Arrel Audio R-506 User manual

R-506
Dual/Mono Band VCA Compressor
User Manual
Issue 0.1
REAL Innovation
R 506
AUDIO
SINGLE Fx10
Hz
X-OVER
SIDE LO CUT
GR / VU
DUAL
ONOFF
+20
+12
+12
0
0
1
1
+5
0
-20
-20
300
200
500
400
100
150
S
S
S
S
MODE
ATT
ATT
REL
THR
THR
RATIO
RATIO
REL
F
F
F
F
50
LINK
SIDE
DRY
LO
WET
HI
HI
LO
VU OUT
ON

ARREL Audio
R-506 User Manual, Issue 0.1
Page 2
SAFETY INSTRUCTIONS
WARNING
Always follow the precautions listed below to avoid any possibility of serious injury or even death from electrical shock, short-
circuiting, damages, fire or other hazards. These precautions include, but are not limited to, the following:
Do not expose the instrument to liquids and rain. Do not use it near water or in damp or wet conditions, or place
containers on it containing liquids. If any liquid seeps turn off the power and unplug the power cord from the AC outlet.
Do not put burning items, such as candles, on the unit. A burning item may fall over and cause a fire.
This instrument contains no user-serviceable parts. Do not open the instrument or attempt to disassemble or modify the
internal circuit.
Never insert or remove an electric plug with wet hands.
Check the electric plug periodically and remove any dirt or dust which may have accumulated on it.
Do not place the power cord near heat sources such as heaters or radiators, and do not excessively bend or otherwise
damage the cord, place heavy objects on it, or place it in a position where anyone could walk on, trip over, or roll
anything over it.
CAUTION
Always follow the precautions listed below to avoid any possibility of serious injury or even death from electrical shock, short-
circuiting, damages, fire or other hazards. These precautions include, but are not limited to, the following:
Do not connect the instrument to an electrical outlet using a multiple-connector. Doing so can result in lower sound quality, or
possibly cause overheating in the outlet itself.
When removing the electric plug from the instrument or an outlet, hold the plug itself and not the cord. Pulling by the cord can
damage it.
Remove the electric plug from the outlet when the instrument is not to be used for extended periods of time, or during
electrical storms.
Do not place the instrument in an unstable position where it might accidentally fall over.
Before moving the instrument, remove all connected cables.
When setting up the product, make sure that the AC outlet you are using is easily accessible. If some trouble or malfunction
occurs, immediately turn off the power switch and disconnect the plug from the outlet. Even when the power switch is turned
off, electricity is still flowing to the product at the minimum level.
When you are not using the product for a long time, make sure to unplug the power cord from the wall AC outlet.
Use only the stand/rack specified for the instrument. When attaching the stand or rack, use the provided screws only. Failure
to do so could cause damage to the internal components or result in the instrument falling over.
Information for Users on Collection and Disposal of Old Equipment
This special symbol on the products, packaging, and/or accompanying documents means that used electrical and electronic products
should not be mixed with general household waste.
For proper treatment, recovery and recycling of old products, please take them to applicable collection points, in accordance with your
national legislation and the Directives 2002/96/EC.
By disposing of these products correctly, you will help to save valuable resources and prevent any potential negative effects on human
health and the environment which could otherwise arise from inappropriate waste handling.
For more information about collection and recycling of old products, please contact your local municipality, your waste disposal service
or the point of sale where you purchased the items.
[For business users in the European Union]
If you wish to discard electrical and electronic equipment, please contact your dealer or supplier for further information.
[Information on Disposal in other Countries outside the European Union]
This symbol is only valid in the European Union. If you wish to discard these items, please contact your local authorities or dealer and
ask for the correct method of disposal.

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R-506 User Manual, Issue 0.1
Page 3
ARREL Audio Contacts
ARREL Audio
Via A. Mondadori, 7
00128 Rome – Italy
Tel [phone]
Fax: [phone]
Info: [email protected]
Web: www.arrel-audio.com
Support: http://www.arrel-audio.com/support
ARREL Audio is continuously working to the improvement of its systems and related documentation.
In any case, we reserve the right to change the specifications without notice but in the respect to the current legislation.
Disclaimer:
The information contained in this manual has been carefully checked and we believed is accurate at the time of publication.
In any case, we do not assume any responsibility for inaccuracies, errors or omissions nor any liability for any loss or damage resulting either
directly or indirectly from use of the information contained in this manual.

ARREL Audio
R-506 User Manual, Issue 0.1
Page 4
TABLE OF CONTENTS
SAFETY INSTRUCTIONS ...................................................................................................2
ARREL Audio Contacts........................................................................................................3
TABLE OF CONTENTS .......................................................................................................4
INTRODUCTION .................................................................................................................5
Housing................................................................................................................................6
Installation Instructions ........................................................................................................6
R-506 Front Panel Controls and Operations........................................................................7
DRY-WET knob ................................................................................................................7
HI-LOW KNOB .................................................................................................................7
OUT LEVEL knob .............................................................................................................7
HI - V.U. – LO SWITCH....................................................................................................7
RATIO KNOB (HI AND LO BAND) ...................................................................................7
THRESH(old) KNOB (HI AND LO BAND) ........................................................................7
REL(EASE) SWITCH (HI AND LO BAND) .......................................................................7
ATT(ACK) SWITCH (HI AND LO BAND)..........................................................................8
OFF-ON-x10 SWITCH .....................................................................................................8
CROSSOVER FREQUENCY KNOB................................................................................8
LINK JACK (3.5 mm STEREO jack).................................................................................8
SIDE JACK (3.5 mm stereo jack) .....................................................................................8
True BY-pass ON switch (LED) ........................................................................................9
R-506 Operating modes.......................................................................................................9
R-506 Dual Band Mode .......................................................................................................9
R-506 Single band (full bandwidth on the envelope) ...........................................................9
R-506 Single band (LO cut on envelope detector).............................................................10
R-506 External connections...............................................................................................10
R-506 SIDE Jack ...............................................................................................................10
R-506 LINK JACK..............................................................................................................10
APPENDIX A: Front Panel ................................................................................................. 11
APPENDIX B: EXTERNAL CONNECTIONS .....................................................................12
APPENDIX C: 500 series module edge connector ............................................................13
TECHNICAL SPECIFICATIONS ........................................................................................14 

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R-506 User Manual, Issue 0.1
Page 5
INTRODUCTION
ARREL Audio R-506 is an advanced dual/mono band VCA based compressor conceived
to offer to the 500 series user the superior audio performance of the ARREL audio high
level products. The R-506 is characterized by high reliability, rugged design, outstanding
audio quality, versatility and ease of use typical of the tradition of ARREL Audio products.
The R-506 is characterized by an extreme flexibility in a single slot 500 module. It includes
the following features.
ARREL high audio quality input and output buffers
Dual envelope detector and dual VCA architecture
Variable crossover with two bands (50Hz-500 Hz, 500Hz/5000Hz)
Attack and Release three position switches separate for the LO and HI frequency
bands
Operative mode switch: Mono Band, Mono Band with LO cut on the envelope
detector and Dual Band.
Compression Ratio and Threshold knobs for the HI and LO band
Compressed HI and Compressed LO bands mix knob
Dry-Wet mix knob (for mono and dual band parallel compression)
Flexible metering system (Compression HI, Compression LO, output level)
Side Chain External input
Side chain stereo link input
True by-pass function
The R-506 provides four operative modes:
1. Single band compressor (full band on the envelope detector).
2. Single band compressor (variable frequency LO cut on the envelope detector).
3. Dual Band compressor 50-500 Hz crossover range.
4. Dual Band compressor 500-5000 Hz crossover range.
An Internal dip switch can be used to set up different mix of LO and HIGH signals at the
input of the respective envelope detector circuits.
R-506 is the one of the ARREL 500 series modules (the other models are R-501, R-502,
R-503, R-504, R-505, R-507) designed to give to the professional user the best audio tools
for its application. To obtain an outstanding audio quality, no servo amplifiers are used in
the R-506 so it is not possible to unbalance the line out of the R-506.If you need an
unbalanced connection follow the indications shown in APPENDIX B. The R-506, offers a
very cool white front panel and a semi closed stainless steel enclosure. R-506 is dedicated
(due to his absolute sonic level quality) to high professional vocal recordings, classical
instruments, high dynamic range instruments such as drums and percussions.
ARREL Audio products are designed and manufactured in Italy.

ARREL Audio
R-506 User Manual, Issue 0.1
Page 6
Housing
The R-506 dual band VCA compressor module has been designed to be compliant with
the 500-series standard.
Installation Instructions
Remove the R-506 module from the packaging.
Turn off the 500-series enclosure and remove mains power.
Find an empty slot in the 500-series rack and remove the 2 fastening screws,
positioned one on the top of the enclosure and one the bottom of the enclosure.
Insert the R-506 into the empty slot in the 500-series enclosure, Be sure that the
rear edge connector on the R-506 module mates correctly with the edge connector
of the 500-series enclosure.
Replace the 2 fastening screws through the top & bottom holes in the R-506 module
and screw into the 500-series enclosure. The module must be secured into the
enclosure before turning the mains on.
Apply mains power into the 500-series enclosure and turn on.
The module is not designed to be hot-plugged, so please ensure the power to the
500-series enclosure is OFF before inserting or removing a module (this
recommendation is useful in order to protect the 500 enclosure circuits, our product
due to a very robust construction could be hot-plugged without problems).

ARREL Audio
R-506 User Manual, Issue 0.1
Page 7
R-506 Front Panel Controls and
Operations
DRY-WET KNOB
The DRY-WET knob is used to mix the dry signal
from the input of the compressor and the WET i.e.
the compressed signal at the output of the
compressor (mono and dual band compression).
HI-LOW KNOB
The HI-LO knob is used to mix the compressed
audio signal at the output of the two channels of the
compressor (HI and LO channel).
OUT LEVEL KNOB
The OUT knob is used to set the output level.
HI/VU/LO SWITCH
It is used to select the measurement on the display.
Select HI to visualize the compression factor on the
HI channel. Select LO to visualize the compression
factor on the LO channel. Select VU to visualize the
level at the output of the compressor.
When the compressor is bypassed the VU meter is
able to measure the input signal level.
RATIO KNOB (HI AND LO BAND)
It is used to set the compression ratio of the
compressor. A knob for each band. The
compression ratio range is 1:1, to ∞:1.
THRESH(OLD) KNOB (HI AND LO BAND)
It is used to set the threshold of the compressor. A
knob for each band. The threshold range is -20
dBu, +13 dBu.
REL(EASE) SWITCH (HI AND LO BAND)
Select one of the three positions to select slow,
medium and fast (separate switch for HI and LO
band).
R 506
AUDIO
SINGLE Fx10
Hz
X-OVER
SIDE LO CUT
GR / VU
DUAL
ONOFF
+20
+12
+12
0
0
1
1
+5
0
-20
-20
300
200
500
400
100
150
S
S
S
S
MODE
ATT
ATT
REL
THR
THR
RATIO
RATIO
REL
F
F
F
F
50
LINK
SIDE
DRY
LO
WET
HI
HI
LO
VU OUT
ON

ARREL Audio
R-506 User Manual, Issue 0.1
Page 8
ATT(ACK) SWITCH (HI AND LO BAND)
Select one of the three positions to select slow,
medium and fast (separate switch for HI and LO
band).
OFF-ON-X10 SWITCH
This is the most important switch of the compressor
unit.
Select OFF to use the compressor as a
single band traditional compressor. In this
operative mode the high section of the
compressor is activated.
Select ON to use the compressor as a dual
band compressor. In this case the crossover
frequency range knob works on a 50Hz-500
Hz range.
Select x10 to use the compressor as a dual
band compressor. In this case the crossover
frequency range knob works on a 500Hz-
5000 Hz range.
CROSSOVER FREQUENCY KNOB
Rotate the knob to change the cutoff frequency of
the crossover.
LINK JACK (3.5 MM STEREO JACK)
The link Jack is used to link two R-506 units. In this
way two R-506 can be linked for stereo
compression. The left channel in the first unit is sent
via the link cable to the second unit (right channel)
and added to the right channel to generate the
control signal to the right channel compressor. The
same happens to the right channel that is sent to
the first unit (left channel) and added to the left
channel in the generation of the control signal for
the left channel compressor. Each channel can then
be controlled with the front panel controls.
SIDE JACK (3.5 MM STEREO JACK)
The link Jack is used to control the VCAs by an
external side chain signal.
LO CUT SWITCH
Used in the mono band mode to insert a variable
frequency Low Cut filter on the side chain. The Low
R 506
AUDIO
SINGLE Fx10
Hz
X-OVER
SIDE LO CUT
GR / VU
DUAL
ONOFF
+20
+12
+12
0
0
1
1
+5
0
-20
-20
300
200
500
400
100
150
S
S
S
S
MODE
ATT
ATT
REL
THR
THR
RATIO
RATIO
REL
F
F
F
F
50
LINK
SIDE
DRY
LO
WET
HI
HI
LO
VU OUT
ON

ARREL Audio
R-506 User Manual, Issue 0.1
Page 9
Cut, cut off frequency is changed by rotating the cross over knob in the range 50 Hz, 500
Hz.
TRUE BY-PASS ON SWITCH (LED)
The compressor can be bypassed (true by-pass) by pressing the bypass button.
R-506 Operating modes
The R-506 provides three main different operating modes:
1. Dual Band compressor.
2. Single Band compressor (full band on the envelope detector).
3. Single band compressor (LO cut on the envelope detector).
The operating mode is selectable by the ON-OFF-x10 switch shown in Fig. 1 and 2.
Moreover the side chain can be externally controlled by using one external 3.5 mm jacks.
The Side chain jack is mono.
R-506 Dual Band Mode
In this operative mode the R-506 is a true dual band compressor.
The two channels at the out of the crossover circuit are compressed in parallel on two
different gain processors.
The signal at the input of the two side chains (envelope detectors) can be user defined by
an internal dip switch.
Four possibilities are provided:
DP1 DP2 Function
OFF OFF The side chain are controlled by the corresponding crossover output
ON OFF The LO side chain is controlled by a mix of the signals from the
crossover outputs (68% signal from LO and 32% from HI)
OFF ON The HI side chain is controlled by a mix of the signals from the
crossover outputs (68% signal from HI and 32% from LO)
ON ON The LO side chain is controlled by a mix of the signals from the
crossover outputs (68% signal from LO and 32% from HI)
The HI side chain is controlled by a mix of the signals from the
crossover outputs (68% signal from HI and 32% from LO)
In the dual band mode, the two true RMS detectors (envelope detectors) speeds are
optimized for the low and high band of the compressor.
R-506 Single band (full bandwidth on the envelope)
In this case the compressor architecture is typical single band architecture. The HI gain
control circuit and the corresponding chain are used to process the input signal (red
knobs).
The envelope detector is controlled directly from the dry signal (input signal). The
crossover is excluded.

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R-506 User Manual, Issue 0.1
Page 10
R-506 Single band (LO cut on envelope detector)
In this case the compressor architecture works as single band architecture. The HI gain
control circuit and the corresponding chain are used to process the input signal. The
envelope detector is controlled from the HI out of the crossover. So in this case the user is
able to control the amount of low frequency signals to be used in the computation of the
envelope.
R-506 External connections
The R-506 can be connected in many different ways for the maximum flexibility.
R-506 SIDE Jack
By using this 3.5 mm mono jack the HI side chain section of the compressor can be
controlled by an external signal. In this way the user can build the side chain signal by
using external units (for example a multiband equalizer controlled by the same signal at
the input of the R-506).
R-506 LINK JACK
By using this 3.5 mm stereo jack two R-506 units can be linked. In this way two R-506 can
be linked for stereo compression for example. The left channel in the first unit is sent via
the link cable to the second unit (right channel) and added to the right channel to generate
the control signal to the right channel compressor. The same happen to the right channel
that is sent to the first unit (left channel) and added to the left channel in the generation of
the control signal for the left channel compressor. Each channel can then be controlled
with the front panel controls.

ARREL Audio
R-506 User Manual, Issue 0.1
Page 11
APPENDIX A: Front Panel
FIG. 1 R-506 Front Panel
R 506
AUDIO
SINGLE Fx10
Hz
X-OVER
SIDE LO CUT
GR / VU
DUAL
ONOFF
+20
+12
+12
0
0
1
1
+5
0
-20
-20
300
200
500
400
100
150
S
S
S
S
MODE
ATT
ATT
REL
THR
THR
RATIO
RATIO
REL
F
F
F
F
50
LINK
SIDE
DRY
LO
WET
HI
HI
LO
VU OUT
ON

ARREL Audio
R-506 User Manual, Issue 0.1
Page 12
APPENDIX B: EXTERNAL CONNECTIONS
FIG. 2 External connections
WIRING R - 506
MAIN OUTPUT
LINE INPUT
XLR
XLR
On the back panel
On the back panel
1
1
2
2
3
3
1 = Ground
1 = Ground
2 = PHASE +
2 = PHASE +
3 = PHASE -
3 = PHASE -
disconnect pin 3
Unbalanced line
Balanced line only - To use unbalanced lines
Unbalanced line
Balanced line Can be unbalanced
AUDIO
STEREO LINK
SIDE-CHAIN On the front panel
On the front panel
JACK MONO/STEREO 3.5 mm
JACK STEREO 3.5 mm
RETURN
INPUT
SEND
GROUND
GROUND
GROUND

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R-506 User Manual, Issue 0.1
Page 13
APPENDIX C: 500 series module edge connector
FIG. 3 500 Series module edge connector
- OUT
+ IN
- IN
+ 16 V.
- 16 V.
+ 48 V.
GROUND
GROUND
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1GROUND
+ OUT
R - 500
MODULE

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R-506 User Manual, Issue 0.1
Page 14
TECHNICAL SPECIFICATIONS
Number of
Channels: 1
Power Supply ±16 VDC, very low power supply currents with respect to the 500
series standard
Line Input
Elecronically Balanced,
Impedance 20KΩ,
Input Level +4dBu, Max +20 dBu.
Output Level
Electronically Balanced,
Level +4 dBu, Max +27 dBu,
Output Impedance 100 Ω
Bandwidth 5 - 150 KHz ±1 dB, perfect square wave up to 20 KHz
Distortion + Noise <0.003% ( typical 0.001%).
Front Panel Controls
True By-Pass button (LED),
DRY-WET mix knob
LO-HI mix knob
OUT level knob
Ratio knobs (HI and LO) 1:1 to ∞:1
Threshold knobs (HI and LO) – 20 dBu, +13 dBu
Attack switch (separate HI and LO): three positions (slow, mid, fast),
Release switch (separate HI and LO): three positions (slow, mid,
fast)
Mode switch: dual band, mono band dry, mono band with side chain
controlled by a variable cut off frequency LO cut filter.
Crossover frequency
Metering selection switch: three positions (Ho compression, LO
compression, Output level)
Attack Time HI (slow, mid, fast)=(33 msec, 10 msec, 2.3 msec)
LO (slow, mid, fast) =(120msec, 23 msec, 5msec)
Release Time HI slow, mid, fast=(1 sec, 490 msec, 85 msec)
LO (slow, mid, fast)=(200msec, 1 sec, 1.5 sec)
Crossover
Frequency Bands
50Hz-500 Hz OFF-ON-X10 SWITCH in ON position
500Hz-5000 Hz OFF-ON-X10 SWITCH in X10 position
Front panel
connectors
3.5 mm SIDE mono/stereo jack
3.5 mm LINK stereo jack
Rear Panel Input
Connectors 500 series compatible connector
Construction Compliant 500-series rack with PSU and external audio connections,
Single 500-series rack slot required for each R-501 module.
Dimensions Series 500 standard
Weight 500 g

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R-506 User Manual, Issue 0.1
Page 15