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OPERATION

Setting the Controls

1. Initially set the subwoofer's Volume control to the minimum

position.

2. Initially set the subwoofer's Crossover Frequency control to

12 o'clock.

3. Set the subwoofer's Phase switch to the “NOM” position

Turn the Power On

4. Turn on the entire audio system and play any music

source.

5. Turn the Volume control to its mid position. If no sound

emanates from the subwoofer, check the AC line cord and

input cables. Are the connectors on the cables making proper

contact? Is the AC plug connected to a “live” receptacle?

Adjusting the Volume

6. Set the overall volume control of the preamplifier or stereo

to a comfortable level. Adjust the subwoofer's Volume control

until you obtain a pleasing blend of bass. Bass response

should not overpower the room but rather be adjusted so

there is a harmonious blend across the entire musical range.

Many users have a tendency to set the subwoofer volume too

loud following the belief that a subwoofer is there to produce

lots of bass. This is not entirely true. A subwoofer it there to

enhance bass, extending the response of the entire system

so the bass can be felt as well as heard. However, overall

balance must be maintained; otherwise, the music will not

sound natural. An experienced listener will set the volume of

the subwoofer so its impact on bass response is always there

but is never obtrusive.

The Crossover Frequency Controls

7. The Crossover Frequency control sets the high-frequency

roll-off, adjustable from 50 to 150Hz. Where you set this

control depends on the low-frequency capabilities of your

satellite speakers, system placement, and other factors

affecting the mid-bass region. Turn the control UP

(clockwise) until you feel there is too much mid-bass

information (around 100Hz), then back the control down a bit

until that area sounds more natural. To hear more low bass,

turn the Crossover Frequency control DOWN a bit and the

Volume control UP by about the same amount. This will

increase low bass while leaving the mid-bass sounding the

same as it did before the adjustment. To reduce low bass

without changing midbass, turn the Crossover Frequency

control UP and the Volume control DOWN. Switch the Phase

switch between “NOM” and “REV” positions while listening to

music. The selection that sounds the best is the correct

adjustment for your system.

Room Placement

8. The room placement of the subwoofer is the most critical

aspect of its installation. It will be necessary for you to try

various locations in your listening room before you choose

the final location. Some possible starting points include:

behind the right channel satellite speaker, along the back

wall between the satellites, along a side wall (but not too

close to a corner), or behind a couch or a chair.

In general, the closer the subwoofer is to wall and corners,

the greater the effect of low-frequency enhancement.

Experiment with the Crossover Frequency and Volume

controls in different locations until you are pleased with the

result you obtain from your particular application.

A Word of Advice

The Low-Frequency Roll-off and Volume controls may be

set anywhere within their rotation. However, it will be a most

unusual circumstance if you have to set the Volume control

completely clockwise. This may indicate an unbalanced

condition in your system (too much bass) or an especially

large room, or room placement may not be correct. Try

several other locations before concluding that the Volume

control must be set at maximum.

A Word About Tone Controls

The tone controls on your electronic components

(preamplifier, receiver, etc.) should be used with the utmost

discretion. Excessive boost can create severe power

demands on your power amplifier. Maximum bass boost

can create a demand for literally hundreds of watts in the

bass region, whereas in the “flat” position, or with the tone

controls switched out of the system, your average listening

level may be impressively and realistically loud at less than

10 watts. The remaining power capacity required is on

reserve for power peaks on sharp transients and powerful

crescendos.

1 1

Amplifier/Subwoofer

BU-150

Summary of Contents for BU-150

Page 1: ...Infinity Systems Inc 250 Crossways Park Drive Woodbury N Y 11797 1 800 553 3332 A Harman International Company Rev A 3 2000 BU 150 Powered Subwoofer SERVICE MANUAL...

Page 2: ...lacement C1 2 2200uF 100V electrolytic filter caps Be sure replacement part is at least the same working voltage and capacitance rating Also the lead spacing is important Incorrect spacing may cause p...

Page 3: ...LE OF CONTENTS SAFETY INFORMATION 2 GENERAL SPECIFICATIONS 3 DETAILED SPECIFICATIONS 4 CONTROLS AND THEIR FUNCTION 6 BU 150 CONNECTIONS 7 OPERATION 11 BU 150 TEST SET UP AND PROCEDURE 12 BU 150 POWER...

Page 4: ...ol Max 1 input driven AP source Z 600 ohms Speaker Hi Level Input 7 Vrms 2dB To Rated Power Vol Max 1 input driven AP source Z 25 ohms Signal to Noise SNR A Weighted 100 dBA 90 Relative to rated outpu...

Page 5: ...er Input w 1 ch Driven Signal Present Turn on time 1 sec Amp connected and AC on then input signal applied Auto Mute Turn OFF Time 3 min T before muting after signal is removed Power on Delay time 1 s...

Page 6: ...roll off points 4 Power On indicator 5 Phase 0 180 switch to change audio signal polarity 6 Level This controls the volume level of the subwoofer TO REDUCE THE RISK OF ELECTRIC SHOCK DO NOT EXPOSE TH...

Page 7: ...one end of each stereo pair of leads to the preamplifier s left and right outputs and connect the other end to the corresponding left and right LOW LEVEL INPUTS 1 on the subwoofer If you are using a t...

Page 8: ...woofer pair See Figure 3 Figure 3 Use this method when using single subwoofer or two subwoofers The subwoofer may be connected to your system using the HIGH LEVEL INPUTS 4 on the plate located on the...

Page 9: ...necting one subwoofer to satellites Depending on whether you are using one or two subwoofers connecting your satellites can be accomplished in one of two ways If you are using a single subwoofer with...

Page 10: ...ofer has a variable frequency control that can be used to block unwanted frequencies between 50 150Hz from being reproduced by the subwoofer When you set this control depends on the low frequency capa...

Page 11: ...This will increase low bass while leaving the mid bass sounding the same as it did before the adjustment To reduce low bass without changing midbass turn the Crossover Frequency control UP and the Vol...

Page 12: ...om port tube opening 5 Turn off generator turn VOLUME control fully counterclockwise disconnect RCA cables 6 Connect one pair of speaker cables to either high level input terminal on UUT Cables should...

Page 13: ...k I P of module to GND 0V D C Power up with no signal I P LED RED OK OK OK OK OK OK OK OK Check C29 and Pre AMP Check O P to module for 80Vpp square wave measure to GND Check L1 L2 L3 L4 C6 C24 Check...

Page 14: ...PLASTIC BAG CARTON 200420 SCREWS 10 SCREWS 8 TRIM RING 200401 SCREWS 4 FOOT BASE Each 200870 FEET PART Set of 4 200310 CABINET NOT FOR SALE 15 WOOFER 200400 BU 150 CABINET ASSEMBLY BU 150 PACKING AMPL...

Page 15: ...ws to secure input jacks 5 6 70171 10 x 1 machine screw Bolts 4 7 70172 10 Keps Nut 4 8 70173 6 x 0 5 Screws for fuse PCB 2 9 80124 Transformer MCI4700 SAFETY PART 1 10 80123 250V 1 5A T type SLO BLO...

Page 16: ...1 6 Amplifier Subwoofer BU 150 BU 150 PCB Version 3 52 Component Side Trace Version 3 52 Component Side Trace Layer 5 5 4 4 3 3 2 2 1 1 A A B B C C D D E E F F G G...

Page 17: ...1 7 Amplifier Subwoofer BU 150 Version 3 52 Solder Side Trace Layer as viewed through the board 5 5 4 4 3 3 2 2 1 1 A A B B C C D D E E F F G G BU 150 PCB Version 3 52 Solder Side Trace...

Page 18: ...1 8 Amplifier Subwoofer BU 150 BU 150 PCB Version 3 53 Component Side Trace Version 3 53 Component Side Trace Layer 5 5 4 4 3 3 2 2 1 1 A A B B C C D D E E F F G G...

Page 19: ...1 9 Amplifier Subwoofer BU 150 BU 150 PCB Version 3 53 Solder Side Trace Version 3 53 Solder Side Trace Layer as viewed through the board 5 5 4 4 3 3 2 2 1 1 A A B B C C D D E E F F G G...

Page 20: ...itors C1 30710 2200uF 100V 80 20 Electrolytic Radial 1 Safety part C2 30710 2200uF 100V 80 20 Electrolytic Radial 1 Safety part C3 30514 47nF 50V 80 20 Mono ceramic axial 1 C4 5 30504 100nF 50V 80 20...

Page 21: ...FOLLOW ONE OR MORE OF THESE STEPS MAY RESULT IN THE INSTANT DESTRUCTION OF THE MODULE WHEN POWERED UP Align white indent marker on Amp Module with indent marker on main PCB alternately observe positio...

Page 22: ...2 2 Amplifier Subwoofer BU 150 BU 150 SCHEMATIC 1 of 2 5 5 4 4 3 3 2 2 1 1 A A B B C C D D E E F F G G BU 150 Schematic 1 of 2...

Page 23: ...2 3 Amplifier Subwoofer BU 150 5 5 4 4 3 3 2 2 1 1 A A B B C C D D E E F F G G BU 150 Schematic 2 of 2 BU 150 SCHEMATIC 2 of 2...

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