Advertisement
Quick Links
PROJECT NAME
AXION
BASED ON
Echoplex EP-3 Preamp
EFFECT TYPE
Preamp, tone enhancer
PROJECT SUMMARY
An adaptation of the JFET input stage of the Echoplex EP-3 tape delay unit, famously used by Jimmy
Page, Brian May and many others.
Actual size is 2.3" x 1.86" (main board) and 1.78" x 0.86" (bypass board).
AXION JFET PREAMP
BUILD DIFFICULTY
Easy
DOCUMENT VERSION
1.0.0 (2025-03-28)
1
Advertisement
Subscribe to Our Youtube Channel
Related Manuals for aion AXION
Summary of Contents for aion AXION
- Page 1 An adaptation of the JFET input stage of the Echoplex EP-3 tape delay unit, famously used by Jimmy Page, Brian May and many others. Actual size is 2.3” x 1.86” (main board) and 1.78” x 0.86” (bypass board). AXION JFET PREAMP...
-
Page 2: Table Of Contents
10 Document Revisions INTRODUCTION The Axion JFET Preamp is based on the Chase Tone Secret Preamp, an adaptation of the input section of the Echoplex tape echo delay from the 1970s. The Secret Preamp was originally released in 2013 and traced by Aion FX in 2025. -
Page 3: Parts List
MLCC capacitor, X7R Power supply filter capacitor. 1N5817 Schottky diode, DO-41 1N4743A Zener diode, 13V, DO-41 1N5817 Schottky diode, DO-41 1N5817 Schottky diode, DO-41 1N5817 Schottky diode, DO-41 1N5817 Schottky diode, DO-41 1N4748A Zener diode, 22V, DO-41 AXION JFET PREAMP... - Page 4 DC jack, 2.1mm panel mount Mouser 163-4302-E or equivalent. BATT Battery snap 9V battery snap Optional. Use the soft plastic type—the hard-shell type will not fit. 3PDT Stomp switch, 3PDT 125B Enclosure, die-cast aluminum Can also use a Hammond 1590N1. AXION JFET PREAMP...
-
Page 5: Build Notes
Because of this, there is another ground wire that needs to be connected on the right side, to the left of the “Out” wire. The wiring diagram shows this added wire, but since it’s otherwise identical to most other Aion projects, it could easily be overlooked. -
Page 6: Schematic
1N5817 1N5817 1N5817 220uF 100n 470n LT1054CP 10uF 10uF 10uF 220uF 100k 2N5457 VOLUME 100k 500kA 220pF MODE GND GND Early = center (no cap) Late = down (22n cap) Mod = up (10n cap, in between) AXION JFET PREAMP... -
Page 7: Drill Template
3mm bezel, a plastic bezel, or just a plain LED. 125B INCH 0.625” 0.625” ø3/8” ø3/8” ø1/2” VOLUME x: 0, y: +1.71 ø9/32” MODE x: 0, y: +0.41 ø1/4” CENTER (0,0) FOOTSWITCH x: -0.775, y: -1.20 x: 0, y: -1.20 ø5/16” ø15/32” AXION JFET PREAMP... -
Page 8: Enclosure Layout
ENCLOSURE LAYOUT Enclosure is shown without jacks. See next page for jack layout and wiring. 125B AXION JFET PREAMP... -
Page 9: Wiring Diagram
GND +V +V JACK GND JACK GND GND PCB 125B Shown with optional 9V battery. If battery is omitted, both jacks can be mono rather than one being stereo. Leave the far-right lug of the DC jack unconnected. AXION JFET PREAMP... -
Page 10: Document Revisions
(In other words: you don’t have to go out of your way to advertise the fact that you use these PCBs, but please don’t go out of your way to hide it. The guitar effects industry needs more transparency, not less!) DOCUMENT REVISIONS 1.0.0 (2025-03-28) Initial release. AXION JFET PREAMP...
Need help?
Do you have a question about the AXION and is the answer not in the manual?
Questions and answers