venueflex Choirflex-A User manual

choir
owner’s guide
venueflex.com

2
choirflex owner’s guide
Copyright and Notices
e contents of this manual are furnished for informational purposes
only, are subject to change without notice, and should not be construed
as a commitment by Venueex. Venueex assumes no responsibility or
liability for any errors or inaccuracies that may appear in this manual.
No part of this manual may be reproduced, stored in any retrieval sys-
tem, or transmitted in any form or by any means, electronic, photo-
graphic, mechanical, recording or otherwise, without the prior written
permission of Venueex. Choirex, Venueex and the Venueex logo,
are trademarks of Venueex. All third-party trademarks mentioned
herein are the property of their respective trademark holders.
Venueex products contain additional soware licensed under various
separate third-party license terms. Please see venueex.com/licensing
for additional information and copies of third party licenses.
Audinate® is a registered trademark of Audinate Pty Ltd.
Dante™ is a trademark of Audinate Pty Ltd.
Choirex Owner’s Guide v1.00 ©2020 Venueex
Contact Information
Venueex
8620 Westmoreland Drive NW
Concord, NC 28027
[phone]
www.venueex.com
Technical Support
Technical Support for Choirex can be obtained by contacting Venueex
at:
support@venueex.com
[phone]
Warranty
Venueex warrants its products as free from defects under normal use
and service for a period of one year from the date of shipment. If an
item becomes defective within the warranty period we will repair or
replace the defective item, as determined solely by Venueex.
Warranty repairs will be conducted at Venueex’s service facility.
Customer is responsible for shipping product to Venueex for service.
If repairs are conducted at the customer site, reasonable out-of-pocket
charges will apply. Return packing, shipping, and special handling costs
are the responsibility of the customer.
is warranty is void if products are subjected to misuse, neglect, acci-
dent, improper installation or application, or unauthorized modication.
In no event shall Venueex be liable for direct, indirect, special, inci-
dental, or consequential damages (including loss of prot). Implied
warranties, including that of merchantability and tness for a particular
purpose, are expressly limited to the duration of this warranty.
is warranty is transferrable to subsequent owners, subject to Venue-
ex’s notication of change of ownership.
Important Safety Instructions
• Read these instructions.
• Keep these instructions.
• Heed all warnings.
• Follow all instructions.
• Do not use this apparatus near water.
• Clean only with a dry cloth.
• Do not block any ventilation openings. Install in accordance with
the manufacturer’s instructions.
• Do not install near any heat sources such as radiators, heat regis-
ters, stoves, or other apparatus that produce heat.
• Do not defeat the safety purpose of the polarized or ground-
ing-type plug. A polarized plug has two blades with one wider
than the other. A grounding type plug has two blades and a third
grounding prong. e wide blade or the third prong is provided
for your safety. If the provided plug does not t into your outlet,
consult an electrician for replacement of the obsolete outlet.
• Protect the power cord from being walked on or pinched particu-
larly at plugs, convenience receptacles and the point where they exit
from the apparatus.
• Use only with the accessories specied by the manufacturer, or sold
with the apparatus.
• Unplug this apparatus during lightning storms or when unused for
long periods of time.
• Refer all servicing to qualied service personnel. Servicing is
required when the apparatus has been damaged in any way, such
as power-supply cord or plug is damaged, liquid has been spilled
or objects have fallen into the apparatus, the apparatus does not
operate normally, or has been dropped.
• DO NOT ATTEMPT TO OPEN THE APPARATUS ITSELF; IT IS
NOT USER-SERVICEABLE.
• WARNING: e apparatus is supplied with an AC mains power
cable. Depending on the voltage model ordered, this cable is cong-
ured with the most common AC mains connector for that voltage.
If the connector is not compatible with the local ac mains recep-
tacle, employ a licensed electrician to re-congure the cable with
the proper connector. Ensure that AC power supply has a properly
grounded safety ground. Failure to follow this warning could cause
equipment damage, injury, or death.
Regulatory information
is device complies with part 15 of the FCC Rules. Operation is subject
to the following two conditions: (1) is device may not cause harmful
interference, and (2) this device must accept any interference received,
including interference that may cause undesired operation.
is equipment has been tested and found to comply with the limits for
a Class A digital device, pursuant to part 15 of the FCC Rules. ese lim-
its are designed to provide reasonable protection against harmful inter-
ference when the equipment is operated in a commercial environment.
is equipment generates, uses, and can radiate radio frequency energy
and, if not installed and used in accordance with the instruction manual,
may cause harmful interference to radio communications. Operation of
this equipment in a residential area is likely to cause harmful interfer-
ence in which case the user will be required to correct the interference at
his own expense.

3
choirflex owner’s guide
Introduction
Providing sound reinforcement for choir can be one of
the most dicult tasks in live audio. Providing sucient
gain-before-feedback, minimizing stage-to-microphone
leakage, and getting the choir “on top of the mix” with
clarity are classic challenges that prove dicult to over-
come. Choir reinforcement typically makes use of con-
denser microphones covering large groups, and is therefore
subject to excessive room reverberation, PA system eects,
and feedback. e common result is a deteriorated choir
mix that is prone to electroacoustic feedback and suers
from poor intelligibility. Proper engineering practices such
as optimizing microphone placement and console equal-
ization can help, but are quite oen not enough, and these
“solutions” oen deteriorate musicality and tone.
Choirex is a proprietary, adaptive digital audio processor
designed to increase the clarity and stability of choir mixes
and greatly reduce feedback while maintaining the natural
sonic qualities of the choir. In combination with its use
in sound reinforcement, Choirex is equally eective for
sending processed choir sounds to broadcast and recording
mixes. Choirex can be connected into the mixing system
via analog audio or via Dante-based network audio, de-
pending on the version of hardware. Choirex intelligently
learns and adapts to the venue’s acoustical environment by
monitoring both the microphone signals and the overall
mix bus. is provides an enhanced choral sound that re-
sults in much greater acoustical gain, overall loudness, and
increased clarity while maintaining natural tonality.

4
choirflex owner’s guide
Hardware description
Choirex is a digital signal processor that receives a stereo
choir audio feed plus a stereo reference audio feed, and
produces a stereo choir audio feed for reinforcement or
recording.
Choirex is available in two variants:
• Choirex-A has analog audio inputs and outputs;
• Choirex-D has network-based Dante audio inputs
and outputs.
Both versions provide a primary stereo output pair, plus
a secondary split output that can be used for recording or
broadcast.
Mounting
Choirex may be mounted in a standard 19-inch equip-
ment rack, or placed on a desktop. In either case, do not
cover or obstruct the ventilation ports on the sides of the
Choirex unit.
Power connection
Connect the supplied power supply to the port labeled DC
POWER. Do not use any power source other than the AC
adapter supplied with Choirex, as doing so may damage
the unit and void your warranty! e port labeled
CONTROL is a standard 10/100/1000Mbps Ethernet con-
nection allowing service of the unit. is can be connected
to a network switch or computer for purposes of service if
requested by a Venueex technician.
1
REFERENCE
L R
CHOIR
L R
CHOIR
L R SPLIT L R
ANALOG
INPUT
ANALOG
OUTPUT
PRIMARY SECONDARY
DC
POWER
CONTROL
2
1DC Power input. Connect to included power DC supply.
Secure the cable with the cable clip.
2Control network Ethernet connection. Connect to control
network or computer for service.

5
choirflex owner’s guide
Connecting to audio signals
Choirex is designed to receive a stereo mix of the unpro-
cessed choir microphones and produce a processed stereo
choir to then be placed in the nal house PA mix. ere
are two ways to pre-mix the choir microphones:
1. A small external mixer may be used to pre-mix the
choir to stereo. e output of this mixer is then fed to
Choirex. e processed choir is then fed from Choir-
ex to the main mixing console as a stereo signal.
2. Alternately, stereo pre-mixing of the choir can be per-
formed within the main mixing console itself. In this
case, the choir microphones are sent collectively to a
dedicated stereo group bus feeding Choirex. Do not
send this choir microphone group bus or any indi-
vidual microphone signals to the main loudspeaker
mix!
In either conguration, the processed output of Choirex
is returned to the main mixing console as a stereo signal. It
is essential that the stereo choir signal sent to Choirex is
unprocessed and static (unchanging). is means that you
should NOT assign the choir microphones or the bus mas-
ter to VCAs, mute groups, or other processing. Only the
return signal should be varied in level or muted according
to the mix requirements.
Choirex must also receive a reference signal of the main
stereo PA mix. It is recommended that you route the main
stereo mix through a dedicated matrix bus, or similar, to
allow the signal level feeding Choirex to be appropriately
trimmed.
Analog audio connections for
Choirflex-A
Four input connections are provided on 3-pin Female XLR
connectors. ese are labeled CHOIR and REFERENCE,
and can be connected to professional audio equipment
using line-level signals. Four output connections are
provided on 3-pin Male XLR connectors, labeled CHOIR
and SPLIT. ese are used to connect to the sound
reinforcement mixer, and optional recording or broadcast
equipment. Do not connect these terminals to inputs
containing phantom power! Doing so may compromise
the integrity of the Choirex circuitry or cause perma-
nent damage.
REFERENCE
L R
CHOIR
L R
CHOIR
L R SPLIT L R
ANALOG
INPUT
ANALOG
OUTPUT
PRIMARY SECONDARY DC
POWER
CONTROL
3 4
1
1CHOIR input. Connect the unprocessed stereo choir
mix to these inputs. is may be from an external choir
pre-mixer, or from a dedicated stereo group bus within the
house console.
2REFERENCE input. Connect a stereo reference signal here
that is equivalent to the main loudspeaker mix output of
the house console.
3CHOIR output. Connect these outputs to two balanced an-
alog console inputs on the mixing console. ese contain
the choir sound that should be mixed to the house speaker
system.
4SPLIT output. ese are extra outputs carrying the same
signal as the CHOIR output, and can be used to feed re-
cording or broadcast equipment.
2
CHOIR MIXER
or SUBMIX
HOUSE MIXER
HOUSE
LOUDSPEAKERS
CHOIR MICROPHONES
CHOIR
Input
CHOIR
Output
REFERENCE
Input

6
choirflex owner’s guide
Dante network audio
connections for Choirflex-D
Two Ethernet connectors are provided for connection to
the Dante™ network, labeled PRIMARY and SECOND-
ARY. If using a single network, connect the PRIMARY
connection to your Dante-compatible equipment or eth-
ernet switch. If also using a redundant network, connect
the SECONDARY port to that network. Do not connect
the PRIMARY and SECONDARY ports to the same
network at the same time as this may cause unstable
operation!
Note that, at this time, Choirex is only compatible with
Dante systems running at a sampling rate of 48kHz.
Dante audio patching
Dante network audio channels must be patched using the
Audinate Dante™ Controller soware application. is
application may be downloaded for free from
www.audinate.com and is available for Windows or
MacOS.
Choirex will appear in Dante Controller with 128 chan-
nels of input and output. Only the rst four (4) inputs and
outputs are active, with inputs labeled CHOIR and
REFERENCE, and outputs labeled CHOIR and SPLIT.
ese may be connected to other devices in your system
(mixing consoles, signal processors, preampliers, etc.).
Note that standard Dante unicast and multicast rules may
be employed, as long as all devices connected are using the
same 48kHz sampling rate and a common clock master.
REFERENCE
L R
CHOIR
L R
CHOIR
L R SPLIT L R
ANALOG
INPUT
ANALOG
OUTPUT
PRIMARY SECONDARY
DC
POWER
CONTROL
1Dante Primary network port. Connect to the primary
Dante audio network.
2Dante Secondary network port. Connect to the secondary
Dante audio network. Do not connect to this port if no
secondary network is in use.
1 2
1 2
1CHOIR input. Connect the unprocessed stereo choir
mix to these inputs. is may be from an external choir
pre-mixer, or from a dedicated stereo group bus within the
house console.
2REFERENCE input. Connect a stereo reference signal here
that is equivalent to the main loudspeaker mix output of
the house console.
3CHOIR output. Connect these outputs to two console in-
puts on the mixing console. ese contain the choir sound
that should be mixed to the house speaker system.
4SPLIT output. ese are extra outputs carrying the same
signal as the CHOIR output, and can be used to feed re-
cording or broadcast equipment.
3 4

7
choirflex owner’s guide
Starting up
Aer connection to an appropriate power source, the
POWER button may be momentarily depressed to start
the processor. Upon power-up, the LED ring surrounding
the button will glow and the center LCD display will illu-
minate. At any point, momentarily depress the POWER
button to turn Choirex o. Do not shut down Choirex
by removing power to the unit before safely turning o
the unit with the power button. Only remove power aer
the system has been safely shut down using the POWER
button and the LED ring around the button is no longer
illuminated.
Input levels and metering
Choirex works by analyzing the stereo choir signal and
the main loudspeaker mix, and then processing the choir
audio accordingly to enhance gain and tonality. is adap-
tive learning is threshold dependent; therefore, it is essen-
tial that gain structure is optimized.
e LCD screen contains four channels of input metering,
with two channels labeled CHOIR and two channels la-
beled REFERENCE. e system operates most optimally
when driving input signals in the “amber” range. Audible
clipping will result with input signals exceeding the max-
imum input level capability of the processor. e LCD
screen also shows four channels of output metering, with
two channels labeled CHOIR and two channels labeled
SPLIT. ese stereo output pairs are identical and can be
used simultaneously and interchangeably.
1 2 34
1POWER button. Press once to turn the system on, press
again to turn the system o. e LED ring around the
button will illuminate when the system is powered on.
2INPUT metering for Choir and Reference input signals.
3Output metering for Choir and Split output signals.
4Ideal range for input and output signals during a perfor-
mance. Avoid clipping (top of red meter range) as audible
artifacts will result.

8
choirflex owner’s guide
Adjusting choir microphone
input settings
Once Choirex is correctly interfaced with the mixing con-
sole, its inputs must be properly calibrated and adjusted.
First conrm that the stereo choir signal feeding Choirex
is unprocessed - that is, the choir microphones do not
have equalization, dynamics, or other processing applied.
Also, if the choir microphone submix is onboard the main
mixing console, conrm that these input channels and the
choir submix bus are not routed to the PA mix, but only to
Choirex.
Ensure that the choir microphones are panned in stereo.
e choir microphone channels may be panned to any
position throughout the stereo image as desired for artistic
purposes. e only recommended processing of the choir
mic channels is a modest high-pass lter at 50-60Hz. e
choir microphone input channels and stereo bus feeding
Choirex should remain on and active at all times. is
means that Choirex constantly sees an active input level
on its CHOIR inputs, whether or not the choir returns are
active in the house mix.
Adjusting signal levels
and returns
While the Choirex return channels remain muted at the
console, allow the processor to begin listening to its inputs.
Slowly raise the Choirex returns in the PA system to a
level where the room ambience or nearby sounds can be
heard, but below feedback. Allow Choirex to continue
listening and adapting. en, with Choirex returns down
and muted in the PA, soundcheck the choir by having them
perform at a typical loudness. Adjust the stereo choir sig-
nal feeding Choirex as necessary to maintain proper input
signal level without clipping on the CHOIR inputs. e
main PA mix reference signal feeding the REFERENCE
inputs should also be trimmed for excellent signal level
without clipping.
Creating the final mix
Once all four inputs of Choirex are receiving proper sig-
nal levels, begin mixing the output of Choirex to the PA
system. Ensure that the stereo Choirex output is hard-
panned (Le-Right) at the console and has no channel
processing applied. Raise this return slowly in the PA to
audition the sound. Choirex will continue to listen and
adapt. Continue raising Choirex slowly to determine
the appropriate mix level and gain-before-feedback point.
If any modest equalization is desired for the nal choir
sound, it may be applied to these return channels at this
time. Note that modications to equalization may slightly
reduce the available gain before feedback.
When the choir is not performing, the return signal may
be muted or faded down in the mix, as is good mixing
practice, but the reference signals feeding Choirex should
remain active.
Tips and observations
Typical Choirex installations see 8-12 dB additional
gain-before-feedback margin relative to their unprocessed
congurations. In addition, it is oen possible to obtain
a far more natural, wideband choir sound than what was
possible without Choirex. is means that low tones, in-
cluding male voices, may be far more naturally reinforced.
Aer applying Choirex, it is oen possible to use a smaller
quantity of choir microphones at a larger distance from the
voices. is enhances a natural sense of blend and musi-
cal unity from the choir, avoiding “spotty” coverage or an
unnatural reinforced quality.
At higher gain levels, Choirex adds a natural reverberant
decay to the choral sound, generated from real reections
inside the room. is can be used for enhancement for
larger choral pieces and can be varied by the amount of
overall gain on the return channels by the mix engineer.
e return channels, including the SPLIT channel, may be
used for broadcast or recording feeds. Using these outputs
provides a cleaner broadcast sound, with a reduction of
room artifacts and smoothing of room reverberation.

9
choirflex owner’s guide
Choirflex-A Choirflex-D
Power supply External 90-264 V AC at 50/60 Hz, FCC Part 15 Class B, UL62368-1
Power consumption 70 VA 90 VA
Audio input 4 channels line-level audio on balanced female XLR connectors,
10kΩ impedance 4 channels of Dante™ network audio (48kHz only)
Audio output 4 channels line-level audio on balanced male XLR connectors, 50Ω
impedance 4 channels of Dante™ network audio (48kHz only)
Frequency response 20Hz to 20kHz +/- 0.2dB 20Hz to 20kHz
Network 1000/100 Mbps ethernet (service only) on Neutrik etherCON
1000/100 Mbps ethernet (service only), 1000/100 Mbps ethernet
Primary Dante™, 1000/100 Mbps ethernet Secondary Dante™ on
Neutrik etherCON
Dimensions (W x H x D) 482.6 x 88.1 x 338.2 mm (19 x 3.5 x 13.3 in)
Weight 5.5 kg (12.2 lb), accessories and packaging not included
*Specifications subject to change without notice.
Specifications
3.5 [88.1mm]
19 [482.6mm]
13.3 [338.2mm]
19 [482.6mm]

8620 Westmoreland Drive NW — Concord, NC 28027
[phone]
venueflex.com — [email protected]