being able to be run from a standard negative centre pin 2.1mm dc power supply too.
Do not omit the 100 ohm resistor and 220uf electrolytic capacitor in the fuzz face power supply line though - unless you want enormous hiss
cheers
bajaman

Nice work! Thanks for listening to my ramblings!

Your design isn't far from mine - I started work on something similar after I put the "Philosophy" posting up here. The are some differences in mine - I used BC550 for both transistors, and 56k instead of the 100k from the emitter of Q2 to the base of Q1. I used 47p from base to collector of the second transistor (because I wanted some fizzy top to cut off later), and I fed the supply to the transistors through a 470R resistor and across a 47µF cap. I tapped the output of the transistors at a higher level point (though I kept the traditional bias point for Q2), so that I had level I could afford to lose in a passive "James" tone control circuit (which is quickly becoming my favourite). Your "Gain" control is slightly different to mine, but the principle's the same.

The only other significant difference is that I'm using entirely electronic switching and active bypass. The reasons are quite obvious - I can buy really good quality push-to-make stainless steel "vandal proof" push buttons for less than half the cost of the nasty, fragile, unreliable 3pdt foot switches that everybody seems to use. The electronic switching uses two or three cheap ICs (4013, 4066), and can be built small. It draws practically no additional current, and can drive LEDs easily. I use high efficiency multicolour or bicolour LEDs, which give clear indication of mode and battery condition. The push switches I use are also waterproof, which also aids reliability (the biggest cause of destruction of pedals on the road is ingress of liquids!). Active bypass just makes sense these days, and is effectively transparent apart from the lowered output impedance which allows long capacitive cables to be driven with minimal treble loss.

I hasten to add, this is not meant as a critique of your work - I'm impressed. Your is a very good approach!

mictester · Post by **mictester** » 05 Jun 2010, 23:13

devastator wrote:looks interesting but do we keep the possibility of controlling the gain with the guitar's volume pot ? (that's one of the things why I like this circuit)

The guitar volume control will still have the same effect as it would with a basic Fuzz Face. The only caveat is that you should put this pedal first in the chain, so that any amplitude-modifying effects aren't in the way!

jimbob_400 · Post by **jimbob_400** » 05 Jun 2010, 23:36

Currently unverified; I won't be building it soon.

I've got no time for building pedals at the moment

Enjoy.

jimbob_400 · Post by **jimbob_400** » 05 Jun 2010, 23:38

ibodog2 wrote:Perfect timing for a rainy day here.

My BD139 has HFE of 135. And I used a reverse audio taper pot for the gain.

Quick and sloppy audio clip (unboxed circuit into Pod X3). Starts with Gain and guitar volume all the way up. Then pull back a little on the fuzz Gain and play with the guitar volume after that.

The vero is easily changed to accommodate a different pinout for Q2 (R7 and the far right jumper). C10 is a little tight, but just use 16V electrolytic and it will fit OK.
Baja Brighton Fuzz vero verified v1.0.gif

bbf.jpg

You got there 6 mins before me on the post for a vero! hehe. oh well.

RnFR · Post by **RnFR** » 05 Jun 2010, 23:44

very cool. sounds great, too!

johnnyg · Post by **johnnyg** » 06 Jun 2010, 00:14

This looks fantastic - thank you Bajaman... and Mictester! I've been very curious to see what Mictester's original post would result in.

However!!!!

I must strongly object to the name - Brighton Fuzz

.

bajaman wrote: it will be called the BRIGHTON FUZZ (because that is where I live - New Brighton )

It should be New Brighton Fuzz!

Because New Brighton in New Zealand is not named after Brighton down south - but after New Brighton up here near where I live, at the mouth of the Mersey... I checked this out on Wikipedia

http://en.wikipedia.org/wiki/New_Brighton,_Merseyside
http://en.wikipedia.org/wiki/New_Brighton,_New_Zealand

bajaman · Post by **bajaman** » 06 Jun 2010, 01:06

Hi johnnyg - well I never knew that - thanks for the info

I was going to call it the New Brighton Fuzz but it isn't a particularly new circuit (well maybe a new adaptation of an old one

), and I could not fit New and Brighton on one line

Hi mictester - thanks for your inspiration with this design and your nice comments - I personally have never had any problems with the blue tpdt switches, but I too have used the CMOS switches on many occasions and they do work well at low voltages. I decided to put this project up as true bypass instead of buffered bypass, although it can be modified very easily for buffered bypass - I may redo the board layout to incorporate the buffered bypass function, but this is not really a problem in my pedal board situation because the output of my Brighton Fuzz connects directly by a very short high quality patch lead to one of my Baja Real Tube Overdrive pedals. A non buffered output could result in some treble loss if this is the only pedal one is using and the output cable to the amplifier input socket is longer than say 5 metres (or 15 feet for the Americans here

). Nevertheless it is a good point that you have made - thanks

Also thanks to ibodog2 and jimbob_400 for their vero contributions - I like using vero a lot - especially for guitar active preamps and one off designs.
For ease of manufacturing though I prefer the lazy way that one board holding all the components offers. I can expose, etch, develop, drill, stuff and test a fully working board without an enclosure in a very short space of time - i do get sick of stripping connecting wires

. But for a one off build there is nothing wrong with going the vero route.

The board layout is for off centred hole type PCB mounting jack sockets - i bought a swag of these from Aron over at "the other forum" some years back, but I think i cleaned him out of them.
I have noticed similar sockets in some of the current Peavey and Fender amplifiers. If someone knows a cheap source for these sockets please let us know. In the meantime I am sure www.tubesandmore.com have suitable sockets in stock.

One final note - I connect the chassis ground wire from the 100n capacitor in parallel with the 100 ohm resistor to the metal body of the tpdt footswitch.
I find it easiest to file a small piece of metal plating off the corner of the switch to make a good soldered contact.

Cheers
bajaman

atreidesheir · Post by **atreidesheir** » 06 Jun 2010, 01:25

I personally find this concept extremely stimulating. I have been brainstorming since mictester threw down the gauntlet in the fuzz face design thread. This will be my next build and I await mictester's layout as well. I expect to love both. I have fulltone 69 and 70 to compare. They are my personal benchmark for this tone. I am more than ready to move this design to the 21st century.

Bajaman, you are good example to me of how I should learn and share. I love the optical limiter. It stays on at the end of my overdrive/distortion chain at all times. It gives a beautiful gloss to my sound.
You are a man among men and I salute you.

bajaman · Post by **bajaman** » 06 Jun 2010, 01:31

hI - glad you like the optical limiter - thanks for the nice comments.
cheers
bajaman

atreidesheir · Post by **atreidesheir** » 06 Jun 2010, 02:18

I think you are a good example for us with much less expertise and experience. You innovate, inform, and share.

There are several wise men here that guide my thinking and show me what can be done.

Bajaman is the cordial college professor that will share a drink with the students and encourage and make them feel less overwhelmed.
Mictester is the gentleman scientist explorer and Mojo exposer.
Soulsonic is the mad scientist who says perfection can be improved.
Analogguru is the professor everyone dreads taking because they will make a bad grade after working their asses off to meet his challenges. They will avoid attracting his attention because it leads to being publicly tested. You also leave his class much smarter.
Briggs is the rebel professor giving the finger to the admin and all authority and inspiring students to challenge accepted forms.

You gentlemen are outstanding.