BENSON: Preamp

One of my older vero layouts for the Benson Preamp that I posted on Guitar FX layouts forum a while back - updated due to the bass and treble outer lugs being the wrong way around...

I have previously posted the point-to-point version, but I forgot to post the vero layout at the time.  I never actually boxed this one up, as I prefer the Fairfield Barbershop as far as JFET overdrives go.

It's a JFET adaptation of a Benson amplifier pre-amp.  Treble is a basic cap to ground situation - like a guitar tone control, and bass is cut, with the pot bypassing a small capacitor that limits how much bass can pass.

BENSON PREAMP - VERO LAYOUT

FAIRFIELD CIRCUITRY: Barbershop Millennium Edition

I just realised I had not uploaded a vero layout for my all-time favourite JFET-based guitar effects.  The Barbershop from Fairfield Circuitry.   

This is a workalike for the Millennium; if you want to make the standard Barbershop, remove the switch and the two capacitors attached.  The caps for the tone switch can be anything you prefer.

The JFETS:  definitely test the bias resistors on the JFETS.  I've listed stock values, but I had to use larger values to get mine to bias correctly.  Bias is really important on this, as is using real J201s.  If the sag control doesn't do much, you haven't biased correctly, or you have dodgy JFETS.   

FAIRFIELD CIRCUITRY BARBERSHOP MILLENIUM - VERO LAYOUT

This is one of the first circuits I ever built due to the simplicity, and it's hard to go past as a simple boost with a bit of fattening up of the signal.  

The Echoplex EP-3 preamp doesn't provide tons of gain, but it does work very nicely as a slight boost, or as an always on type effect.   I plan on adapting this to be the front section of a Valve Caster, to provide some extra grit. 

I used the Aion Electronics schematic, as I like the idea of the fat switch, but I did not include the volume control or output buffer.  Pretty easy to add a volume control, I'm sure anyone reading this knows how.  

ECHOPLEX EP-3 PREAMP - POINT TO POINT LAYOUT

version update:  corrected switch wiring.  pin 2 to ground (thanks Solderholic)

RUNOFFGROOVE: Supreaux Deux

The follow-up on the Runoffgroove Supreaux, the Supreaux Deux.   An improved version of the original Supreaux design, running at 18v and with some changes to match the sound of the original amp as closely as possible.

Please follow the link to the runoff groove site, as there's an amazing amount of info on the development of this circuit available.  I swapped the 100k input resistor out for a capacitor; you can easily change this back to the original if that's what you prefer.

RUNOFFGROOVE SUPREAUX DEUX - VERO LAYOUT

RUNOFFGROOVE: Supreaux

This is the Runoff Groove Supreaux, their first interpretation of a Supro 16T amp.  

It's also known as the JHS Superbolt - which is almost identical to the Supreaux, but runs at 18v with a gain switch added.   Just put the schematics side by side, and you will see what I mean.  

I added the 22n input cap, which is missing from the original (it appears on the JHS version).  Swap it for a 100k resistor if you prefer the original - or you could do both.

Like anything using J201s - make sure you buy real ones or prepare for disappointment.  Bias drains to half voltage as a starting point and then tune by ear.

RUNOFFGROOVE SUPREAUX  - VERO LAYOUT

This is a JFET version of one of the Benson amps, which is I think why the pedal doesn't really have a proper name.

It's hard to find a B2M pot for the bass control, but you can use a dual B1M pot and gang the two sides together to reach 2M.  Check the Pedal PCB 'Son of Ben' build docs to see how.   

Or you can change somme values and use a 1M pot instead, see this post for values.

Like any pedal using J201 FETs, make sure you get proper ones, or it just won't work very well (I naively tried cheap J201 FETs once - it sounded awful).   

There's a thread on Freestompboxes where Mr Benson jumps in with advice too.  Nice guy...   note: the schematic on freestompboxes has a 330pf cap listed instead of the 250pf cap on the Pedal PCB schematic.  The 250pf value was supplied by Benson.

BENSON PREAMP - POINT TO POINT LAYOUT

FAIRFIELD CIRCUITRY: The Barbershop + Barbershop Millenium, Point to Point Layouts

My all time favourite JFET overdrive, the Fairfield Circuitry Barbershop.  The Fairfield Barbershop has a really wide range of useful tones.  From clean right through to heavy drive bordering on fuzz.   Nice easy build too, as it's not complicated.  

I also included a layout for what I imagine is the Barbershop Millenium edition (the one with the tone switch).  I've built it, and it does the job very nicely.   It's not hard to add, maybe give it a try and see what you think - try some different capacitors to tune it to your liking.   

FAIRFIELD CIRCUITRY THE BARBERSHOP - POINT TO POINT LAYOUT

note:  If sag doesn't seem to do much, the JFETs are not biased correctly / they are cheap fake JFETS