Fairfield Barbershop Overdrive

[closetmonster.]

Hey folks!

A little history. I play rhythm guitar in an alt-folk band and given the style of music, for the first year or so I was constantly struggling with a balance between too quite or too loud, too much gain or not enough, etc. I had tried quite a few pedals to solve this problem including a tubescreamer, a cheapo danolectro OD and the voodoo labs sparkle drive but nothing quite fit.

This little beauty caught my eye in my local shop one day and I had to take it home with me. The transparency, responsiveness and variety of tones I could get out of this box astounded me. Solved all of my problems, now it is the base tone of my sound. If I need a little extra hair, I just hit a clean boost before it.

Just give it a listen.

Luckily Guillaume (the creator of the pedal) has made the schematic readily available, with the help of WhiteKeyHole.


From La Revolution Deux blog:

So what have we got? It's two cascaded Jfet gain stages followed by a simple NPN transistor emitter follower. The mosfet device is there for polarity protection. The 10kB pot is the "Sag" control that affects the overall supply voltage to the circuit and the clipping in the cascaded jfet/emitter follower stages. Guillaume has suggested that he sets the bias of the two jfets at around 2/3 of the supply voltage (when measured at the jfet's drain). I'd replace the drain resistors with 25k trim pots which will allow you to dial in the 6.66v bias point a little easier than using trial and error with set resistors.

Here's a vero layout by IVIark:


Aaaaaand here's a demo of the build:

Please note that none of this is my work. I am just trying to make it readily available for anyone who is looking for an overdrive... Or is bored.

I personally plan on building one of these with a rangemaster in the same enclosure, once I've gotten a bit better.

Have fun!

[closetmonster.]

I just realized, should I have put this in the schematics section?

[Jopn]

This one has been on my "to do" short list for awhile now.  I had never heard it recommended for lighter OD "folky-er" music, but that recommendation is bumping it up a number of spaces on the list.

So many awesome pedals, so little time. 

[closetmonster.]

This thing is a tone machine, it never gets turned off on my board.

I would say we're more on the alternative side of the alt-folk spectrum as of late, but I would recommend this pedal to anyone. No matter the genre they play.
Save perhaps for grindcore 

Another nice thing about it, is it plays very well with others.
If it's after a fuzz, you can tweak the sag down and get some pretty nice sputtering going on.

[GoranP]

a word of warning... i've built one from Mark's vero layout and i can't get it to sound right. it sounds good but not like in the clips. if you are going to build this be prepared to audition a bunch of j201s to be biased just right with the resistors that are asked for. either that or replace the biasing resistors with pots.i honestly didnt examine the schematic in detail and see whether it's the same thing as wampler black65 where the biasing resistor also affects the tonestack and the biasing pot influences the tone. hopefully someone else can chime in on this.
also, i may have misread this someplace but i think that Guillaume himself wrote someplace that the jfets in this particular circuit are biased to 2/3 supply voltage.

[Jopn]

..i may have misread this someplace but i think that Guillaume himself wrote someplace that the jfets in this particular circuit are biased to 2/3 supply voltage.

bingo.  The 8k2 and 9k1 are odd values for that very reason, they were tweaked to whatever jfets were in the dissected pedal.  A trim pot or at the very least some sockets would be advisable.

[closetmonster.]

Yeah, it's in the notes.

Guillaume has suggested that he sets the bias of the two jfets at around 2/3 of the supply voltage (when measured at the jfet's drain). I'd replace the drain resistors with 25k trim pots which will allow you to dial in the 6.66v bias point a little easier than using trial and error with set resistors.

I think the key is experimentation when it's still on a breadboard.

As it stands, this build is a little over my head. Gotta get through my current build list then tackle it.

[closetmonster.]

For curiosity's sake, I'll have to check the values of the resistors on mine.

[Mark Hammer]

Guillaume is a local guy.  I've chatted with him and his brother on several occasions.  Both terrific guys.
Guillaume gets the legending done by a buddy of his who sits with a set of punches and legends each chassis.  He probably needs to switch to a different method if his demand/output ever picks up significantly, but one thing I have to say in its favour is that the pedal is probably going to look exactly the same 4 years from now as it did when you bought it.

Give him your business.  He deserves it.

[rutabaga bob]

I put up a perf layout on the 'other' forum, if you prefer perf.  Larry

[closetmonster.]

Give him your business.  He deserves it.

I agree completely, all of his designs are great. I more posted this in the spirit of DIY and to give this original design some exposure.

Sorry if I offended Mark.

You go by mhammer on the GuitarsCanada forum, don't you?

[Mark Hammer]

Yes I do (was somehow prevented from using my full name there), and no you didn't offend.  I'd just like to see him get a little more out of his efforts, and if folks can afford it, great.

[Plexi]

Thread reborn 

I was messing around with this circuit a bit.
Nice clean / transparent overdrive. Not too much gain, but tons of volume output.

Due J201 inconsistencies (I've never deal with another J-fet so problematic like these..) the important thing here is to get 6,6v to Dv with Sag pot at min (no resistance). Avoid values over R5 and R7.. and made your own way there.

Is possible to get more gain?