Contemporary Research 232-Amp+ User manual

Product Manual
232-Amp+
232-Amp+W
RS-232 Stereo Mixer/Amplifier
Ver 1.9 February 28, 2014

Contemporary Research 2 232-AMP+
Table of Contents
Overview ............................................................................................................................................. 3
Specifications...................................................................................................................................... 4
Field Setup .......................................................................................................................................... 5
Mix/Ducking Operation ...................................................................................................................... 5
RS-232 Control Protocol ..................................................................................................................... 6
RS-232 Commands ............................................................................................................................. 7
Control Commands ................................................................................................................................... 7
Terminal Communication Commands ......................................................................................................... 8
RS-232 Command Hints and Tips .............................................................................................................. 8
Gating and Volume ................................................................................................................................... 8
Response Strings ................................................................................................................................ 9
Input 0 (Stereo) Status Response String (V0):............................................................................................ 9
Input 1 Status Response String (V1):......................................................................................................... 9
Input 2 Status Response String (V2):......................................................................................................... 9
Amp Status Response String (SV):............................................................................................................. 9
Amp Gain Response String (VG): ............................................................................................................... 9
RS-232 Cable Connections................................................................................................................ 10
Single 232-Amp+ ....................................................................................................................................10
Tuner/232-Amp+ Daisy-Chain ..................................................................................................................10
RK1 and RK1-HD Single Unit Rack Mount ..................................................................................................11
RK3 AV Tool Rack Kit ...............................................................................................................................11
Safety Instructions ........................................................................................................................... 12
Limited Warranty and Disclaimer ..................................................................................................... 13

Contemporary Research 3 232-AMP+
Overview
232-AMP+
232-Amp+W
The Contemporary Research 232-Amp+ is a compact, programmable mixer/amplifier aimed at integration
with flat-panel displays and video projectors. The versatile amp features a stereo line-level display/projector
audio input and two mono aux inputs, and outputs stereo sound at 40 watts RMS. The aux inputs mix levels
with the stereo input, and can be set to mute or lower other inputs when active, ideal for wireless mics and
paging applications. The Class D amplifier is highly energy-efficient, using 90% of DC power for
amplification, operating with very little heat, and consuming almost no power at all when quiet.
The 232-Amp+ fastens to the top of CR’s 232- and iC-series tuners with the optional SMA Surface-Mount
Adapter, mounts to displays or projectors, or in optional rack-mount. New iC-series tuners can link to the
232-Amp+ for interactive volume control, and one 12 VDC DC supply can power both units.
The 232-AMP+W has integrated flanges for easy surface mounting
Full RS-232 control and status is available, allowing integration with custom control systems. In addition to
setting master gain and input levels, the commands can also set aux input threshold, timing, and ducking
levels. Installers can adjust performance manually in the field using onboard switches and level
potentiometer.
Drives stereo speakers at 16 watts RMS –32W (16W per channel) @ 8 ohms, 40W (20W per
channel) @ 4 ohms
Mixes one stereo line input with two mono inputs, mono inputs can "duck" other inputs, with
programmable ducking on/off, threshold, timing, and mute levels
Features programmable input levels and volume (volume affects stereo input, mono inputs are fixed)
Offers field adjustment with onboard DIP switches and level potentiometer
UL 2043 plenum rated
Integrates via 2-way RS-232 with three options:
—Connect to data link on new iC-Net tuners for interactive volume control
—Control from AMX, Crestron or other custom control systems
—Daisy-chain RS-232 control with a 232-series tuner (Amp is Device 1)
Links DC power to CR tuner to provide single 12 VDC power source for amp and CR tuner (Amp level
will be lower at 12 VDC)
Connects speakers and control from captive screw terminals
Mounts to top of CR tuners with optional SMA bracket, next to CR tuners in new RK-1, and RK-3 AV
Tool rack kit
Includes 4 A DC power supply (domestic only), and captive-screw control terminals
Options:
—SMA Surface-Mount Adapter
—PMT-1 Pole Mount Adapter for 232- and IC-series tuners
—DC-2 Y Adapter supplies DC power to tuner and amp @ 12 VDC
Firmware
Version 1.7 –Fixes bug where a bump command did not affect Line input volume
Version 1.5 –Improves ducking performance, Mono 1 and 2 will trigger amp on as well as Line
Version 1.8 - Adds a Mute On/Off to inputs
Version 1.9 –Helps to reduce noise in some applications, requires a board modifications in older
232-AMP and AMP+ units.

Contemporary Research 4 232-AMP+
Specifications
Physical
232-Amp+: 5.5" [140mm] wide x 1.1” [28mm] height x 3.5” [86mm] deep
7.7” [196mm] wide with SMA bracket
232-Amp+W: 7.7” [196mm] W x 1.1” [28mm] H x 3.5” [86mm] D
Weight: 8 oz [226g]
Enclosure: All aluminum with durable black powder coat paint
232-Amp+ Mounting: Optional SMA Brackets attach 232-Amp+ to CR tuner or surface,
mount alongside CR tuner in RK-1, rack-mount in RK3 rack kit
232-Amp+WMounting: Integrated flanges for surface mounting
Standards: RoHS compliant and energy-efficiency meets new California standards, UL
2043 plenum rated
Audio
Amplifier
Inputs
Class D, highly energy-efficient, operates with very little heat
Stereo: Stereo 3.5 mm jack, unbalanced, 7.5K ohms impedance, 1.4 V RMS max
Programmable input level
Inputs 1 and 2: Two Mono 3.5 mm jack, unbalanced, 7.5K ohms, 1.4 V RMS max
Programmable for input level and ducking gating, timing, and mute levels
Gain Potentiometer: Adjusts volume in normal mode, sets other levels in program mode
DIP switches: Located on bottom of 232-Amp+ interact with Gain for field setup
Operation: Master volume commands affects Input 1 only
Output
Speakers: 5-pin captive-screw terminal for stereo speaker installation, 8 or 4 ohm
Watts @ 18 VDC: 32W RMS (16W per channel) @ 8 ohms
40W RMS (20W per channel) @ 4 ohms
Watts @ 12 VDC: 16W RMS (8W per channel) @ 8 ohms
30W RMS (15W per channel) @ 4 ohms
Gain: Added gain 20 dB (default), programmable to 26, 32, or 36 dB
THD + Noise: 0.25% typical
Response: +/-1 dB, 20 Hz to 20 kHz, 1 watt output
Crosstalk: >65 dB @ 1 kHz, >58 dB @ 20 kHz
Protection: Thermal and short-circuit protected, auto-recovery
Control
5-pin captive-screw terminal
RS-232: GND, TX and RX
Signal (Sig): future IR input
Power (V+): 12-18 VDC output to tuner or accessory
DIP switches on bottom of 232-Amp+ interact with Gain for field setup
Power
Power LED: Green LED flashes when DC power is active, slow flash in standby mode
Power In: 5-pin captive-screw terminal
3 A maximum @ 18 VDC, 11.5 to 19 VDC, 18 VDC typical (may be unregulated)
Includes
18 VDC 3 A digital switching power supply (North American shipments only)
Two 5-pin captive screw terminals
Options
PMT-1 Pole Mount for 1RU CR tuners
SMA Surface Mount for AV Tools
RK-1 Rack Kit to mount 232-Amp+ alongside CR analog 232-series tuner
RK-3 Rack Mount Kit for mounting up to 3 AV Tools across in 19” rack, 1 RU

Contemporary Research 5 232-AMP+
Field Setup
All the parameters can be programmed via RS-232, but many can be set using the DIP switch on the bottom
of the case and the Gain potentiometer on the front panel
Select Input and Gain
1. Stereo input = Switches 1 and 2 OFF
2. Mono 1 = Switch 1 ON to In 1
3. Mono 2 = Switch 1 off , switch 2 ON to In 2
4. Use GAIN pot to set gain for selected input
RS-232 Baud Rate
Set switch OFF for 9600 baud or ON for 1200 baud.
Status LED
The green LED will stay lit when the unit is powered and the output is active. A slow flash on the LED
indicates the amplifier is in standby mode (no audio input level, timed out to standby).
Mix/Ducking Operation
Inputs 1 and 2 can serve as mix or ducking inputs. Ducking means that, when audio on one input rises about a
trigger level, it will mute the other inputs. The 232-Amp+ allows you to set several parameters for automatic
ducking operation for both inputs.
Volume –This sets the gain level for the input.
Gate Threshold –Set the input audio level that triggers ducking .
Gate Hold Time –Sets how long the gate will be held open before checking the Gate level.
Ducking Level –Sets the volume level for the stereo input during ducking –the other mono input will
be muted.
Input 1 always has priority –use this input for audio from a paging system.

Contemporary Research 6 232-AMP+
RS-232 Control Protocol
Overview
The 232-Amp+ full duplex RS-232 enables a system programmer to control all functions as well as monitor
status. All commands are sent as ASCII strings. No delays between characters or commands are required, as
data is interrupt driven and buffered.
There are four status strings for the 232-Amp, three for each input channel and one for general Amp status.
One 232-Amp+ may be daisy-chained together with a CR 232-series tuner from a single RS-232 port. The
232-Amp+ is pre-set to Unit 1, and the tuner would be set to Unit 2.
Communications parameters (Front Panel Mode 1) are 300 to 19200 baud, 8 data bits, No parity, and 1 stop
bit. Factory default is 9600 baud, Unit#1.
All settings are saved to NVRAM in the 232-Amp.
The tuner will accept non-standard RS-232 control such as voltage that swings from 0 to +5 VDC, commonly
found when IR ports are used to send RS-232 commands.
General protocol specifications
Characters in command strings to the 232-Amp+ are common ASCII keyboard characters.
Command strings sent to the 232-Amp+ begin with the ASCII > (greater than symbol) as an 'Attention'
character and end with carriage return - ASCII CR, Hex $0D, or keyboard Enter - as an 'End-of-command'
character.
Responses from the 232-Amp+ begin with the ASCII < (less than symbol) as an 'Attention' character and
end with a carriage return followed by line feed an ASCII LF or Hex $0A as 'End-of-command' characters.
A carriage return is required at the end of each command and is assumed in all examples.
Command String Structure
[Attention] (Unit#) [Command] (Parameters) [Return]
Attention Single character (>) starts the string
Unit# The Unit# is expressed as an ASCII 0-9 when used in multiple tuner applications.
To address all units, use a Unit # of 0 (Zero)
No unit number will default to Unit#1
Command A two-character command
Parameters Added attributes to some commands
Return A carriage return ends the command string, you may use ASCII CR, Hex $0D, or keyboard
‘Enter’ in programming. For simplicity, the programming examples in the manual will not
show the ‘CR’ – so remember, you’ll need to add it in your control code.
Command and Status Response
Commands can be sent back to back at any time without any delay. To allow for rapid, multiple commands,
status responses are intentionally delayed by about 125mS, sending the most current status in response to
control commands or user actions.

Contemporary Research 7 232-AMP+
RS-232 Commands
Control Commands
Code
Function
Operation
Level
You can skip leading zeros on values –so 5 can be 5, 05 or 005
VL=
Stereo input volume
0 (mute) to 63 (full)
VM
Stereo input mute on
Mutes input
VX
Stereo input mute off
Restores volume to previous level
VU
Ramp volume up
Starts volume ramping up
VD
Ramp volume down
Starts volume ramping down
VV
Stop volume ramp
Stops volume ramping
VT
Toggle Volume Mute
Alternates audio mute on and off
VG=
Amplifier Gain
Sets gain level
Sent alone returns amp gain status
0=20 dB (default)
1=26 dB
2=32 dB
3=36 dB
Inputs
Volume Parameter “Bump”
Send input volume parameter with 255 will bump value to next
step. Send parameter with 254 will bump value down one step
This allows wall panels that can’t send a volume ramp from
press and a ramp stop from release to just bump the level up
with each button press.
V0=
Stereo Input
Stated with <parameter>,<value>
V0 alone will return status for Stereo
(xx)=Default setting
1=Volume level 1-63 (40)
2=Max gain level 0-63 (0-63, also acts as mute on/off)
3=Min gain level 0-63 Fixed at 0, variable in future
4=Power On Threshold 0-63 (4)
5=Power On Hold delay 0-99 seconds (99) 0=Always On
Ex: ‘>V0=1,30’
V1=
Mono 1
Stated with <parameter>,<value>
V1 alone will return status for Input 1
Input 1 always has priority for ducking
(xx)=Default setting
1=Volume level 0-63 (40)
2=Max gain level 0-63 (0-63, also acts as mute on/off)
3=Min gain level 0-63 (Fixed at 0), variable in future
4=Gating threshold level 1-63 (10)
5=Gating hold time 0-50 in 0.1 seconds (15)
00=Ducking off, acts as mixed input
6=Ducking level for the stereo input 0-63 (10)
Example: ‘>V1=1,20 V1=4,03 V1=5,10 V1=6,05’
V2=
Mono 2
Stated with <parameter>,<value>
V2 alone will return status for Input 2
(xx)=Default setting
1=Volume level 0-63 (40)
2=Max gain level 0-63 (0-63, also acts as mute on/off)
3=Min gain level 0-63 (Fixed at 0), variable in future
4=Gating threshold level 1-63 (10)
5=Gating hold time 0-50 in 0.1 seconds (15)
00=Ducking off, acts as mixed input
6=Ducking level for the stereo input 0-63 (10)
SV
Amp Status
Returns Amp/Stereo status string

Contemporary Research 8 232-AMP+
RS-232 Commands
Terminal Communication Commands
EF
Echo Off
Characters received will not be re-transmitted (power up default).
EN
Echo On
Characters received will be re-transmitted.
Example: ‘ >EN’ Characters received will be re-transmitted.
ID
Product ID
Returns the product model number and software version.
Z!
Zap
Reconfigures unit for all factory default settings:
Unit #1
VG: 0
V0: 40,63,0,4,99,0
V1: 40,63,0,10,15,10
V2: 40,63,0,10,15,10
RS-232 Command Hints and Tips
You can control a 232-Amp+ and a 232-series tuner from a single RS-232 port by daisy-chaining RS-232
between the Amp and Tuner. Set the Tuner to ID 2, the Amp will always be unit 1.
Example: ‘ >1VM2P0’Sets the 232-Amp+ to mute, and the tuner to Off.
The carriage return line feed at the end of each 232-Amp+ response allows for easy monitoring of responses
with an ASCII terminal program. You may use ASCII CR, Hex $0D, or keyboard ‘Enter’ in programming.
You don’t have to use the ‘=’ character between the command and parameter –the string works either way.
Gating and Volume
If you want the 232-Amp+ to act as a straight mixer, set Mono 1 and Mono 2 Gate Threshold (4) and Gate
Hold (5) to zero (00). Note that both need to be turned off, the 232-Amp+ works best as either a fully gated
smart mixer or as a standard mixer, not both.
Usually, gating works well at the default settings, but feel free to adjust the Gate Threshold (4) and Gate Hold
(5) to work best with your application.
Try testing the system with the 232-Amp+ set higher than the default 20 dB gain (VG command). There are
slight changes in gating performance at the highest levels, but usually 26 dB offers a good blend of volume and
performance.
Cloning Amplifiers
If you are installing a number of units in the same facility, you can clone your settings using HyperTerminal,
Tera Term, or other Terminal app. Most allow you to send a text file instead of typing all the settings. Type in
the series of commands in Notepad or other text editor such as:
>VG=1
>VL=60
>V0=5,00
>V1=1,60
>V21,60 (if you want to skip the ‘=’sign)
Once you’ve refined all the settings, just sent the file to the other 232-AMPs in the site. After that, the installer
can use a screwdriver and the DIP switches to tweak volume levels for the room.

Contemporary Research 9 232-AMP+
Response Strings
Typical: [Attention] [Unit#] [data ...data] [cr] [lf]
232-Amp+ status response strings contain ASCII characters similar to those used for the same functions in
command strings. An ASCII 'carriage return' and ‘line feed' follow each response string. Functions shown as N/A
are not applicable; characters will appear in status strings as lower-case x.
Input 0 (Stereo) Status Response String (V0):
Start
Unit
CMD
Volume
Max
Min
On
Hold
Power
1
0-63
2 digits
0-63
2 digits
0-63
2 digits
0-63
2 digits
0-99
2 digits
Preset
2 digits
<
1
V0
XXX
63
63
00
03
20
20
XXXXXX
Input 1 Status Response String (V1):
Start
Unit
CMD
Volume
Max
Min
Gate
Hold
Duck
1
0-63
2 digits
0-63
2 digits
0-63
2 digits
0-63
2 digits
0-50
2 digits
0-63
2 digits
<
1
V1
XXX
63
63
00
10
15
03
XXXXXX
Input 2 Status Response String (V2):
Start
Unit
CMD
Volume
Max
Min
Gate
Hold
Duck
1
0-63
2 digits
0-63
2 digits
0-63
2 digits
0-63
2 digits
0-50
2 digits
0-63
2 digits
<
1
V2
XXX
63
63
00
10
15
03
XXXXXX
Amp Status Response String (SV):
Start
Unit
CMD
Power
Volume
Mute
Stereo
1
U=On
M=Off
0-63
2 digits
U=Off
M=On
<
1
V
M
63
U
S
Amp Gain Response String (VG):
Start
Unit
CMD
Gain
1
0-3
1 digit
<
1
VG
1
XXXX

Contemporary Research 10 232-AMP+
RS-232 Cable Connections
Single 232-Amp+
RS-232 wiring for control or programming should only use pins 2, 3, 5. Cables with all pins wired can lock
out front-panel programming and data communication (Pins 4 and 9 are inputs).
Tuner/232-Amp+ Daisy-Chain
One 232-Amp+ and 232-series tuner can be controlled from one RS-232 control port. The 232-Amp+ will be
Unit 1, and the 232-series tuner will be set to Unit 2.
The flow of information will start at the tuner, which will respond to Unit 2 commands, passing on Unit 1
commands to the 232-Amp.

Contemporary Research 11 232-AMP+
Rack Mounting
Two options are available for rack-mounting the 232-Amp.
RK1 and RK1-HD Single Unit Rack Mount
1. Install tuner on one side
2. Drill out the two detents, 4.25” apart, on the long bracket, used for mounting AV Tools
3. Mount the 232-Amp+ using the included two 4-40 ¼” screws.
RK3 AV Tool Rack Kit
Install 232-Amp+ into the center of the RK3 rack mount using included 4-40 ¼” screws.

Contemporary Research 12 232-AMP+
Safety Instructions
Read before operating equipment.
1. Cleaning - Unplug this product from the wall outlet before cleaning. Do not use liquid cleaners or
aerosol cleaners. Use a damp cloth for cleaning.
2. Power Sources - Use supplied or equivalent UL/CSA approved low voltage DC plug-in transformer.
3. Outdoor Antenna Grounding - If you connect an outside antenna or cable system to the product, be
sure the antenna or cable system is grounded so as to provide some protection against voltage surges
and built-up static charges. Section 810 of the National Electrical Code, ANSI/NFPA No. 70, provides
information with respect to proper grounding of the mast and supporting structure, grounding of the
lead-in wire to an antenna discharge unit, size of grounding conductors, location of antenna discharge
unit, connection to grounding electrodes, and requirements for the grounding electrode.
4. Lightning - Avoid installation or reconfiguration of wiring during lightning activity.
5. Power Lines - Do not locate an outside antenna system near overhead power lines or other electric
light or power circuits or where it can fall into such power lines or circuits. When installing an outside
antenna system, refrain from touching such power lines or circuits, as contact with them might be
fatal.
6. Overloading - Do not overload wall outlets and extension cords as this can result in a risk of fire or
electric shock.
7. Object and Liquid Entry - Never push objects of any kind into this product through openings as they
may touch dangerous voltage points or short out parts, resulting in a fire or electric shock. Never spill
liquid of any kind on the product.
8. Servicing - Do not attempt to service this product yourself as opening or removing covers may expose
you to dangerous voltage or other hazards. Refer all servicing to qualified service personnel.
9. Damage Requiring Service - Unplug this product from the wall outlet and refer servicing to qualified
service personnel under the following conditions:
When the power supply cord or plug is damaged.
If liquid spills or objects fall into the product.
If the product is exposed to rain or water.
If the product does not operate normally by following the operating instructions. Adjust only those
controls that are covered by the operating instructions. An improper adjustment of other controls
may result in damage and will often require extensive work by a qualified technician to restore the
product to its normal operation.
If the video product is dropped or the cabinet is damaged.
When the video product exhibits a distinct change in performance, this indicates a need for
service.

Contemporary Research 13 232-AMP+
Limited Warranty and Disclaimer
Contemporary Research Corporation (CR) warrants this product to be free from defects in material and
workmanship under normal use for a period of two years from the date of purchase from CR. Should such a
defect occur CR will repair or replace, at their option, the defective product at no cost for parts or labor.
This warranty extends to product purchased directly from CR or an Authorized CR Dealer. Consumers should
inquire from selling dealer as to the nature and extent of the dealer's warranty, if any.
All warranty claims must be shipped pre-paid to the factory. Call or fax to obtain a Return Material
Authorization (RMA) number.
CR is not liable for any damages caused by any of its products or for the failure of any products to perform,
including any lost profits, lost savings, incidental damages, or consequential damages. CR is not responsible
for any claim made by a third party or made for you by a third party. This limitation of liability applies
whether damages are sought, or a claim is made, under this warranty or as a tort claim (including
negligence and strict product liability), a contract claim, or any other claim. This limitation of liability cannot
be waived or amended by any person. This limitation of liability will be effective even if CR or an authorized
representative of CR has been advised of the possibility of any such damages.
Some states do not allow a limitation of how long an implied warranty lasts. Some states do not allow the
limitation or exclusion of incidental or consequential damages for consumer products. In such states, the
limitation or exclusion of the Limited Warranty may not apply to you. This Limited Warranty gives you
specific legal rights. You may also have other rights that may vary from state to state. You are advised to
consult applicable state laws for a full determination of your rights.
Except as expressly set forth in this Limited Warranty, CR makes no other warranties, expressed or implied,
including any implied warranties of merchantability or fitness for a particular purpose. CR expressly disclaims
all warranties not stated in this Limited Warranty. Any implied warranties that may be imposed by law are
limited to the terms of this Limited Warranty.