Everything Car Audio

Pioneer Video Bypass

2011-08-26T10:27:00.000-07:00

Since the high demand for the Pioneer parking brake bypass; I have decided to come up with a easy diagram for you to follow which will allow you to play videos while you are in motion.

1. Connect the blue system turn on (Remote) wire to spade #85 (If you have or installing and amplifier connect your amplifier turn on (Remote) wire to this prong also)

2. Connect a grounding wire to spade # 87 which jumps and connects to spade # 86. Then connect the wire to a good ground.

3. Connect the parking brake wire from the head unit (Green Wire) to spade # 30

4. Finish installing your stereo and enjoy your video.

Flared Ports vs. Slot Ports

2011-08-03T17:06:00.000-07:00

Many people question what the difference is between flared ports and slot ports. There are fairly basic differences between the two, and depending on your situation, one might suit you better than the other. The common purpose of the two ports is that they must be the correct length for the particular subwoofer box to achieve the desired sub box tuning. There are a few differences that may help in your decision between flared and slot ports for your custom subwoofer box.

Flared ports are very good at virtually eliminating port noise. Port noise is the noise created by the friction of air moving through the port. If you have sharp edges on a port (as with standard round ports, which we do not use), you are going to have significantly more port noise than with a flared port. A flared port requires the smallest acceptable port area for a subwoofer box. Since the ends are flared, and the inside of the port is round (no sharp edges), it is unlikely you will be able to notice any port noise from the subwoofer enclosure. However, if you are running a large, high-powered subwoofer, you will want to use two flared ports. A single flared port is still capable of creating port noise when very large amounts of air pass through it.

With a slot port, you can use as much port area as needed for your application, which is especially helpful in SPL applications. A slot port requires more port area than a flared port to minimize port noise. We generally use a rule of 12 square inches of port area per cubic foot of internal volume of the custom sub box. You may go with a larger port area, but this will increase the total volume and length of the port. In turn, a large port area will mean an increase in the total size of your subwoofer box. Slot ports are the standard for our ported custom subwoofer boxes.

If you are not limited on space, we would recommend going with a slot port for your subwoofer box. If space is tight, and you have a few extra bucks, you'll probably want to use a flared port (or two, depending on your subwoofer size and power). It is possible to achieve the same result from both subwoofer boxes, so the decision between flared ports or slot ports depends on your specific needs for your custom subwoofer box.

For Help with Port Sizing go to calculateing port size

Installing a subwoofer in a pre-fabricated enclosure

2011-08-03T16:56:00.000-07:00

This guide will cover the installation of one or more subwoofers in a pre-fabricated enclosure. It will also cover the process of hooking up an amp to power the sub.

The easiest way to add low-end punch to your car’s stereo is to install a subwoofer. This guide will cover the installation of one or more subwoofers in a pre-fabricated enclosure. It will also cover the process of hooking up an amp to power the sub.

The first thing to do is to put the woofer into the box. This should be easy as long as you got the right size enclosure. Before actually screwing down the speaker, be sure to connect the included leads to the terminal in the back of the box. Next, screw the woofer down tight into the front of the box and mount the protective grille directly over the speaker.

Put the box in the trunk. For the best sound, the woofer should be facing the back of the car. To keep it from sliding around, consider using high-strength Velcro strips to secure it to the trunk floor. If this is not possible, L-brackets may be mounted to the cargo floor, but be sure not to put any screws through the side of the box. However you decide to secure it, make sure that it is out of the way of anything you put in the trunk.
Now it is time to install the amplifier. Begin by mounting the unit in the desired location. This should be a flat area with a lot of open space so that the amplifier can cool properly. Do not mount the amplifier on the subwoofer enclosure, as the vibrations from the speaker can damage the internal parts.

The next step is to hook the amp up to power. Before doing this, disconnect the negative terminal from the battery. Hook the long positive power cable for the amp to the positive terminal of the battery. If the cable does not have a fuse, you should install one inline within three feet of the battery connection. Consult the amplifier owner’s manual for the size of the fuse. Run the fused positive cable through the firewall and back into the cabin. Remove any trim panels necessary and pull back the carpet so you can run the cable underneath. Once the cable can reach the amp, trim off any excess, strip the end, and connect it to the positive power terminal of the amplifier. For the negative cable, connect it first to the amplifier, then run it beneath the cargo floor of the trunk and connect it to a ground point on the chassis or floor pan.
Next, you need to connect the amplifier to the head unit. You should do this using the subwoofer pre-amp hookup on your stereo. This can be either a stereo (paired RCA plugs) or mono (single RCA plug) connection. Unless you have a mono subwoofer amp, you will need to use a paired RCA cable to plug into the amp. If your head unit has a mono RCA out, this means you will need to use an RCA mono-to-stereo adapter to plug the stereo cable into the mono jack. Run the RCA cable underneath the carpet on the opposite side of the car from the power lines to avoid interference. When you get the cables back to the amplifier, plug them in at the RCA in terminals. Before putting the carpet and trim back, run a small 16-18 gauge wire from the head unit amp remote connection to the remote control terminal on the amplifier. At this point you can replace the carpet and trim panels to make the installation look clean.

The last step is to plug the subwoofer into the amplifier. To do this, use 12-14 gauge speaker wire. If you have a bridgeable stereo amp, you should bridge the amp by plugging the positive wire into the positive terminal for the left output and the negative wire into the negative terminal of the right output. The actual configuration of the bridge will vary from amp to amp, so read the owners manual for specific instructions. If you have a mono amp, simply connect the positive and negative wires. Finally, plug the wires into the back of the sub. If you have more than one sub, you can run a length of stereo from one sub terminal to the other.
Finally, put the negative terminal back on the battery and fire up your system. You will need to adjust the gain and filters on your amp, if it has them. First, turn on the low pass filter (LPF) option. Then, turn the gain all the way down. Turn up your stereo until the speakers begin to distort, then turn it down just a hair until it no longer distorts. With the stereo playing at this volume, turn up the gain on the amp just until the subwoofer begins to distort. At this point, turn the gain down a bit. That’s it; you’re done, and good luck with your new subwoofer.

2 10" KICKER Solo X

2011-08-03T16:52:00.001-07:00

2 KICKER SOLO X on 5,000 WATTS!!!

2011-08-03T16:51:00.001-07:00

2 10's Flexing Hatch

2011-08-03T16:50:00.001-07:00

2 DD 6.5" subwoofers on Term Lab

2011-08-03T16:49:00.001-07:00

Digital Designs 15's in Ext. Cab Chevy

2011-08-03T16:48:00.001-07:00

SUNDOWN AUDIO SA-8

2011-08-03T16:47:00.001-07:00

2 Sundown SA-8's on 200 WATTS!!

2011-08-03T16:46:00.003-07:00

Window Flex with 2 8's

2011-08-03T16:46:00.001-07:00

Subwoofers Break Iphone

2011-08-03T16:45:00.001-07:00

PORT DESIGN INFORMATION

2010-03-11T10:41:00.000-08:00

WHY GO PORTED?
Efficiency is the easiest one word reason for choosing ported over a sealed box. Everything is better with a little efficiency sprinkled on it. Ask any motor builder what they would do to a motor if it were theirs and they'd say turbo charge it! What does turbo charging do for an engine? It raises the efficiency. Why not apply this same thing to your audio system. Making the most out of the air space you have for a subwoofer enclosure, is the first step in raising the efficiency of your system. This means that you will utilize this space in the most efficient manner possible.

Designing a ported a.k.a. vented enclosure will not only give you added output, but can give you more low-frequency extension. This means louder and lower! Since the speaker system is the least efficient part of the whole audio chain, would it not make sense to make it as efficient as possible? Of coarse it does.

MORE SOUND, BETTER BASS
This is why venting is basically free output, and free sound quality. Local shops tell you that a small sealed box is the best way to go? Hit up your local hi-end home audio store and find out how many of those $20,000.00 pairs of speakers are sealed designs. You won't find many. Think efficiency, this will help you clear all of that smoke out of your eyes that most car audio manufacturers have been pumping all along.

HOW DOES A PORT WORK
Think of a box port not as a vent in the terms of a venting path for air to travel into and out of a box, but rather as extra cone area that is propagating acoustic energy from the enclosure to the cabin. The air in a port is fixed; it is trapped within the confines of the port walls. When the cone moves there is a corresponding change to the pressure in the box, that pressure change then causes the trapped air in the port to move either forward or backward. It moves as a solid unit, just like a speaker cone does. When you build a properly vented enclosure, its kind of like a two for one special! Since the port is essentially another woofer!

MORE RADIATING AREA
A passive radiator and a vented port work on the same theory. When a port mass moves back and forth, a pressure wave (sound wave) is sent into the cabin. The larger the port, the larger the radiating area is that creates the pressure. Tuning a port is tuning the mass of the trapped air in the port to the air mass in the box volume.

For all out no holds barred SPL efficiency, rule of thumb is the larger the box, the higher the output. The larger the box, the larger the ports can be for a given frequency tuning range. There is no substitute for cubic inches. Some drivers can achieve high efficiency in moderate sized vented enclosures (3 to 4 cubic feet) but will continue to increase in output with increase in volume and port size. Multiple drivers in such enclosures can yield a frightening amount of output and should be used with caution.

THE RIGHT PORT AREA
Most modeling programs that simulate box responses were written for home audio use. They are not suited for high output systems. The port area defaults are inadequate. The port area must be commensurate with cone area. If the port velocity gets too high, the port no longer functions as a port, you end up with a leaky sealed box, double bad.

Lets say we have a 12 inch speaker in a box, roughly 100 sqin of surface area. Many programs and manufacturer sites will suggest a 4" diameter port for a 12" vented box. A 4" diameter port has about 12 sqin of area. This is about an 8-1 ratio of cone area to port area. If the 12 inch cone moves 0.25", the port must move 2.0". It can handle this, but when the cone is moving 1.0", the port must move 8 inches! Now you've got a leaky sealed box.

You need more port area for a clean sounding, high output system. The perfect port formula is this: 16 sqin of port area per cubic foot of box volume. The port should be 16 inches long. Remember, the port is tuned to the box volume, not the sub(s).

This formula was derived from 1000s of hours of in-car testing and 1000s of installs. It works. It takes into account the need for increasing port area for increasing cone area. When combined with the correct box requirements, you'll end up with the perfect match.

VARIABLE PORT TUNING
The design philosophy of low moving mass, well controlled suspension and strong, linear magnetic systems allow the user many design applications never realized with traditional speakers. The growing popularity of the SPL competitions has led to new engineering requirements for an audio system.The problem lies in the fact that the frequencies where a vehicles peak SPL may occur rarely ever coincide with a tuning frequency that promotes utmost sound quality. The peak SPL frequency is usually somewhat higher that the tuning frequency for sound quality.

The use of a larger than normal port will allow the user to find the cars peak frequency for greatest SPL. Reducing the port opening will lower the box tuning frequency and provide loading to the woofer over a wider bandwidth. This will improve the transient response and impact of the system. The higher tuning frequency redirects the woofers radiating energy into a narrow band which when tuned to coincide with the vehicles peaks can yield dramatic SPL numbers. The focus of attention here should be to tune the system to each application. Although the general box recommendation will yield very satisfying results, competing at the highest levels of SPL or SQ contests, or simply yielding the best possible results are directly related to methodical tuning.

Calculating Port Size

2010-03-11T10:40:00.000-08:00

Calculate Port Size
The box port can be calculated with a simple formula. Box volume in cubic feet X 16 (the amount of port area in square inches per cubic feet of box volume). For example, 3.4 cuft X 16 sqin= 54.5 square inches of port area. Try to stay within 10% of this number.

The port length should be 16 inches deep. This tunes the boxes to about 40 Hz.

How To Make A Slot Port
The easiest and most effective way to build a port is to use a slot shaped port that uses 3 sides of your enclosure as port walls. If the port is located at one end of the box, only one additional piece of wood is required to complete the port. The additional piece of wood should be spaced off the end of the box.

The port area is in square inches, meaning it takes height times width to calculate total area. A port 4 inches high by 4 inches wide would calculate as 4 X 4= 16 square inches.

In our example box, we have an inside height of 14.5 inches. To calculate the slot width that would make a total area of 54.5 square inches, and we use 14.5 inches as the height: divide 54.5 by 14.5= 3.76. Round that figure to nearest ¼ inch, and you get an offset measurement of 3 ¾ inch wide. The slot port would be 3 ¾ inches wide by 14 ½ inches tall.

You don’t have to get too critical about the box and port volume, a good rule of thumb is that if you stay within 5-10% of calculated volumes, there will be very little if any audible effects.

Port Length Obstructions
Some port lengths do not allow for 16-inch port depths without some sort of modification. The rule of thumb is not to let the end of the port get any closer to the back wall than the width of the port. So back to our example, we have an internal box depth of 12.5 inches. We need a 16-inch deep port. We will have to bend the port along the back wall to get the full port length. To calculate where to make the bend, subtract the port width from the inside box depth. 12.5 – 3.75=8.75. We must bend the port at 8.75 inches, then continue the port parallel to the back wall for an additional 7.25 (8.75+7.25=16).

You now have an L shaped port totaling 16 inches in depth.

WHY GO PORTED?

High Output Sub Enclosures

2010-03-11T07:57:00.000-08:00

I don’t believe in the tiny sub box theory. If you are looking for tiny sound, get a tiny sub and put it in a tiny box. Be happy. If you are looking for real bass, you need to have a real box.

In order to get true high performance, you have to make the most of the available airspace you have. To do otherwise is wasting your time, energy and money. Don’t try to fit a larger speaker in a box that is better suited for the next size down. The smaller sub in the right space will outperform the larger sub in too small of airspace.

The first step in getting major bass in your vehicle is to allocate the space for your enclosure. If you really want to flex some sheet metal, the old adage applies, “there is no substitute for cubic inches”. The more space you make available, the higher the potential spl.

You don’t have to use a large amount of enclosure space to make a loud system; loud can be done with a single sub. The amount of loud needs to be determined as you figure out what space you plan to give up. Really loud bass, where you have to scream at your passengers, can be done on a single or double woofer setup. Stupid loud bass, where there is no point in trying to communicate in the vehicle, takes more space and bigger/more subs. F@#$ing crazy loud bass, where it is impossible for the car next to you to communicate inside his vehicle, takes even more space, even more subs and a gazillion watts of power.

A few tips on what to pay attention to when determining the box shape:

If you plan to use a rear firing setup in a trunk car, make sure your box doesn’t seal off the trunk from the passenger compartment. You need to leave some space for the waves to pass back into the interior of the car. Either make the box as low as possible so the wave passes over the box and enters the cabin via the seatback and rear deck, or reduce the width of the box so the wave can pass to the side and into the car’s interior. A big, giant box may make your trunk extremely loud, but all you’ll hear is muffled rattle if the box takes up the whole space behind the rear seat and under the rear deck.

If you have a hatchback car, keep the box as far back in the vehicle as possible. Keep the port as far to the rear as possible.

Amplifier Troubleshooting

2009-08-30T00:08:00.000-07:00

Please try these things before sending in your amplifier. By the numbers, 40% of all amps returned to us work just fine and there is a problem in the wiring or install.
You must have a DMM (Digital Muti Meter) and know how to use it.
If no: take it to someone who does.
If yes: thumb through the following scenarios

Amp will not come on (no lights):

Set DMM to DC voltage and check at the amp. You need to test with both (+ & -) leads on the amplifier Power terminals.

If over 12 volts: check both sides of the fuses in the amp.
If no or low voltage: ground the DMM (-) test lead to a good, clean, metal chassis ground in the vehicle and retest.

If over 12 volts now: problem is in the ground wire or connection (between the amplifier and its chassis ground).

If still no voltage: check both sides of the fuse by the battery.

NOTE: You cannot check a fuse by just looking. Fuses can be “bad” and not blown; especially the larger, cheap-ass, glass ones.

If blown or bad: replace and start beatin’ again!

If all is good with battery voltage, it is now time to check the remote (or turn on) wire. Check voltage at terminal of amp.

If no voltage: check voltage at head unit. You can also make a jumper from the main 12V+ connection to the remote terminal to see if the amp comes on. If it does, the problem is in the head unit remote output or remote wire between the head unit and the amplifier.

If all power wiring tests good, remove the amp from the vehicle and test with short jumper wires directly at the battery, using a jumper wire from amp 12V+ to the remote terminal, just as a “I need to make sure” final test. If it still doesn’t come on, it needs to be sent in.

Amp turns on but goes into protect:

Disconnect RCAs and speakers and try turning the amp on again.

If it still goes into protect with just power, ground and remote; the amp is bad.

If it is now on and not in protect: connect the RCA’s first.
If it goes into protect: the problem is in the cables or headunit. Change and retest.

If still not in protect: reconnect speakers
If it goes into protect: problem is in the speakers or wiring (most likely shorted [or grounded] wiring or burnt coils). Set DMM to 'ohms' and first test by shorting leads together. This number (usually in the .4 range) will be subtracted from any reading you get. Connect DMM leads to each speaker wire pair. If you have a short, reading same as touching the leads together, trace the wiring to find short.

If no short in wiring: test the speakers individually and eliminate problem.

If amp comes on (and not in protect) and has no output:

Check all settings. Turn deck on at low volume.
       Master/Slave switch in master position.
       Gain all the way up.
       Subsonic filter all the way down.
       Boost all the way down.
       X-over all the way up.

If still no sound: you will need to try an alternate input. The best is a signal generator right to the input of the amp. Alternately, you could use another radio wired in with temporary wiring right at the amp with a very short, known-working RCA cord.

If still no sound: try a known-working test speaker with very short wiring right to the amp terminals. If still no sound: amp is bad. This is a very rare failure but it can happen.

Amp has distorted output:

Same test as above. You need to eliminate all the variables.

If you are testing a stereo amp and you have the problem on one channel:

Swap RCA’s: if it changes sides, the problem is in the deck or RCA cables.

If same side: swap speaker outputs at the amp. If it changes sides, the problem is in the amp. If it stays on the same side, the problem is in the wiring or speaker.

Amp plays but has low output:

Check all settings. Turn deck on at low volume.
       Master/Slave switch in master position.
       Gain all the way up.
       Subsonic filter all the way down.
       Boost all the way down.
       X-over all the way up.

Turn up the radio. If problem remains:

Check voltage drop at amp power input terminals. Set your meter to DC voltage with the hold feature activated. If your meter does not have that feature you will need to watch it to see how low the voltage drops when it is trying to play loud. If voltage drops below 11 volts at any time, you need more battery/alternator power and or better wiring.

If voltage remains above 12 the entire time, you need to check the speakers.

Set meter to ohms and check the DC resistance of the speaker load. If it falls within the proper load for the amp, check the amp, hooked to known-working speakers. If new speakers work, the problem is in the speaker system. If it still has low output, you need to check the inputs as described above with a known-working deck and RCAs.

Amp plays but cuts off and on:

Attach volt meter to power and ground terminals at the amplifier.

Set the meter to peak hold (max/min) and display "minimum DC voltage".

Run the system until the amp shuts off and check the voltage. If voltage has dropped below 10 volts at any time, check all wiring.

Leave the meter positive on the battery wire and use a good, clean ground point on the vehicle and test again. If voltage has a higher reading than before, the problem is in the ground connection.

If it has the same voltage, work your way back to the battery; testing at any and all connection points. I.e. distribution blocks, capacitor, fuses, etc.

If at any point voltage goes up, you have found the voltage drop point.

Single vs. Multiple Drivers

2009-08-18T18:49:00.000-07:00

There are advantages and disadvantages to either approach. For this, let's consider a scenario where the cone area of a single driver is equal to the cumulative cone area of multiple drivers: An example of this would be a single 10" woofer with an Sd of 50in^2 versus a pair of 8" woofers with an Sd of 25in^2 each.

The single driver advantage: Linearity. A single driver system isn't subject to the acoustic or electrical forces countering in phase--even if by a fraction of a degree--which typically occurs when multiple pistons share a common space or when multiple inductors share a common circuit.

The single driver disadvantage: It has been my observation that a single larger driver will typically exhibit higher equivalent air compliance (Vas) than the combined compliance of two smaller drivers. This can translate into higher Vb requirements.

The multiple driver advantage: Assuming that the motor structure is the same on both the 8" and the 10" model, the immediate advantage is twice the motor for every square inch of cone area, twice the power handling, and more end-impedance versatility.

The multiple driver disadvantage: As stated above, using multiple independently actuated pistons increases the risk of the electro-mechanical forces countering one another. This is particularly evident with high Qts drivers.

The Perfect Subwoofer Box

2009-07-23T19:36:00.000-07:00

We often hear talk (specially in car audio) about certain boxes being RIGHT for certain woofers. Many folks talk like a given woofer wont even play at all if the box size is not exactly perfect!

What is perfect?

Manufacturers often recommend a certain box for their speakers.

Computer box programs can PICK the box size (or tuning) that works best(?) with the woofer if you input the Thiele/Small parameters.

Is the box size the manufacturer recommends perfect? How can it possibly be perfect when they don't even know what kind of car your installing the box into? We all know the car will change the sound (this is called transfer function)! How can they possibly choose the perfect box size? Many times the speaker manufacturers recommendation is chosen not for perfect sound but for an average that might work well in the average car. Many times they might recommend the box that's easiest to build for beginners or small (since many folks like woofs that work in small boxes) or sealed instead of vented because it is less likely for you to blow your speaker in a small sealed box than a large vented box! (if you blow your speaker (a) they might have to replace it. (b) the company might get a reputation for lousy speakers if they blow a lot) Sure, the manufacturers recommendation will probably sound great! But perfect??? Is the manufacturers recommended box size really right for you?

Is the box size provided by computer programs perfect? Again, how can it be unless they take into account the transfer function of the car??? I don't know of a current popular program that does! Most computer programs will calculate a box for you with the lowest response and with the least ripple. In car audio, this many times IS NOT the best! Sometimes (specially in SPL competitions) the ripple the computer program tries to avoid might actually be an SPL or bass boost! Or for an SQ car, a slight ripple (inaudible, an may likely be made up for by the cars transfer function) might get you much deeper bass... Is the computers recommendation the perfect box? Is the computer programs recommended box right for you?

How bout the difference in CUSTOM made boxes vs PREFAB boxes?

Most real car audio enthusiasts would never consider a PREFAB box, we all know the custom built boxes are far superior sounding... BUT ARE THEY REALLY?

From my experience there is a great amount of BADLY BUILT custom boxes being built! Built so badly in fact that for many cases a prefab box would be miles better!

A prefab box could be better than a badly built custom box! I have heard some darned good systems with prefab boxes and some very poor systems with custom built boxes.. It's important if your gonna pay high dollar for an installer to build you a custom box that the installer be good at building boxes or you might just as well have spent your money on a pre-fab and spent the left over money on something else.

PLUS, since we mentioned installers, how many really have any background in speaker design? Many claim to be experts, but in the real world most installers just build the so called custom boxes with no AUDIO PHYSICS in mind. So for a custom box, its important the installer be not only a carpenter but also an expert at loudspeaker box design... Or a pre-fab box might be the better choice! ;-)

And, in reality, there is no PERFECT box, and to really custom build a box to perform as good as possible in a given vehicle it requires huge stacks of expensive test equipment, lots of woodworking tools and saws, and building, testing then rebuilding and retesting, and rebuilding and retesting again and again and again until no more good is achieved. This is done only by a few crazy competition gurus or a few nutty hobbyists, certainly NOT for the average car audio guy, or even the average installer...

So, I think it would be safe to say most so called perfect boxes are no where near perfect, they can all be improved on. And even if they were perfect, putting them in a car will change them, even the direction the box fires in the car can have an effect!

And it makes me laugh when I hear a fellow say something like " the manufacturer recommends 1.5cu ft for this speaker, it wont work in 1.25cu ft!"

Sure it will!
If that's all the space you have,
build it,
play it,
enjoy it!

There are so many variables involved there is a chance the NON-PERFECT box might even sound better than the so called perfect one! Try it ;-)

Enjoy!

Mapping the Transfer Function

2009-07-23T19:34:00.000-07:00

Putting a speaker in a vehicle (or room for that matter) will make the speaker sound different. This is caused by reflections, absorptions and resonance's that exist in that car. This change is called the transfer function.

All cars have a transfer function, typically the most noticeable change to speakers when placed in a car is MORE BASS. More bass is inherent because the car is like a box, an enclosed space that promotes reinforcing reflections of the bass sounds (because the bass waves are long enough to be reflected and still be close enough to in phase and reinforce)....

But the transfer function is more than just a change in bass, it also can cause major changes in the midrange speakers because of the major glass surfaces for the sound to bounce off of! Or the high frequency sounds from the tweeters can be absorbed into the headliner or car upholstery (intentionally sound absorbent by the car manufacturer to absorb road noise)...

So, we cant easily change the transfer function, but we can map it, and then build our system to take advantage of our cars transfer function.

To map the transfer function you will need a Speaker box, a CD with test tones or an audio test generator or a pink noise generator and a decibel meter. There are several CDs available with test tones, I prefer the tone generator but they are fairly expensive and hard to find an install shop with one, pink noise is OK but pink noise generators are probably just as hard to find as audio generators. And for a decibel meter Radio shack sells one for about $30 that will work. Oh, and a piece of graph paper to write down your results.

First, lets map the speaker box. Take your speaker box outdoors in the back yard and aim it away from the house to minimize reflections, hang the SPL meter or microphone for it a few meters in front of the speaker box. Fire up your test tones and set the volume level where the SPL meter gets a reading on most of your test tones (if the low ones don't register don't worry), but not too loud, we don't want to damage the test speaker! Now without touching the volume control, run your test tones and write down on your graph paper the SPL at each tone. You can even make a graph on the graph paper if you want to.

Your results is the frequency response of your test speaker!

Lets put this box in the car and do the test again and see what changes!

Set the test speaker in a nice location, preferably close to where the real speakers will go later. Hang the microphone in the center of the car near where your ears would be if you were driving, and run through the test tones again, reading the SPL meter and writing down the results on the graph paper.

When you done, subtract the back yard numbers from the in car numbers for each frequency and write down your results. For instance, if you had 90dB at 120Hz in the back yard and 95dB in the car then (95-90=5) write down 120Hz=+5dB, and do this for every frequency you mapped. Some frequencies may have negative numbers, this is OK... When your done, you should have a series of frequencies=numbers something like this: 20=+4, 40=+6, 80=+12, 120=+3, 200=0, 400=-3, 600=-4, and so on...

This is your transfer function, you can now look at any frequency and tell what
your car is going to do to ANY SPEAKER you install.

Simple....

Dual Battery Wiring

2009-05-27T19:33:00.000-07:00

WIRE 1

This POS+ wire connects the two batteries' positive posts. This wire allows the rear battery to receive the charge from the alternator, just like the front battery receives. Without this wire, the rear battery would not maintain a charge.

WIRE 1 should be at least 1/0 awg wire. The reason why is that when batteries are connected together, they will instantly equalize in voltage. This can be hundreds of amps of current that is passed. Anything smaller than 1/0 awg wire is likely to be too small to transfer these high currents.

If you intend on pulling more than 300A of current across WIRE 1, you should add an additional run of 1/0 awg for each additional 300A of current you intend on pulling. So if you plan on pulling 600A, you would need two runs of 1/0 awg minimum. The more runs of 1/0 awg you have, the less voltage you can expect to lose due to resistance.

WIRE 2

This POS+ wire connects your amp(s) to your rear battery. This wire should be sized based on the input of your amp(s). If your amp has a 4 awg input, this should be a 4 awg wire. If your amp accepts 1/0 wire, then this should be a 1/0 awg wire.

If you decide that it is better for your setup, you can choose to use a distribution block between the battery's POS+ post and the amps' POS+ inputs. Some people prefer to use a distro block, but it is easier in my mind to simply run the wire directly from the POS+ post to each amp, in effect using the battery as the distro block. There is no right or wrong here, it is up to you to decide.

WIRE 3

This NEG- wire connects the two batteries' negative posts. This wire size should be identical to the size (and quantity) of WIRE 1. So, if you have two runs of 1/0 awg being used for WIRE 1, then you will need two runs of 1/0 awg for WIRE 3 as well.

Some people will argue that using the chassis instead of wire for your NEG- (grounds) connections is fine, but when you have multiple batteries, that is no longer going to be sufficient in most cases. If your car does not have one solid piece of steel running the length of the car, then you will have multiple pieces of steel that are welded together. Steel, as you well know, is a poor conductor when compared to copper (or other highly conductive metals). The conductivity of steel is highly reduced when welded together with another piece of steel. Imagine the weld as a speed bump.

Now the other issue here that is frequently overlooked is that as you begin to draw more current over a conductor, the impedance will actually rise. So simply measuring the resistance of your chassis without a current draw is pointless.

WIRE 4

This NEG- wire is to connect the NEG- connections on your amp to the NEG- post of the rear battery. It is important that this wire matches the size (and quantity) of WIRE 2. Again, just like with WIRE 2, the size of this wire should be determined by your amps' inputs.

Some people again would tell you to not wire this to the battery, but instead to the chassis. This would be OK if you did not have a rear battery and you had a very small amp. But since this discussion is assuming the rear battery is installed, you need to wire the NEG- connection for the amp directly to the battery.

WIRE 5

These wires are to ground each battery to the chassis for devices that may not have a NEG- wire running directly, but are still pulling power from the battery. A good example would be lights or other chassis grounded devices.

One last wire that is not shown, but would fall under the WIRE 5 category would be a wire from the front battery NEG- post to the engine block. This in essence would be the NEG- wire to the alternator, since the engine block is electrically connected to the alternator. If your alternator in fact has a NEG- post, of course the wire should connect there and not at the engine block.

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And now on to the fuses. Each fuse shown above serves a specific purpose. There are some people who live life on the edge and feel they are a waste of money. There are others who claim that they affect voltages in your vehicle. I am neither of these. I like feeling safe and secure knowing that my electrical system is protected by a fuse. These fuses will not only protect you from improper wiring, but also protect you in case of an accident that shorts out a POS+ wire. Also, good ANL fuses have very little added resistance, so the voltage drop across a fuse is usually not measurable.

FUSE A

This fuse should be located as close to the POS+ post of the front battery as possible. This fuse should be rated to match the current rating of WIRE 1. If you are using a single run of 1/0 awg wire for WIRE 1 and it is rated up to 300A, then FUSE A should be rated at the same 300A.

What FUSE A does is protect your wire from transferring more current (amps) than it is rated for. In the case of a short circuit in the middle on WIRE 1, the front battery will try to push all of it's energy through WIRE 1 to that short. When this happens, the amount of current will exceed the fuse value and cause the fuse to blow. When the fuse blows, the short is alleviated and no more current will pass along WIRE 1 from the front battery.

If the fuse would not have blown, the excessive amount of current would have exceeded the capacity of WIRE 1, which would have caused a fire.

FUSE B

This fuse does the exact same thing as FUSE A with the exception that it protects WIRE 1 from the current coming from the rear battery. If WIRE 1 were to be shorted, there is a potential for energy to flow from both batteries. A fuse on both ends of WIRE 1 is essential. Again it should be located as close to the POS+ post of the rear battery as possible.

And there is no reason to use only one of these two fuses here on WIRE 1. If you don't have both FUSE A AND FUSE B, then you are not protected from a short. So don't think that having one of the two is going to help you. Unless you have both, you are not protected at all.

FUSE C

This fuse is intended to protect WIRE 2 from to much current. Just as with WIRE 1 and FUSE A & B, you are going to match FUSE C with the current rating of WIRE 2. So if your amp accepts 4 awg wire, WIRE 2 should be 4 awg. If your 4 awg wire is rated up to 125A, then FUSE C should be 125A.

Choosing the Correct Port Tuning

2009-05-22T18:44:00.000-07:00

Tuning of a ported subwoofer box is determined by a combination of port area, port length, and net volume of the subwoofer box. Tuning changes the frequency at which the frequency response peaks (is loudest) and can change the way a subwoofer box sounds in your setup. Your tuning choice will be determined by the goal of your system install.

If you're looking to achieve an SPL setup your car (getting as loud as possible), you'll want to tune fairly high. High tuning for SPL is usually somewhere around 45Hz or possibly higher. At this high of tuning, the sound quality will not be very good, but it will be louder than if you were to tune low.

A SQ (sound quality) based setup will call for a tuning fairly low - even down around 25Hz. This will also allow you to hit the ultra-low notes with your system. Lower-tuned boxes produce better sound quality, more like a sealed box. The downside to lower tuning is that it flattens the frequency response, which will cause the box to lack the boost around the tuning frequency.

To achieve a good mix between SPL and SQ with a ported box, we have found that it's good to be in the lower 30's for tuning. If you tune up around 35Hz, you'll get a fair amount of SPL out of the box and still have fairly good sound quality. If you tune closer to 30, the box will yield better sound quality but have a little less output than the 35Hz. A range between 30 and 35 Hz is generally good for most general setups.

If you want SPL, tune high. If you want SQ, tune low. If you want somewhere in-between the two, we have found a good tuning is right at 33Hz. This is why we default the port tuning to 33Hz on our customization pages for our ported enclosures. When choosing a ported subwoofer box, the freedom to tune the enclosure is a great way to get your system sounding the way you want it to sound.

Quad DVC Subwoofer Wiring

2009-05-22T18:36:00.000-07:00

Parallel/Parallel DVC Subwoofer Wiring:

* Four 4 ohm DVC subwoofers = 0.5 ohm amplifier load
* Four 8 ohm DVC subwoofers = 1 ohm amplifier load

Series/Parallel DVC Subwoofer Wiring:

* Four 1 ohm DVC subwoofers = .5 ohm amplifier load
* Four 2 ohm DVC subwoofers = 1 ohm amplifier load
* Four 4 ohm DVC subwoofers = 2 ohm amplifier load
* Four 8 ohm DVC subwoofers = 4 ohm amplifier load

Parallel/Series DVC Subwoofer Wiring:

* Four 1 ohm DVC subwoofers = 2 ohm amplifier load
* Four 2 ohm DVC subwoofers = 4 ohm amplifier load
* Four 4 ohm DVC subwoofers = 8 ohm amplifier load
* Four 8 ohm DVC subwoofers = 16 ohm amplifier load

Triple DVC Subwoofer Wiring

2009-05-22T18:32:00.000-07:00

Parallel/Parallel DVC Subwoofer Wiring:

* Three 4 ohm DVC subwoofers = 0.67 ohm amplifier load
* Three 8 ohm DVC subwoofers = 1.33 ohm amplifier load

Series/Parallel DVC Subwoofer Wiring:

* Three 1 ohm DVC subwoofers = 0.67 ohm amplifier load
* Three 2 ohm DVC subwoofers = 1.34 ohm amplifier load
* Three 4 ohm DVC subwoofers = 2.67 ohm amplifier load
* Three 8 ohm DVC subwoofers = 5.36 ohm amplifier load

Parallel/Series DVC Subwoofer Wiring:

* Three 1 ohm DVC subwoofers = 1.125 ohm amplifier load
* Three 2 ohm DVC subwoofers = 2.18 ohm amplifier load
* Three 4 ohm DVC subwoofers = 2.45 ohm amplifier load
* Three 8 ohm DVC subwoofers = 2.82 ohm amplifier load

Dual DVC Subwoofer Wiring

2009-05-22T18:27:00.000-07:00

Parallel/Parallel DVC Subwoofer Wiring:

* Two 1 ohm DVC subwoofers = 0.25 ohm amplifier load
* Two 2 ohm DVC subwoofers = 0.5 ohm amplifier load
* Two 4 ohm DVC subwoofers = 1 ohm amplifier load
* Two 8 ohm DVC subwoofers = 2 ohm amplifier load

Series/Parallel DVC Subwoofer Wiring:

* Two 1 ohm DVC subwoofers = 1 ohm amplifier load
* Two 2 ohm DVC subwoofers = 2 ohm amplifier load
* Two 4 ohm DVC subwoofers = 4 ohm amplifier load
* Two 8 ohm DVC subwoofers = 8 ohm amplifier load

Parallel/Series DVC Subwoofer Wiring:

* Two 1 ohm DVC subwoofers = 1 ohm amplifier load
* Two 2 ohm DVC subwoofers = 2 ohm amplifier load
* Two 4 ohm DVC subwoofers = 4 ohm amplifier load
* Two 8 ohm DVC subwoofers = 8 ohm amplifier load

Single DVC Subwoofer wiring

2009-05-22T18:25:00.001-07:00

Parallel DVC Subwoofer Wiring:

* One 1 ohm DVC subwoofer = 0.5 ohm amplifier load
* One 2 ohm DVC subwoofer = 1 ohm amplifier load
* One 4 ohm DVC subwoofer = 2 ohm amplifier load
* One 8 ohm DVC subwoofer = 4 ohm amplifier load

Series DVC Subwoofer Wiring:

* One 1 ohm DVC subwoofer = 2 ohm amplifier load
* One 2 ohm DVC subwoofer = 4 ohm amplifier load
* One 4 ohm DVC subwoofer = 8 ohm amplifier load
* One 8 ohm DVC subwoofer = 16 ohm amplifier load