Powered Subwoofer II by Henry Kloss Installation and Operating Instructions © 1995 Cambridge SoundWorks Inc. Powered Subwoofer II by Henry Kloss Contents Important--Please Read First .......................................................... 1 Unpacking The System .................................................................... 2 Setting Low-Pass Filter Frequency ................................................... 3 Cleaning The Cabinets ..................................................................... 3 Placement ........................................................................................ 4 Low-Cut Filters ................................................................................ 5 Audio And AC Power Connections .................................................... 6 Setting Subwoofer Level And Intial Listening ................................. 8 Difficulty? ........................................................................................ 8 The Powered Subwoofer II Limited Warranty ................................... 9 Important ­ Please Read First B ass drums, organs, and electronic synthesizers are among the very few instruments that produce extremely low-frequency sounds. As a result, comparatively few home loudspeakers are designed to reproduce bass below about 50 Hz. Today, however, home loudspeakers are called upon to reproduce more than music: in home theater systems, they are called upon to reproduce movie soundtracks. And modern movie soundtracks contain a lot of energy at very low frequencies--on sound effects. To do full justice to these effects, as well as to the musical low-frequencies missed by most speakers, the Cambridge SoundWorks Powered Subwoofer II reproduces, at high power, the lowest bass sounds the human ear can detect. You should keep in mind when installing your Powered Subwoofer II and investigating its capabilities that you will be dealing with a relatively unfamiliar range of sounds. These are sounds more felt than heard, and are encountered more often in the well-equipped movie theater than in the concert hall. Also keep in mind that a Cambridge SoundWorks Audio Expert is only a toll-free call away should you need advice or assistance (8 AM to midnight Eastern time): Cambridge SoundWorks 1-800-FOR-HIFI (1-800-367-4434), 8 AM to Midnight, Eastern time In Canada: 1-800-525-4434 Outside US or Canada: Tel: 617-332-5936 Fax: 617-332-9229 1 Unpacking And Checking For Shipping Damage 1. Upon unpacking your Powered Subwoofer II, please examine it carefully for any signs of shipping damage. If there is evidence of shipping damage, do not discard the shipping carton or its inserts, and do not install or use the Powered Subwoofer II, in case it needs to be returned. Call the store where you made your purchase or, if you bought directly from Cambridge SoundWorks, call 1-800-FOR-HIFI immediately. Your store or a Cambridge SoundWorks Audio Expert will tell you how to proceed and will help minimize any inconvenience. 2. Check the accessory pack for the following items (inform your store or call Cambridge SoundWorks if there is anything missing): · One spare five amp, fast-blow fuse · Four square rubber feet 3. We suggest that you keep the shipping carton and packing materials in case you later move, or have to ship your speakers. 2 Setting The Low-Pass Filter Frequency The Powered Subwoofer II has a four position "low-pass" switch. One of the four settings of this switch will enable the Powered Subwoofer II to best "take over" the very low bass seamlessly from your existing speakers. The following guidelines will help you choose the appropriate setting for your system. Alternatively, you may choose to set the switch by ear. · 55 Hz, 80 Hz: Use one of these two positions with Cambridge SoundWorks' Ensemble® or Ensemble II, or with any other wide range speaker system. Typically, this would be a large acoustic suspension bookshelf speaker, where bass reach has not been sacrificed for efficiency. Which switch position to choose will be affected by where the main speakers and subwoofer(s) are placed in your listening room. The closer your main speakers are to the corners of the room, the more likely the 55Hz setting will be the better choice. See the "Placement" section which follows for more information. Note: The Powered Subwoofer II is intended to supplement, not replace, the separate woofers supplied with Ensemble systems. Do not disconnect your Ensemble woofers when using Powered Subwoofer II. · 100 Hz: This position is appropriate to high-quality systems with less low-bass reach, such as those designed to achieve higher efficiency at the expense of low bass. · 140 Hz: This position can be used with small speakers for creating your own satellitetype system. 140 Hz is the highest frequency recommended for this purpose; the ear tends to localize sounds that are higher in frequency. See page 8 for advice on how to set the overall subwoofer level. Cleaning The Cabinets If more than dusting is needed, the vinyl finish of the Powered Subwoofer II can be cleaned with a window or vinyl cleaning product. Avoid spraying the cleaner directly on the speaker grilles to prevent damage to the speaker. 3 Placement 1. The ear cannot localize the very low bass sounds reproduced by the Powered Subwoofer II. This is why it is possible to use a single unit to reproduce all the low bass for a stereo or multi-channel surround system, and why it need not be located particularly close to the other speakers or aimed directly at the listeners. The Left Satellite Powered Subwoofer II can be placed horizontally or vertically (stick-on feet are provided for attachment once you have decided on its final orientation). It can go most anywhere within the listening room, although we don't recommend placing it behind the listeners. It can be hidden under or behind furniture. Right Satellite Left Satellite The strength of the low bass output produced by the Powered Subwoofer II is markedly affected by its placement with respect to adjacent room surfaces. The strongest bass will be reproduced with the speaker on the floor in a corner (See Figure 1, C). The least strong bass will result if the speaker is placed out in the room away from the walls. (Figure 1, A.) We suggest you first place the subwoofer on the floor against the same wall as the front speakers (Figure 1, B). After extended listening, you can try other placements if the initial location results in too much or too little bass. Right Satellite Left Satellite Right Satellite Powered Subwoofer II Powered Subwoofer II Powered Subwoofer II A. Least bass B. More bass C. Most bass Surround Surround Surround Surround Surround Surround FIGURE 1: HOW ROOM PLACEMENT AFFECTS BASS RESPONSE 4 Low-Cut Filters Note: Do not place the subwoofer in shelving that houses a phono turntable. Strong bass from the speaker, including the turntable's own rumble, could be picked up by the turntable, fed back out the speakers again, picked up by the turntable yet again, and so on. This condition, known as acoustic feedback, will muddy the sound, or worse, set up a loud, low-frequency rumbling. 2. A listening room's construction also has a marked affect upon the very low frequencies reproduced by the Powered Subwoofer II. Thin, relatively flexible walls allow bass to dissipate readily, as do open doors, archways opening into another room, and even open windows. In addition, the larger the room, the greater the demand for low-frequency acoustic energy. Therefore, for best low-bass, the ideal room for a home theater would be moderate in size, solidly constructed, with no openings to other rooms. Obviously, not all rooms meet all these criteria. However, if you have the option, set up your home theater in the room that comes closest. When listening, shut the room's doors and windows if practical, which can make a surprising difference. If your listening room is very large and/or opens out into another room, the higher acoustic output of our original larger Powered Subwoofer may be necessary (consult your store or a Cambridge SoundWorks Audio Expert). An option is available from Cambridge SoundWorks to optimize your system. Low-cut filters keep the low frequencies best left to the subwoofer out of the main front speakers. This "eases" the burden on front speakers and amplifier, letting them play more cleanly at higher levels. Our inexpensive Low-Cut Filters are ideal for use with Cambridge SoundWorks Model SeventeenTM, Model SixTM or Ambiance® speakers, or other conventional systems of reasonably wide range. You connect these filters between your main speakers and your amplifier. The filters begin to block bass signals to your main speakers below about 140 Hz, so that below 100 Hz, almost no bass signals reach your main speakers. A filter for your center channel speaker is not necessary with Dolby® Pro Logic® if you set its Center Mode control to Normal (which rolls off frequencies below 100 Hz). · The filters can go at either end of the left and right speaker wires. You can, for example, connect the filters' INPUT FROM AMP leads to the speaker terminals on your receiver or amplifier, then connect the speaker wires to the filters' OUTPUT TO SPEAKER leads (using the wire nuts supplied). Or, you can attach the filters at the back of your speakers. Connect the OUTPUT TO SPEAKER leads to the speaker terminals. Connect the speaker wires coming from your amplier to the INPUT FROM AMP leads with the wire nuts. · As with all speaker connections, be sure to maintain consistency with respect to the + and -- terminals on the receiver and those on the speakers. The connecting wires on the filters are coded by the use of one copper-colored lead and one silver. 5 Audio And AC Power Connections Note: Make all connections with the Powered Subwoofer II switched off. The Powered Subwoofer II can be connected one of three ways. Connection Method One: Connect directly to an amplifier or receiver's speaker output terminals using conventional speaker wire (Figure 2). This is the easiest way to connect the Powered Subwoofer II and we strongly recommend it, even if you have a separate preamp output. You can use very thin speaker wire, as the Powered Subwoofer II uses virtually none of the amplifier or receiver's output power. Be sure to connect the speaker wires to the same speaker output terminals used by your main speakers. Do not use any additional speaker output terminals your amplifier or receiver may have. Alternatively, you may connect these speaker wires to the termi INTEGRATED AMP OR RECEIVER (FRONT) SPEAKER OUTPUTS LEFT RIGHT PREAMP OUTPUTS TO POWER AMP L R SURROUND DECODER, RECEIVER OR PREAMP OUTPUTS L FRONT SURROUND R CENTER SUBWOOFER* "Y" Adapters *Labeled "Mono" on some units To left (front) speaker To right (front) speaker To left and right power amp inputs Stereo phono cable BASS LEVEL 4 3 2 1 0 10 5 6 7 8 9 LOWPASS FILTER FREQUENCY (Hz) 80 55 100 140 3 2 1 BASS LEVEL 4 5 6 7 LOWPASS FILTER FREQUENCY (Hz) 80 55 8 9 100 140 3 2 1 BASS LEVEL 4 5 6 7 LOWPASS FILTER FREQUENCY (Hz) 80 55 8 9 100 140 0 10 0 10 SPEAKER LEVEL LEFT INPUT LINE LEVEL LEFT INPUT SPEAKER LEVEL LEFT INPUT LINE LEVEL LEFT INPUT SPEAKER LEVEL LEFT INPUT LINE LEVEL LEFT INPUT SPEAKER LEVEL RIGHT INPUT LINE LEVEL RIGHT INPUT SPEAKER LEVEL RIGHT INPUT LINE LEVEL RIGHT INPUT SPEAKER LEVEL RIGHT INPUT LINE LEVEL RIGHT INPUT POWERED SUBWOOFER II POWERED SUBWOOFER II POWERED SUBWOOFER II Figure 2. Using speaker wire. Figure 3. Using"Y" adapters and phono cable. Figure 4. Using a full-range signal output. 6 nals of your main speakers instead of the amplifier or receiver's speaker output terminals. Be sure the speaker wire connects the positive (+) terminals of the subwoofer to the positive (+) terminals of the amplifier or receiver (and similarly connects the negative (­) terminals together). All two-conductor speaker cable is coded along one conductor by lettering, a stripe or a raised bead -or- the appearance of the two conductors differs, usually one copper and one silver. This allows you to easily connect the proper conductor to each terminal. Connection Method Two: Connect between a stereo preamp output and a stereo power amp input using phono cable "Y" adapters and standard shielded stereo cable with phono plugs (Figure 3). Some receivers and integrated amplifiers have preamp outputs and power amp inputs that are accessible by removing jumpers from the back panel. Connection Method Three: Connect from a subwoofer output (on either a receiver, amplifier, preamp or surround unit) using a single shielded cable with phono plugs at each end (Figure 4). The subwoofer output should be a fullrange mono signal. Check the specifications for the subwoofer output. Do not use a subwoofer output that cuts off the signal above some arbitrary frequency (usually between 80 and 200 Hz) ...