KICKER Comp / CompVR / L5 / L7 Series, Comp 8, Comp10, Comp12, Comp15, CompVR8, CompVR10 Manual

Introduction

The KICKER subwoofer has always been at the forefront of speaker technology and the latest versions are no different. Our technical and R&D staffs have designed some extreme enclosures beyond the sealed boxes to give the end user some choices when it comes to earth shaking bass in their car. After all, that is what we are famous for!
In this manual we explore some applications for KICKER subwoofers complete with box drawings and cut sheets plus some important information regarding the break-in period for our speakers.

Important Break-In Information

Due to the complex nature of any speaker, it requires time to break-in. Especially in sealed enclosures, break-in is a must in order for woofers to produce optimum low bass response. Approximately two weeks of daily playing will allow the suspension to break-in and reach its optimum equilibrium. The "broken-in" sub will exhibit stronger bass performance, smoother response, and greater low bass extension.
For those of you with more sophisticated audio equipment, KICKER subwoofers can be broken-in on the test bench overnight with the following procedure.

Freeair Break-in Procedure

1. Connect the speaker to a power amp of about fifty watts or more. The speaker should not be mountedin any enclosure - just freeair. Please make sure it will not walk off the bench while it is playing!
2. Connect an audio generator to the input of the power amp, and adjust the generator to approximatelythe frequency in the chart below.
3. Now adjust the gain on the amplifier and generator so that the cone is moving to Xmax. This can bedetermined visually by looking at the "blur depth" of the logo on the ISD. A close approximation will do. See chart below.

NOTE: Keep in mind that as the speaker is used under normal conditions the break-in will continue, so if you don't have time for the complete break-in period the speaker will still break-in itself under normal usage.

Characteristics of Sealed Enclosures

The most basic and simple of all speaker enclosures is the sealed box or acoustic suspension design.
The acoustic suspension design has several advantages; it is easy to build, easy to tune, and offers high power handling, tight response, and extended low end output. Acoustic suspension enclosures roll off at 12 dB per/octave. Cone motion is better controlled at all frequencies because of the constant pressure on the back side of the cone, which enables you to run more power to the woofer. They are called acoustic suspension enclosures because the air inside the box acts like a viscus brake to control the woofer. That is why the box must be sealed tight. If there are any air leaks in the enclosure, the woofer cannot function properly.

Pros

1. High power handling capability
2. Extended low frequency response and smooth roll off (12 dB/octave).
3. Excellent transient response.
4. Tolerant of minor enclosure size variations.
5. Easiest enclosure to build.

Cons

1. Not as efficient as other designs.

Another type of brace, called a cross brace, should be used in any span that is 12" (30cm) or more to prevent panel vibration. The most common application will be from the front baffle to the rear wall and between the top and the bottom walls. This type of brace is usually made of 3/4" x 2" wood. The brace will contact the enclosure only on its ends where it should be glued and screwed or stapled. Place the brace slightly off center for maximum rigidity. A perfectly centered cross brace can actually increase cabinet flex and resonance (at a higher, more audible frequency).

Designing General Enclosures

The fundamental Thiele-Small calculations can be performed using a scientific calculator and a little knowledge of algebra. However, it is important to note that the basic calculations have some factors averaged or removed for simplicity, and the answers they give are only approximate. Your best bet is to use known enclosure design data such as given here, or to use a computer program such as Leap along with our published driver specifications to assist you in designing enclosures.
When you have completed your enclosure, it is important to make sure the speaker is at least close to your design spec. For 100% certainty that everything is correct, you may want to measure the box tuning frequency for vented enclosures. If you did the calculations by hand or with a simple computer program (any program that requires only Qts, Vas, and Fs for enclosure performance calculations is simple), you will definitely want to measure tuning frequency because the vent dimensions given by the calculations could be off enough to reduce the speaker's performance. Be sure to measure the tuning with the enclosure in the vehicle, the acoustic environment of the speaker can also affect its tuning.
When designing an enclosure, it is best to follow what we call "The Design Sequence". This is a simple, three step process that can save you a lot of time and hair pulling!

The Design Sequence

1. Determine size of enclosure.
   This is the easy part. Get a tape measure and get in the vehicle. Consult your customer on exactly how much space he or she is willing to give up for their system. They must understand, you have got to give in order to get. In other words, if they want big bass they must be willing to give up space. Measure this area and write down the height, length and width dimensions in inches or fractions of a mile if you are really good at math. A piece of paper is a good place to write these numbers down, but if you only have a piece of MDF, remember not to throw it away or cut it up to make a piece of the box!
   Now we'll learn how to calculate volume for a cabinet from the dimensions we just took.
   Let's say that after we have subtracted golf bag, misc. shoes and bag o clothes we are left with the available space that measures:
   14" High 41" long x 14" wide
   The formula for figuring volume is pretty simple. Memorize it now (or for quick reference, Write it down on the wall near the table saw) You will be using it so much it will become mundane.
   Height x Length x Width = Total Cubic Inches
   Total Cubic Inches/ 1728 = Total Cubic Feet
   Total Cubic Feet/ # of Drivers = Total Cubic Feet Per Driver
   
   So you're asking yourself...Where did 1728 come from anyway. Did we make it up? Nope! 1728 is one cubic foot or 12 x 12 x 12. Is it magic? Nope, wrong again, Thank you for playing! Dividing by this figure converts total cubic inches into total cubic feet. You'll want to stay with me on this one, it could get tricky. Divide the total cubic feet by the number of drivers to be installed in the enclosure, usually two, to get the total cubic feet per driver. This is how the manufacturer usually lists specifications.
   When calculating an enclosure's volume you will work with EXTERNAL and INTERNAL dimension. External dimensions are what you have to work with after measuring the space available in the vehicle. Internal dimensions are what you'll want to go by when selecting a speaker for the enclosure. So you say, What's the Dif. Huh? External, internal, it doesn't matter! It could mean the difference of having a 12" woofer in too small of a box or a 10" woofer in the right box. We all know, a 10" woofer in the right box will sound better than a 12" woofer in the wrong box! Let's look at the numbers: if you're using 3/4" MDF, you would subtract double the thickness of the MDF from each dimension to get internal dimension. I know you hear me, but let me show you!
   Since we are using 3/4" or.75" MDF
   .75" +.75" = 1.5"
   14" - 1.5" = 12.5"
   41" - 1.5" = 39.5"
   14" - 1.5" = 12.5"
   12.5" x 39.5" x 12.5" = 69171.88 INTERNAL cubic inches
   6171.88 / 1728 = 3.57
   INTERNAL cubic feet
   3.57 / 2 drivers = 1.79 cu. ft. per driver
   
2. Calculating Displacement
   Displacement refers to the space used by things inside an enclosure that influence total volume and is mostly associated with drivers in an enclosure. However, other factors will also influence an enclosures total volume, like ports, bracing and occasional screw driver that gets left inside the box by accident. It is a good idea to look in the box before sealing it up, to make sure you have not left any tools inside. To calculate exact enclosure volume, we'll need to consider port, bracing and speaker displacement.
   Port Displacement: Calculating the amount of space taken by a port will test your memory of high school geometry. This is one of those things back in school you said to yourself, "I'll never use this"( so you slept through that class). Guess what? It is coming back to haunt you! It really is pretty simple. If only the teacher could have related it to car audio, we might have paid more attention. Are you ready?
   Area x Length = Volume.
   Isn't that simple?
   
   Let's break it down. First you will need to know the port's dimensions. Let's use a 12" long port with a 2" diameter. Now we need to calculate the area of a circle the same size as the port, 2" in this case. ARGH! Here comes that Geometry stuff again! The area of a circle is the radius squared multiplied by "pi" ( "pi" is cool, he he.) or 3.14". In case you were wondering, the radius is half of the diameter for all those who slept through Geometry!
   Area of a Circle = r² x 3.14
   The radius of our circle is 1"
   1² x 3.14 = 3.14"
   Next, we'll multiply this by the ports length, 12". 12" x 3.14" = 37.68 cu. in.
   So, to get the accurate volume of the enclosure, we'd need to deduct 37.68 cu. in. from the total volume.
   
   Brace Displacement: After figuring port displacement, brace displacement is relatively easy. Braces are discussed in detail a little later so trust us for now. We'll use a 1" x 1" x 20" brace for an example. All we do is multiply the dimensions together(1" x 1" x 20" = 20 cu. in.) and deduct this amount from the cabinet's total volume. Piece of cake, Joey! Remember to do this for all braces in the enclosure, there may be quite a few of them!
   Driver Displacement: The driver also takes up air space inside the enclosure. If you use Kicker speakers, we've made calculating driver displacement real simple for you, just flip to the chart of this section. The recommended enclosure volumes we give in this manual already have the driver displacement deducted. If you do the intelligent thing and use our speakers, you won't have to figure driver displacement. We have a staff of engineers, whom we lock away in a special hermetically sealed room in order to calculate driver displacement. Depending on how many new models we release, they may not see the light of day for months. Let's revisit the example, shall we. We currently have 1.79 cu. ft. per driver before displacement. This size box might work for a 12" driver or a 10' driver.. Let's calculate driver displacement now to where we are now.
   12" driver displacement = 0.070 cu. ft. 1.79 -.070 = 1.72 cu. ft. per 12"
   10" driver displacement = 0.044 cu. ft. 1.79 -.044 = 1.746 cu. ft. per 10"
   Now we'll look at braces. Two different types of braces are corner braces and cross braces. For this example, we are building a sealed enclosure in a simple rectangular box. We'll have twelve corner braces( one for each joint), and six cross braces (one for each wall).
   We have eight corner braces that are 1" x 1" x 12.5". Each one uses 12.5 cu. in. of our enclosures total volume, so eight of them use: 8 x 12.5" = 100 cu. in.
   Four corner braces are 1" x 1" x 37.5". We deducted two inches from the length so the braces would meet instead of overlap the other corner braces. Each one of these uses 37.5 cu. in. of our volume, so multiply this figure by four = 4 x 37.5" = 150 cu. in.
   So all bracing combined uses 250 cu. in. Now we'll divide by 1728 to convert to cubic feet.
   250 cu. in. / 1728 = 0.0289 cu. ft.
   Now we go back to the enclosure volume figures we got after figuring driver displacement and deduct brace displacement:
   12" driver 1.72 - 0.0289 = 1.69 cu. ft.
   10" driver 1.746 - 0.0289 = 1.717 cu. ft.
   Result - we use 12" Kicker Comp VR woofers in a sealed enclosure! Another possibility though, is the 10" Kicker Comp VR in a ported enclosure. It can be quite a long process to figure all these different things, but trust us, going through all the trouble is worth it when you get done and have an enclosure that sounds awesome!
   Let's say say you're measuring a customer's vehicle for available space and it's basically unlimited in one direction. If two dimensions are known and the other is unset, we have another way to calculate volume for a specific speaker. For example, we'll say the customer wants to use our Comp VR 12" driver. We know that the recommended enclosure volume for a C12VR is 1.0 cu. ft., so for two it's 2.0 cu. ft. Our two known dimensions are 39.5" and 12.5" (internal). First we'll find the total cubic inches on our known figures, just multiply them together.
   39.5" x 12.5" = 493.75 "
   Next we need to figure the total cubic inches needed for two Comp VR 12's. All we do is multiply 2.0 cu.ft. (recommended for two Comp VR12's) by 1728 to convert to inches.
   Now we divide the total cubic inches needed (3456) by the cubic inches that we have already (493.75) to determine the missing dimension.
   3456 / 493.75" = 6.999 inches for the depth
   To check this, multiply all three figures:
   39.5" x 12.5" x 6.999" = 3456 cu. in.
   3456 / 1728 = 2.0 cu.ft.
   Building an Angled Enclosure
   To figure enclosure volume on angled boxes, draw a diagram of your enclosure. It will help a lot to visualize what you're doing.
   17" High x 54" Width x 5" Top Depth and 13" Bottom Depth
   
   Since the formula to determine enclosure volume does not allow for two different depth dimensions (5" Top and 13" Bottom), we must find an average of these two figures.
   To find the average, add the figures together (5 +13) then divide by the number of figures added (2). Once again, it would have been helpful to stay awake in geometry class! Are you with me? Let's look at the numbers.
   5" + 13" = 18" 18"/2 = 9"
   In essence, averaging the 5" depth and 13" depth gives us a rectangular box to work with instead of an angled one ( note the "dotted line" enclosure). Now the formula for figuring volume works.
   3.53 / 2 = 1/765 cu. ft. per driver
   To calculate internal volume, you must subtract the thickness of the wood. We're using 3/4" MDF again, so deduct 1.5" from each dimension.
   54" - 1.5" = 52.5"
   9" - 1.5" = 7.5"
   17" - 1.5" = 15.5"
   52.5" x 7.5" x 15.5" = 6103.13 cu. in. 6103.13 / 1728 = 3.53 cu. ft.
   
   Angled Enclosures with Risers
   This type of enclosure is a little more difficult to work with than just an angled enclosure, but we'll help you through. Follow the calculations below for volume on an angled enclosure with a riser.
   Dimensions: 17" Height x 44" Width x 5' Depth(Top) and 13" Depth (Bottom) with a 4" riser.
   First, make the box into a rectangle like we did before by averaging the top and bottom depth measurements:
   5 + 13 = 18 18/2 = 9
   Instead of using the entire height dimension, deduct the height of the riser, 4" for this example.
   17" - 4" = 14" High
   
   So the external dimensions for the first part are ( see the second diagram on previous page):
   13" Height x 44" Width x 9" Depth
   We'll go ahead and figure the volume of this enclosure (using internal dimensions). Subtract only one thickness of wood from this height.
   12.25 x 42.5 x 7.5 = 3904.68 cu.in. 3904.68 / 1728 = 2.25 cu. ft.
   2.26 cu. ft. / 2 = 1.13 cu. ft. per driver
   Notice that there is a 4" x 44" x 13" enclosure left over. This is just another airspace that we'll figure volume for and add to the first part. ( Use internal dimensions!) Again, subtract only one thickness of wood from this height.
   3.25 x 42.5 x 11.5 = 1588.43 cu. in.
   1588.43 / 1728 = 0.92 cu. ft.
   0.92 cu. ft. / 2 = 0.46 cu. ft. per driver
   Now, add 0.46 cu. ft to the first figure:
   0.46 + 1.13 = 1.59 cu. ft. total per driver
   This is your net internal airspace for each side of this enclosure. That was not very tough, was it?
   

KICKER Woofer Displacements

Dr. Koneairea's Discussion of Terms

Acoustic Suspension- The support that a calculated amount of trapped air gives to the motion of a driver. Acoustic suspension woofers are designed for use in relatively small sealed enclosures. Dr. Koneairea says, "The air inside of the box acts as a viscus brake for the woofer".
Active Crossover- Crossover networks designed to be placed before the amplifier in the signal path of an audio system. Electronic crossovers are designed to have the ability to vary the crossover frequencies.
Attenuate- To reduce the level of a signal. Commonly used to match the output of one driver to another. Dr. Koneairea likes to keep cousin Bernie attenuated at all times to keep him from saying inappropriate things.
Baffle- A panel that a driver is mounted to. Either one part of an enclosure or in the case of a freeair mounting its the panel that separates the front wave from the back wave, eliminating cancellations.
Bandpass- That which results in only a certain band of frequencies being reproduced- either an enclosure or a crossover network.
Bandwidth- Those frequencies that a system or a driver reproduces. Usually measured with some reference to deviation: such as 20 to 20 kHz + or - 1.0dB.
Bass Reflex- A subwoofer enclosure design that utilizes a port or vent to augment the woofer output at or about the tuning frequency. From a trademark of the Jensen Co. in the 1930's.
Boomy- In reference to the sound quality of a subwoofer system, boomy refers to an increase in output at upper bass frequencies ( 80 to 100Hz). The lower bass, if present, is covered up by the undesirable upper bass and lacks good damping.
Butterworth- We do not use it to cover our pancakes in the morning. It is used to define the roll off characteristic of a crossover or a woofer system. Named after the engineer who first mathematically described the response of that shape which has a Q of.707.
Channel Separation- Refers to the crosstalk (the leaking of signal from one channel to another) between the channels of a stereo system.
Clipping- A situation that occurs when an audio signal is made larger than the power supply that supports it. When this happens the top and the bottom portion of the wave form is 'clipped' off, creating a very distorted signal. Clipping can occur at line levels or at the output of an amplifier and will usually damage speakers.
Compliance- A measurement of the main restoring force for a speaker. Generally indicates the springiness of the suspension.
Cycles per Second- See Hz
Damping Factor- It is the ability of the amplifier to control the motion of the speaker's cone after the signal disappears.
dB- Decibel. The unit of measure for acoustic intensity level. It is a ratio of two sound intensities in logarithmic form. The smallest change in loudness that a human can detect is defined as one decibel.
Directionality- Determined by the angle into which a speaker radiates its sound. A speaker with a narrow angle of dispersion is very directional, while a wide angle of dispersion is more nondirectional.
Driver- A speaker, an electromechanical transducer that converts electrical energy to mechanical energy. Also the most troubling club in your golf bag!
Dub- The name given to 20 inch rims on a phat ride! Originally, it referred to a copy of a recorded tape!
Efficiency- As it refers to speakers; the ratio of acoustic energy output to the total electric energy input, expressed as a percentage or in dB per watt at a set distance. Usually it is measured at 1 watt at 1 meter, so when comparing speakers make sure both are measured the same.
Fiberglass- Not Plexiglass. Popular material used to create exotic looking enclosures. See Plexiglass!
Flat Frequency Response- A term used to describe a theoretically perfect speaker which produces a constant output over a specified frequency range. It does not peak or dip at any frequency or band of frequencies.
Flux Density- A measure of magnetic strength in a given area. In car audio it refers to the magnetic field in the gap between the front plate and the pole piece of a driver, measured in Teslas.
Halfspace- An environment for measuring a speaker system which simulates the driver flush with a planar surface radiating into a 180 hemispherical field.
Frequency- The speed of change in an electrical signal or of air pressure in an acoustical signal, measured in Hz.
Gain Control- IT IS NOT A VOLUME CONTROL KNOB! It controls the ratio of the input signal level to its output signal level. It does not make the amplifier put out more power, cousin Bernie!
Hz- Hertz...Not Exactly!. Cycles per second. A unit of measurement for alternating current waveforms or frequency of an audible tone. The standard bandwidth for human hearing is 20 to 20 KHz. Most men have a drop out in their hearing between 1.6k and 6.4k.( Hint: the female voice is in that bandwidth!)
High Frequency- In audio, the frequencies from about 5KHz to 20KHz.
Highpass- When information lower in frequency than a given crossover point is attenuated, a highpass filter is in use. Used to reduce intermodulation distortion and increase power handling in a particular driver.
Imaging- The ability to localize the instruments when listening to a stereo recording.
IM Distortion- Intermodulation distortion occurs when a lower frequency affects the faithful reproduction of a higher frequency. The most audible case is when a driver is trying to reproduce an extremely wide range of frequencies.
Impedance- AC resistance. The combined restriction to current flow including DC resistance, inductive reactance, and capacitive reactance. Impedance (Z) is measured in Ohms ( Ω ).
Infinite Baffle- Freeair. Mounting a driver on an infinitely large baffle board that completely separates the sound radiated from the front of the speaker from the sound radiated from its back. For practical purposes the baffle board can be part of the vehicle. An enclosure larger than the Vas of the driver with the front and rear waves isolated from each other would essentially be an infinite baffle application.
Lowpass- When information higher in frequency than a given crossover point is attenuated, a lowpass filter is in use. A common application is for woofers.
L-Pad- Attenuation network. Two resistors wired in an L shaped configuration, which converts some of the amplifier power into heat and reduces the amount of power available to the driver.
Masking- Certain types of noise tend to cover up or mask desirable information. A common example is when road noise( or a loud exhaust!) covers up low bass in a car audio system.
Midbass- Those frequencies from 100Hz up to 350Hz, often overlooked or not reproduced faithfully in a car audio system.
Midrange- A critical band of frequencies from 350Hz to 5KHz which includes most of the musical information.
Octave- One octave is either a halving or doubling of a frequency. One octave below 1KHz would be 500Hz. One octave above 1KHz would be 2KHz.
Ohm-The unit of measure of electrical resistance or impedance.
Order- In crossovers the shape of the roll off measured in dB per octave is equal to 6 times the order. For example, a 12dB per octave rolloff is called a 2nd order. This also applies to the rolloff of a driver in a given situation. An acoustic suspension enclosure has a 12dB per octave rolloff and is considered a 2nd order box. It is too confusing to use orders on more complex enclosures because it is possible to derive higher orders in different manners and by combining orders with those of the enclosure.
Passive- Any device that has no built in amplification is considered passive. A passive device will always have some insertion loss. Crossovers used after an amplifier are called passive.
Peak- A point in a speaker's response range where a frequency or band of frequencies are produced louder than other frequencies.
Phase- A term used to describe the relative position of two sound waves in relation to one another as it relates to the arrival time to the listener.
Pink Noise- It is a type of random noise which has a constant amount of energy in each octave band. Plexiglass- Not fiberglass. See Translucent!
Power Compression- As the operating temperature increases around the coil the impedance of the driver will increase. It is a good idea that when competing in an SPL contest, you refrain from running your system hard prior to going through the lanes, this will keep your coils cool.
Power Handling- In speaker systems, the maximum amount of power that can be safely accommodated without damage to the speaker or distortion of musical reproduction. The limiting factor in a particular driver may be thermal or mechanical depending on the application.
Processors- Any unit in the signal path that is added with the intention of changing the existing signal is called a processor. Equalizers, delays, and electronic crossovers are all forms of processors.
Qts- The driver's magnification at resonance. A measure of the driver's ability to dampen its resonance.
Resonant Frequency- (Fs). Frequency at which a driver most easily responds to an external force and continues to vibrate after the force is removed. Measured in Hz.
Roll off Frequency- (Fo). The most common means of measuring the rolloff point of a system is to note frequency where the energy is 3dB less than that in the passband.
Sealed- An enclosure of finite size that has no exchange of air between the inside volume and the outside world. Commonly used to control cone motion in acoustic suspension woofers.
Sensitivity- The sensitivity of power amplifier is that input voltage which will result in reaching full rated output. For a speaker it is the acoustic output as measured at one meter away with one watt of input.
Shelving- In equalizers if the response curve is to be boosted or cut through a certain range of frequencies in an equal amount, it is said to be a shelving equalizer. The resulting response curve has a flat area that resembles a shelf.
SPL- Sound Pressure Level. The measure of sound pressure (loudness), expressed in dB.
Transducer- Any device that converts one form of energy into another. A microphone converts sound energy into electrical energy and a speaker converts electrical energy into sound.
Transient Response- The ability of an amplifier or speaker to follow sudden changes in audio levels.
Translucent- Clear. NOT opaque! See Fiberglass!
Tweeter- A driver used to reproduce the upper range of the musical spectrum, usually from 3.5KHz to 20KHz.
Vas- The volume of air having the same compliance as that of a driver, measured in cubic feet or liters.
Vented- Ported. When an enclosure has the capability of exchanging air from that inside the enclosure with the outside world through a tuned orifice it is said to be vented or ported.
White Noise- It is a type of noise that has equal energy per Hertz.
Woofer- A driver designed to reproduce low frequencies. In car audio it is usually restricted to 100Hz and below. A woofer that is used down below 40Hz can be called a subwoofer.
Z- See impedance.

Dr. Koneairea's Hearing Chart

Dr. Koneairea wanted to include a chart to show you just how much your hearing could be affected by long term exposure to loud sounds. Dr. Koneairea enjoys poppin' a little slam in the system in his Six-Four as much as the next guy, but just keep in mind the effects of long term exposure.

Box Building & Mounting Hints

All the cubic feet numbers given in the supplied charts include the displacement of the woofer. For the ported boxes, the displacement of the port must be added to the final design. It will be impractical to use round ports for these designs. The rectangular port information given will yield the best results.

Always use 3/4" or thicker MDF and make sure all the joints are secure and well sealed. The peak pressure in a ported box can exceed that of a sealed enclosure. All of these designs need some internal bracing. Be sure to add 2"x2" to 3"x3" triangle braces between each of the larger unsupported panels. Kicker recommends using a good grade of wood glue and silicone sealer for an airtight box.

Note: If you prefer an ultra-smooth bass response, you should loosely fill your ported Solo-Baric Enclosure with polyfil. If you do so, the entrance to the port (inside the box) must be covered with hardware cloth, chicken wire, or expanded metal to prevent the polyfil from being blown out through the port. Use of polyfil will slightly decrease efficiency, but will deepen and extend low bass response.

Do not install a ported box with the port against a solid surface. The port opening must remain unobstructed. Use the smallest dimension of the rectangular port as the minimum amount of space required between the port and any surface to insure unrestricted airflow.

If you would like to use a vented enclosure, but the box designs we provide you with (in this manual) do not fit because of width or depth, the designs can be modified. The shape of the enclosure is not vital, but The Volume Is. The volume, of the design you choose, must stay the same. The following diagrams provide you with some help to insure your enclosure is built correctly.


Remember:
If you are going to bend the port at 90° you will need to add 1/2 of the ports height to the length! See Below.
Example: (Fig. 1) H port = 3" W port = 10" L port = 20"
(Fig. 2) Since H port is 3" you need to add
1.5"( 1/2 of H port ) to L port. This
means that L1 + L2 = 21.5"
Always measure L1 and L2 down the center to get an accurate measurement!

Here are a couple more examples of the different shape enclosures you can build. The woofer can be mounted on the same side as the port or the back side of the enclosure can be slanted to fit up against your back seat.. On the cut sheets we provide, change the dimensions to accommodate the woofer and the vent on the same side. Make sure the internal volume does not change!

Resistance Formulas

Comp Mounting Hole Cutouts

Comp VR Mounting Hole Cutouts

L5 Mounting Hole Cutouts

L7 Mounting Hole Cutouts

Dr. Koneairea Sits Down with Greg Davis

Dr. Koneairea makes a visit to KCG World Headquarters for a "Sit Down with Greg Davis"
We have two of the most sought after minds in the Audio world sitting down to discuss system tuning.
Greg Davis is the "Kingpin" of the Kicker Competition Group. A founding father of IASCA and its predecessor NACA. He has been cited by Audio Gurus magazine as having some of "the best ears in the business". He is the personal tuner of many of the top competitors in the KCG and a host of other World Champions. He collects Vintage Tube Amps and lives and breathes Car Audio.
Dr. Koneairea (pronounced Co nair e ah) has a PhD from the Earology Institute located in the lateral lobial region of the cranium. He is a highly published author of many books dealing with sound and its effects on the human mind, including the runaway bestseller, "I Can Hear your Music, But You Can Feel Mine".
Dr. K: Good afternoon Greg, I am glad you could make it!
Greg: No problem dude, I am always glad to help fellow Audio Freaks.
Dr. K: How about we jump right in? Greg: Right on!
Dr. K: First of all, explain to me why you are so into the competition scene.
Greg: Tuning vehicles for competition is a passion for me. First-time competitor or World Class pro, seeing a competitor on stage is one of the most rewarding aspects of my position at Kicker. Tuning is a vast, and sometimes controversial subject that I cannot fully cover in the scope of one interview. My goal is to get the competitor to approach tuning with a systematic approach. The key is to develop a routine that you will use consistently in setting up the system in your vehicle. I recommend that you use a checklist to keep yourself on track, and a logbook to document your results.
Dr. K: That makes sense, but how do we get started?
Greg: Before you ever start on your car there are a number of things to address. Do you know what the test recordings are supposed to sound like? If you cannot score tickets to the symphony, there may still be hope for a newbie's you're yet to be trained ears, so now is the time to listen up. A great way to get a good reference is to invest in a good pair of headphones. This takes the playback room out of the equation, and it's portable! Last year several of the top judges in Perry came over to listen to a set of Stax headphones we had in the tune-up booth. It helped everyone involved to keep a reference. Buy a set and keep them as close as Brittany does lipstick. Then get your hands on the choice cuts. Not the butcher's, but the ones on the top labels like Opus, Chesky, Telarc, and reference Recordings. Next, do not venture into tuneland without calling Autosound 2000 for a copy of their tech briefs and a set of their setup discs. You can save several years of hardknocks with one phone call. Maybe you could even convince Uncle Sam to give you a tax deduction.
Dr. K: Yes, that would be great, maybe I could also write my wife's off...
Greg: (interrupting the Dr.) Hey Toto, pay attention to the stage maps and liner notes included with the various discs mentioned; they are the Yellow Brick Road to the Promised Land.
Dr. K: Wow, I am looking forward to prepping my sick Six Four for the lanes...
Greg:(rolling his eyes) The choice of vehicle is another often overlooked part of competition. A wide vehicle with a low dash, like a truck, or your Konekruiser can be trouble! The relatively flat dash and close path lengths provided by a late model Civic would provide fewer obstacles on the road to acoustical nirvana. Think this though before you spend a court settlement on a set of 20s that will not deliver the points without a megabuck rebuild.
Now that we have the disclaimers out of the way, Dr. K, let's get serious about a systematic approach to a winning tune. Remember the scientific method from grade school? There is a reason that it has stood the test of time. Keep that in mind when you get the urge to jump in and start manhandling the EQ's.
Dr. K: Can I just replace my factory speaker and expect to win?
Greg: No way Beavis! There are a couple of of things to keep in mind with speaker placement.

1. Minimize the difference of the pathlengths ( distance from the right speaker to your right ear and left speaker to left ear) and B.) Control dispersion. Dr. K let me save you some time. Using a set temporary enclosures (PVC pipe is quick and inexpensive) you can experiment with setting up the angles of the drivers in your front stage. I usually start with just the mids. Fine-tune the angles of the drivers before you build the kick panels. You may find that one side needs to be drastically different than the other. Use the seven drumbeats on the IASCA disc and the recording of the three spoken voices to check for imaging.

Autosound 2000's CD102 is also a must here. Try tracks 1-24. You can use double stick tape for trying different locations for the tweeters. Make a jig or take a series of measurements to replicate your findings. Here is a cool trick you can use even if you have already built kicks. Make a ring that tapers from one quarter of an inch to an inch on which to mount the mids. By rotating the ring you can fine-tune the angle of the driver. Subtle changes can have a pronounced effect on the image location. It may take you several days, but nail the driver locations before you proceed.
Dr. K: How about loaning me some of these capacitors on your desk for my crossovers?
Greg: Dr. K, no offense, but your vest is a little tight. So let's get active! From my perspective, I would highly recommend that you use active crossovers whenever you can. Experience has taught me that the advantages afforded by 24 dB per octave slopes are the way to go in a car. The fast slopes in this design provide the necessary control to tackle the problems in the mid-bass region generated by most vehicles' interior dimensions without adding phase shift problems. Sure you can use passive networks, but be ready for massive trial and error. The charts designed for fixed resistance in many manuals do not take into account the changing impedance of the speaker over the course of its operating range. They are helpful to get generally a good sound, they just are not as accurate for serious competition. Why make things difficult? Do not be afraid to overlap crossover points. This technique can be very useful in the sub-bass to mid-bass transition and the mid-bass to midrange area. If price or power class consideration prevents using all active crossovers, my advice is to use the active on the mid-bass to sub-bass section of your system. Speaking of mid-bass, many competitors miss the boat by crossing over the front stage too high. If you had point deductions for not having bass up-front, try using a 24 dB per octave crossover at 60Hz on the front stage (provided the speakers are up to the task).
(Greg takes a drink of water)
One final advantage to an active crossover is the ability to quickly change the subwoofer's crossover point to improve you SPL score. You can also vary your crossover points between the mid and tweet to optimize imaging. The dispersion patterns of these two drivers can be quite different, so this is a big plus to finetune the soundstage. Vocals and instruments such as a piano that feature a wide frequency range should be used to evaluate this area. this will help you to minimize the frequency dependent shift quite common in many competition vehicles.
Greg: Have you eaten yet?
Dr. K: No, let's order some food?
Greg: How about Thai?
Dr. K: Ahh, Jack talk Thai very well! Sounds great.
Dr. K: What about this business of gain matching?
Greg: Glad you asked Dr. K!
The trouble is most competitors by-pass this stage of setup, compromising the signal to noise ratio of their system. The result: poor dynamics, linearity, and sometimes noise. It's too easy to pass up, "so just gain it". You can use an oscilloscope to set gains, or use the CD104 disc from Autosound 2000 with an inexpensive Radio Shack amplified speaker (part#277-1008). The later system is explained in detail in the notes from the disc. It is quick, cheap, and effective. After you have completed this sequence listen to the results. Chances are your system will improve dramatically. Tracks 25-29 on CD102 are also helpful. Listen to the overall spectral balance at this point. You may make subtle changes to the gain to improve spectral balance. For example, if the top end of the system sounds "hot" from the crossover frequency up, you may reduce the output of the tweeter amp instead of shelving the entire top-end of the EQ later. Just make sure that you do not take it too far, reducing the overall dynamic range. By having a 3-to-1 gain ratio, you have the luxury of some adjustment for the benefit of spectral balance. The instructions for this procedure are included with the disc. Try track 4 on CD104 and watch your scores soar.
(Greg takes a drink and there is a short pause.)
At this point a good competition car should begin to take shape, and you have not even touched the EQs yet. You can look at the overall curve on a RTA, but your ears should be the final judge. Here is a cool trick that may save your bacon at a critical time: Once your gain structure is set, document it. Pick a frequency in the middle of each passband on the 104 disc, then set your head unit for a moderate volume and document it using the digital readout on the deck or measure it with a volt meter. Measure each section, at the amp's speaker outputs, sub, mid-bass, etc with a voltmeter set for AC., and write it down. In the event that you ever have an amp failure or tear the system down, you can now set it back in a jiffy, even if it is in the lanes.
Dr K: Hey look the food has arrived.
( He has secretly switched the brand of coffee Greg usually drinks with Folgers instant, with flavor crystals. Let's see if he notices.)
Greg: Now that's great coffee!
Dr. K: I cannot slide anything past you, Greg. ( They both enjoy a big laugh.)
Dr. K: Excellent Greg. Now what about those EQs. Are we ready to adjust them yet?
Greg: Easy big fella. Remember, stick to the procedure!
Now is a good time to go through the IASCA setup disc and use tracks 2-4 to evaluate the system's relative polarity. This track is more effective than the simple in-phase / out-of-phase track on the judging disc, as it is repeated at three frequencies. Use the liner notes, you may have to reverse the polarity on a sub, midbass, or midrange to improve staging and imaging. For more detailed instructions, reference the articles on polarity vs. phase in the tech briefs and read the liner notes of the IASCA setup discs.
Dr. K: (getting anxious) Surely we can adjust the EQ, now?
Greg: That's right, now you finally get to put your paws on the EQs. I hope you have at least a pair of one third octave EQs. For those that are new to the game I recommend that you use tracks 33-60 on the IASCA setup disc. Listen to the tracks on that set of headphones that you just bought. This is good ear training. It takes a passage of music, adding boost and cut at several different frequencies. After you have become familiarized with it, you will find it to be a quick way to get a car in the ballpark. Most novice tuners tend to boost EQs, with some experience it tends to go more the other way around.
I usually start in the driver's seat with the balance set to the passenger side at low volume. The first point of attack for me is the 125Hz- 400Hz region. This is a real trouble spot for most cars. Use program material with an acoustic bass, a Piano, and possibly a Cello. The announcer's voice on the setup disc is also very useful here. I will usually sweep each slider on the EQ as I work my way up. The 500Hz-3kHz range in most of the top cars I tune is usually pretty flat, requiring minor tweaks. A recording with a big horn section is very useful, as is a female vocal.
When you work your way up to the top end, use piano, cymbals, and strings. Pay close attention to simblence on a female vocal. I usually finish up by returning to the extreme low end, a pipe organ is King here. When you have the lowest octaves tweaked to perfection, re-visit the mid-bass area to ensure that you have a smooth transition from the sub-bass.
Here are a couple of hints if you are just getting into tuning: When you make spectral changes, go back and check the imaging tracks on CD102, or just take a second and listen to the movement of the seven drum beats to make sure you have not gone backwards! The snare is electronic and has a wide bandwidth with artifacts out to 8kHz. It is a good idea to constantly go back to it as you work your way through the tonal spectrum as a quick check. One other hint to help you get a better"feel" for tuning is to use a RTA set on medium to help you identify a particular trouble spot (like a sax burst). This is not foolproof, but it can help you to get started. Finally, with a partner (with ears you can trust!) in the car you can go back and do some fine-tuning with the tracks on CD102 and track 96 on the setup disc. When you think you are finished, go back and check for linearity and noise.
Dr. K thinks to himself: (This interview has run way too long and I am going to miss the final episode of the Osbournes, Ozzy finally learns how to use the remote control.)
Dr. K: Sorry Greg, you were saying.
Greg: As I was saying, I used the IASCA and Autosound 2000 discs as a reference here because they are the tools of my trade. The aforementioned labels provide top quality material that I rely on, but for the novice tuner, I would recommend that you limit your palette of choices to start.
Greg: Dr. K, you are a legend, I know you can enlighten me on a few subjects, too. But, here are some parting shots.
Always take into account the noise floor of the contest, if it is too loud then you will certainly want to turn up the sub-bass.
Adjust the seat angles relative to the height of the listener. Small differences can skew the stage dramatically.
Try and document your tune! Many competitors use templates to keep track of them at different shows. Take the time to ensure that your RTA settings are always done with the same mic position. Likewise, know the resonance frequency of your system to maximize your SPL score. Finally, if you have the privilege of having one of the top judges from finals judge your car, take time to talk to them about your progress after the show, and thank them for the work they do.
Dr. K: Thank you Greg for taking time to talk to us about how to properly tune a car audio system. Greg: No sweat dude, anytime.
Join us next time when Greg will sit down with Billee Ray, just off tour with AC/DC, to discuss the comeback of the Mullet!
For Autosound 2000 Discs and Technical Papers go to www.Autosound2000.com