REFERENCE 644s

SERIES AND PARALLEL WIRING

2-4 ohm drivers in parallel

= 2 ohms

4-4 ohm drivers in parallel

=1 ohm

2-4 ohm drivers in series

= 8 ohms

SOUNDSTREAM TECHNOLOGIES

120 Blue Ravine Road Folsom California 95630 USA ph 916.351.1288 fax 916.351.0414

rev A - 5.20.96

24

REFERENCE

644s

4/3/2 Channel

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 ______________________________________

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

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

POWER

SPECIFICATIONS

4

Stereo

(8

Bridged)

(12 Vdc)

75 x 4

(150 x 2)

2

Stereo

(4

Bridged)

150 x 4

(300 x 2)

1

Stereo

(2

Bridged)

160 x 4

(320 x 2)

1/2

Stereo

(1

Bridged)

Watts

160 x 4

(320 x 2)

THD

Signal to Noise

Frequency Response

Stereo Separation

Damping

Input Sensitivity

Input Impedance

Crossover Output

<0.1%

>100 dB

20 Hz to 20 kHz

±

0.5 dB

>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”

23

TROUBLESHOOTING

PROBLEM CAUSE

No sound and power LED is not lit

No power or ground at amp

No remote turn-on signal

Blown fuse near battery

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

No signal input

The AIRBASS™ switch is in the

"IN" position. Move it to the

"OUT" position

Fault LED is lit

Amp power supply fuse is blown or missing

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

Speaker or leads may be shorted

Verify adequate amplifier ventilation

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.

SERVICE

Your Soundstream REFERENCE644s amplifier is protected by a limited

22

TABLE OF CONTENTS

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 Stereo

TM

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

Chassisink

TM

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 Chassisink

TM

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.

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

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

21

SAMPLE SYSTEM #5

2 channels of RCA input

2 bridged channels of low pass output

RCA line output set to high pass

Line output to an external amplifier driving satellite speakers

to drive virtually any load—all the way down to 1/2 ohm stereo (1 ohm mono).

Dual Discrete Class A Drive Stages - Over six times the drive current of most amplifiers, which maintains performance into low impedance loads.

Drive Delay

TM

Muted Turn-on/off Circuit - A unique circuit which completely eliminates any amplifier-related turn-on/off noises.

Flexible Dual Input Level Sensitivity accepts 2 voltage ranges; from 200 mV to 2.0 V and from 500 mV to 5.0 V, permitting maximum output from the amplifier with virtually any source unit.

Differential Balanced Input Design for added immunity to noise caused by component and vehicle electrical system interaction when using unbalanced RCA inputs.

True Balanced Input for professional-quality performance and noise cancellation. The 6-pin din plug carries (+) and (-) Signal information for left and right channels, audio ground, and ±15 Vdc to operate the

Soundstream BLT Balanced Line Transmitter.

AIRBASS™ Upgradable - This feature allows RF remote control level adjustment while the low pass filter on the amplifier's internal crossover is being used.

20

5

Reference644s

SAMPLE SYSTEM #4

4 channels of RCA input

2 stereo channels of high pass output

1 bridged channel of low pass output

(NOTE: Due to the internal summing circuitry of the amplifier's low pass filter, fading to the satellites will never completely defeat the subwoofers.)

6

19

SAMPLE SYSTEM #3

2 channels of RCA input

4 stereo channels of high pass output

RCA line output set to low pass

Line output to an external amplifier driving subwoofers

18

Key to Callouts

1.

Fault LED - Indicates a blown fuse.

2.

High Power LED - Indicates amplifier power on in "High Power" mode.

3.

Auto High Current LED - Indicates amplifier power on in "High Current" mode.

4.

Line Out Crossover Switch - Select high pass, low pass or full range low level output to an auxiliary amplifier.

5.

Input Overload Indicators - Channels 1 & 2; Indicates the signal input level or input gain level is too high.

6.

Input Level Selector Switch - Channels 1 & 2; Selectable input sensitivity range from 0.2-2

Volts RMS, or from 0.5-5 Volts RMS.

7.

Left Channel Balanced / Unbalanced Input Selector Switch - Channel 1; Select "Balanced" to use the 6 pin Balanced signal input. Select "Unbalanced" to use the RCA signal inputs.

8.

Right Channel Balanced / Unbalanced Input Selector Switch - Channel 2; Select

"Balanced" to use the 6 pin Balanced signal input. Select "Unbalanced" to use the RCA signal inputs.

9.

Input Overload Indicators - Channels 3 & 4; Indicates the signal input level or input gain level is too high.

10. Input Level Selector Switch - Channels 3 & 4; Selectable input sensitivity range from 0.2-2

Volts RMS, or from 0.5-5 Volts RMS.

11. Left Channel Balanced / Unbalanced Input Selector Switch - Channel 3; Select "Balanced" to use the 6 pin Balanced signal input. Select "Unbalanced" to use the RCA signal inputs.

12. Right Channel Balanced / Unbalanced Input Selector Switch - Channel 4; Select

"Balanced" to use the 6 pin Balanced signal input. Select "Unbalanced" to use the RCA signal inputs.

13. +12V - Connected to a fuse or circuit breaker, then to the battery's positive post.

14. GND - Main ground connection. Bolt to a clean chassis ground in the vehicle.

15. REM - Remote turn-on input from the head unit. Accepts +12V.

16. Speaker Output Connections - Channels 1 & 2 speaker connection terminal.

17. Crossover Output - High pass, low pass or full range output to an auxiliary amplifier.

18. Subwoofer Level Control - Additional level control to any channel or line output receiving information from the internal low pass filter.

19. Low Pass Crossover Adjustment Pot - Crossover frequency setting for the low pass filter;

Amplifier channels 1 - 4 and crossover outputs.

20. High Pass Crossover Adjustment Pot - Crossover frequency setting for the high pass filter for channels 1 & 2 and crossover outputs.

21. Input Level - Channels 1 & 2; Independent left and right channel input level controls.

22. Balanced Signal Input Connector - Channels 1 & 2; 6-pin Balanced signal input connector for use with the Soundstream BLT Balanced Line Transmitter.

23. Inputs - Channels 1 & 2; right and left RCA (Unbalanced ) inputs.

24. Speaker Output Connections - Channels 3 & 4 speaker connection terminal.

25. High Pass Crossover Adjustment Pot - Crossover frequency setting for the high pass filter for channels 3 & 4.

26. Input Level - Channels 3 & 4; Independent left and right channel input level controls.

27. Balanced Signal Input Connector - Channels 3 & 4; 6-pin Balanced signal input connector for use with the Soundstream BLT Balanced Line Transmitter.

28. Inputs - Channels 3 & 4; right and left RCA (Unbalanced ) inputs.

29. Main Fuse - Main power supply fuses. Replace only with the same value fuses.

30. Amplifier Crossover - Channels 1 & 2; Select high pass, low pass or full range operation.

31. Coherent Stereo/Bridge/Mixed Mono switch - Channels 1 & 2; Input mode selector.

32. Channels 3 & 4 Input Select - Selectable inputs from internal (from channels 1 & 2) or external (from channels 3 & 4 local balanced or unbalanced inputs).

33. Amplifier Crossover - Channels 3 & 4; Select high pass, low pass or full range operation.

34. Coherent Stereo/Bridge/Mixed Mono switch - Channels 3 & 4; Input mode selector.

7

AUTO HIGH CURRENT™ POWER SUPPLY

The REFERENCE644s amplifier employs an extremely efficient Auto High

Current™ power supply (patent pending). This new power supply circuitry automatically customizes your amplifier for optimum efficiency and power output into virtually any impedance load. When other brand amplifiers are driven at low impedances (i.e., 1 ohm or less), they shut down, squash dynamics and power output (called current limiting), or waste huge amounts of power (i.e., low efficiency). All of which reduce the "real world" power the amplifier can produce in the car. Soundstream's Auto High Current™ power supply allows the REFERENCE amplifiers to be one of two types of amps: either producing maximum power at higher impedances (perfect for satellites) or at lower impedances (usually with multiple subwoofers). This is done by letting the amplifier's power supply continuously monitor the impedance of the load the amplifier is driving. If the impedance drops too low, the power supply will automatically switch into High Current mode. It will stay in this mode until the amplifier is turned off. The next time it is powered up, it will be in the High

Power mode.

Unlike other amplifiers, Soundstream’s REFERENCE644s amplifier can be configured to drive virtually any impedance and make maximum power! The major advantages of this power supply are:

• awesome dynamic power capabilities

• added continuous power with higher voltages

• increased amplifier efficiency and reliability

Because of the dynamic properties of most music, all audio components should be able to react accordingly. Thanks to their unique power supplies, the REFERENCE amplifiers can comfortably exceed their rated power for dynamic portions of the music.

SAMPLE SYSTEM #2

4 channels of RCA input

4 stereo channels of high pass output

RCA line output set to low pass

Line output to an external amplifier driving subwoofers

8

17

SAMPLE SYSTEM #1

4 channels of RCA input

4 stereo channels of full range output

INSTALLATION STEP 1

COHERENT STEREO™ /

MIXED-MONO / BRIDGED MONO

The REFERENCE644s amplifier has the ability to operate in any one of the following modes:

Coherent Stereo™

with identical left and right stereo channels for maximum fidelity. Best choice for satellite speakers. Use this mode unless

Mixed-Mono is necessary.

Mixed-Mono

in order to drive stereo and mono simultaneously; works well for center channels. It can be used anytime you need a summed mono channel. Somewhat sacrifices sonic accuracy as additional circuitry is introduced to one channel. In Mixed-Mono, the left channel is inverted, see

diagram below or on the bottom of the amplifier.

Bridged Mono

for dedicated single channel operation; ideal for driving subwoofers. It is also used when large amounts of power are necessary for single speakers. In bridged mono, only the right channel input is active.

16

In bridged mono, only the right channel input is active.

NOTE: If you intend to drive a REFERENCE644s amp in mono but have stereo outputs from your crossover or source unit, you can put the switch in

Mixed-Mono but follow the normal wiring for Bridged

9

INSTALLATION STEP 2

BALANCED / UNBALANCED INPUT

The REFERENCE644s amplifier has the ability to accept either standard

Unbalanced RCA signal inputs, or Balanced "Pro Audio" inputs with the use of the Soundstream BLT Balanced Line Transmitter or some other balanced line audio source. Before installing your system, you should decide upon which

UNBALANCED INPUT

ADVANTAGES

1. Most preamplifier / source units have "UNBAL" RCA outputs. (Industry standard)

2. No Interface module is nec-

BALANCED INPUT

1. Improved Signal to Noise

Ratio. (S/N Ratio)

2. Excellent noise cancellation characteristics.

3. Immune to noise radiated in

The REFERENCE644s amplifier's signal inputs accept two ranges of input signal levels: 0.2 - 2.0 Vrms, or 0.5 - 5.0 Vrms for both Balanced and

Unbalanced inputs. The input range switch position and level settings are dependent upon the preamplifier / source unit output signal level. For the best system Signal to Noise Ratio, we recommend that the input level controls be set as far down as possible (rotated counter-clockwise), while maintaining an acceptable level of output.

Using the "Unbalanced" RCA input

When using the Unbalanced RCA input, the RIGHT channel ( channels 2) input signal switch MUST be in the "UNBAL" position. Also, when first installing the amplifier using this input configuration, we suggest that the remaining input signal switches be in the "UNBAL" position as well. If you

experience alternator whine or other installation noise with both switches in the "UNBAL" position, try moving channels 1,3 & 4 input

signal switches to the "BAL" position. This should remove any system noise due to installation.

Using the "Balanced" RCA input

When using the Balanced 6-pin DIN input, both switches MUST be in the

"BAL" position. Also, we recommend that when using this input configuration, the "INPUT LEVEL" switch be in the "0.5 - 5V" position, and the gains on the amplifiers be set to "minimum" (rotated counter-clockwise). The system gains

NOTE: The pin configuration shown in the diagram is the view looking into the

Balanced input jack on the amplifier.

10

INSTALLATION STEP 6

CROSSOVER ADJUSTMENTS

The REFERENCE644s amplifier incorporates an on-board staggered electronic crossover, with RCA outputs to drive an external amplifier. No external electronic crossover is necessary. The high and low pass portions of the crossover can be set independently of one another.

In most car audio installations, there is a tendency for a “midbass boom.”

Because of their interior dimensions, most cars will resonate or ring at these midbass frequencies. If we design the system so there is less musical information in this region, the final response is very smooth and natural sounding. The high pass filter is variable from 60 to 240 Hz at 12 dB/Octave, while the low pass filter is variable from 30 to 120 Hz at 24 dB/Octave.

For initial crossover setup, try setting the low pass filter to approximately 60

Hz, and the high pass filter(s) to approximately 100 Hz. Change the crossover points to accommodate a good mixture of frequency response, power

24 dB/Oct. Low Pass

12 dB/Oct. High Pass

NOTE: RCA signal output in high pass and full range is derived from Channels 1 & 2 input. In low pass, RCA signal output is summed from Channels 1, 2, 3 & 4 input. The

Subwoofer Level adjustment also applies to

AIRBASS ACCESSORY OPTION

Soundstream's new AIRBASS feature can be added to the REFERENCE644s amplifier. This feature allows wireless RF remote control level adjustment of the amplifier, while the low pass filter on the amplifier's internal crossover is engaged. (AIRBASS does not control the level of the RCA signal outputs.)

NOTE: The AIRBASS accessory is intended to be used only while the

REFERENCE644s amplifier is driving a subwoofer(s). When the AIRBASS

accessory is added to a REFERENCE644s, it controls the level of any channel receiving information from the low pass filter in the amplifier. The Coherent

Installing AIRBASS involves removing the bottom plate of the amplifier, adding the AIRBASS circuit board, and flipping a switch. The switch is labeled on the amplifier's main circuit board. DO NOT set the AIRBASS switch to the

"IN" position unless the AIRBASS module has been added. DO NOT move the AIRBASS switch while the amplifier is "ON". Doing so may damage your speakers. (Please refer to the AIRBASS owner's / installation manual for more details.)

15

INSTALLATION STEP 5

LEVEL SETTING

The input levels are adjusted by means of the individual channel input level controls located on the front of the amplifier. This is a unique dual-stage circuit that adjusts both level and gain. This topology maintains better Signal to Noise ratios even when using sources with minimal output.

In the ideal situation, all components in the audio system reach maximum undistorted output at the same time. The reason is because an amplifier will only make what comes into it bigger. So, if you send it a distorted signal from the head unit, the amplifier is going to amplify distorted information. The same thing holds true if an outboard processor or crossover begins to distort before you have maximum output from the amplifier. By setting all components to reach clipping at the same time, you can maximize the output of your system. For the REFERENCE644s amplifier, follow the steps below for the quickest, easiest means of setting the levels.

1.

Turn the amp’s input levels to minimum position (fully counterclockwise). If any channel is in low pass mode, set the subwoofer level pot to the 0 dB position (12 o'clock).

2.

Begin with the input level switches in the 0.5 - 5.0 Volt position.

3.

Set source unit volume to approximately 3/4 of full volume.

4.

While playing dynamic source material, slowly increase the amplifier’s input levels until a near maximum undistorted level is heard in the system.

5.

If you can't get enough gain out of the amplifier, set the input level switch to the 0.2 - 2.0 Volt position, and repeat steps 3 and 4.

6.

If any channel is in low pass mode, you may have to adjust

NOTE: It may be necessary to adjust the balance between low and high pass levels after listening to the system.

These settings are dependent upon personal preference.

If your preamplifier / source unit has an extremely high output level, be sure to pay attention to the clipping indicators located on the top of the amplifier.

These indicators will notify you if you are clipping the PREAMPLIFIER stage of the amplifier. If the amplifier's output is distorted and the clipping lights are not blinking, you are most likely clipping the OUTPUTS of the amplifier, or driving the speaker to distortion.

There is an additional control for subwoofer level adjustment. The purpose of this control is to provide additional range of adjustment for the subwoofer signal in relation to the high pass signal. This control adjusts the level of any

14

INSTALLATION STEP 3

WIRING

POWER AND GROUND

To ensure maximum output from your REFERENCE644s amplifier, use high quality, low-loss power and ground cables. The REFERENCE644s amplifier will accept up to 4 gauge power and ground cables. Determine from the chart

up to 10’

REFERENCE644s

Soundstream Power40 or

Power80

up to 20’

Soundstream Power40 only

(4 ga.)

Read this, or sparks will fly!

The Soundstream REFERENCE amplifiers have extensive internal power supply capacitance, called the Ultra-Low ESR Capacitance Bank. Multiple small input power capacitors act as an internal "stiffening capacitor". Because of the large amount of internal capacitance, there may be a sizable spark when connecting the power and ground lead to the amplifier for the first time.

In order to charge the capacitor bank without a spark, we suggest you do the following:

1. Connect the +12 volt cable to the amplifier and to the battery.

2. Connect one end of the ground cable to the chassis of the vehicle.

3. We have supplied a 150 ohm, 2 watt resistor with the amplifier. One leg of the resistor has been connected to the ground terminal of the amplifier.

4. To charge the capacitor bank, touch the loose end of the ground cable to the open leg of the resistor for at least 45 seconds.

CIRCUIT BREAKERS/FUSES

EXTERNAL

Like all audio components, the REFERENCE644s amplifier must be fused near the battery. A fuse or circuit breaker must be located within 18” of the battery. This will prevent a fire in the event of a shorted cable. See the chart on the next page to determine the correct fuse value.

INTERNAL

The REFERENCE644s amplifier is fused with automotive-type fuses. In the

(Continued on page 12)

11

(Continued from page 11)

event of blown power supply fuses, the “Fault” indicator on the top panel will light. The fuses are accessible via a plastic plug on the bottom of the amplifier. See the chart below to determine the fuse value. Never replace

REFERENCE644s Amplifier Fuse Values

Amplifier

REFERENCE644s

Amplifier Fuse

(2) 30 amp automotive

Battery Fuse /

Circuit Breaker

80 amp

REMOTE TURN-ON

Connect the “Remote” to the turn-on lead from the source unit. When +12 volts is received, the amplifier will turn on.

SIGNAL CABLE

Use a high-quality cable that will be easy to install and has minimal signal loss to guarantee optimum performance. Soundstream’s DL1 and SL1 are ideal when using the Unbalanced RCA inputs. While using the Balanced DIN input, use the cable supplied with the BLT.

SPEAKER CABLE

The REFERENCE amps will accept up to 8 gauge speaker cable. Use a high quality, flexible, multi-strand cable for best performance and longevity.

WIRING DIAGRAM

12

INSTALLATION STEP 4

INSTALLATION AND MOUNTING

1. AMPLIFIER LOCATION

The REFERENCE644s amplifier employs highly efficient circuitry and a unique

Chassisink

TM

design to maintain lower operating temperatures. Additional cooling may be required if the amplifier is located in a tightly confined area or when driving especially low impedance loads at extremely high levels.

When mounting the amplifier, it should be securely mounted to either a panel in the vehicle or an amp board or rack that is securely mounted to the vehicle.

The mounting location should be either in the passenger compartment or in the trunk of the vehicle, away from moisture, stray or moving objects, and major electrical components. To provide adequate ventilation, mount the amplifier so that there are at least two inches of freely circulating air above and to the sides of it.

2. SWITCHES

Set the Coherent Stereo

TM

/Mixed-Mono/Bridged Mono and Amplifier crossover switches on the bottom of the amplifier to the appropriate positions before bolting down the amplifier (see pages 16 - 21). Be sure to replace the hole plugs.

3. MOUNTING THE AMPLIFIER

a. Using the amplifier as a template, mark the mounting surface. b. Remove the amplifier and drill the holes. c. Mount the amplifier to the surface using the provided hardware.

4. WIRING

a. Run and connect the audio signal and remote turn-on cables to the amplifier from the source unit. b. Carefully run the positive cable from the amplifier to a fuse or circuit breaker within 18” of the battery. c. Connect the fuse or circuit breaker to the battery. Leave the circuit breaker off or the fuse out until everything is bolted down. d. Secure the ground cable to a solid chassis ground on the vehicle. It may

NOTE: There may be a sizable spark when connecting the power and ground lead to the amplifier for the first time. Please see the comment on page 11 for

be necessary to sand paint down to raw metal for a good connection. e. Double check each and every connection! f. Re-connect the fuse or circuit breaker.

13

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