Jbl 3120 a brochure

Page 1

PROFESSIONAL SERIES

3105 3120A
31 10A 3160

FREQUENCY DIVIDING NETWORK

3115A -' INSTRUCTION MANUAL

Introduction

JBL Professronaf Series high fevel
passtve frequency drvrdlng networks
are orecrsron devrces made Wllh highest
ouaflty components throughout none
inductive nonroofanzed capacrtors
haying high AC current capacrty burtt
expressfy for use In drvrdrng networks
rhdtviduafty cafibrated Tow-Toss Induce
tors and heavy duty swrtches and
resistors

These networks have 12 dB oer
octave paraflef L-C Circuits, Additional
conjugate efements are used to cancef
out the inductive reactance of the few
frequency loudspeaker Since the 3105
crossover f5 above 5 kHz. additional
conjugates are not needed

The 3105 SttOA 3tt5A, and 3120A
are generaf application networks The
3t60 is a high power unrt desrgned pn-
marrfy for theater auditorium or
rerntorcernent appfrcatrons

The 3t05 IS optimized tor any JBL 16
ohm compressron driver With a srngfe
2402H 2404H, or 2405H tweeter

Applications

JBL frequency drvrdrng networks can
be used With many different combina-
110118 of drivers The choice of network
should be made on the basrs of desrred
crossover frequency power handfrng
capacrty and impedance of both the low
and high frequency drivers

Page 2

Specifications

Power C8030!

High Frequency

Crossover Continuous Continuous impedance Gain High Frequency
Modal Frequency Program' Pink Norse? Low Frequency High Frequency [Attenuation] Boost
31053 7000 Hz 70 walls 35 walls 16 ohms 8 ohms Continuously N/A
Variable
3i 10A 800 Hz 300 walls lSOwatts 8(7th leohms 6»B-10dB Minimum,Medluml
Switch Maxrmum Swrtch
3115A 500 Hz 300 watts i5!) walls 8 ohms 16 ohms 64340 (18 Minimum. Medium
Switch Maximum Switch
3120A i250 Hz 300 watts tso watts 8 ohms i6 ohms era-lo dB. Minimum, Medium,
Switch Maximum Switch
31 60 500 HZ 600 watts 300 watts 4 ohms 16 ohms 0724757808, in [Maximum). Out
Strap (MInImum),Swrtch

i Continuous progiam powar capacity rs deirnod as 3 dB grealer than conlinuous Dink noise power

2 CONinuOuS pink noise power rating is based on a test svgnal oi llliereo random noiseconiovmlng lo mlemaliohai standard lEC 268 5 (plnk NOISE with i2 GB
per octave rolloll below 40 Hz and above 5 000 Hz wrrh a peak l0 average rallo ol 6 63) two hours duration

a the alas is optimized tor a smqie 240m 240m or 2405M Iweeier mslalled m a syslem wilh any I6 ohm Jai. compression driver

Matching the impedance of the
drivers to the network is highly impor-
tant, because the specified crossover
point of the network is dependent upon
correct driver impedances, as shown
in Figure 1.

n mimaonmmmmmzmo

20 to mom

son mama swmzmo

Figure l. Properly and Improperly
Matched Driver/Network Combinations
[LF Driver impedance lower than
required by network)

Selection of the network is based on
the acoustical performance charac~
leristics, acoustic loading, and properly
matched impedances, JBL networks
and drivers are designed to work
together Some drivers have actual
impedances in their crossover regions
which differ enough from the rated
impedance to create mismatches with
JBL networks, and their response can

be quite different from what might
otherwise be predicted

It is not always possrble to develop
proper network load impedances with
series and/or parallel driver intercon-
nections in such circumstances, the
use of the JBL 9375 autofcrmer be-
tween the network and drivers can be
helpful in developing proper load
impedances.

In some applications, connection of
more than one network to the output
of an amplifier may be required Auto-
formers can be used for this application
if the amplifier does not have the proper
output impedances to match the net-
work combination

Power Capacity

JBL rates power handling capacity
on the basis of continuous program.
which is defined as 3 dB greater than
the continuous rating, The continuous
program rating is a conservative ex-
pression of the ability of the network
and associated transducers to handle
normal speech and music program
material.

Continuous pink noise power ratings
are based on a test signal of filtered
random noise conforming to interna-
tional standard IEC 268s [pink horse
with 12 GB per octave rolloff below
40 Hz and above 5.000 Hz with a peak
to average ratio of 6 dB), two hours