Aion Electronics MERIDIAN User manual

MERIDIAN EXCITER / COMPRESSOR 1
PROJECT NAME
MERIDIAN
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
PS-021 Guitar Exciter / Compressor
A gem from the 1980s, this effect combines a Dyna-style compressor with an exciter that enables
control over the even & odd harmonics.
Compressor, frequency enhancer 1.0.0 (2019-08-31)
BUILD DIFFICULTY
Intermediate
Actual size is 2.3” x 2.43” (main board) and 1.78” x 0.86” (bypass board).

MERIDIAN EXCITER / COMPRESSOR 2
TABLE OF CONTENTS
1Project Overview 8Drill Template
2Introduction & Usage 9Enclosure Layout
3-5 Parts List 10 Wiring Diagram
6Build Notes 11 Licensing
7Schematic 11 Document Revisions
INTRODUCTION
The Meridian Exciter/Compressor is a clone of the Guyatone (Nady in the USA) PS-021 Guitar Exciter /
Compressor and its cousin, the PS-020 Bass Exciter / Compressor.
The PS-021 can be looked at as three distinct circuits chained together. First is the classic Dyna Comp,
nearly a direct copy but with somewhat reduced sensitivity on the Sustain control, so its use is more as a
limiter than a sustainer.
The following stage is an exciter, which is very similar to a circuit from a Japanese electronics book in the
1980s (and not unlike the BBE Sonic Stomp, but with no frequency-specific control).
The last stage is a Big Muff-style tone control that pans between a bass emphasis and treble emphasis.
However, unlike the BMP’s classic mid-scoop, there is a very slight mid hump throughout the rotation.
So while it’s composed of familiar circuits, the end result is, as they say, more than the sum of its parts.
This is a killer tone enhancer that still enjoys revered status with many, but flies under the radar since it
doesn’t have an association with any big-name artists or records.
The PS-020 is the bass version. The circuit is identical to the PS-021 except for five parts that have been
changed in the exciter and tone control to make the frequencies more suitable for bass. It also changes
the tone control to bring back the mid-scoop frequency curve, more similar to the Big Muff.
The Meridian is a direct clone of the original PS-021 and PS-020 except for two changes. First, it’s been
converted to true bypass and the JFET switching has been removed. Second, the obsolete CA3080 chip
has been replaced by the current-production LM13700, which performs identically.
USAGE
The Meridian has the following controls:
• Sustain sets the compression threshold and amount of sustain, from subtle limiting to squish.
• Exciter increases the emphasis on harmonics. At 50%, there is no change. When turned to the left,
even-order harmonics are increased. To the right, odd-order harmonics are increased.
• Color is a tone control that pans between bass boost and treble boost.
• Level is the output volume control.

MERIDIAN EXCITER / COMPRESSOR 3
PARTS LIST
This parts list is also available in a spreadsheet format which can be imported directly into Mouser for
easy parts ordering. Mouser doesn’t carry all the parts—most notably potentiometers—so the second
tab lists all the non-Mouser parts as well as sources for each.
View parts list spreadsheet →
PART VALUE TYPE NOTES
R1 1k Metal film resistor, 1/4W
R2 1M Metal film resistor, 1/4W
R3 10k Metal film resistor, 1/4W
R4 1M Metal film resistor, 1/4W
R5 470k Metal film resistor, 1/4W
R6 15k Metal film resistor, 1/4W
R7 1M Metal film resistor, 1/4W
R8 560k Metal film resistor, 1/4W PS-020 uses 470k here.
R9 150k Metal film resistor, 1/4W
R10 10k Metal film resistor, 1/4W
R11 10k Metal film resistor, 1/4W
R12 1M Metal film resistor, 1/4W
R13 1M Metal film resistor, 1/4W
R14 150k Metal film resistor, 1/4W
R15 10k Metal film resistor, 1/4W
R16 47k Metal film resistor, 1/4W
R17 39k Metal film resistor, 1/4W PS-020 uses 43k here.
R18 10k Metal film resistor, 1/4W
R19 10k Metal film resistor, 1/4W
R20 10k Metal film resistor, 1/4W
R21 4k7 Metal film resistor, 1/4W
R22 10k Metal film resistor, 1/4W
R23 1k Metal film resistor, 1/4W
R24 10k Metal film resistor, 1/4W
R25 10k Metal film resistor, 1/4W
R26 22k Metal film resistor, 1/4W
R27 10k Metal film resistor, 1/4W
R28 10k Metal film resistor, 1/4W
R29 33k Metal film resistor, 1/4W
R30 33k Metal film resistor, 1/4W

MERIDIAN EXCITER / COMPRESSOR 4
PARTS LIST, CONT.
PART VALUE TYPE NOTES
R31 100k Metal film resistor, 1/4W
R32 10k Metal film resistor, 1/4W
R33 10k Metal film resistor, 1/4W
R34 1M Metal film resistor, 1/4W
R35 10k Metal film resistor, 1/4W
R36 10k Metal film resistor, 1/4W
R37 5k6 Metal film resistor, 1/4W
R38 33k Metal film resistor, 1/4W
R39 33k Metal film resistor, 1/4W
RPD 2M2 Metal film resistor, 1/4W
LEDR 4k7 Metal film resistor, 1/4W
C1 10n Film capacitor, 7.2 x 2.5mm
C2 1uF Film capacitor, 7.2 x 3.5mm
C3 10n Film capacitor, 7.2 x 2.5mm
C4 1uF Electrolytic capacitor, 4mm
C5 1n Film capacitor, 7.2 x 2.5mm
C6 10n Film capacitor, 7.2 x 2.5mm
C7 10n Film capacitor, 7.2 x 2.5mm
C8 10uF Electrolytic capacitor, 5mm
C9 100n Film capacitor, 7.2 x 2.5mm
C10 33n Film capacitor, 7.2 x 2.5mm PS-020 uses 68n here.
C11 2n2 Film capacitor, 7.2 x 2.5mm PS-021 uses 4n7 here.
C12 33n Film capacitor, 7.2 x 2.5mm
C13 22n Film capacitor, 7.2 x 2.5mm
C14 1uF Film capacitor, 7.2 x 3.5mm
C15 22n Film capacitor, 7.2 x 2.5mm
C16 10n Film capacitor, 7.2 x 2.5mm PS-020 uses 100n here.
C17 220n Film capacitor, 7.2 x 2.5mm
C18 1uF Film capacitor, 7.2 x 3.5mm
C19 100uF Electrolytic capacitor, 6.3mm Power supply filter capacitor.
C20 47uF Electrolytic capacitor, 5mm Reference voltage filter capacitor.
C21 47uF Electrolytic capacitor, 5mm Reference voltage filter capacitor.
C22 100n MLCC capacitor, X7R Power supply filter capacitor.

MERIDIAN EXCITER / COMPRESSOR 5
PARTS LIST, CONT.
PART VALUE TYPE NOTES
D1 1N5817 Schottky diode, DO-41
D2 1N914 Fast-switching diode, DO-35
D3 1N914 Fast-switching diode, DO-35
Q1 2N5088 BJT transistor, NPN, TO-92
Q2 2N5088 BJT transistor, NPN, TO-92
Q3 2N5088 BJT transistor, NPN, TO-92
Q4 2N5088 BJT transistor, NPN, TO-92
Q5 2N5088 BJT transistor, NPN, TO-92
Q6 2N5088 BJT transistor, NPN, TO-92
IC1 LM13700N Transconductance amplifier, DIP16
IC1-S DIP16 socket IC socket, DIP-16
IC2 JRC4558D Operational amplifier, DIP8
IC2-S DIP-8 socket IC socket, DIP-8
IC3 JRC4558D Operational amplifier, DIP8
IC3-S DIP-8 socket IC socket, DIP-8
IC4 JRC4558D Operational amplifier, DIP8
IC4-S DIP-8 socket IC socket, DIP-8
SUST. 1MB 16mm right-angle PCB mount pot
COLOR 100kB 16mm right-angle PCB mount pot
EXC. 25kB 16mm right-angle PCB mount pot
LEVEL 50kB 16mm right-angle PCB mount pot
BIAS 2kB Trimmer, 10%, 1/4” (Bourns 3362P)
LED 5mm LED, 5mm, red diffused
IN 1/4" mono 1/4" phone jack, closed frame Switchcraft 111X or equivalent.
OUT 1/4" mono 1/4" phone jack, closed frame Switchcraft 111X or equivalent.
DC 2.1mm DC jack, 2.1mm panel mount Mouser 163-4302-E or equivalent.
FSW 3PDT Stomp switch, 3PDT
ENC 125B Enclosure, die-cast aluminum Can also use a Hammond 1590N1.

MERIDIAN EXCITER / COMPRESSOR 6
BUILD NOTES
Bass version
If you’re building this for bass, the PS-020 version can be built by substituting the following five parts:
PART PS-021 (GUITAR) PS-020 (BASS)
R8 560k 470k
R17 39k 43k
C10 33n 68n
C11 2n2 4n7
C16 10n 100n
Sustain modication
The compressor portion of the circuit is identical to the classic Ross / Dyna Comp circuit, except that the
sustain control has more limited range in the PS-021. But, it can easily be modified to give a more Dyna-
style effect. Change R8 to 27k and the Sustain pot to 500kC.

SCHEMATIC
MERIDIAN EXCITER / COMPRESSOR 7
Q1-Q6: 2N5088
IC1: LM13700
IC2-4: JRC4558D
GND
2M2
100uF
1MB
50kB
GND
25kB
100kB
GND
10n
1k
1M
GND
VB
VA
VA
10k
10n
47uF
VB
33k
47uF
VC
33k
GND GNDGND
5k6
GND
VA
GND
2kB
470k
1M
1M
15k
560k
10k
10k
150k
10k
1M 1M
150k
47k
39k
10k
10k
10k
4k7
10k
1k
10k
10k
22k
10k
10k
33k
33k
100k
10k
10k
10k
GND
VA
GND
GND
VA
1n
10n
10n
2n2
33n
33n
22n
10uF
GND
VA
VB VB VA
GND
VC
VC
VC
VC
VC
VC
VC
22n
10n
GND
GND
VA
GND
1M
VC
10k
100n
220n
1uF
1uF
1uF
1N5817
+9V
VA
GND
VA
GND
1uF
LM13700N
LM13700N
LM13700N
LM13700N
GND
VA
GND
100n
IN
OUT
RPD
C19
SUSTAIN
1
2
3
LEVEL
1
2
3
EXCITER
1
2
3
COLOR
1
2
3
2
3
1
IC4A
6
5
7
IC4B
84
Q1
Q2
Q5
Q3 Q4
Q6
C1
R1
R2
R3
C3
C21
R38
C20
R39 R37
BIAS
1
2
3
R5
R4
R7
R6
R8
R15
R11
R9
R10
R13 R12
R14
R16
R17
R18
R19
R20
R21
R22
R23
R24 R25
R26
R27
R28
R29
R30
R31
R32
R33
R35
C5
C6
C7
C11 C12
C10
C13
C8
D3 D2
C15
C16
R34
R36
C9
C17
C14
C18
C2
D1
C4
IC1A
3
4
5
1
IC1_BUF1
V+
7
8
IC1B
14
13
12
16
15 IC1_BUF2
V+
10
9
116
IC2A
2
3
1
IC2B
6
5
7IC3A
2
3
1
IC3B
6
5
7
84
84
C22
GND

MERIDIAN EXCITER / COMPRESSOR 8
DRILL TEMPLATE
Cut out this drill template, fold the edges and tape it to the enclosure. Before drilling, it’s recommended
to first use a center punch for each of the holes to help guide the drill bit.
Ensure that this template is printed at 100% or “Actual Size”. You can double-check this by measuring
the scale on the printed page.
Top jack layout assumes the use of closed-frame jacks like the Switchcraft 111X. If you’d rather use
open-frame jacks, please refer to the Open-Frame Jack Drill Template for the top side.
LED hole drill size assumes the use of a 5mm LED bezel, available from several parts suppliers. Adjust
size accordingly if using something different, such as a 3mm bezel, a plastic bezel, or just a plain LED.
0 1 2
CM
0 1
INCH
ø3/8” ø1/2”
0.385”
0.625” 0.625”
x: -0.65, y: +1.71 x: +0.65, y: +1.71
ø9/32” ø9/32”
x: -0.65, y: +0.41
ø9/32”
x: +0.65, y: +0.41
ø9/32”
x: 0, y: -1.775
ø15/32”
x: -0.775, y: -1.775
ø5/16”
CENTER (0,0)
ø3/8”
125B
OUT
LEVEL SUSTAIN
COLOR EXCITER
FOOTSWITCHLED
DC IN

MERIDIAN EXCITER / COMPRESSOR 9
ENCLOSURE LAYOUT
Enclosure is shown without jacks. See next page for jack layout and wiring.
125B

MERIDIAN EXCITER / COMPRESSOR 10
WIRING DIAGRAM
125B
IN +VGND NC NC OUT
PCB
IN
GND +V +V JACK GND JACK
OUTIN
GND GND PCB
OUT