Bosch Application Note (Places Of Worship) En US 1886152203

User Manual: Bosch Application note (Places of worship) Plena Public Address Solutions

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Plena Feedback Suppressor

Places of worship

Application Note | Plena

The Plena Feedback Suppressor is an easy-to-use solution

for reducing acoustic feedback in places of worship. It uses a

DSP to suppress feedback by actively filtering out unwanted

room reverb. By shifting the frequency of the output signal

by 5 Hz or by adding inaudible noise to the output signal, it

detects the reverb component of a signal and removes it be-

fore feedback occurs. A built-in 2-input mixer allows two

microphones to be used to capture the voice of a moving

speaker without increasing the risk of acoustic feedback. It

does this by automatically reducing the gain of the micro-

phone with the weakest signal and increasing the gain of the

microphone with the strongest signal, thus tracking the

moving speaker and optimizing speech intelligibility. The

feedback suppressor’s adaptive filter has a fast mode (for

where the microphone positions change over time) and an

accurate mode (for fixed microphone positions).

House of worship:

This application note describes how the Plena Feedback

Suppressor overcomes potential acoustic feedback prob-

lems in houses of worship where typically several micro-

phones are used, for example by the minister (or other re-

ligious leader) in the pulpit and alter, and another for the

choir.

Introduction:

In general, houses of worship are large rooms with hard

surfaces such as marble, concrete, exposed brick, tiled

walls and high ceilings. This type of environment is very

reverberant, and when loudspeakers are carefully posi-

tioned for adequate coverage, there is an increased risk of

feedback from any of the several microphones typically

used in this type of venue.

Communication you can rely on

Application Note | Plena

Summary of requirements:

• Several fixed microphone positions

• No acoustic feedback

• Amplified sound should originate close to person

speaking

• Quality loudspeakers with speech intelligibility

and music reproduction

Solution:

The Plena Feedback Suppressor is an ideal solution for this

type of application. It suppresses feedback before it even oc-

curs and automatically adapts itself to the difficult acousti-

cal environment. In this example, the feedback suppressor

(5) is connected to the insertion sockets of a Plena Mixer

Amplifier (2), using a dual cinch-to-cinch cable. In this way,

the feedback suppression will be effective on the signals

from all microphones. Up to four microphones (items 3

and 4) can be connected to this mixer amplifier. If neces-

sary, additional microphones can be connected using a

Plena Universal Preamplifier.

Line array loudspeakers:

The LBC 3201/00 Line Array Loudspeakers (1) complete

the system. They can cover a large area and deliver high-

quality reproduction of both speech and song. The used

line array technology provide an uniform sound distribu-

tion throughout the entire listening area, so not too loud at

the front and no too quiet at the back. For a more extensive

listening area, additional loudspeakers connected to delay

units can be positioned further down the venue.

Easy set-up:

In common with all Plena equipment, the Plena Feedback

Suppressor is easy to set-up according to the ‘plug and play’

philosophy. The suppression process is completely automatic,

and does not require the manual setting up of unpredictable

filters to achieve perfect results. The LBC 3201/00 Loudspeak-

er is also easy to adjust for a specific coverage area by deter-

mining the appropriate mounting height using a chart sup-

plied with the loudspeakers. This means that the complete

installation can be installed and functionally optimized with-

out the need for specific expertise.

Configuration

LBB 1968/00 Plena Feedback Suppressor : 1 x (5)

LBC 3201/00 XLA 3201 90/60 W Line Arrays : 4 x (1)

LBC 1912/10 Plena 180/120 W Mixer Amplifier : 1 x (2)

LBC 1949/00 Gooseneck microphone : 1 x (3)

LBC 2900/xx Dynamic hand-held microphone : 1 x (4)

Bosch Security Systems

For more information please visit

www.boschsecuritysystems.com

Data subject to change without notice | Printed in The Netherlands | PA-EH-en-06_4998144561_01

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