Tag: subwoofer

Subwoofer Enclosure Buying Guide

Belva BBLE212 Dual 12" Loaded Enclosure


Buying a Subwoofer Enclosure

Find the Perfect Enclosure for Your Subwoofer

Building your perfect car audio setup requires more than just the components; you also are going to need the right mounting hardware to have your system meet its potential. Your subwoofer is no exception when it comes to a subwoofer enclosure. A subwoofer without an enclosure isn’t capable of functioning to it’s full potential. If you want to really make your subwoofer bump, this means finding the right enclosure not only to meet the requirements of your sub, but also the space limitations for your car. You can also build an enclosure yourself to meet your subwoofers requirements, however it is not recommended unless you are an experienced craftsman and have a complete understanding of the various specifications.



What Size Subwoofer Do You Have?

Your first step in purchasing a subwoofer box should be obvious, what size is your subwoofer? You can’t buy a box designed for an 8” subwoofer and use it with a 12” sub, it simply won’t fit. The cut out dimensions need to match your subwoofer exactly for the box to function properly. It is also imperative for you to know the mounting depth of your subwoofer, if you purchase a box that is too shallow for your woofer, you’re also going to be in trouble. You also need to know how many subs you plan on installing. If you’re only going to be putting one subwoofer in your car, you’ll need to get a single sub enclosure. However, if you plan on installing 2 subwoofers, dual sub boxes are also available (however they can take up a significant amount of space).



What are Your Subwoofers Airspace Requirements?

Once you have determined what size enclosure you need for your subwoofer, it’s time to get into some of the finer details to get your bass to really hit hard. Matching your subwoofer to the proper enclosure is no simple task as you need to know the precise Thiele/Small (T/S) Electromechanical Parameters as well as the air space requirements of your specific sub. The T/S parameters as well as the air space requirements of your subwoofer should be provided by the manufacturer.



What Kind of Box Do You Need?

There are 3 types of subwoofer enclosures: sealed boxes, ported boxes and bandpass boxes. Subwoofer enclosures are most commonly (but not exclusively) constructed from medium density fiberboard (MDF). Each box type has its own merits and features, but not every subwoofer is designed to work with any box type.

Sealed Enclosures are More Compact than Other Types of Enclosures

Sealed Boxes are airtight enclosures to house your subwoofer. A sealed box provides deep, precise bass and is ideal for any music that demands tight and accurate bass. Sealed enclosures are not overly boomy, provide outstanding power handling as well as incredibly deep bass extension. Sealed enclosures also typically more compact and can fit in more places in your car easier. As a general rule, sealed enclosures require more power than a ported box and use of an amplifier is usually recommended.


Ported enclosures (or vented enclosures) feature an additional port for air flow in and out of the box. The added air flow of ported boxesallows the box to play louder with less power required. Ported boxes are best used for rock, heavy metal or any other genre of bass heavy music.

Bandpass enclosures are more specialized enclosures which place the sub between a sealed and ported box. These enclosures are designed to provide the hardest hitting bass performance. They produce much more bass than their sealed and ported counterparts, however it is over a much more narrow frequency range. These enclosures are ideal for rap, R&B, hard rock, metal and other bass heavy music. Bandpass boxes are often the largest enclosure type.



What Else Do You Need to Know?

Among other considerations you need to make when purchasing a subwoofer enclosure is the amount of space you have in your car. Subwoofer enclosures can take up a large amount of space and depending on what kind of car you have, any type of enclosure may not work. Not all vehicles have the room of an SUV, van or even a hatchback to accommodate the larger sub enclosures and you’ll need to know how much open space you have (and are willing to sacrifice) to add an enclosure.

Install Your Enclosure Under the Seat to Save Space

Trucks are often the most difficult vehicle to install a sub enclosure in simply because there is very little free space in the cab. Enclosures in pickup trucks can generally only be installed behind the driver and passenger seats. These types of enclosures feature an angled design to fit snuggly up against the seatback. Another potential location for the installation of your subwoofer enclosure is under the seats in your car. These enclosures are perfect if you’re trying to keep your sound system inconspicuous as they will be hidden from view. The most common type of enclosure is the trunk mount enclosure. These ‘big box’ enclosures fit in the trunks of sedans and in the cargo area of hatchbacks, vans and SUVs. Trunk mount enclosures can vary quite a bit in size and take up a significant chunk of your storage space.

Many Vehicle Specific Enclosures Install in Out of the Way Places

Vehicle specific enclosures are also available for select vehicles. These enclosures are designed to fit precisely into specific vehicles and will often fit in out of the way places. These types of enclosures can be constructed out of MDF like most common enclosures as well as fiberglass. Fiberglass is an ideal material for vehicle specific enclosures because it can be molded to fit in virtually any space.

Preloaded enclosures are also available to purchase; these enclosures eliminate the guesswork of selecting a box to match your subwoofer as they come with the subwoofer built-in. A preloaded enclosure can also include an amplifier, making your installation process even simpler.

Once you have your enclosure installed in your vehicle and subwoofer mounted in it, you’re ready to enjoy your new sound. At Sonic Electronix, we have everything you need to get your bass up to par.

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Car Amplifier Buying Guide



Buying an amplifier for a car audio system can be a daunting task. It can be a challenge for someone new to the industry to select the perfect amplifier for their application, so we’ve put together this guide to help you find out what type of amplifier you need for your new system. Remember – you should either choose an amplifier first and build your system around it, or you choose the other components first and choose an amplifier (or amplifiers) to power the components. This guide assumes you have an idea of what type of system you want without any idea about the amplifier.
Let’s get started!

Selecting a Channel Configuration

All amplifiers are designed to output power into different “channels”. This helps pair the amplifier to the application it’s being used in. The most common amplifiers are 2-channel, 4-channel, and monoblock. Now, just because an amplifier is branded as “2-channel” doesn’t mean it’s only capable of powering 2 speakers. In theory, it’s possible to have as many speakers as you want paired with a 2-channel amp, it will just change the impedance (ohms) and change how the power is distributed between the speakers. Even though it’s possible to wire many additional speakers, it’s most common to use a 4-channel amplifier for 4 speakers, a 2-channel for 2 speakers, and so on.

Here’s a list that helps identify each different amplifier channel configuration and more information about each one.



  • Stereo
  • Full-range
  • Bridgeable
  • Can be used to power one set of speakers (2 total speakers)
  • Most commonly used to power a subwoofer, or multiple subwoofers
  • Usually has Class A/B Circuitry, but can also have full-range Class D as well

Perhaps one of the most popular selections, 2-channel amplifiers are great for multiple purposes. Two channel amplifiers output dedicated power to two separate channels, great for powering one set of car speakers (2 total speakers). The two channels can also be combined, or bridged together to provide more output to one dedicated channel, and is commonly done to power a subwoofer or subwoofers. 2-Channel amplifiers are stereo, meaning they have a Left and Right output. This is important for staging, and tuning. These amplifiers are capable of playing what is considered the full spectrum of sound that humans can hear, usually around 20-20,000 Hz.



  • Stereo
  • Full-Range
  • Bridgeable (most of the time)
  • Usually used to power two sets of speakers (4 total speakers)
  • Also able to be used in other configurations, however this is not as common
  • Usually has Class A/B Circuitry, but can also have full-range Class D as well

Another popular option, 4-channels, are commonly used to power an entire set of door speakers (4 total speakers). 4-Channel amplifiers are also bridgeable, allowing for a ton of configurations, but the most popular application we find these amplifiers in is powering door speakers.



  • Mono (one channel, no Left/Right differentiation)
  • High-powered car amplifier
  • Not full-range since subwoofers do not play higher frequencies
  • Usually used to power one or more subwoofer
  • Commonly has Class D circuitry, however can also have Class A/B as well

Monoblock amplifiers are designed primarily for subwoofers. Subwoofers require a lot more power than standard speakers, and the signal does not need to be as clean as the signal going to a full-range amplifier. Bass doesn’t need to be processed as much for high quality sound, like a really nice full-range amplifier does. Monoblocks are also not usually full-range capable, because higher frequencies are not played by subwoofers. Having these amplifiers capable of playing high frequencies would be a huge waste in efficiency. Because subwoofers require much more power than smaller tweeters or door speakers, monoblock amps are designed for maximum efficiency and power output first.



  • Stereo
  • Hybrid amplifier
  • Front 4-channels are stereo/1 channel is mono
  • Basically a 4-channel amp and a monoblock amp combined
  • Allows an entire system to be powered from one amplifier (4 speakers, 1 or more subwoofer)
  • Good for those who don’t want multiple amplifiers powering their entire system

5-Channel amplifiers are basically a mixture of a 4-channel amplifier and a monoblock amplifier, built into the same chassis. This helps eliminate the need for multiple amplifiers and elaborate wiring scenarios. These amplifiers are a great, simple solution for those looking to power 4 speakers and a subwoofer. They’re a bit more difficult to use for high powered audio applications, since 5-channels are usually only capable of running around 600-1000W RMS. This amount of power is perfect for mid-tier audio systems though.



  • Hybrid Amplifier
  • Front 2-channels are stereo/1 channel is mono
  • Basically a 2-channel amp and a monoblock amp combined
  • Most commonly allows an entire truck system to be powered from one amplifier (2 speakers, 1 or more subwofer)

3-Channel amplifiers are a smaller version of a 5-channel. They’re basically a 2-channel amplifier and a monoblock combined. They’re most commonly used to power an entire audio system in 2-door truck, or other small vehicles similar to this. You’ll also find 3-channel amps used to power just the front speakers and a subwoofer in a budget system.



  • Stereo
  • Full-range
  • Similar to a 4-channel amplifier, but with 2-extra channels
  • Allows powering of a center channel, or two additional sets of speakers
  • Usually for specific audiophile applications

6-Channel amplifiers are usually reserved for audio enthusiasts or those with specific audio applications in mind. These amplifiers are most commonly used in vans, SUVs, and boats where you may require more than the traditional 4-speaker setup. They can be used in a lot of installations, but usually they’re bought with a certain application in mind.

Determining Power Requirements

Trying to match up your system’s power requirements with an amplifier can look confusing, but really it’s easier than it seems. The first thing to always remember is to only look at RMS power. Looking at peak or max power without a deeper understanding of it, will only confuse you. Secondly, impedance (or ohms) is a way to measure resistance. All speakers have an ohm rating, or impedance that tells the amplifier how much power to output. Lower impedance means more wattage from the amplifier. At 4 ohms an amplifier will output less power than at 2 ohms; however, an amplifier is more comfortable running at higher impedance and will tend to run cooler. For example, an amplifier at 4 ohms may put out 75 watts RMS, and at 2 ohms this same amplifier will output 100 watts RMS. Finally, you’re going to want to match up the impedance and RMS wattage of the speaker and amplifier. For example, if the manufacturer specifies that each speaker will require 100 watts RMS at 4 ohms, you will want to find an amp which pushes between 70-130 watts RMS at 4 ohms.


For more information regarding impedance, check out this video on matching subwoofers and amplifiers:

You may also want to check out our subwoofer wiring diagram:
Subwoofer Wiring Guide

Although you will get sound from a speaker even if you’re powering it with less than 70% of the rated RMS power, it’s usually not advised. When underpowering a speaker or subwoofer there’s a problem you’ll run into called “clipping”. This occurs when the amplifier tries to push more power to the subwoofer or speaker than the amplifier is safely capable of reproducing. For more on clipping, check out this video.



Determine if Auxiliary Battery is Required

Batteries are underused in car audio, when in reality they should be overestimated and overused. It’s understandable, considering that adding an additional battery is a bit of an investment to an already expensive complete system build, however the investment can be put to exceptional use in moderate and higher powered systems. Personally, I agree with the rule of thumb that systems running over 1000 watts of total RMS power should ALWAYS have at least an upgraded starting battery. An auxiliary battery should also be highly considered in these types of systems. The reason for this is, car audio systems are very demanding when it comes to using power. Your vehicle has a battery used to start your car, but also power things like your head unit, air conditioner, power windows, illumination on the dash, and, perhaps most importantly, headlights.

A common symptom you’ll see when adding a higher powered car audio system (600W RMS and up) is that when the bass hits, you’ll see your headlights dimming. This is because bass is very demanding, and every time it’s hitting it’s pulling a ton of voltage from your battery. In order to combat this, I’d personally recommend any system over 600 watts of RMS power (or fuses that add up to 60 amps or more) should highly consider either upgrading their starting battery to one more capable of keeping up with their system, or adding an auxiliary battery.

Determining Wire Gauge

Now, you’ve picked out your amplifier, you’ve picked out the speakers and subwoofer(s). You’re reading to get this system ordered and installed. Hold up. One last final thing to mention is wiring. Now, we’ve stressed before the differences between Copper Clad Aluminum(CCA) and Oxygen-Free Copper (OFC) wiring before in some of our videos and blogs. This is important to consider, but mainly we’re going to assume you went with OFC and are curious about the gauge of wire to choose.

The fuses on your amplifier (if your amplifier has them, lately more manufacturers have been opting out of external MIDI fuses and relying on your main fuse near the battery to protect your amplifier) are a good place to start to determine what wire gauge to choose. The reason for looking at fuses instead of rated power, is because power ratings with amplifiers can be very misleading. Reliable manufacturers in the industry who follow CEA compliant power ratings are much easier to determine wire gauge for than manufacturers who just list peak power or over-inflate their RMS power ratings.

Looking at total RMS power for your amplifier(s) is the way to determine the main run from your battery to your amplifier area. Another factor to consider is the length of the wire run. If you have your amplifiers under your front seat, you may be able to get away with a small gauge then if you’re running it to a trunk. Consider the RMS power, the length of the run, and the quality of wire that you’re choosing to find out if you’re using large enough wire to allow for proper system requirements.


Now that we’ve talked about some of the main points to consider when purchasing your next car audio system, get to building out that system! If this seems like a bit too much info for you, and you just want that sound in your car, give us a call! We have experts on the line who are complete car audio enthusiasts who will be happy to help you get exactly what you’re looking for!


Damping Factor

The Damping Factor of Your Amplifier Tells You How Well it Controls The Movement of Your Speakers

When you look at an amplifier’s specifications you may come across one that says “Damping Factor”. The damping factor describes the ability of the amplifier to control the movement of a speaker, more specifically, unwanted movement. This is especially important for lower frequency speakers such as car subwoofers.  Damping factor can be looked at from many different angles and several factors affect the overall damping factor in a system.

In a simple sense, the damping factor tells you how well an amplifier can control a speaker system. The larger the number associated with damping factor the better an amplifier is at controlling speakers. Anything above 100 tends to be very good while below 30 is poor. Most aftermarket car audio amplifiers to date won’t have such poor damping factor specifications to the point where it would become a concern for the average listener if they follow specs. This means that if you’re trying to get the best sound possible you need to look for a higher damping factor, assuming everything else is equal.  Below I will get slightly more technical, so the above information is very simplified.

Most manufactures do not specify damping factor accurately in their specification charts. An accurate damping factor will look something like this: Damping Factor = 100 at 4 Ohms. Rarely is the impedance (ohms) listed. Damping factor is the speaker systems final impedance (load impedance) divided by the amplifiers output impedance. So if you have one speaker at a perfect 4 ohms impedance and divide it by the amplifiers output impedance, let’s say 0.4, you get a damping factor of 100 (4.0 / 0.04 = 100). If your final impedance is 1.0 ohms and the amplifiers output impedance is 0.04 your damping factor becomes 25 (1.0 / 0.04 = 25). Using this formula, as long as you know the amplifiers output impedance and your speaker systems final impedance, you can calculate the damping factor. This is why it is important for the manufacture to list what impedance they list their damping factor at for the most accurate number. However, using the formula you can find out if you have most of the other information.

Let’s throw a monkey wrench into the mix. In the real world, a speaker’s impedance is affected by everything in the system. A  car audio speaker will fluctuate anywhere from 1 ohm to even 30 or 40 ohms while it is operating. So if damping factor is based off of the speaker’s impedance but it’s always jumping up and down then that means the damping factor can’t be a single number. Damping factor is a major simplification of what is actually going on but it is still important! If everything is relatively equal you would be able to notice the difference between a damping factor of 100 and 25. While this should not be your go-to to find the best quality in an amplifier, if all the other specs are closely matched you can look at it to help make a final decision. Knowing all the specifications and what they mean can really help put everything into perspective when selecting an amplifier and speaker combination. Remember, it all comes down to what sounds best to YOUR ears.

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What is the Difference Between 2 and 4 Ohms?


Ohms are the measure of resistance to the flow of electricity in an electric circuit. Think of it like a freeway, the more cars congesting the freeway, the slower everyone will move due to traffic. Electricity, like the cars, can be slowed down in the circuit due to higher resistance.  The higher the ohm value, the more difficult it is for current to flow through a circuit. Likewise, the lower the value, the easier it is for current to flow. Based on this, is there any other differences between the most common 2 and 4 ohm impedances?

Certain amplifiers are designed to power subwoofers at different impedances (ohms). For example, a 2 ohm rated amplifier will power a 2 ohm subwoofer, so long as the woofers “final impedance (ohms)” is 2. You can connect multiple subwoofers together and run them off an amplifier, so long as their final impedance is equal to the amplifiers impedance. We cover this in a different article. If you have 100 watts at 2 ohms, and 100 watts at 4 ohms, is there a difference? The answer is subjective, you will hear people say there is a sound difference, and some say there isn’t. It depends on how efficient the amplifier runs at the specified ohm level, as well as the speaker itself.

If you get technical, the different resistance values of a speaker will change the sound slightly, assuming wattage is the same. A lower impedance subwoofer has a voice coil with fewer windings, meaning less weight. A higher impedance subwoofer will have more coil windings, meaning more weight. It has more windings to counter act the resistance, so it’s like adding more lanes to the freeway to ease up traffic. This slight difference in weight will produce a slight sound quality difference. At 2 ohms you tend to have more projection of sound (louder), which causes poorer sound quality. At 4 ohms you will have less mid bass frequencies then at 2 ohms; however the sound quality is slightly improved.

If you’re not an audiophile, does this matter? Honestly, no it does not. Do not let this be a make or break when looking for sound system components. Two of the same subwoofers, just with different impedances, will produce almost the same sound if they are run at the same wattage. The difference in sound is so slight that it has little impact, especially when dealing with subwoofers, that you likely can’t tell the difference.

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Subwoofer Box Conversion Chart

Make Sure You Get the Right Enclosure for Your Woofer

Constructing your own subwoofer box is the best way to ensure that your subwoofer will sound the best it possibly can.  The manufacturers of subwoofers release detailed information about a subwoofer so that a box builder creates the proper enclosure.  Making a subwoofer enclosure can require a lot of math, formulas, and conversions.  Below is some information that will make your box building experience easier and faster.


Triangle Area = 0.5 x (Base) x (Height)
Circle Area = (Radius) x (Radius) x 3.1415
Box Volume = Height x Length x Width
Total Cubic Feet Per Driver =  Total Cubic Feet / Number of Drivers
Total Cubic Feet = Total Cubic Inches / 1728

Unit Conversion Charts:

1 inch = 25.4 mm
1 mm = 0.0394 inches
1 liter = 0.0353 cubic feet
1 cubic foot = 28.32 liters
1 gallon = 0.134 cubic feet
1 cubic foot = 7.48 gallons
1 cubic foot = 1728 cubic inches
1 cubic inch = 0.00433 cubic feet
milli = 0.001
micro= 0.000001
kilo = 1000
Mega = 1,000,000

Port Diameter Inside Area Outside Area (1/4 in walls) Outside Area
1 in 0.785 sq in 1.767 sq in 0.89 x 0.89 in
1.5 in 1.767 sq in 3.142 sq in 1.33 x 1.33 in
2 in 3.142 sq in 4.909 sq in 1.77 x 1.77 in
3 in 7.069 sq in 9.621 sq in 2.66 x 2.66 in
4 in 12.566 sq in 15.904 sq in 3.54 x 3.54 in
5 in 19.635 sq in 27.758 sq in 4.43 x 4.43 in
6 in 28.274 sq in 33.183 sq in 5.32 x 5.32 in
8 in 50.265 sq in 56.745 sq in 7.09 x 7.09 in

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What are the Differences Between Single and Dual Voice Coil Subwoofers?


You’re shopping for subwoofers and you see two identical looking woofers. You read the specifications on the label and notice they are the same for both car subwoofers. The price is slightly different and the model numbers are slightly different, but everything else is the same! But wait, you turn them over and one says “Single 4 Ohm” and the other says “Dual 4 Ohm”. This is no deception, your eyes don’t lie. Before you bag one up and take it home, do you know the difference between a Single and Dual voice coil subwoofer?

First of all, what is a voice coil? The voice coil in a subwoofer is a coil of wire wrapped around a cylinder called the former, which accepts the amplifiers current. Current from the amplifier causes the coil to react with the stationary magnet, moving the former up or down. The former is attached to the speaker cone which produces changes in air pressure when moved, producing sound.

A single voice coil (SCV) is one length of wire wrapped around the former. A dual voice coil (DVC) has 2 coils of wire wrapped around the former. A single voice coil subwoofer will have a positive and negative terminal, while a dual voice coil subwoofer will have 2 positive and 2 negative terminals, one for each coil. The price of a DVC subwoofer will usually be slightly higher than its SVC brethren due to the extra coil. There is no performance advantage between the two types of voice coils, so why bother?

The advantage of a DVC subwoofer over the SVC subwoofer is your available wiring options and flexibility. Single voice coil subwoofers can only be wired at the ohm level specified, for example 4 ohm. A dual voice coil will say 4 ohm, but it will actually wire to 2 ohm or 8 ohm. That last sentence alone tends to blow the minds of many, you are not alone. The ohm level needs to match up with the ohm level your amplifier can handle. A DVC woofer has 2 wiring options while the SVC has only one option.

When everything is all said and done, the only real difference between a single and dual voice coil subwoofer is the number of coils, which means a greater wiring flexibility. The power handling, frequency response, box volume specifications, etc. will remain the same for both types of woofers (except in rare cases). Feel free to use the Sonic Electronix subwoofer wiring diagram to help you configure the right subwoofers.

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T/S (Thiele/Small) Parameters

T/S Parameters

Thiele and Small Parameters (also referred to as T/S parameters) are used to define technical electromechanical parameters for a loudspeaker.  These specifications are used primarily by advanced consumers that are looking for low frequency performance of a subwoofer.  A manufacturer runs a series of tests to determine the parameters of the loudspeaker and will typically print this information in the product manual of the subwoofer.  This information is used by intermediate to advanced car audio box builders to make a subwoofer enclosure designed to the exact specifications of the subwoofer. The ratings are named after A. N. Thiele and Richard H. Small, the two men responsible for these detailed parameters.

Here is an example of the T/S parameter from an RE Audio SEX12D4

  • Qes Electrical Q Value: 0.49
  • Qms Mechanical Q Value: 4.5
  • Qts Total Speaker Q Value: 0.44
  • Fs Free Air Resonance: 25.1 Hz
  • Vas Equivalent Compliance: 72.9 liters
  • Xmax One-Way, Linear Excursion: 18 mm
  • Efficiency (SPL 1W/1m): 86.1 dB SPL
  • Sd Effective Piston Area: 480 cm2
  • Re DC Resistance: 2.8 ohm
  • Znom Nominal Impedance: Dual 4 ohm
  • Pe Thermal Power Handling: 600 W
  • BI Force Factor: 17.7

What exactly do these abbreviations and numbers mean?  Below is a list of the different types of parameters that manufacturers can use to define their subwoofers.

Fs: The free-air resonance frequency of the subwoofer, measured in Hz.  At this frequency the weight of the moving parts is perfectly balanced with the subwoofers suspension system.
Q: This refers to the relative damping of a loudspeaker.  This is the “Q” that is in the other Q parameters. The damping is the effect that reduces the amplitude of oscillations within the subwoofer
Qms: This is the subwoofers relative damping (Q) at the resonance frequency  (Fs), including mechanical losses.  Also called the mechanical damping of the subwoofer.  This unitless measurement usually varies from 0.5 – 10.
Qes: The subwoofers relative damping (Q) at the resonance frequency (Fs), including electrical losses.  Also called the mechanical damping of the subwoofer.  The unitless measurement usually varies from 0.5 – 10.
Qts: This is the subwoofers relative damping (Q) at the resonance frequency  (Fs), including all dimensionless losses.
Mms: The total mass of the subwoofers cone, coil, and other moving parts.  It is measured in grams.
Rms: The mechanical resistance of the subwoofer, taking into account the driver’s suspension losses (damping).  It is measured in kg/s
Vas: This is the amount of air that has the same stiffness as the subwoofers suspension. The greater the rating, the lower the stiffness and larger recommended enclosure.  It is measured in Liters.
Xmax: The maximum amount of linear excursion a subwoofer is capable of.  It is typically measured in millimeters. The excursion is the amount of linear movement that the voice coil can travel.  Also referred to as maximum linear peak or peak-to-peak.
D: This is the effective diameter of the subwoofer.  It is usually measured in metric units, however some manufacturers will list it with different units.
Sd: The surface area of the cone measured in square centimeters.
Vd: This is the maximum amount of linear volume displacement the subwoofer is able to produce.  It is the total air volume the subwoofer’s cone will move, measured in cubic meters. The formula Xmax multiplied by the surface area (Sd) is used.
Re: Amount of DC resistance of the subwoofer when measured with an ohm meter.  Typically, this will read less than the impedance rating of the subwoofer.
BL: Total magnetic strength of the motor structure measured in Tesla meters.
n0: The reference efficiency of the system.  It is often more accurate than the manufacturers sensitivity rating and is expressed as a percentage.
SPLo: Represents the subwoofers Sound Pressure Level (SPL).  The rating is measured at 1 watt, from 1 meter in front of the subwoofer.
Pe: This is the thermal capacity of the subwoofer. Using the driver at higher ratings can cause damage and failure to occur. It is measured in watts.
Pt: This is the thermal power handling of the subwoofer and is typically the recommended RMS rating of the subwoofer measured in watts.

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Car Subwoofer Wiring Rules

Wiring a Subwoofer Can Be a Complicated Process

Two of the most important specifications to look at when matching subs to an amplifier are impedance and RMS rating. The total combined RMS rating of all the subwoofers should not exceed the power the amplifier produces at the impedance that your subwoofer draw. Remember, ohms measure resistance. The lower the ohm rating, the lower the resistance. The lower the resistance, the higher the power flow from the amplifier.

Here is an example that will help illustrate how to figure out possible wiring combinations. For our example, we will use a Kicker ZX750.1 monoblock amplifier. Despite the monoblock designation, a monoblock amplifier can power more than one subwoofer. In fact, monoblock amps usually produce greater amounts of power than multi-channel amps, which makes them ideal for powering car subwoofers.

The Kicker ZX750.1 has the following power specifications:
–   RMS Power (4 ohms) 375 watts x 1 channel
–   RMS Power (2 ohms) 750 watts x 1 channel

Based on the amplifier’s specifications, the possible subwoofer combinations are as follows:
-    2 subs: 4 ohm SVC
-    1 sub: 2 ohm SVC
-    1 sub: 4 ohm DVC
-    2 subs: 2 ohm DVC

Since we know that this amp can provide power up to 750 watts of RMS at 2 ohms, we should use a subwoofer combination that requires less than 750 watts. Add the RMS ratings of each subwoofer together and make sure it is less than 750 watts. Most manufacturers recommend slightly overpowering your subwoofers. Contrary to popular belief, underpowering your subwoofers can lead to blown or damaged cones. Of course, this refers to RMS ratings, so be sure that you do not exceed peak power ratings.

I have included a table below to help you learn how to match subwoofers with amplifiers. This is not a comprehensive guide to wiring but it does contain some good guidelines.

Single Voice Coil (SVC) Wiring Rules

4 ohm SVC

# of Subs   Final Impedance
1 Sub 4 ohm
2 Subs 2 or 8 ohm

2 ohm SVC

1 Sub 2 ohms
2 Subs 1 or 4 ohms

Dual Voice Coil (DVC) Wiring Rules

4 ohm DVC

# of Subs   Final Impedance
1 Sub 2 or 8 ohm
2 Subs 1 or 4 ohm

2 ohm DVC

1 Sub 1 or 4 ohms
2 Subs 2 ohms

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How to Install Car Subwoofers

Required Tools:

    • Wire Cutters
    • Wire Stripper
    • Electrical Tape
    • Speaker Wire
    • Panel Remover

You may also need one or more of the following:  Screwdrivers (Flat, Phillips) and Screws, Right angle Phillips, Drill, Wrench, Pliers, Saw, Glue gun, Caulk, Wire ties, Soldering Iron, Knife, Flashlight

Subwoofers are vital to a car audio system because they reproduce low audio frequencies that give an overall depth to the sound of your music. Installing and wiring subwoofers requires numerous tools. You will need electrical tape, speaker wire, and a wire cutter and crimping tool. Depending on the extent of the install, you may also need a power drill, screwdrivers (Phillips and flat head), right angle phillips, wrench, panel remover, saw, pliers, glue gun, caulk, soldering iron, knife, wire ties and a flashlight.

First cut about 1′ in length of positive speaker wire and negative speaker wire. Depending on how you wire your sub, you may need more than one piece of each type of wiring. You need to strip 1/8″ to 1/4″ of insulation at the ends of the wire using your crimping tool. At this point you will run the wire through the subwoofer terminals. Turn the subwoofer on its face in order to access the wiring terminals. After you wire the voice coils, cut one additional piece each of positive and negative wire. Determine the amount of length you will need based on where you plan on mounting the amplifier. This wiring will connect to the first negative and positive terminals on the subwoofer and run through the box terminal to connect to the amplifier.

To mount the subwoofer, line up the subwoofer’s screw holes along the diameter of the enclosure’s hole. After you align the subwoofer to your liking, mark the screw holes with the drill. Remove the subwoofer and drill the holes into the enclosure. Now place the subwoofer back into the enclosure’s hole and use the drill to screw in the subwoofer. Note: before screwing in the subwoofer, you can add Poly-Fill to the inside of the enclosure using spray adhesive. This further enhances the sound since adding Poly-Fill it simulates a larger box.

Decide how to wire the subwoofer based on the subwoofer’s type and number of voice coils. Also consider the impedance and power ratings of the subwoofer and amplifier. To wire in parallel, simply connect the positive leads of both subs to the amp’s positive terminal and the negative leads to the amp’s negative terminal. Wiring in parallel will lower your impedance, and a lower impedance value will enhance your amp’s power capability. To wire in series, simply connect the positive leads of the subwoofers to the amp’s positive terminal, but then connect the negative terminal of one subwoofer to the positive terminal of the second sub. Then connect the latter sub’s negative terminal to the amp’s negative terminal.

If you do not want to bother with wiring and mounting a subwoofer, you can order preloaded enclosure packages. All you need to do is fasten the loaded enclosure and connect it to the amplifier using speaker wires. Powered subs are an even simpler option because they include both an amplifier and woofer inside an enclosure.

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How To Choose An Amp


An amplifier modulates power from your car battery to supply your car stereo system with the juice it needs to keep the bass booming and the speakers crooning. There are many aspects to consider when selecting an amplifier for your car stereo system. Here is quick list of what you should keep in mind.

  • First Choose your Speakers and Subs

Once you have settled on what types of speakers and subwoofers you will be running, you will now be able to choose an amp based on the speaker’s power ratings, impedance, efficiency, and voice coil configurations. This will help you figure out how much power you will need from your car amplifier and in planning how you will go about wiring your amp. For example, if you are only choosing one subwoofer, you will want to know if you can bridge the 2-channel amp that you have in mind.

  • A Powerful Amp Will “Amp” Up Your System

The higher the impedance of the speakers, the higher the impedance you must run the amp at. Along with that, the higher the impedance an amplifier runs at, the lesser the amount of power generated by the amp. Many amplifiers can run at either 2 ohm or 4 ohm loads, but some are stable at 1 ohm loads for optimal RMS performance.

Be sure to pay attention to the RMS power ratings, which refers to the amount of continuous power produced by an amplifier. Ignore the peak power ratings, these ratings are totally insignificant when trying to match up an amplifier with subs and speakers.

  • Efficiency Matters

The ratio of power output to power input, expressed as a percentage. For example, consider a Class A amplifier that produces 100 watts of power output from 200 watts of power input. This amplifier is rated at 50% efficiency.

To measure an amplifier’s efficiency, you need to know the power output and input levels, the car battery voltage, and the amp fuse size (measured in amperes). In the example above, assume the Class A amp uses a fuse size that is 10A and the car battery voltage is 14.4 volts. Multiplying 14.4v times 10A gives 144 watts in. 100 watts out divided by 144 watts in equals .6944. This means an amplifier with a 10A fuse and 14.4 v battery will need to be rated at 70% efficiency to produce 100 watts.

Since this is way beyond the realm of possibility, you will need to find an amplifier with a higher fuse rating to produce 100 watts. For example, take the same Class A amplifier above except imagine it with a 15A fuse instead of a 10A. 15A multiplied by 14.4v equals 216 watts in. 100 watts divided by 216 equals .4629, which means a Class A amp with a more realistic requirement of only 47% efficiency is needed to produce 100 watts.

Remember, Class A Amplifiers only offer a theoretical maximum of 50% efficiency. Class B amplifiers have a maximum theoretical efficiency of 78.5%, and Class D amps can operate at levels between 80-95% efficiency. This is important to note when considering the fuse sizes and power ratings of an amplifier.

  • Heat Sink Keeps Amplifier Temperature in Check

Consider the size and quality of the heat sink. The heat sink is used to dissipate heat and to keep the amplifier running efficiently. A heavy duty heat sink will provide better thermal stability. To further help prevent the amplifier from overheating, check out amps with cooling fans.

  • Damping Factor: Control Your Speakers

The damping factor measures how well the amp will control unwanted movement of the speaker coil. The higher the damping factor, the better the amplifier will be in controlling the speaker’s undesired movements. To calculate damping factor, divide the speaker’s impedance by the amp’s output impedance.

  • Speaker Level Inputs and RCA Terminals

An amplifier with speaker level inputs will allow you to run your amplifier from a factory receiver. Additionally, if you have no remaining preamp outputs left on your aftermarket car receiver, you can use the amp’s speaker level inputs. You want to make sure the speaker level inputs and the RCA connection terminals are secure, since your amp will have to survive the bumps and dips in the road.

  • Price

Make sure you plan your budget ahead of time. To install your amplifier, you will need amplifier wiring kits, and other accessories. You may also consider purchasing digital capacitors or other items to keep your system running at full throttle. We can help you choose which amplifier is right for you. Give us a call at 1-877-289-7664.

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