LENNARD AUDIO CLASSIC FET COMPRESSOR User manual

CLASSIC FET COMPRESSOR
User Manual
www.lennardaudio.com

Table of Contents
-Introduction
-Installing your compressor
-Front & Rear Panel Drawings
-Control Description
-VU-Meter Indication
-Calibration
-Linking two units
-Specs and Measurements
-Recall Sheet
-Warranty and Legal
-Health and Safety considerations
Classic FET Compressor - User Manual 1

Introduction
Thanks for purchasing our Classic FET Compressor, this is our version of the well
known FET compression designs, including all the character and fast response you
could expect from it, as well as some added features like True bypass or Sidechain
HPF which are extremely useful in the modern studio environment.
Built in a 19” 2U. Rack chassis, uses high quality VU-Meter for Gain Reduction or
Output Level monitoring. using RGB LED illumination, the meter also displays useful
information like overcompression or bypass state. Additionally, Bypass is Wi-Fi
controllable, allowing you to make precise A/B comparison from the listening spot.
Below you can find the block diagram for the audio path.
Installing your compressor
Before plugging the unit to mains power, check the rear voltage switch position is set
for your local voltage (110VAC 60Hz. or 220VAC 50Hz.)
The audio input and output uses XLR connectors to receive and send balanced
signals. Although we highly advise using balanced cables, the unit will work with
unbalanced input and will feed unbalanced devices through it’s output, just keep in
mind the 6db’s loss when using unbalanced cables.
Although all our products are built, tested and packed conscientiously, some
problems may occur during transport. If you find any problem or malfunction please
unplug the unit and contact us to [email protected] to find a solution or
replace the unit.
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Front & Rear Panel Drawings
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Control Description
Input:Signal attenuator at compressor input, set
the amount of signal coming into the
compressor
Attack: adjusts how fast does the unit react when
the threshold level is reached by the input signal,
continuously variable from 20us to 800ms.
Release: sets the speed of the gain recovery after
the input signal falls below the threshold level,
continuously adjustable from 50ms to 1,1s.
Output: control the output level of the signal
coming out the unit.
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Ratio: amount of compression applied, 4
different options 4, 8, 12 & 20:1, select a higher
ratio when you look for harder compression and
a lower setting for a smoother transient control.
SC HPF: High Pass Filter inserted in the Side
Chain circuitry, tuned at 180Hz. It reduces low
frequency energy coming into the detector so
lower frequency sounds don't create overshoot
in gain reduction level, resulting in a smoother
compression and a more natural sound.
ALL IN: Emulates the behaviour of the All Buttons
In or British Mode found in classic models.
Bypass: True Bypass vía Relays, It feeds the
input signal to the Compressor circuit or directly
to the output XLRs, taking out completely the
unit of the signal path when bypassed.
Classic FET Compressor - User Manual 5

VU-Meter Indication
Using RGB LEDs for the meter lighting allows us to use different colours as a visual
feedback for different situations.
When the unit is turned on, the meter shows a blue light until the FET reaches its
optimal working conditions. During this “Warm-Up” mode, the Bypass is engaged,
routing the input signal directly to the output.
In normal operation, the meter will light in a nice and warm orange, reminiscent of
classic incandescent bulb feel.
When the signal is being heavily compressed (more than 12db’s of gain reduction)
the meter will light slightly red, similar to the use of “overload” or “peak” indicators in
some mixers and preamps.
Finally, when the unit is bypassed, the meter will light in green, letting you know the
compressor is out of the signal path.
Calibration
Each unit is conscientiously calibrated and tested after building it, and the circuit
design assures consistent and stable along time calibration. However, Zero indication
in GR Mode, could need some correction from time to time, it won’t affect the sound
of the unit in any way, and you can re adjust it from the front panel, using the small
hole between Output and Ratio controls to introduce a small flat screwdriver and turn
the small potentiometer inside it.
Linking two units
Link connector helps pairing two compressors for stereo usage, using a standard
cable with ¼” TS connectors it will join the GR signal of two units to accomplish the
same GR on both compressors. Note this will only work with Lennard Audio Classic
FET Compressors, please, don’t use link to chain two different units as it could
damage this processor (probably the other unit won’t be happy either)
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Specs and Measurements
Input Impedance 10kΩ
Output Impedance 600Ω
Max. Input Level +18dBu
Max. Gain 40dB
Max. Out Level +28dBu
Freq. Response +/- 1dB 20Hz-20Khz
THD @ +4dBu no compression 0.025%
THD@ +4dBu 6dB Gain Reduction 0.12%
S/N Ratio 75 dBs
Classic FET Compressor - User Manual 7

Recall Sheet
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Warranty and Legal
All our products have 5 years of warranty. Warranty will be avoided in case of
misuse, unauthorized repairs or modifications as well as damages caused by not
following health and safety rules described in this document. Warranty coverage
doesn’t include shipping costs.
This document and all its content is property of Lennard Audio and could be changed
without further notice.
Health and Safety Considerations
Please, read this chapter carefully and follow all the guidelines explained here.
Before powering the unit, be sure the power source provides the voltage selected in
the back of the unit (110 or 220VAC). Never connect it to an unknown condition
power source. Ground or Earth connection should be perfect in order to avoid safety
issues.
Only use this device in a clean environment, with controlled temperature and
humidity. Keep the device away from any source of liquid, moisture or vibration.
Avoid direct sunlight and maintain an optimal ventilation.
Special care should be given to the power and signal cables, don’t run them where
they could be pierced, stepped on or damaged by mechanical stress.
This device should be operated only by trained personnel who can understand and
follow all the guidelines presented in this chapter.
To clean the device start by unplugging both signal and power cords. Use a clean
piece of soft cloth and, only if needed, use a lightly wet cloth and the dry the
remaining moisture using a clean dry cloth. Never use any kind of chemical of
solvents to clean it.
Never, under any condition, try to open, modify or repair the unit yourself. Only
Lennard Audio or authorized technicians should attempt to service the unit.
Don’t turn on the unit if it shows physical damage, the cables connected to it are not
in perfect condition or if it has been hit due to a fall or any similar situation.
Failure to comply with any of these rules will result in the immediate revocation of the
warranty.
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Technical Support
For any doubt about installation or usage, as well as claim warranty, you can contact
us via email in [email protected]
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