aion Lab Series User manual

L5 PREAMP DRIVE CHANNEL 1
PROJECT NAME
L5 PREAMP DRIVE CHANNEL
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
Lab Series®L5 (Channel 2)
A pedal adaptation of the second channel of the Lab Series® L5 amplifier from the late 1970s, often
considered to be the best solid-state amp ever designed.
Preamp & overdrive 1.0.0 (2022-11-25)
BUILD DIFFICULTY
Advanced
Actual size is 3.44” x 2.42” (main board) and 3.44” x 0.97” (bypass board).

L5 PREAMP DRIVE CHANNEL 2
TABLE OF CONTENTS
1Project Overview 12 Drill Template
2Introduction 13 Enclosure Layout
3Usage & Circuit Design Notes 14 Wiring Diagram
4-7 Parts List 15 Licensing
8-10 Build Notes 15 Document Revisions
11 Schematic
INTRODUCTION
The L5 Preamp Drive Channel is an adaptation of the second channel of the Lab Series®L5 amplifier,
originally released in 1976 and discontinued in 1981.
The Lab Series L5 amp was designed to compete with the Fender Twin Reverb, and the first channel was
specifically designed to be Fender-inspired. However, the second channel was completely original from
the ground up, with active tone controls, a parametric midrange, and a unique (and patented) multi-pole
fixed EQ called the “Multifilter”.
The drive channel of the L5 was most famously used by Ty Tabor on the first four Kings X albums. (BB
King also used these amps, but only the clean channel, for which we have a different project.)
This project recreates the entire signal path of the drive channel except for the multifilter—including
the OTA overdrive, compressor and master volume. It also runs on the same +/-15V voltage as the
original unit. The only change we’ve made is to convert the input stage from inverting to non-inverting.
This reduces the noise, but the way we’ve designed it, the input impedance and frequency response are
exactly the same as the original amp’s “Lo” input (the higher-gain mode designed for guitar).
The clean channel is available as a separate project, and like this one, it recreates the entire signal path
of the first channel. The full L5 Preamp pedal is still available.

L5 PREAMP DRIVE CHANNEL 3
USAGE
The L5 Preamp Drive Channel has the following controls:
• Volume controls the amount of gain in the first stage, before the EQ and drive section.
• Bright (toggle switch) adds a treble-bleed capacitor to the volume control, which keeps it from
getting dull at lower volumes.
• Treble and Bass form a standard 2-band Baxandall control. Each band is flat at the 12:00 position,
and can either cut (CCW) or boost (CW).
• Frequency selects the frequency that will be boosted or cut by the Mid control for the semi-
parametric midrange.
• Master sets the output volume after the drive section of the preamp.
• Comp Level sets the threshold of the compressor at the end of the circuit.
• Comp On/Off (toggle) disengages the compressor.
CIRCUIT DESIGN NOTES
Power supply design
Like most solid-state preamplifiers of the era, the L5 operated on a bipolar +/-15V supply. This voltage
can’t be supplied by an external adapter, and the current draw of the circuit is too high to use a charge
pump.
When developing the original Lab Series L5 Preamp, we adapted a supply scheme from Alesis rack units
in the early 1990s that involved a 9VAC adapter and an AC voltage tripler. This was then rectified to
bipolar +/-19V DC and regulated down to 15V on each rail.
This solution used cheap and readily-available parts, and it has worked very well for several years since
the L5 Preamp was first developed. But the power adapter requirement has always been the major flaw.
A 9VAC adapter will destroy most other pedals if it’s plugged in, and if you own one, there’s an infinitely
higher chance that it’ll be mistaken for a 9VDC adapter and plugged into the wrong pedal at some point.
Because of this, when developing the IVP Preamp project in 2021, we set out to find a reliable way to
supply +/-15V from a standard DC adapter. Fortunately, there are a few more options available today
than there were in 2015 when the L5 Preamp was originally developed, and a high-quality DC-DC
converter module will give us exactly what we need. They’re not cheap (USD$9-15 each), but once you
account for the fact that you no longer need a specialized power adapter, the total cost is about the
same. We have begun using these DC converters in all of our preamp projects going forward, including
this new variant of the L5 that started it all.
See the build notes on page 8 for more information on the specific DC-DC converters that are
recommended for use in this project.

L5 PREAMP DRIVE CHANNEL 4
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 10k Metal film resistor, 1/4W
R2 220k Metal film resistor, 1/4W
R3 2k2 Metal film resistor, 1/4W
R4 47k Metal film resistor, 1/4W
R5 1k Metal film resistor, 1/4W
R6 1k5 Metal film resistor, 1/4W
R7 10k Metal film resistor, 1/4W
R8 27k Metal film resistor, 1/4W
R9 27k Metal film resistor, 1/4W
R10 18k Metal film resistor, 1/4W
R11 18k Metal film resistor, 1/4W
R12 18k Metal film resistor, 1/4W
R13 18k Metal film resistor, 1/4W
R14 18k Metal film resistor, 1/4W
R15 1k5 Metal film resistor, 1/4W
R16 1k5 Metal film resistor, 1/4W
R17 2k2 Metal film resistor, 1/4W
R18 2k2 Metal film resistor, 1/4W
R19 24k Metal film resistor, 1/4W
R20 2k2 Metal film resistor, 1/4W
R21 22k Metal film resistor, 1/4W
R22 100k Metal film resistor, 1/4W
R23 39k Metal film resistor, 1/4W
R24 10k Metal film resistor, 1/4W
R25 15k Metal film resistor, 1/4W
R26 1k Metal film resistor, 1/4W
R27 6k8 Metal film resistor, 1/4W
R28 33k Metal film resistor, 1/4W
R29 220R Metal film resistor, 1/4W
R30 10k Metal film resistor, 1/4W

L5 PREAMP DRIVE CHANNEL 5
PARTS LIST, CONT.
PART VALUE TYPE NOTES
R31 470k Metal film resistor, 1/4W
R32 2k Metal film resistor, 1/4W
R33 47k Metal film resistor, 1/4W
R34 3k3 Metal film resistor, 1/4W
R35 330R Metal film resistor, 1/4W
R36 100k Metal film resistor, 1/4W
R37 6k8 Metal film resistor, 1/4W
R38 2k7 Metal film resistor, 1/4W
R39 15k Metal film resistor, 1/4W
R40 220R Film capacitor, 7.2 x 2.5mm
R41 220R MLCC capacitor, NP0/C0G
R42 10M Film capacitor, 7.2 x 2.5mm
R43 820R Film capacitor, 7.2 x 5mm
R44 22k Film capacitor, 7.2 x 2.5mm
R45 3k3 Film capacitor, 7.2 x 2.5mm
R46 33k Film capacitor, 7.2 x 5.5mm
R47 10k Film capacitor, 7.2 x 2.5mm
R48 10k Film capacitor, 7.2 x 2.5mm
R49 47k Film capacitor, 7.2 x 3.5mm
R50 47k Electrolytic capacitor, 5mm
R51 10k Film capacitor, 7.2 x 3.5mm
R52 100k Electrolytic capacitor, 5mm
R53 100k MLCC capacitor, NP0/C0G
R54 22k Film capacitor, 7.2 x 2.5mm
RPD 2M2 Film capacitor, 7.2 x 2.5mm Input pulldown resistor. Can be as low as 1M.
LEDR 10k Film capacitor, 7.2 x 3.5mm LED current-limiting resistor. Adjust value to change LED brightness.
C1 8n2 Film capacitor, 7.2 x 2.5mm
C2 22uF Electrolytic capacitor, 5mm
C3 10n Film capacitor, 7.2 x 2.5mm
C4 4n7 Film capacitor, 7.2 x 2.5mm
C5 4.7uF Electrolytic capacitor, 4mm
C6 68n Film capacitor, 7.2 x 2.5mm
C7 68n Film capacitor, 7.2 x 2.5mm
C8 2n2 Film capacitor, 7.2 x 2.5mm
C9 4n7 Film capacitor, 7.2 x 2.5mm

L5 PREAMP DRIVE CHANNEL 6
PARTS LIST, CONT.
PART VALUE TYPE NOTES
C10 68n Film capacitor, 7.2 x 2.5mm
C11 2.2uF Film capacitor, 7.2 x 5mm
C12 10n Film capacitor, 7.2 x 2.5mm
C13 220pF MLCC capacitor, NP0/C0G
C14 330n Film capacitor, 7.2 x 2.5mm
C15 68n Film capacitor, 7.2 x 2.5mm
C16 2.2uF Film capacitor, 7.2 x 5mm
C17 10uF Electrolytic capacitor, 5mm
C18 100pF MLCC capacitor, NP0/C0G
C19 10n MLCC capacitor, X7R
C20 10n MLCC capacitor, X7R
C21 10n MLCC capacitor, X7R
C22 10n MLCC capacitor, X7R
C23 10n MLCC capacitor, X7R
C24 10n MLCC capacitor, X7R
C25 10n MLCC capacitor, X7R
C26 10n MLCC capacitor, X7R
C27 100uF Electrolytic capacitor, 6.3mm
C28 10uF Electrolytic capacitor, 5mm
C29 10uF Electrolytic capacitor, 5mm
C30 47uF Electrolytic capacitor, 5mm
Z1 1N4743A Zener diode, 13V, DO-41
D2 1N4004 Rectifier diode, DO-41
D3 1N4004 Rectifier diode, DO-41
D4 1N914 Fast-switching diode, DO-35
D5 1N914 Fast-switching diode, DO-35
Q1 2N3904 BJT transistor, NPN, TO-92
Q2 2N3904 BJT transistor, NPN, TO-92
Q3 2N5457 JFET, N-channel, TO-92 Substitute. Original uses 2N4303 (PN4303).
Q4 2N3906 BJT transistor, PNP, TO-92
Q5 MPSA13 Darlington BJT, NPN, TO-92
L1 10uH Inductor, 10uH Bourns 78F100J-RC
L2 10uH Inductor, 10uH Bourns 78F100J-RC
L3 10uH Inductor, 10uH Bourns 78F100J-RC
DC1 TEC 3-0923 DC-DC converter, +9V to +/-15V See build notes for alternatives.

L5 PREAMP DRIVE CHANNEL 7
PARTS LIST, CONT.
PART VALUE TYPE NOTES
IC1 LF356N Operational amplifier, DIP8
IC1-S DIP-8 socket IC socket, DIP-8
IC2 RC4558P Operational amplifier, DIP8
IC2-S DIP-8 socket IC socket, DIP-8
IC3 RC4558P Operational amplifier, DIP8
IC3-S DIP-8 socket IC socket, DIP-8
IC4 RC4558P Operational amplifier, DIP8
IC4-S DIP-8 socket IC socket, DIP-8
IC5 LM13700N Transconductance amplifier, dual, DIP16
IC5-S DIP-8 socket IC socket, DIP-8
IC6 RC4558P Operational amplifier, DIP8
IC6-S DIP-8 socket IC socket, DIP-8
COMP. TRIM 20k trimmer Trimmer, 10%, 1/4"
DIST. TRIM 20k trimmer Trimmer, 10%, 1/4"
VOLUME 25kA 16mm pot, right angle
BASS 25kB 16mm pot, right angle
TREBLE 25kB 16mm pot, right angle
FREQUENCY 100kC dual 16mm dual pot, right angle
MID 25kB 16mm pot, right angle
MASTER 25kA 16mm pot, right angle
COMP. LEVEL 50kC 16mm pot, right angle
BRIGHT SPDT Toggle switch, SPDT on-on
COMP SPDT Toggle switch, SPDT on-on
LED 5mm LED, 5mm, red diffused
LIMIT 3mm LED, 3mm, red diffused
DC 2.1mm DC jack, 2.1mm panel mount Mouser 163-4302-E or equivalent.
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.
BYPASS 3PDT Stomp switch, 3PDT
ENCLOSURE 1590BBS Enclosure, die-cast aluminum

L5 PREAMP DRIVE CHANNEL 8
BUILD NOTES
DC converter selection
There are several brands and models available, all with the same pinout and similar specifications. Here
are the DC converters we’ve found that will work in this circuit.
BRAND PART # MOUSER # SUPPLY NOTES
Traco TEC 2-0923 495-TEC2-0923 4.5-13.2V Preferred option. More sources on Octopart.
CUI PQMC3-D12-D15-S 490-PQMC3-D12-D15-S 9-18V
XP Power IZ1215S 209-IZ1215S 9-18V
Recom RS-1215D 919-RS-1215D 9-18V
Recom RS3-1215D 919-RS3-1215D 9-18V
Mornsun WRA1215S-3WR2 N/A 9-18V NAC Semi: https://aionfx.com/link/mornsun/
The Traco TEC 2-0923 is preferred for this circuit because its supply voltage range (4.5V to 13.2V) is
perfectly suited for any type of pedal power supply. The TEC 3-0923 can also be used if you can’t find
the 2-0923. It has higher current handling, more than necessary for this circuit, and as a result it is more
expensive, but it’s otherwise identical.
The other brands all have a minimum supply voltage of 9V. Most nominally 9VDC adapters put out
around 9.6V, which is more than enough—but one very notable exception is the Voodoo Labs Pedal
Power series (and likely other similar pedalboard supplies) which regulate to exactly 9.00V.
These DC converter modules are usually specced very conservatively, so it’s very unlikely that there
would be any issues even if the supply voltage was slightly lower than 9V. However, operating on the
extreme lower end of a spec is not ideal from an engineering standpoint, so if we’re going to point you to
a specific module, it’s going to be the one that works reliably in all use cases.
If you are using a standard wall-wart supply that puts out more than 9V, then all this is immaterial and
any of the five units listed above will work the same. All significant specifications are the same aside
from this input voltage range. We haven’t tried all of them directly, but their datasheets indicate they
will perform identically and they have the same pinout and physical dimensions.
This is fortunate, because most suppliers don’t stock more than 20 or 30 of each type at a time. So while
we recommend the Traco TEC 2-0923 as the best overall, it will likely not always be in stock, especially
as we release more preamp projects with converters and more people are using them.
If you’re having a hard time finding any that will work, try searching Octopart for the part number
shown in the Part # column. Most of these brands are also carried by Digi-Key, Newark, and several
other suppliers, and this engine will search all of the major distributors at once for easier sourcing.
The Mornsun unit is not available from Mouser, but it’s included here because it’s cheaper than the
others (USD$8.22 as of the time of this writing) with the exact same specs. If you need more than one, it
quickly becomes much more cost-effective than the other options.

L5 PREAMP DRIVE CHANNEL 9
BUILD NOTES, CONT.
Calibration
The L5 Preamp has two different calibration trimmers. To set these, all you will need is a multimeter and
a signal generator (which can be a computer or smartphone).
Note that all voltages are taken in AC, not DC, since we are dealing with audio signal levels. The voltages
are also all RMS rather than p-p, so confirm that your multimeter measures RMS if you’re not sure.
Before you start, turn both trimmers all the way down.
Distortion trimmer
The distortion trimmer should be set first. This sets the level at which the overdrive kicks in. The
procedure calls for a 1kHz 30mV sine wave to be inserted onto pin 4 of IC5, and for the trimmer to be
adjusted until you measure 4.4V on pin 5 of IC5.
For convenience, there is a pair of pads marked “TEST” right underneath the “Frequency”
potentiometer’s pads where you can insert your signal. The “+” pad connects to pin 4 of IC5 and the
other is connected to ground. It’s recommended to solder short pins to these pads (about 3/4” in length)
to act as ‘posts’ for alligator clips to attach to. (The clipped leads from a 1N4004 diode work well for this
since they are more rigid than normal component leads.)
If you don’t have a signal generator, look for a smartphone or Mac/PC app that allows selection of wave
type, frequency and gain level. These come and go, so we can’t recommend anything specific, but there
are several free ones available at any given time and they all do the same basic thing.
From here, hook up a 3.5mm male-to-male headphone cable and turned up the phone or computer
volume to maximum, then set the frequency to 1kHz and the wave type to sine. Using a multimeter set
to AC millivolt mode, adjust the volume in the app until you read 30mV. (Don’t rely on the app to tell you
the output signal level; they have no way of knowing the actual real-world level.)
Now, use alligator clips to connect the sleeve and the tip of the headphone cable to the two wires
coming from the test pad. Since it’s AC, the polarity does not matter. This will insert the signal to pin 4 of
IC5 so you can adjust the trimmer as specified earlier, targeting 4.4V on pin 5.
Once you know the correct factory setting, feel free to adjust the trimmer up or down and see if you
prefer it in any other position (but consider first marking the trimmer with a Sharpie so you can get
back to the calibrated setting). Since this is a pedal adaptation, you may find it worthwhile to adjust the
distortion so it comes on earlier than it did in the original amps.
Compressor/limiter trimmer
With the 30mV sine wave signal still inserted into pin 4 of IC5, turn the master volume up all the way
and turn the compressor on (switch in the “up” position). Then turn the compressor knob up to about
2:00 (2/3 of the way up) and touch your probe to the “PCB OUT” pad on the right side of the footswitch
board. Turn the trimmer until you measure 1.17VAC.
This will get you in the range of the original amps. If you’re using the L5 primarily as a pedal, you may
want to set this lower so it’s more sensitive to lower-level signals.

L5 PREAMP DRIVE CHANNEL 10
BUILD NOTES, CONT.
LM13700 vs. CA3080
The original L5 Preamp used CA3080s as in the original amp. These have been discontinued for a long
time, and while they have been reissued and are not terribly hard to find, they are expensive.
The LM13700 is essentially a dual version of the CA3080/CA3094 and is still readily available. Since the
L5 circuit uses two CA3080s, it seemed like a good opportunity to replace them with a single LM13700.
The only change that this required was to add a second 100k resistor (R53) to cut the compressor LED’s
voltage in half, since the LM13700’s IABC pin sits at twice the voltage of the CA3080’s pin. This extra
resistor prevents the LED from staying on all the time, which was the only side-effect of substituting the
LM13700 in place of the CA3080.
Enclosure size
This project was designed for the Hammond 1590BBS enclosure, which has the same height as the
125B or 1590N1. If you don’t use the Hammond brand, be careful—not all 1590BBS enclosures are the
same. For example, Love My Switches sells two different types, and the CNC Pro version is correct while
the standard one is too short.
The 1590BB2 seems like a close equivalent, but it’s about 4mm shorter. It may be possible to fit this
circuit in a 1590BB2, but we have not tested it, so you’re on your own!
Another alternative is the 1590C (also available from Tayda and Love My Switches). It’s about 10mm
taller than necessary, but if that’s all you can find then it will definitely work.