JBL 660GTI, 560GTI User Manual

560GTi/660GTi

COMPETITION SPEAKER SYSTEMS

60TH ANNIVERSARY EDITION

OWNER’S GUIDE

FOR MORE THAN 60 YEARS, JBL®HAS

DELIVERED PRODUCTS THAT EXEMPLIFY THE TECHNOLOGY

AND EXPERTISE GAINED THROUGH A LEADERSHIP ROLE IN

PROFESSIONAL SOUND REPRODUCTION. THE JBL NAME HAS

BEEN SYNONYMOUS WITH THE PRECISE, NATURALLY

ARTICULATED SOUND FOUND IN MANY OF THE WORLD’S MOST

PRESTIGIOUS LOCATIONS, INCLUDING CLUBS, CINEMAS AND

RECORDING STUDIOS, AND LIVE-MUSIC REINFORCEMENT IN

VENUES RANGING FROM CONCERT HALLS TO OUTDOOR

STADIUMS. JBL LOUDSPEAKERS ARE FOR THOSE WHO WON’T

COMPROMISE – IN THE STUDIO, AT HOME OR ON THE ROAD.

MORE THAN ANY OTHER COMPONENT, SPEAKERS DEFINE

THE SOUND OF AN AUDIO SYSTEM. THEY ARE THE CRITICAL

CHOICE THAT DETERMINES ULTIMATE PERFORMANCE. HOW

DOES A MARKET-LEADING BRAND LIKE JBL BUILD LOUD-

SPEAKERS THAT SATISFY SO MANY PEOPLE? WE USE THE

INDUSTRY’S MOST ADVANCED TESTING METHODS AND

EQUIPMENT, WITH A PANEL OF TRAINED LISTENERS TO

SCIENTIFICALLY QUANTIFY AND QUALIFY THE PERFORMANCE

OF EVERY JBL SPEAKER TO ENSURE THAT IT EXCEEDS EVEN

THE MOST DEMANDING EXPECTATIONS. THE INTRODUCTION

OF THE 560GTi AND 660GTi COMPETITION SPEAKER SYSTEMS

SETS YET A NEW STANDARD IN AUTOMOTIVE SOUND.

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TABLE OF CONTENTS

INTRODUCTION ................................................2

SCIENCE OF JBL SPEAKER DESIGN ................4

PRODUCT FEATURES........................................6

SYSTEM DESIGN ............................................10

SPECIFICATIONS ............................................11

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ENGLISH

THERE ARE THREE STAGES IN ENGINEERING
LOUDSPEAKERS AT JBL:

Computer-aided design and modeling, prototyping and testing. JBL speakers are
thoroughly tested and qualified at each stage to ensure that the finished product
performs flawlessly.

Every speaker design starts with physical dimensions that facilitate installation in
factory locations, along with a complete set of performance targets. Performance
targets include maximum SPL, or how loud the speaker must play at its limits.
From the maximum SPL target, we determine the amount of power required to
drive the speaker to its output limit and set a power-handling target. Sensitivity,
another important performance target, indicates how efficiently the speaker con­verts electrical input into acoustic output. A frequency-response target is also
included. This target describes not only the shape of the speaker’s response but
also the maximum allowable magnitude of narrow peaks and dips in its response.
Finally, target Thiele/Small parameters are defined to describe the speaker’s
behavior at low-frequency cut-off in its intended application, whether that appli­cation is a custom-built enclosure or the interior of a car’s door. A careful analysis
of all these targets determines the excursion and heat dissipation required for the
speaker to produce the necessary frequency response at maximum SPL and maxi­mum input power. With that information, engineers design the motor, choosing
voice coil and magnet dimensions.

COMPUTER-AIDED DESIGN AND MODELING

During this phase of development, the engineers draw intricate diagrams of the
proposed speaker’s construction. Once the computerized drawing is complete,
it is imported into an analysis program. At JBL, we use extensive Finite Element
Analysis (FEA) to model the performance of the speaker’s motor and moving parts.
FEA divides the device being modeled into thousands of small parts or elements,
and predicts performance based on the shape of the design and the materials that
will be used in construction. The motor is analyzed using magnetic and thermal
FEA. This analysis helps to ensure magnetic-field symmetry for low distortion,
proper motor force required to drive the speaker’s moving assembly, and the heat
dissipation needed for high power handling. The moving assembly – composed of
the cone, voice coil and former, spider and surround – is analyzed using structural
FEA, which enables the engineers to observe the movement of the assembly to
guarantee symmetry for low distortion. This analysis also permits the engineers to
determine the proper elasticity of the spider and surround to provide the appropriate
restoring force and perfect performance at the speaker’s excursion limits.

PROTOTYPING

Once the computer-modeling phase is complete, technicians hand-build proto­types, machining metal parts and attaching them to prototype frames which are
built using a stereo lithography machine. The stereo lithography, or SLA, machine
uses a computer-guided laser to form a speaker basket out of a bath of plastic
resin. Once the basket fit and finish are perfected, off-tool parts are built and then
fully working, production-grade samples are assembled.

AT JBL, SPEAKER DESIGN IS

ALL SCIENCE.

Real-Time FFT Laser Vibrometry: This breakthrough technology uses
scanning infrared-laser impulses that are reflected off a speaker’s
diaphragm and analyzed by a computer. The analysis creates a three­dimensional graphic representation of the cone’s movement so that
cone distortion, which contributes to frequency-response aberrations,
can be observed. Improvements to the cone’s shape and composition
can be implemented to ensure that the diaphragm operates as a rigid
piston throughout its usable frequency range, resulting in flat response.

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Anechoic Chambers: JBL’s anechoic chambers are expensive…but
worth the investment. The baffles on the walls of the chamber absorb
sound at all audible frequencies. In this setting, JBL engineers can
assess critical details of the speaker’s performance without the effects
of extraneous noise or reflected sound.

Environmental Test Lab: JBL’s environmental test lab includes machines
that subject speakers to hot and cold temperatures, humidity, ultraviolet
light and vibration. These tests are designed to simulate a lifetime of
abuse in the most adverse environmental conditions.

TESTING

At JBL, we spare no expense in testing loudspeakers. Prototype and production
samples are first tested for frequency-response range and uniformity in one of
our anechoic chambers using MLS and swept sine-wave analyzers. Sine-wave
analysis measures harmonic distortion, which is a critical element in determining
the sonic accuracy of the speaker. MLS, or maximum length sequence, analysis
compares the noise output from the analyzer to the output of the speaker to
determine the speaker’s impulse response, a measure of transient response
accuracy. The speaker’s impulse response measurement is then converted into
a high-resolution frequency-response measurement using a mathematical
operation called Fast Fourier Transform, or FFT. Real-Time Laser Vibrometry is
used to measure the structural behavior of the moving assembly. The Klippel
analyzer measures magnetic field symmetry during the speaker’s operation.
Careful analysis of all these measurements determines the location and causes
of unwanted resonance and distortion in the speaker’s output, enabling the
engineers to refine the speaker’s design to eliminate them.

Once the design is perfected, power handling is verified for production-grade
samples by subjecting them to filtered octaves of pink noise at rated power for
100 hours. That’s right, 100 hours. Finally, samples are tested for longevity in our
environmental test lab, according to the rigorous standards set by the automotive
industry. The last phase in our extensive testing involves the most critical
instruments in our possession – our ears. We listen…and listen…and listen.

Klippel Analyzer: This revolutionary analyzer developed by Klippel GmbH
separates the distortion generated by transducers into two categories:
distortions caused by the speaker’s motor and those caused by the
speaker’s suspension. By analyzing the symmetrical and linear nature of
the measured results, JBL engineers can formulate a cure for almost any
distortion caused by motor or suspension nonlinearity.Klippel analysis
provides accurate Thiele/Small parameter verification at virtually any
input power level.

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ENGLISH

GTi COMPETITION SPEAKER

SYSTEM TECHNOLOGY:

1. Spider-Landing Vents: Minimize distortion from mechanical noise.

2. Nomex

®

Spider: Provides linear force in both movement directions.

3. Nitrile-Butylene Surround: Ensures superior longevity.

4. Copper Polepiece Cap: Provides linear inductance over the full

range of forward voice-coil travel for reduced intermodulation
distortion. Provides crystal-clear vocals and midrange, even
during heavy bass signals.

5. Polished and Flared Polepiece Vent: Provides a low-velocity inlet
and outlet for the movement of air in and out of the motor structure.
Minimizes distortion from mechanical noise.

6. Neodymium Magnet: Provides high flux density. Also allows more
room for larger steel motor components to provide critical heatsink
mass for the voice coil.

7. Vented Gap Cooling

™

Ports: Provide movement of air over the voice

coil for superior power handling.

8. Flux Stabilization Ring: Provides global stabilization of the static
magnetic field and works with the copper cap to minimize
coil inductance during inward movement of the voice coil.

9. Voice Coil: Long, over-hung 2" diameter, aluminum edge-wound
voice coil provides high excursion for improved low-frequency
capability. Reduces distortion at low frequencies and high input
power.

10. Vented Voice Coil Former: Minimizes distortion from mechanical
noise.

11. Screw-Down Terminals: Ensures reliable high-quality
connections.

12. Kevlar

®

Dustcap and Cone Body: Ultrarigid Kevlar dustcap and

cone body minimize unwanted cone flexing for smooth frequency
response.

13. Cast-Aluminum Basket: Provides a rigid support for motor and
moving assembly.

LOW-DISTORTION WOOFER

Distortion – sound produced erroneously – is the enemy of great speaker
performance. At its worst, distortion makes speakers sound broken. At more
moderate levels, distortion clouds the midrange, making vocals sound muddy
and obscuring the music’s detail. At JBL, we’ve had more practice than any other
speaker company at eliminating distortion, and it shows. GTi competition speaker
systems include the lowest-distortion woofers we’ve ever built.

In a loudspeaker, distortion can be produced by the cone, the motor, the suspen­sion and even the movement of air through the speaker’s assembly. In designing
the 560GTi and 660GTi woofers, JBL engineers have left no stone unturned. The
basket, polepiece and voice coil former all include vents to eliminate any potential
distortion caused by the movement of air trapped within these parts. The ultra­rigid Kevlar

®

cone eliminates unwanted cone flexing (also called modal distortion),
which can cause big peaks and dips in the midrange response. The spider and
surround are designed to ensure linear forward and rearward motion, minimizing
distortion caused by the speaker’s suspension. The motor includes a copper pole­piece cap and a flux stabilization ring that work together to produce a linear voice
coil inductance that minimizes intermodulation distortion. Finally, an extralong
voice coil ensures that the coil remains in the magnetic gap to minimize distortion
at low frequencies and their harmonics, and during high-output transients. The
result is crystal-clear midrange, snappy mid-bass without any audible ringing or
hang-over, and a smooth frequency response that needs no compensation circuitry
in the crossover (see Figure 1).

Figure 1

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