Do It Yourself

The Edge of Your Seat: Build Your own Boss FA-1 FET Amplifier

  • By Nicholas Kula @tonereport
  • September 24, 2016
  • 3 Comments

The year was 1984, and Boss was still garnering praise for its relatively new line of compact stompboxes. At this time, Boss hadn’t yet seized the mind of guitarists when the word “pedal” was spoken, but it was close.  Pros everywhere were starting to assemble boards full of Boss pedals, because they finally could. By this point, Boss had the foundation of its empire laid down—the company had the sound of the ‘80s firmly in hand with chorus, delay and flanger offerings, while its older roots were firmly underfoot, so to speak. Boss was on top of the world.

When the 1984 Boss product catalog was released, there was a curious entry, and that entry was called the Pocket Series. Intended as a parallel offering to its wildly popular compact pedals, the Pocket Series was meant to be clipped to a belt or pocket seam by using an included plastic hook. Only two effects in this series were ever produced, with only one of them being an effect at all. The latter was a small amp, the MA-1 Mascot Amplifier. The other was the FA-1 FET Amplifier.

The FA-1 was realized at a time when FETs were the big new thing in effect design. Not many pedals before 1984 used them for anything dirt-related (MXR’s Phase [xxx] and Dan Armstrong’s Orange Squeezer are two early pedals with them) and not many pedals intentionally left out a bypass switch. All in all, the FA-1 was a confusing beast, and its own catalog entry admitted, in a roundabout way, that even Boss itself didn’t know the demographic best assisted by its arrival. It was discontinued shortly and the concept of the Pocket Series was promptly slashed and burned.

Of course, an effect with no clear vision is only without a clear vision so long as nobody famous hitches their wagon to it. Well, after a few years, somebody did. His name is The Edge.

Almost overnight, the prices on second-hand FA-1s shot skyward, and this once-confused pedal suddenly commanded huge sums on the secondary market. Aided by its rarity, the prices reached legendary status when the Internet began globally uniting gearheads. The prices have come down a bit, but this is one Boss pedal that’s not getting any less scarce, and it sounds excellent. And guess what? You’re going to build one.

But first, the disclaimer: Neither I, nor Tone Report Weekly bears any responsibility for any kind of personal or property damage that may occur as a result of the instructions provided herein. Legal mumbo-jumbo aside, we ask that readers be familiar with a soldering iron and its accompanying safety procedures before trying anything listed here. Furthermore, if you fire the pedal up and it does not work, it will need troubleshooting. Assuming the components are not damaged, the pedal will work. I built this very unit according to these instructions and it fired up, first shot, so I know the instructions are correct.

Secondly, we’re going to need some parts. The original FA-1s contained some parts that aren’t so easy to find anymore, so we have to make some substitutions. The original op-amp was actually two single HA1457W SIP op-amps and the original FET was a 2SK246, neither of which I’m going to make you scavenge. Here’s the parts list:

Resistors:

1x 470 ohm

1x 4.7k (for the LED)

1x 6.8k

2x 8.2k

2x 10k

1x 15k

1x 22k

2x 33k

1x 100k

2x 470k

1x 3.3m

Capacitors:

2x 5.6nF film (0.0056uF)

1x 10nF film (0.01uF)

2x 33nF film (0.033uF)

1x 47nF film (0.047uF)

1x 470nF film (0.47uF)

3x 10uF electrolytic

1x 100uF electrolytic

Potentiometers:

2x 50kA

1x 1mB

Semiconductors:

1x LM1458 IC (I used MC1458, a modern equivalent. Both will work)

1x J201 FET

Miscellaneous:

1x piece of stripboard (Veroboard) cut and made according to the diagram

1x 8-pin DIP socket

1x transistor socket (optional, buy a strip of SIP sockets and cut to fit)

Wire

Alright, let’s go!

Step 1: Insert all the resistors, bend their leads outward to hold them in place, then flip over the board and solder them in. Clip the leads, but save them.

Step 2: Using the leads from Step 1, create the jumper wires, solder them in and clip off the extra.

Step 3: Place the IC socket and transistor socket (if using) in the board, then place a flat object on top and flip the board over, holding the socket(s) in place. Solder them in.

Step 4: Insert the film capacitors, bend the leads outward, solder and clip.

Step 5: Insert the electrolytic capacitors, bend the leads outward, solder and clip.

Step 6: Insert the semiconductors into their sockets and solder. If not using a transistor socket, bend the leads, solder and clip.

Step 7: Insert all the wires and solder them in. Run the wires to the potentiometers and toggle, then solder those in.

Before you continue, I must advise you to get a multimeter and check continuity (the sound wave setting) across ALL cuts and adjacent rows. Make sure there are no solder bridges across either avenue. Note that in four positions, the multimeter will tell you that adjacent rows are connected, because you connected the adjacent rows with jumpers. However, there should never be continuity across cuts.

Let’s build that enclosure! You will need:

1x enclosure of any size that can accommodate these parts. I use a 1590B for this project. It will need to be drilled for one footswitch, three knobs, one toggle, input and output jacks, DC power and an LED.

1x 3PDT latching footswitch (not momentary)

2x ¼” mono jacks

1x DC power jack

1x LED

1x LED bezel (same size as the LED, obviously)

3x knobs of your choosing

Wire

Step 1: Mount the power, input and output jacks, the switch and the LED.

Step 2: Feed the negative leg of the LED (the shorter one) through its lug on the footswitch, then join lugs 3 and 9 as shown. Solder the LED leg in, and lug 3 of the switch. DO NOT solder lug 9.

Step 3: We will ground the pedal in this step. Connect a wire from lugs 2 and 6 on the footswitch to the DC negative lug (the one unlike the other two), and solder the switch lugs. Then, connect a wire from the DC negative to the sleeve lug on one of the jacks, and solder the negative DC lug. Then, connect a wire from one jack sleeve lug to the other, and solder the first one. DO NOT solder the second sleeve lug.

Step 4: Your potentiometers have tiny metal tabs on them that prevent them from being mounted. Snap those off with pliers, then mount them. Connect the wires from the board to their appropriate spots, including the switch, the power and the LED positive leg. Connect the black ground wire from the circuit board to the unsoldered jack sleeve lug, and solder that.

Step 5: Connect wires from the input and output jack tip lugs to the switch, including the unsoldered lug 9 on the footswitch.

Step 6: You’re done! Crank it up!

So, what does it sound like?

Due to the Baxandall-style EQ, the pedal becomes so much more than a “clean boost,” and that’s a very good thing. The tones coming from this thing are light and airy, jangly and responsive—“preamp” was definitely the right word to use here. Plugging it before any other dirt pedal yields a clarity that simply cannot be equaled by that pedal alone. The Volume control acts as a “non-master” volume such that it reacts differently as you turn it up. Simply put, the FA-1 is a deceptively inspiring box that sounds great on its own or stacked. Here’s a clip of Andy playing it.

 

 

Until next time, up the irons!

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3 Comments

  1. rich

    where can I purchase green veroboard? thanks

  2. Drusca

    The diagram indicates there should be some cuts made to the stripboard, yet I don’t see any cuts in the pictures. Did the copper traces get scratched off on the other side of the board, instead?

    Generally speaking, in these DIY features it would help to see a picture of the other side of the board, in order to see how the soldering should look.

  3. Don Keith

    Nice compact layout, but be aware that there are 10 jumpers and only 13 rows…