PRESONUS Smart Compressor User manual

SMART COMPRESSOR
USERS MANUAL
Version 1.0
1997, PreSonus Audio Electronics, Incorporated.
All rights reserved.

WARRANTY
PreSonus Limited Warranty
PreSonus Audio Electronics Inc. warrants this product to be free of defects in material and
workmanship for a period of one year from the date of original retail purchase. This warranty is
enforceable only by the original retail purchaser. To be protected by this warranty, the
purchaser must complete and return the enclosed warranty card within 14 days of purchase.
During the warranty period PreSonus shall, at its sole and absolute option, either repair or
replace, free of charge, any product that proves to be defective on inspection by PreSonus or its
authorized service representative. To obtain warranty service, the purchaser must first call
or write PreSonus at the address and telephone number printed below to obtain a Return
Authorization Number and instructions of where to return the unit for service. All inquiries must
be accompanied by a description of the problem. All authorized returns must be sent to the
PreSonus repair facility postage prepaid, insured and properly packaged. PreSonus reserves
the right to update any unit returned for repair. PreSonus reserves the right to change or
improve the design of the product at any time without prior notice. This warranty does not cover
claims for damage due to abuse, neglect, alteration or attempted repair by unauthorized
personnel, and is limited to failures arising during normal use that are due to defects in material
or workmanship in the product. Any implied warranties, including implied warranties of
merchantability and fitness for a particular purpose, are limited in duration to the length of this
limited warranty. Some states do not allow limitations on how long an implied warranty lasts, so
the above limitation may not apply to you. In no event will PreSonus be liable for incidental,
consequential or other damages resulting from the breach of any express or implied warranty,
including , among other things, damage to property, damage based on inconvenience or on loss
of use of the product, and, to the extent permitted by law, damages for personal injury. Some
states do not allow the exclusion of limitation of incidental or consequential damages, so the
above limitation or exclusion may not apply to you. This warranty gives you specific legal
rights, and you may also have other rights which vary form state to state. This warranty only
applies to products sold and used in the United States of America. For warranty information in
all other countries please refer to your local distributor.
PreSonus Audio Electronics, Inc.
501 Government St.
Baton Rouge, LA 70802
[phone]
1997, PreSonus Audio Electronics, Incorporated. All rights reserved.

TABLE OF CONTENTS
TABLE OF CONTENTS
3
1Overview
A Word About Compression 4
1.1
Introduction 6
1.2
Features 6
2 Controls & Connections
2.1
Front Panel Basic Layout 8
2.2
Back Panel Basic Layout 12
2.3
Presets 14
3 Basic Setup & Operation
3.1
Quick Start 18
3.2
Basic Connections 19
3.3
Basic Operating Procedures 21
4 Technical
4.1
Specifications 24

1
OVERVIEW
OVERVIEW
4
AWordAboutCompression....
Punch , apparent loudness, presence just three of many terms used to
describe the effects of compression/ limiting.
Compression and limiting are forms of dynamic range (volume) control.
Audio signals have very wide peak to average signal level ratios
(sometimes referred to as dynamic range which is the difference between
the loudest level and the softest level). The peak signal can cause overload
in the audio recording or reproduction chain resulting in signal distortion.
A compressor/limiter is a type of amplifier in which gain is dependent on
the signal level passing through it . You can set the maximum level a
compressor/limiter allows to pass through, thereby causing automatic gain
reduction above some predetermined signal level or threshold .
Compression refers basically to the ability to reduce the output level of an
audio signal by a fixed ratio relative to the input. It is useful for lowering
the dynamic range of an instrument or vocal, making it easier to record
without distorting the recorder. It also assists in the mixing process by
reducing the amount of level changes needed for a particular instrument.
Take, for example, a vocalist who moves around in front of the
microphone while performing, thus making the output level vary up and
down unnaturally. A compressor can be applied to the signal to help
correct this recording problem by reducing the louder passages enough
to be compatible with the overall performance.
How severely the compressor reduces the signal is determined by the
compression r atio and compression threshold . A ratio of 2:1 or less is
considered mild compression, reducing the output by two for signals
greater than the compression threshold. Ratios above 10:1 are considered
hard limiting. Limiting refers to the point at which the signal is restrained
from going any louder at the output.
The level of input signal at which the output is reduced is determined by
the compression threshold. As the compression threshold is lowered, more
and more of the input signal is compressed (assuming a nominal input
signal level). Care must be taken not to over compress a signal. Too

OVERVIEW
5
much compression destroys the acoustical dynamic response of a
performance. (Over compression, however, is used by some engineers
as an effect, and with killer results!)
Compressor/limiters are commonly used for many audio applications. A
kick drum can get lost in a wall of electric guitars. No matter how much
level is increased, the kick drum stays lost in the mud. Add a touch of
compression and tighten up that kick drum sound allowing it to punch
through without having to crank the level way up.
A vocal performance usually has a wide dynamic range. Transients (the
very loudest portion of the signal) can be far outside the average level of
the vocal signal. It is extremely difficult to ride the level with a console
fader. A compressor/limiter automatically controls gain without altering
the subtleties of the performance.
A solo guitar can seem to be masked by the rhythm guitars. Compression
can make your lead soar above the track without shoving the fader
through the roof .
Bass guitar can be difficult to record . A consistent level with good attack
can be achieved with proper compression . Your bass doesnt have to be
washed out in the low end of the mix . Let the compressor/limiter give
your bass the punch it needs to drive the bottom of the track .

OVERVIEW
6
1.1 INTRODUCTION
Thank you for purchasing the PreSonus Blue Max smart
compressor/limiter with presets. Your Blue Max was designed with you,
the end user in mind. As far as we know, it is the only compressor in the
world with built-in compression presets. The presets were created not
only to assist in setting up the compressor but to offer you the experience
of professional engineers in using compression. If this is your first
compressor, you will instantly gain valuable insight into what can be a
confusing experience. The experienced user will gain a few tricks of the
trade usually kept in the arsenal of professional engineers.
This dynamics processor was built with state of the art components to
deliver crystal clear compression for an infinite period of time. We
believe the Blue Max to be an exceptional sounding unit at an exceptional
price. We hope you agree. Feel free to contact us at 1-800-750-0323
anytime for any reason. We value your comments and suggestions.
Please pay close attention to how you connect your Blue Max to your
system. Improper grounding is the most common cause of noise problems
in both live and studio applications. We suggest you look at the
connection diagrams which are part of this manual to insure optimum
operation.
Good luck and enjoy your Blue Max!
1.2 FEATURES
The following is a summary of the features of the Blue Max:

OVERVIEW
7
•
P
RESETS
.
There are 15 studio proven settings for voice,
percussion, fretted instruments, keyboards, stereo processing
and effects.
•
V
ARIABLE
I
NPUT
C
ONTROL
.
In addition to normal stereo
inputs the input control allows low signal levels such as direct
output of electric guitars and basses to be increased to
optimum levels.
•
M
ANUAL
M
ODE
.
Full operator control of ratio, attack and
release is offered in manual mode.
•
S
TEREO
I
NPUTS
/O
UTPUTS
.
¼ inch unbalanced stereo inputs
(left side mono) and ¼ inch unbalanced stereo outputs (left
side mono) for stereo recording and mix down use.
•
F
ULL
M
ETERING
.
Full metering for input and output levels
are available as well as separate meters for gain reduction.
•
V
ARIABLE
O
UTPUT
.
Output control allows gain changes
from -20dB to +20dB.
•
S
IDECHAIN
I
NSERT
.
Sidechain insert allows the Blue Max to
be used for special processing applications such as de-essing
and ducking.
•
+4dBu O
R
-10dBV O
PERATION
.
Internal operating levels
are switchable from +4dBu to -10dbV for system matching
requirements.
•
I
NTERNAL
P
OWER
S
UPPLY
.
No Wall Wart!

2
CONTROLS & CONNECTIONS
CONTROLS & CONNECTIONS
8
2.1 FRONT PANEL BASIC LAYOUT
The front panel on the Blue Max is divided into three sections. These are:
1. Presets:
Fifteen detented preset positions and Manual select.
The Presets for the Blue Max are controlled by this sixteen
position rotary encoder. As the encoder is rotated, parameters are
digitally switched, simultaneously controlling attack, release, ratio
and threshold.
2. Controls: & Meters
Input

CONTROLS & CONNECTIONS
9
The Input control adjusts the gain on the input amplifiers for both
channels. Amplification gain varies widely from -20dB to +40dB.
The large range is necessary to amplify instruments such as guitar.
Thus the input stage to the Blue Max is actually a pre-amp.
Note: The input control is always active, even in manual mode.
Ratio
Ratio sets the compression slope. This is defined as the output
level versus the input level. For example, if you have the ratio set
to 2:1, any signal levels above the threshold (note: threshold is a
preset parameter in the Blue Max) will be compressed at a
compression ration of 2:1. This simply means that for every 1dB
of level increase into the compressor, the output will only increase
1/2dB, thus producing a compression gain reduction of 0.5dB. As
you increase the ratio, the compressor gradually becomes a limiter.
A limiter is defined as a processor that limits the level of a signal
to the compression threshold. For example, if you have the ratio
set to 20:1, input set at 0dB, the output of the Blue Max will be
limited to the internal threshold of the compressor, which is set to -
10dB in manual mode.
Note: The ratio control is only active in manual mode.

CONTROLS & CONNECTIONS
10
Attack and Release
Attack sets the speed at which the compressor acts on the input
signal. A slow attack time (fully clockwise) allows the beginning
envelope of a signal (commonly referred to as the initial transient )
to pass through the compressor uncompressed, whereas a fast
attack time (fully counter-clockwise) immediately subjects the
signal to the ratio and threshold settings of the compressor.
Release sets the length of time the compressor takes to return the
gain reduction back to zero (no gain reduction). Very short release
times can produce a very choppy or jittery sound, especially in
low frequency instruments such as a bass guitar. Very long
release times can result in an over compressed sound, sometimes
referred to as squashing the sound. All ranges of release can be
useful at different times however and you should experiment to
become familiar with the different sound possibilities.
Note: The Attack and Release controls are only active in
Manual mode.
Input / Output Meter
The Input/Output meter shows the signal level being processed by
the Blue Max. Input refers to the signal level being processed by
the Blue Max before processing. Output refers to the signal level

CONTROLS & CONNECTIONS
11
after processing. 0dB on the meter is referenced to the +4/-10
switch on the rear of the unit. In +4 mode, 0dB = +4dBu. In -10
mode, 0dB = -10dBV.
Gain Reduction Meter
The Gain Reduction meter indicates the amount of gain being
reduced by the compressor in dB.
3. Output & Pushbuttons
Output Level Control
The Output control is used to set the desired output of the Blue
Max. It is sometimes referred to as gain makeup control. This
terms is derived from the fact that as the compressor lowers the
output level during gain reduction, the overall signal level is
lowered, requiring the user to makeup the gain thereby restoring
the original signal level.
Input / Output Meter Select
This button selects the function of the Input/Output meter. Pushed
in, the meter gives you the level of the input signal. Pushed out,
the meter gives you the level of the signal after compression; the
output level.

CONTROLS & CONNECTIONS
12
Process In/Out
The Process button is similar to a bypass button except that the
signal is still effected by the Input of the Blue Max. Pushed in, the
Blue Max is processing the signal (compressing). Pushed out, the
Blue Max is no longer compressing the signal, however the input
gain setting remains active.
2.2 BACK PANEL LAYOUT
Input
The input jack accepts unbalanced tip-sleeve connectors. The
input can handle up to +24dBu unbalanced levels. The left input
is a dedicated mono input.
Output
The output jack accepts unbalanced tip-sleeve connectors. The
output will deliver up to +24dBu in signal level unbalanced. The
left output is a dedicated mono output.
Sidechain
The sidechain jack on each channel interrupts the signal that the
compressor is using to determine the amount of gain reduction to
apply. When no connector is inserted into this jack, the input
signal goes directly to the compressors control circuitry. When a
connector is inserted into this jack, the signal path is broken. If
you have inserted a tip-ring-sleeve connector, the input signal is
sent back out of the Blue Max via the tip of the connector. This

CONTROLS & CONNECTIONS
13
signal can then be processed by an equalizer for example to reduce
sibilance (de-essing) in a vocal track. The signal is then returned
to the unit via the sleeve of the connector.
The signal sent to the sleeve could be that of a narrator or vocalist.
In this application, the audio that you are passing through the
compressor will automatically duck when the narrator speaks or
vocalist sings.
+4/-10 Switch
This switch adjusts the internal operating level of your Blue Max
when it is connected to line level (0dB = -10dBV) gear. With the
switch in the -10 position, the signal is raised internally so that it
is processed at the lower noise floor of your Blue Maxs internal
circuitry. The signal level is lowered on the way out to match up
with your line level gears input. When the switch is in the +4
position, the signal is not changed since this matches the internal
operating level of your Blue Max.
This function may also be useful in creating special effects with
the compressor and gate of the channel by overcompressing.
2.3 PRESETS
Vocal
SOFT - Easy compression. A low ratio setting for ballads allowing a
wider dynamic range. Good for live use. This setting lets the vocal sit
in the track.
Threshold Ratio Attack Release
-8.2dB 1.8:1 0.002mS 38mS
MEDIUM - More limiting than preset 1 for a narrower dynamic range.
1
2

CONTROLS & CONNECTIONS
14
It moves the vocal more up front in the mix.
Threshold Ratio Attack Release
-3.3dB 2.8:1 0.002mS 38mS
SCREAMER - For loud vocals. Fairly hard compression for a
vocalist who is on and off the microphone a lot. It puts the voice in
your face.
Threshold Ratio Attack Release
-1.1dB 3.8:1 0.002mS 38mS
Perc.
SNARE/KICK - Allows the first transient through and compresses the
rest of the signal giving a hard snap up front with a longer release.
Threshold Ratio Attack Release
-2.1dB 3.5:1 78mS 300mS
L/R (Stereo) OVERHEAD - A low ratio and threshold gives a fat
contour to even out the sound from overhead drum mics. Low end is
increased and the overall sound is more present and less ambient. More
boom less room.
Threshold Ratio Attack Release
-13.7dB 1.3:1 27mS 128mS
Fretted
ELECTRIC BASS - A fast attack and slow release to tighten up the
3
1
2
1

CONTROLS & CONNECTIONS
15
electric bass and give you control for more consistent level.
Threshold Ratio Attack Release
-4.4dB 2.6:1 45.7mS 189mS
ACOUSTIC GUITAR - This setting accentuates the attack of the
acoustic guitar and helps maintain an even signal level keeping the
acoustic guitar from disappearing in the track.
Threshold Ratio Attack Release
-6.3dB 3.4:1 188mS 400mS
ELECTRIC GUITAR - A setting for crunch electric rhythm guitar.
A slow attack helps get the electric rhythm guitar up close and personal
and gives punch to your crunch.
Threshold Ratio Attack Release
0.1dB 2.4:1 26mS 194mS
Keyboards
PIANO - A special setting for an even level. Designed to help even up
the top and bottom of an acoustic piano. Helps the left hand be heard with
the right hand.
Threshold Ratio Attack Release
-10.8dB 1.9:1 108mS 112mS
SYNTH - Fast attack and release for synthesizer horn stabs and for
bass lines played on a synthesizer.
Threshold Ratio Attack Release
-11.9dB 1.8:1 0.002mS 85mS
2
3
1
2

CONTROLS & CONNECTIONS
16
ORCHESTRAL - Use this setting for string pads and other types of
synthesized orchestra parts. It will decrease the overall dynamic range for
easier placement in the mix.
Threshold Ratio Attack Release
3.3dB 2.5:1 1.8mS 50mS
Stereo
STEREO LIMITER - Just as the name implies. A hard limiter
setting (brick wall) ideal for controlling level to the 2 track mixdown deck
or stereo output.
Threshold Ratio Attack Release
5.5dB 7.1:1 0.001mS 98mS
CONTOUR - A contoured setting for use on the stereo output to fatten
up the mix.
Threshold Ratio Attack Release
-13.4dB 1.2:1 0.002mS 182mS
Effects
SQUEEZE - Dynamic compression for solo work, especially electric
guitar. It gives you that glassy tele/strat sound. A true classic.
Threshold Ratio Attack Release
-4.6dB 2.4:1 7.2mS 93mS
3
1
2
2
1

CONTROLS & CONNECTIONS
17
PUMP - Make the Blue Max pump up the prime. A setting for
making the compressor pump in a desirable way. This effect is good for
snare drum to increase the length of the transient by bringing the signal up
after the initial spike. Very contemporary.
Threshold Ratio Attack Release
0dB 1.9:1 1mS 0.001mS
2

3
BASIC SETUP & OPERATION
BASIC SETUP & OPERATION
18
3.1 QUICK START
1. Connect your Blue Max using one of the diagrams below.
2. Select either +4 or -10 operating level. (Reminder: +4 is for pro
levels such as consoles, -10 is for consumer levels or
instruments)
3. Select your preset. (Refer to the preset descriptions above.
Remember that the Ratio, Attack and Release knobs are only
active in Manual mode.)
4. Push the Process button in .
5. Turn the Input knob all the way to -20 (counter-clockwise).
6. Set the Output knob on 0.
7. Slowly turn the Input knob up (clockwise) until the Gain
Reduction meters begin to move. Continue to rotate the Input
knob until the Gain Reduction meters read between -5 and -7.
8. Adjust the Output knob to the desired output level.
You should now have a very natural sounding compressed signal. Of
course you should experiment with the settings to suit your taste.

BASIC SETUP & OPERATION
19
3.2 BASIC CONNECTIONS
Inserting into your mixers insert point.
Note: If you dont get any signal flow at first, try swapping the input and
output connections.