Soundstream Reference 644sx Owner's Manual

SERIES AND PARALLEL WIRING

REFERENCE

644s

4/3/2 Channel

2-4 ohm drivers in parallel

= 2 ohms

2-4 ohm drivers in series

= 8 ohms

SOUNDSTREAM TECHNOLOGIES

120 Blue Ravine Road  Folsom  California 95630 USA

ph 916.351.1288  fax [phone]

rev A - 5.20.96

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4-4 ohm drivers in parallel

=1 ohm

Power Amplifier

OWNERS MANUAL

AND

INSTALLATION GUIDE

1

CONGRATULATIONS!

You now own the REFERENCE644s Amplifier, the product of an
uncompromising design and engineering philosophy. Your
Soundstream REFERENCE amplifier will outperform any other
amplifier in the world.

To maximize the performance of your system, we recommend that you
thoroughly acquaint yourself with its capabilities and features. Please
retain this manual and your sales and installation receipts for future
reference.

Soundstream amplifiers are the result of American craftsmanship and
the highest quality control standards, and when properly installed, will
provide you with many years of listening pleasure. Should your
amplifier ever need service or replacement due to theft, please record
the following information, which will help protect your investment.

Model and Serial # ____________________________________
Dealer’s Name _______________________________________
Date of Purchase _____________________________________
Installation Shop ______________________________________
Installation Date ______________________________________

PROTECTION CIRCUITRY

Your REFERENCE644s amplifier is protected against both overheating and
short circuits by means of the following circuits:

• Main power supply fuses

• Auto High Current™ power supply

• Smart Power Supply Thermal Rollback activating at 85°C

• A fail-safe thermal protection circuit activating at 95°C

Your amplifier also incorporates an innovative Fault Diagnosis system that

NOTE: If you experience blown main power supply fuses, it is likely that the
amplifier is seeing a dead short, either in the speaker wire or in the speaker
itself. Rectify the problem before blowing multiple fuses! DO NOT increase
values beyond the original fuse value! Doing so will void your warranty and

SPECIFICATIONS

POWER

Watts

4 Ω Stereo

(8 Ω Bridged)

(12 Vdc)

75 x 4

(150 x 2)

THD
Signal to Noise
Frequency Response

2 Ω Stereo

(4 Ω Bridged)

150 x 4

(300 x 2)

1 Ω Stereo

(2 Ω Bridged)

160 x 4

(320 x 2)

<0.1%
>100 dB

20 Hz to 20 kHz ± 0.5 dB

1/2 Ω Stereo

(1 Ω Bridged)

160 x 4

(320 x 2)

CAUTION!

Prolonged listening at high levels may result in hearing loss. Even
though your new Soundstream REFERENCE644s amplifier sounds
better than anything you’ve ever heard, exercise caution to prevent

hearing damage.

2

Stereo Separation
Damping
Input Sensitivity
Input Impedance
Crossover Output

>90 dB
>200
200mV - 2.0V, or 500mV to 5.0V
10K ohms
340 mV output w/ 200 mV input (+4.5

dB)

Crossover Specifications

Low Pass: 30 - 120 Hz at 24 dB/Octave
High Pass: 60 - 240 Hz at 12 dB/Octave

Dimensions (W x D x H)

REFERENCE644s: 16.5” x 9.8” x 2.25”

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TROUBLESHOOTING

PROBLEM CAUSE

No sound and power LED is not lit

No sound, a power LED is lit, and
the AIRBASS™ option has not
been added.

Fault LED is lit

Repeatedly blown amp fuse, fre­quent activation of Smart Power
Supply Circuit

Not enough input sensitivity while
using the Balanced input

Left and Right Input Overload indi­cators lighting

Alternator whine while using Un­balanced RCA inputs

• No power or ground at amp

• No remote turn-on signal

• Blown fuse near battery

• No signal input

• The AIRBASS™ switch is in the

"IN" position. Move it to the
"OUT" position

• Amp power supply fuse is blown
or missing

• Speaker or leads may be shorted

• Verify adequate amplifier ventila-

tion

• Be sure both Left and Right Input
Signal Switches are set to the
"BAL" position

• Input signal level is too high - re­adjust input gains, or select the

0.5-5V input signal level range

• Make sure the channel 2 Input
Signal Switch is in the "UNBAL"
position.

• Try the Input Signal Switch for
channels 1, 3 & 4 in the "BAL"
position; leave the switches in
the quietest position. This will
not affect the performance of the
amplifier.

TABLE OF CONTENTS

Design Features .................................................................4 - 5

Reference644s Diagram ....................................................6 - 7

High Power / Auto High Current™ Power Supply Design ....... 8

Selecting Input Modes ............................................................. 9

Balanced / Unbalanced Input ................................................ 10

Wiring & Wiring Diagram ................................................ 11 - 12

Installation and Mounting ...................................................... 13

Level Setting ......................................................................... 14

Crossover Adjustments ......................................................... 15

AIRBASS™ ........................................................................... 15

Sample Systems ..............................................................16-21

Troubleshooting .................................................................... 22

Service .................................................................................. 22

Protection Circuitry ................................................................ 23

Specifications ................................................................ ....... 23

SERVICE

Your Soundstream REFERENCE644s amplifier is protected by a limited

22

3

DESIGN FEATURES

• Uncompromising Design and Construction including mil-spec
glass epoxy circuit boards and high current custom gold-plated solid
brass connections that will accept up to 4 gauge power/ground wire.

• Auto High Current™ - Soundstream’s newest exclusive circuit which
automatically customizes your amplifier to its particular application—
High Current, low impedance loads (multiple subwoofers, less than 2
ohms mono) or High Power, higher impedance loads (2 ohms mono
and up).

• Coherent StereoTM/Mixed Mono selection for either “pure” stereo
operation or mixed mono for simultaneous stereo and mono.

• ChassisinkTM Darlington Power Array - Soundstream’s
“overbuilding” of the output section incorporates multiple output
transistors instead of a few for faster, stronger power delivery. The
transistors are sandwiched between the circuit board and the heatsink
in a design called ChassisinkTM to ensure cool, efficient amplifier
operation.

• PowerGrid Power Supply Design - All power supply components
are located near one another, connected by thick, wide PCB traces,
which ensures rapid, high current delivery. The entire power supply is
isolated on one side of the circuit board while the audio stage is
located opposite it, guaranteeing minimal noise.

SAMPLE SYSTEM #6

2 channels of RCA input

2 bridged channels of high pass output

RCA line output set to low pass

Line output to an external amplifier driving subwoofers

• Ultra-Low ESR Capacitance Bank - Multiple small input power
capacitors are used to provide a lower ESR (Equivalent Series
Resistance), which means more power in and out faster.

• Smart Thermal Rollback - Most amplifiers shut off when they get too
hot. In the unlikely event the REFERENCE644s amplifier reaches
85° C, it will gradually roll back its average power (without affecting
the dynamics). Once the amplifier has cooled off, it returns to full
power output. If overheating should continue, a second thermal
sensing protection circuit will shut off the amplifier if the heatsink
reaches 95° C.

• Fault Monitor LED on the top panel notifies you of blown power
supply fuses.

• 1/2 ohm Drive Ability - The REFERENCE644s amplifier is designed

4

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