BACK PANEL
1. AC POWER ENTRY MODULE
Accepts standard IEC power cord (included) for 115v or 230v AC mains
supply. A fuse is included with each unit for the voltage/current expected
at the location being shipped to. Only use a fuse with the same rating
and voltage as marked on back of chassis.
2. AC VOLTAGE SLIDE SWITCH
Each unit is factory set to the voltage expected at the location being
shipped to. If voltage does not match mains voltage at your location,
switch to reveal the appropriate voltage. Do not operate unit set to incor-
rect voltage. Harm to the unit may result.
3. MODEL/SERIAL # TAG
When registering your product for your 2-year warranty, please see
the hand stamped tag to obtain the serial number.
4. BALANCED XLR LINE INPUTS
5. BALANCED XLR LINE OUTPUTS
6. STEREO LINK
Connect two separate 14B units with a 1/4” cable (balanced or unbal-
anced) to make use of the “Link/Mono” switch on the front panel.
CHANGING TUBES
Each Model 14B will leave Locomotive Audio with a new set of tubes that
should last for several years. We encourage you to utilize these tubes,
but also experiment with with other brands of New Old Stock tubes to
acheive your sounds! There are no rules with brands or age of tubes. But,
be sure to use only 6BC8 or 6BZ8, balanced 12AY7 and matched 6V6
tubes in the appropriate tube sockets. This will prevent any issue with the
performance of the 14B and damage to the unit.
VU METER CALIBRATION
The VU meters in our units have been pre-calibrated. When needle is de-
flected to 0dB on the VU meter, a signal voltage of +4dBu will be present
on the output of the unit. Turning the small calibration screw on the rear
of the VU meter will allow a qualified technician to adjust display levels.
INTERNAL ADJUSTMENTS
CAUTION:
Interior adjustments must be made by a qualified technician.
The voltages inside of the 14B are very high and can be lethal. You may
contact Locomotive Audio to have this procedure done free of charge. It
is also advised to use a nonconductive adjustment tool to avoid shock
when the 14B is open.
The adjustments located on the inside of the 14B deal directly with gain
reduction 6BC8 input tube. This push-pull gain stage requires a strong
balance, otherwise the engineer may hear strange artifacts such as
thumping, uncontrolled oscillation or rippling apparent on the compres-
sion attack. Each 14B will leave Locomotive Audio fully calibrated. As your
6BC8 ages or with the installation of another 6BC8 tube, the following
procedure must be made as no two tubes are the same.
Plate Balance:
This potentiometer feeds both halves of the 6BC8 tube
the high voltage B+ power.
Cathode Balance:
This potentiometer places a resistance on each of the
two 6BC8 cathodes and can change cathode current, directly influencing
the voltages on the 6BC8 plates. The plate and cathodes work hand-in-
hand to change bias points, current and gain within the tube.
Test/Operate Switch:
This switch sends a 50/60Hz signal to the input of
each half of the 6BC8 tube which can be helpful in balancing.
USE ON
LY
WITH 250V FUSE
MODEL No.
DESIGNED & MANUFACTURED
IN SAINT LOUIS, MISSOURI
SERIAL No.
LOCOMOTIVE AUDIO
PLATE
BALANCE
6BC8 BALANCE ADJUSTMENT
TEST
OPER.
CATHODE
BALANCE
1
2
3
4
6
5
PROCEDURE FOR
A GOOD BALANCE
There are no rules on how to make
the adjustment, so we will give you a
couple options that work well for us
here at Locomotive! The first involves
using the “TEST/OPER.” switch and the
second will utilize a snare drum loop
available at www.locomotiveaudio.com
TEST/OPERATE SWITCH PROCEDURE
1.
Remove any signal entering the 14B.
2.
Set attack and release to the approximate “50” settings
3.
Turn both the “Input” and “Output” knobs fully counterclockwise
4.
Set “Meter Select” switch to “Output.”
5.
On the “6BC8 BALANCE ADJUSTMENT PANEL” set the “TEST/OPER.
switch to the “TEST” position.
