aion Ephemeris Handbuch - Seite 5
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C5/C6 and C8/C9 capacitors
The EP Booster uses 10uF capacitors (C5 and C8) as signal couplers immediately after both the JFET
and transistor stages. We recommend keeping electrolytic capacitors out of the signal path wherever
possible. This PCB includes space for an alternate film capacitor (C6 and C9) in each of these positions,
in which case C5 and C8 can be omitted entirely.
Due to the low source impedance, 1uF is more than enough to pass all useful bass frequencies. However,
if you want to stick as closely as possible to the original circuit, use 10uF for both.
Bass switch
The original EP Booster (Rev. 1) had an internal switch to add bass. Overwhelmingly, players felt like the
switch didn't actually do anything, and this was our experience in prototyping as well. We recommend
using 1uF for C3 and 10uF for C4. The original values are 10uF for C3 and 100uF for C4.
The 22n setting (middle position) is an addition to our version of the circuit, inspired by the original EP-3
unit that used this value in one of the variants.
Volume knob
The Rev. 2 circuit replaced the bass switch with a +3dB Boost switch. This is actually a slickly-marketed
volume cut, since the +3dB setting is equivalent to the stock Rev. 1 circuit. We have replaced this with a
full volume knob so that the circuit can get down to unity gain. Just note that
Transistor substitutions
The EP Booster uses the BC849C for Q2, which is the SMD equivalent of the BC549C. The Ephemeris
PCB uses the USA E-B-C convention, so we recommend using the 2N5088 or 2N5089. If you do want to
use a BC549C, just make sure to rotate it 180 degrees from the silkscreen.
Q1 is a MMBF5457, which is the SMD version of the 2N5457. These are
available from Aion FX
mounted to through-hole adapters and will perform identically to the ones used in the original.
EPHEMERIS JFET BOOSTER
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