The Jeds Peds Plexi is a DIY guitar effects pedal kit: a Plexi in a box that Jeds Peds describes as "a responsive overdrive pedal recreating the greatest tones" of the classic Marshall JTM451. Instead of buying a finished overdrive pedal, you buy the parts, solder it together yourself, and end up with a JTM45-styled overdrive on your board1.
The circuit is built around JFETs, transistors that behave more like tube gain stages than the op amps found in many overdrives, which is what gives this kind of design its amp-like character1.
What it does and how you control it
The three pots control Drive, Tone and Volume, and the fourth control is a Fat switch that brings in some extra bass1. That gives you the usual Plexi-in-a-box layout: gain into a tone shaping stage into a level control, with a switchable low-end boost for when the circuit sounds too thin.
Jeds Peds notes one parts caveat worth knowing before you build: stocks of the JFET type listed in the parts list are depleting globally, so the type supplied may be replaced with a readily available substitute1.
The JFET type in the parts list may be substituted with a readily available equivalent, because global stocks of the listed type are depleting1.
Kit versions and what you build
The kit comes in six versions, so you can choose how much of the work you want to do yourself1:
| Version | What you get |
|---|---|
| PCB Only | Just the plain PCB |
| PCB & Components | Board plus the parts to populate it |
| PCB & Components and off board parts | Adds the switches, jacks and other off board components |
| Full Kit | Everything, supplied with an undrilled enclosure |
| Full Kit & Drilling | Full Kit with the enclosure drilled for a small surcharge |
| Pre Built Kit | Built for you, £42.00, with a 1 to 4 week build time1 |
The Full Kit is supplied with a JP1590B sized enclosure, the 3 hole version, and the drilling option covers all the holes needed for a complete pedal, including the toggle switch hole1. You will also need 3 knobs for the kit, and Jeds Peds suggests medium sized ones1.
On the Pre Built Kit, there are no returns accepted, but it carries a 12 month repair warranty, so if a fault develops Jeds Peds will repair it1.
Skill required and biasing the transistors
This is not a beginner's first soldering project. Jeds Peds is direct about what the build asks of you1:
"You will have to identify components, calculate resistor codes and be able to solder them into place."1
The kits require full assembly, so you need to be comfortable reading resistor color codes, telling components apart, and soldering them into the board1.
There is also one step beyond plain assembly: you will have to bias the transistors to get the optimum tone, using a multi meter. Jeds Peds adds, "Don't let that put you off, its really easy with a multi meter"1. Biasing sets the operating point of each JFET stage, and on a circuit like this it is what determines whether the pedal sounds right when you finish it.
How it compares to the Wampler Plexi Drive
Jeds Peds itself says the kit compares to the Wampler Plexi-Drive, the best known commercial take on the same idea1. Vintage Guitar magazine described the Wampler Plexi-Drive British Overdrive as "designed to replicate the sound of a vintage Marshall JTM45"2, which is the same target the Jeds Peds kit aims at.
The two are separate products from different makers, though. The Wampler Plexi Drive line has since grown into a series: the original Plexi-Drive, then the Plexi-Drive Deluxe, which Wampler calls "a direct descendent of the Plexi-Drive Standard but with a few upgraded features"3, and then the Plexi-Drive Mini, which Premier Guitar's 2020 announcement introduced as following the same sequence4. The Mini uses the same FET based circuit as the original with some tonal tweaking5.
The practical difference for a player is simple: the Wampler pedals are finished products you plug in, while the Jeds Peds Plexi is a kit you build, bias and house yourself, at a lower price than a finished boutique overdrive1.
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Questions
Is the Jeds Peds Plexi a kit or a finished pedal?
It is a DIY guitar effects pedal kit, sold in several levels of completeness: PCB only, PCB with components, PCB with components and off board parts, a Full Kit, a Full Kit with drilling, or a Pre Built Kit with a 1 to 4 week build time.
What does the Fat switch do on the Jeds Peds Plexi?
The Fat switch is the fourth control, alongside the Drive, Tone and Volume pots. Switching it on brings in some extra bass, fattening up the low end of the overdrive.
Do I need to bias the transistors when building the Jeds Peds Plexi?
Yes. Jeds Peds says you will have to bias the transistors to get the optimum tone, and that this is easy to do with a multi meter. It is a normal step for a JFET circuit like this one.
What soldering skill does the Jeds Peds Plexi kit require?
You need to be able to identify components, calculate resistor codes and solder them into place. The kits require full assembly, so it suits someone comfortable with a soldering iron and reading resistor values.
Is the Jeds Peds Plexi related to the Wampler Plexi Drive?
No, they are separate products. Jeds Peds says its kit compares to the Plexi Drive by Wampler, which is also a JTM45-style overdrive, but the Jeds Peds version is an independent kit you build yourself.
Does the Jeds Peds Plexi kit come with a drilled enclosure?
The Full Kit is supplied with an undrilled enclosure. Drilling is an optional extra with a small surcharge, covering all the holes needed for a complete pedal, including the toggle switch hole.
Sources (5)
- Plexi | DIY Guitar Effects Pedal Kits, Jeds Peds
- Wampler Effects Pedals, Vintage Guitar magazine, 2016-08-10
- Plexi Drive Deluxe, Wampler Pedals, 2026-09-18
- Wampler Introduces the Plexi-Drive Mini, Premier Guitar, 2020-11-23
- Plexi Drive Mini, Wampler Pedals, 2026-10-13
