Applied Research and Technology (ART) The Levelar Owner's Manual

Professional Vactrol Leveling Amplifier

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Compression is used to alter the dynamic range of a signal. In
recording and live sound situations, compression and limiting is
necessary to manage sounds with wide dynamic ranges. Dynamic
Range is measured as the difference between the loudest and soft­est level of a signal. (i.e. from a scream to a whisper). Once a sig­nal rises above or falls below the set threshold (selectable signal
level), the compressor automatically changes its gain to raise or
lower the overall signal level. Think of this as manually moving a
fader up and down to try to keep a signal at a consistent level.

Limiting can be described as a “ceiling”. When using a limiter,
once the signal level reaches the threshold, it is unable to go any
louder - it is limited to a desired level.

In addition to making signal levels more manageable, it is com­mon practice to apply compression or limiting to a signal to make
it louder or more “in-your-face”. The benefit of using the Levelar
for these applications is in its design. By utilizing opto-electronics,
the Levelar allows you to add

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compression without sound­ing like you’re squashing the daylights out of the signal. Unlike
typical compressors that use VCA’s to control level detection, the
Levelar is very musical. The nature of its operation is much like
the way your eye adjusts to light. Just as your eye transparently
adjusts to changes in light, the Levelar adjusts to changes in signal
level.

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It’s easy to interface the Levelar with other equipment. All connec­tions are made at the back of the Levelar. Standard XLR and 1/4”
inputs and outputs make patching simple. Note: For best audio
quality, always use high-quality cables.

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The Levelar provides both an XLR and 1/4” input jack. Both jacks
are balanced. The 1/4” jack can be used with unbalanced signals
by simply plugging in an unbalanced cable. The inputs are
designed for use with line level signals ranging from -30dBm to
+10dBm. While it is possible to plug an instrument directly into
the Levelar, it is desirable to run the instrument into a preamp
before the signal runs into the Levelar. This will provide a

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Thank you for purchasing the Levelar—and congratulations: You now own
one of the most sophisticated pieces of audio signal processing gear.
Similar in design philosophy to the classic tube limiters, the Levelar utilizes
a VCA-less design for premium, musical performance. This design features
electro-optical (Vactrol) and vacuum tube electronics which deliver classic
sound without the “old” noise.

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Single channel tube and Vactrol based Leveling Amplifier
Hand selected 12AX7 Tube
Vactrol - Optical electronic isolator
Non-VCA design = transparent, classic sound
Balanced XLR and 1/4” TRS inputs
Balanced XLR and 1/4” TRS outputs
Limiting and Compression ratios
Auto or Fast attack and release characteristics
Variable Threshold rotary control
Variable Output level rotary control
Gain reduction LED ladder
10Hz to 20kHz Frequency Response
>100dB Dynamic Range
Extremely low noise
Rugged, portable all steel chassis
Designed & Manufactured in the USA

Fill in the following information for your reference:
Date of purchase: _________________________________
Purchased from: _________________________________
Serial number: 129-______________________________

This is a great time to fill out the User Registration Card included with your
Levelar to become a completely informed A R T Artist. Returning the card
to us ensures you of becoming the first to know about new A R T prod­ucts as well as any further developments from A R T.

129-5004-101