Paul
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Registered: 16th Apr 02
Location: Oop north.
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If you want a full explanation ....
It depends upon what you want.....
Subwoofers Frequently Asked Questions
Q: Which subwoofer will sound the loudest?
A: If you're looking for the sub that will deliver maximum SPL (play loudest), you need to consider sensitivity, enclosure type, and available power.
Start with a subwoofer with a high efficiency (sensitivity) rating housed in a ported or bandpass box.
Next, power the sub with an amplifier that has a power output that is within your sub's recommended power range (preferably in the top third of that range). You'll achieve the slam you're listening for. Using an amplifier with a "bass boost" control can also help.
Consider a multiple subwoofer set-up, as well. It'll require more power, but will play louder.
Q: Which subwoofer will sound the deepest?
A: To experience the lowest possible bass tones, select a large woofer designed for use in a sealed box. This type of enclosure is your best bet for driving your frequency response down.
Ample wattage is also a must if you want to hear those lowest bass notes. A woofer with a very low frequency response spec can help deliver extremely low notes. Additionally, larger woofers, because of their size and excursion capabilities, often have the ability to play deeper than smaller woofers.
Q: Which hits harder: one 12" sub or two 10" subs?
A: This is a popular question, and one that's difficult to answer definitively. There are so many factors that come in to play — power, enclosure type and size, as well as your specific vehicle and your individual perception. But, generally speaking, given adequate power the two 10" subs will sound a little cleaner and punch harder because their combined cone surface area yields more sound pressure. The single 12" sub, however, may sound a little deeper.
Q: How much power do I need?
A: The right answer to this question depends upon which subwoofer you choose. You'll find a recommended power range (in continuous or RMS watts) listed in the specifications for each subwoofer on this website.
The lower number is the absolute bare minimum amount of wattage you need to get acceptable results. Generally, more power is better because bass notes are power hungry. So, to really make your subwoofer deliver, we recommend choosing an amp rated in the upper third of your woofer's maximum RMS power range.
Your amp's RMS output can even exceed the woofer's maximum RMS rating, provided you keep an ear on the sound quality — when the bass starts to distort or "break up," you've reached the performance limit of your amp/speaker combination. Back the volume knob down a bit, and your woofer is safe; clean, high-volume sound will not damage your speaker.
Q: Should I use a mono amplifier or a multichannel amplifier to power my subs?
A: Because mono amps tend to be Class D amplifiers, they are a good choice for powering subwoofers — Class D amplifiers have a high power-to-heat ratio and excellent efficiency, which are exactly what you want when dealing with power-hungry low frequency signals.
Most mono amplifiers are designed to run at 2 ohms; some are even 1-ohm stable. Multichannel amplifiers, on the other hand, are typically designed to work with a 4-ohm load. This is an important difference when using your amp to power multiple subwoofers, because you won't be able to bridge your multichannel, 4-ohm stable amp to power multiple subs that present less than a 4-ohm load. Instead, use a mono amplifier to power a 2-ohm load — two 4-ohm subwoofers, or 2, 2-ohm dual voice coil subwoofers, for example. You'll be able to push your subwoofers with the mono amp's maximum power, without running at a dangerous impedance.
Q: What are the benefits of hooking up 2 subwoofers to a mono amplifier? How would I wire them?
A: The benefits of hooking up two subs to a mono amplifier are the same as hooking up any other number of subs to a mono amp: you can push the subs with more power at lower impedances. Because lower frequencies are less directional (i.e. it's more difficult for your ears to determine where low frequencies come from than highs), bass is often transmitted in mono. Mono here refers to a single channel (as opposed to stereo, or two channels), not one speaker.
Most mono amps have two sets of speaker terminals for convenience of installation: if you are hooking up two subs to the amp and using large-gauge wire, it gives you a place to attach the wires without having to trim them, appearing as if each subwoofer gets its own terminal. But in reality, these terminals are actually tied together inside the amp — both positives are going to the same place inside the amp, as are both negatives. If you are using more than two subs, then you simply use parallel or series wiring (or a combination) to get as close to the minimum impedance of the amp as possible (see our subwoofer wiring diagrams for more information).
Q: Can I bridge my mono amplifier?
No, you can not bridge a mono amp because there is nothing to "bridge" to — whatever impedance load you present to amplifier is the actual load that it sees. This differs from a multichannel amp in that when you bridge two channels together, you halve the load presented to them (for example, 2 4-ohm woofers wired in parallel and bridged to a stereo amplifier is "seen" as a 1-ohm load to that amp).
Q: What difference do cone materials make?
A: Subwoofer cones, like speaker cones, are made of treated paper, synthetics (like Highly Oriented Polyolefine) or composites (like aluminum or injection-molded quartz). Paper tends to be less durable, but, because it is so lightweight, responds quicker than other materials. All these can sound great; you need to experiment with different sounds (and your checkbook) to find the sub that's right for you.
Q: Are square or triangular subwoofers better than round ones?
A: "Better" is a relative term, since the bass you prefer might differ from someone else's taste. If you're into imaginative looks and style, square and triangular subwoofers might be for you. They'll definitely catch the eye! These woofers also reproduce bass extremely well (Kicker's square woofers are big on the competition scene), though traditional round woofers tend to play more accurately. The triangle shaped woofers might be convenient if you lack sufficient cargo space, since triangular boxes fit into places where standard design boxes fear to go.
Q: What's a dual voice coil sub?
A: A dual voice coil subwoofer has two separate voice coils (each with its own connections), offering more flexibility in system wiring than a standard sub. The DVC sub can be wired in three different configurations: parallel, series, or independent. This way, you can wire the subwoofer according to your system design and preferences. Check out the article on dual voice coil subwoofers for more information.
Q: What do I need to know about impedance when wiring subs to an amplifier?
A: Impedance is the amount of resistance speakers provide to the current flowing from the amplifier. Every time you halve the speakers' impedance — switching from a 4-ohm to a 2-ohm sub, for instance — you effectively ask the amplifier to double its output. Some amps can handle this lower impedance, some cannot. The key thing to know about impedance, then, is how to match your speakers to the capabilities of your amp.
The typical car stereo amplifier is stable down to 4 ohms in mono (or bridged) mode or 2 ohms stereo. Some high performance amplifiers can operate safely with loads as low as 1/2-ohm in stereo (1-ohm mono). If you're designing a subwoofer system, ask yourself the following questions:
How many subs do I want? More subs = more cone surface area = more air moved = big bass! Balance this equation against the amount of room in your vehicle.
How much power do I want? If you're powering your vehicle's speakers with your receiver, you'll need less power for your subs. If you use a multi-channel outboard amp for your speakers, you'll need more power for your subs.
Check out suitable amps in your price range. Once you've found the right amplifier, look for subwoofers that complement your amp in terms of power rating and impedance. Most subs are rated at 4 ohms, but 2-ohm, 8-ohm, and dual voice coil subwoofers have become commonplace, so it's easy to find speakers that will bring out the best in the amp you've chosen.
Q: How many subwoofers can I hook up to my amplifier? Can I bridge my amp and run two in parallel?
A: A well-made stereo amplifier that is stable to 2 ohms should be able to handle up to four 4-ohm woofers (two subwoofers wired in parallel to each channel).
If you want to bridge a 2-channel amp to one channel, it's best to only connect one 4-ohm woofer. The minimum impedance for the bridged (mono) output of a 2-channel amp is usually 4 ohms. Mono subwoofer amps, like the Kenwood KAC-819, are stable down to 2 ohms, allowing you to hook up two 4-ohm subs in parallel.
Q: If I put my subwoofer box in the trunk, will I be able to hear the bass?
A: Absolutely. The only situation that might prevent you from hearing bass from a trunk-mounted box would be if your trunk is sealed and soundproofed. Usually, bass travels easily through the materials separating the trunk from the passenger compartment. If you think you're missing out on bass because your seatback and rear deck material are blocking the sound waves, you can alleviate the problem by punching a few small holes in the rear deck and covering it with an acoustically transparent material.
Q: What's Poly-Fill and how will it affect my subwoofer's sound?
A: You're probably already familiar with Dacron polyester fiber-fill, or Poly-Fill — chances are you've slept on a pillow stuffed with this material. But you may not realize how Poly-Fill can help your bass.
Stuffing your enclosure with the right amount of Poly-Fill can make your box behave like it's larger than it really is. This comes in handy if the volume of the box you've built turns out to be a hair shy of the cubic air space recommended for your subwoofer. Depending on how much Poly-Fill you use, you can actually vary perceived box volume by as much as 30%.
You can also "stuff it" if you simply don't have room in your vehicle for the larger box your sub demands. And adding Poly-Fill to any enclosure can clean up your bass by minimizing unwanted box resonances — and at a reasonable cost.
Q: What crossover point should I choose?
A: usually start with a low-pass crossover point around 80 Hz. Through trial and error, we've found that higher crossover points tend to emphasize the source of the bass instead of the overall musical experience. In other words, you can tell the bass is coming from a box in the trunk.
A crossover point between 60 and 80 Hz focuses the power of your subwoofer amplifier on your music's deepest notes (the ones you feel) and helps make the bass you hear seem like it's coming from the front of the vehicle along with the rest of the stereo image.
Your own preferences are also important. If you prefer a hard-hitting midbass boom, or if your front speakers or subwoofers are small, a crossover point of 100 or even 120 Hz is appropriate.
[Edited on 11-04-2004 by Paul]
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never anyone in the ice forum anyhooo
