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Old 02-16-2006, 08:46 AM   #1
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Default LOOK BEFORE POSTING==> Aftermarket Audio F.A.Q

Factory Information

Q: What speakers fit my car?
A: This thread lists all factory speaker sizes for all Mazda3ís: http://www.mazda3forums.com/index.php?topic=4796.0
This thread also lists all the factory dash kits and wire harness available for all Mazda3's.

Q: What equipment came in my car?
A: Non mp3 CD player, mp3 CD player, 6 disc changer, Mini Disc player, Bose system, Tape Player

Q: Why is there no sound in the Mazda3 rear deck speakers?
A: The Mazda3 does not have rear deck speakers. The rear speakers are in the rear doors.

Q: Can I add speakers in the rear deck of the Mazda3?
A: Itís possible. You have to find a few shallow 6x9's though. Not many are built any longer. I am not sure of the actual depth limitation although I guess 3 inches or less. You will also have to buy an amplifier to power these speakers or disconnect the rear doors speakers, intercept their wiring and redirect it to the rear deck.

Q: Can I plug in an Ipod or other device into my stock system?
A: Yes, for the Mazda radio equipped cars, an FM modulator can be used to intercept the FM antenna and use it as an input into the head unit.

Q: Can I install an amp or EQ with my factory head unit?
A: With the Mazda3 itís an easy installation with just some RCA cords to get signal to the amps, you can also use a high quality LOC (Line-Output-Converter) can be used to turn the speaker wires into RCA signals that any amp can use. Also some amps have built in LOCs so external ones are not necessary. I recommend www.davidnavone.com for a great quality LOC.


General Information

Terms

Q: Whatís an Amp?
A: An amp refers to 2 things in car audio. It is most commonly referring to an amplifier. The second is that an amp is the unit of measurement for electrical current. Often you will see that fuses have amp rating. This is how much current they can pass before blowing.

Q: What is Bridging?
A: Bridging refers to combining two amplifier channels to make a single more powerful channel. An amp has to be capable of bridging, not all are! Typically this is done by using the positive of one channel and the negative of another. Every amp is different so fallow the manufacturersí directions when bridging an amp.

Q: Whatís a Deck?
A: A deck is a common term for a head unit, aka radio. It can be a CD player or a tape player.

Q: Whatís a LOC?
A: LOC stands for Line-Output-Converter. A LOC uses the speaker from factory radio and changes them into a line level signal (RCA) that any amp can use.

Q: Whatís an ohm?
A: An ohm is defined as a unit of electrical resistance equal to that of a conductor in which a current of one ampere is produced by a potential of one volt across its terminals. Itís also the value of resistance in an electrical circuit. In short it is the measure of how much opposition something has to electricity flowing. Speakers have a certain ohm value that should be considered when buying. A standard door speaker or component set is usually 4 ohms. A subwoofer can be 2, 4, 6, or 8 ohms. A DVC subwoofer has 2 coils each with its own resistance (ohm). So a DVC can have 2, 4 ohm coils. Amplifiers have a certain resistance they want to see to work there best or at all. Some amps play best to a 2 ohm load and others to a 4 ohm load. Some even hit there sweet spot with a 1 ohm load.

Q: What is RMS?
A: Root Mean Squared, best or at least simplest described as average power. RMS wattage is the realistic power an amplifier can give you.

Q: Whatís the difference Between Peak and RMS power?
A: Peak power refers to the power an amp can give you in VERY brief and infrequent burst. In other words, it is a totally useless statistic and should be ignored. If a piece of electronics only list peak power or does not state if its single power specification is peak or not, then you likely have a bogus product. RMS power is the statistic to pay attention to.

Q: What is series wiring?
A: Series wiring is when the amps positive terminal is wired to the first subs positive terminal then that subs negative terminal is wired to the next subs positive terminal. Next the second subs negative terminal is wired back to the amplifiers negative terminal. The resistance of the subs is simply added together for the final resistance. R1+R2 = Rt
So if 2, 4 ohm subs are wired in series, they will be a total of an 8 ohm load. If 2 subs with dual 2 ohm voice coils are put in series together then they will be a total of an 8 ohm load as well.



Q: What is parallel wiring?
A: Parallel wiring is when each subs positive terminal is wired to the amplifiers positive terminal and each subs negative terminal is wired to the amplifiers negative terminal. With only 2 subs or voice coils, the resistance is simply halved. So 2 4 ohm subs wired in parallel create a 2 ohm total load. If you wire the voice coils of a sub with two 6 ohm voice coils then you get a total of a 3 ohm load. If you wire the voice coils of two subs each with two 6 ohm voice coils then you get a total of a 1.5 ohm load. The actual formula for calculating parallel resistance is a bit complex. 1/ (1/R1+1/R2+1/R3+.....) = Rt



Audio Components

Head Unit

Q: Do I need a new head unit?
A: Although some disagree, my feeling is that an aftermarket radio is best bought for features. For Sound Quality (SQ) the factory Mazda head units are very capable in combination with a good quality look. If there is simply a feature you must have such as MP3 playing ability, separate subwoofer volume control, built in EQs or satellite radio.

Q: Can I bridge a head unit
A: NO!!!!

Q: What features should I look for in a head unit?
A: Head units have about 3000 features these days but not all are actually useful. The most common features to buy a head unit for are:
- Number of RCA preouts
- Preout voltage
- Preout impedance
- Dedicated subwoofer preout
- Subwoofer volume control
- Internal crossovers
- Adjustable crossovers
- Internal EQ/signal adjustments
- Aux input
- CD changer control
- MP3 playing ability
- Number of radio presets
- Satellite radio
- Internal amplifier power
- Available external components

Q: What are some good brands of Head Unit?
A: There are tons of great head unit out there although many people have had varying degrees of success with them. Here are some of the common head units considered to be of good quality. Although I would argue against several of them.
- Alpine
- Blaupunkt
- Clarion
- Denon
- Eclipse
- JVC
- Kenwood
- Nakamichi
- Panasonic
- Pioneer
- Rockford Fosgate

Dash Kits
http://www.metraonline.com/index.php
http://www.scosche.com/scosche_carau...ItemID=MA1536B
http://stores.tw.ebay.com/nabobery
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Old 02-16-2006, 09:00 AM   #2
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Default Re: FAQ

Amplifier

Q: How are Amplifiers rated
A: Like any value, RMS power values are rated with certain conditions. You will notice some RMS values are listed at 14.4 volts and others at 12.6 volts. This is the amplifiers input voltage aka the batteries voltage. Most amps make less power at 12.6 volts then they do at 14.4 volts. 14.4 volts is the power a cars alternator makes when running an under almost no load. 12.6 Volts is the resting voltage of a car and is the voltage most cars will drop to once a powerful amplifier powers a strong base hit. Because of this it is very important to know the rating of a subwoofer amp at 12.6 volts as that is the voltage is may be getting the majority of the time. Resistance is another rating condition to pay attention too. Amps will tend to make more power at lower resistance (ohms). However, that doesn't mean an amp can play into any resistance. Amps can only handle so low of a resistance, any lower then that and they will go into a protection mode or be damaged.

Q: What is CEA 2006?
A: CEA 2006 is a new power rating standard. This standard is intended to make a customer able to accurately compare amplifier power specifications. Although it removes alot of tricks manufacturers could use to cheat power ratings it doesn't remove them all. Also not all manufacturers use this rating system. Look for the CEA 2006 Logo to be sure you are looking at a legitimate power rating and product. Though some non-cea complaint amps make 30 to 40% over their rated power @ 13.8 vdc. so in some cases, the non cea compliant amp is a better performer.

Q: Why do some amps make the same power at 14.4 volts and 12.6 volts?
A: These amps have what is called a regulated power supply. This means that the amp can adjust to any input voltage to maintain the same power output or at least as close as the manufacturers could get to it. These amps are common in Sound Quality systems where even power is necessary. These amps are also immune to sagging input voltages do to powerful amplifiers playing subwoofers. The down side is that these amps can not be given a high input voltage to yield more output power. Non regulated amps can take up to 16 volts to crank out a TON of power. However at 12 volts they can be far less capable.

Q: Why do some amps put out the same power at different resistances (ohms)
A: JL audio took regulated power supplies to the next level in car audio a few years ago when they developed their RIPS circuitry. These circuits allow the amp to output the same power rather you have a 4 ohm speaker or a 2 ohm speaker. This makes it much easier to match various subwoofer combinations to JL amps. The down side is that you don't get the same power increase by running lower resistance speakers like with conventional amps. Or do you? Its been tested that even JL amps with RIPS circuits still increase there power output as you hook them up to lesser resistances. Because of their popularity, MB Quart and Phoenix Gold are following after JL in manufacturing these styles of amplifiers.

Q: Do I need an amp?
A: If you simply need more volume then an amp is right for you. Replacing a factory head unit with an aftermarket one can yield volume increase but that is not its main purpose. Amps are also a necessity for adding additional speakers including subwoofers. Although some subwoofers have built in amplifiers, like the infinity bass link.

Q: Why buy an amp when my head unit has 200 watts?
A: Because your head unit has no where near 200 watts. Head units are mostly advertised with peak power rating, not rms ratings a 50x4 watt rms amplifier is easily twice the amp that any head unit has built in. Also keep in mind that most 50x4 amps can be wired to 2 ohm loads and bridged to 2 channels. That would give you anywhere from 70x4 - 100x4 watts rms or 140x2 - 200x2 watts rms, depending on the amp. No head unit can handle a 2 ohm load and survive. Most HU are roughly 22rms x4.

Q: What size power wire do I need?
A: That depends on the amps being used and the length of the wire. You should total up the possible draw of all the amps in the system. IASCA established a chart for determining proper wire size. Unfortunately it uses amperage and length so not many people can understand it. You can find it here though: http://www.mobileaudio.com/rac-faq/ section 2.3
To make it simple, for anything under 350 watts rms, 8 gauge power wire is fine. For between 350 and 1000 watts rms 4 gauge will do fine. 2 gauge will support up to 1500 watts rms. Anything over 1500 watts rms should be run through 1/0 gauge cable.

Q: Can I run a 100 watt rms amp through the Mazda3 factory power wire?
A: NO!!! The Mazda3 only has 10 gauge power wire. Running a higher powered amp through inadequate wire runs the risk of burning up the wire, and potentially starting a fire in your car. There are guidelines for what gauge wire to use based on how many amps the amplifier draws. These guidelines are not intended so you spend extra money on things you don't need. They are intended for the safety of your system, your car, and you. Not following these guidelines is a very serious safety hazard.

Q: Why is a proper ground important?
A: Proper grounds have a HUGE impact on a system. Improper grounds will literally choke your amp, and make it horribly inefficient. They will lower the voltage the amp intakes, so that will lower the output of the amp. With very large amps, lowering the voltage will cause the amp to draw more current, and if it's too much current, that can cause serious light dimming, and possibly blown fuses. With every part of your system, you are limited by your weakest link. Your ground is not something that you should limit, as it has a direct effect on the efficiency of the amp.

Q: How do I properly ground an amp?
A: The best method is to use a crimp ending terminal on the ground wire, and then chose your grounding location. The location must be a flat metal area of primary body metal, aka the floor. Often a seat belt bolt or another factory bolt point can be used. If one is not available you can simply screw into the floor. Be sure to check under the car first to ensure you are clear of fuel lines, the gas tank and anything else you don't want a hole in. Bare in mind that if you pierce a fuel line or the gas tank itís not only a pain in the ass but you can also get yourself blown up. Once the location has been selected, sand it to bare metal. No paint should remain. Then either bolt the ring terminal down or shoot a screw through the floor fastening the ground.

Q: What features should I look for in an amp?
A: The most important is RMS power at the resistance you are going to be using. Other are:
- Is it bridgeable
- Crossovers
- Adjustable crossovers
- Band passable
- number of channels
- What resistance can it handle
- Brand reputation


Q: What are some good brands of amps?
A: There are a ton!
- Alpine
- Brax
- Cadence
- Clarion
- Coustic
- DEI ( ADS, Orion, PPI, Viper)
- Diamond
- Helix
- JBL
- JL Audio
- Kenwood
- Kicker
- MB Quart
- Memphis
- MTX
- Nakamichi
- Phoenix Gold
- Power Acoustics
- Rockford Fosgate
- Xtant
- USAmps
- Zapco
- Elemental Designs
- Soundstream
- Hifonics
- Zed Audio
- MA Audio
- Tru Technology
- Audison
- monolithic
- Linear Power To series
- ARC Audio


http://ampguts.realmofexcursion.com/

Q: Who makes the best amps?
A: This is a hard question to answer. You need to narrow it down to "what's the best amp for you budget". No sense in looking into brax or sinfoni amps if you don't want to spend the thousands on them. And have reasonable expectations. If you want to spend $100 on a 1000 watt amp, you aren't going to get high quality. Years ago the rule used to be a high quality amp cost $2 per watt. Then it dropped to $1 per watt. Today it's generally between $.50 and $1 per watt, depending on the class of amplifier. Class D amps tend to put out a lot of power and have a low price tag. A class AB amp of the same power will have a much higher price, but will have full range capabilities. Although power is an amplifiers primary function, don't overlook that quality circuits like crossovers cot money too.


Speakers

Q: Do I need new speakers?
A: The best reason to replace your speakers is because you just don't like the overall audio signals sound. Keep in mind this has nothing to do with volume. Nothing determines how a system will sound, more so then the speakers.

Q: What features should I look for in a set of speakers?
A: The most import aspect of any speaker is how YOU think they sound. As you are the one buying them, you are the one that needs to sample them against others to be sure they are best for you. Power handling is about the only other significant feature. If you have no where near the power to offer a speaker your considering then you may want to look into other option. Power doesn't have to be dead on but you don't want to be powering a speaker like the Boston Acoustic Pros off of a factory head unit. If you have an aftermarket deck don't be afraid to pair them up with 50 watt rms speaker.

Q: What are some good brands of speakers?
A: Even more then amps. Speakers are the simplest audio component for a company to build.
- Alpine
- Boston Acoustics
- Clarion
- Coustic
- DEI ( ADS, Orion, PPI, Viper)
- Diamond
- DLS
- Image Dynamics
- Infinity
- JBL
- JL Audio
- Kenwood
- Kicker
- MB Quart
- Memphis
- MTX
- MA Audio
- Nakamichi
- OZ Audio
- Phoenix Gold
- Pioneer
- Polk Audio
- Rainbow
- Rockford Fosgate
- Xtant
- cDT
- Elemental Designs
- Focal


Q: what are the best speakers?
A: everybody hears differently, so what you like, someone else may hate. Go listen to as many different sets of speakers at local shops as you can. If you are looking into high end speakers, go to a decent sized audio competition and ask the sound quality competitors if you can audition their system. Most are happy to demo it for you, and more than likely will help give you pointers and recommendations. Do not sit in factory demo vehicles that have multiple sets of components and a ton of flashy stuff. They get loud, but most all the time they do not sound anywhere near as good as the actual competitors.

Q: How much power can my factory speakers handle?
A: Most factory speaker can actually handle decent power. If you are using a good amplifier with a properly set gain and crossover then it's possible for factory speakers to handle even 50 watts rms. However, they will be more quickly damaged by distortion compared to aftermarket speakers

Q: Should I install rear speakers?
A: This depends on how you like t hear music. Some people like to be consumed by it. Others like to have music mostly in front of them. For the person that likes music to consume them, installing new rear speakers can be a good idea. However most people will argue that spending money on amplifiers to power rear speakers is a waste of money. Again this depends on your listening style. At most I'd replace the rear speakers with a quality coaxial that compliments the chosen front speakers.

Good rear-fill topics of discussion:
http://www.msprotege.com/forum/showthread.php?t=118232
http://www.caraudiocentral.net/forum...ead.php?t=3448
http://www.termpro.com/articles/rearfill.html
http://incolor.inetnebr.com/weisinat...gn/gburear.htm
http://www.caraudio.com/forum/showthread.php?t=202666
http://www.caraudio.com/forum/showthread.php?t=199518


Sensitivity vs Efficiency
Quote:
In several discussions on here people are calculating predicted SPL values based on the "db/watt-meter" ratings given for their loudspeakers. This is not strictly correct, and in fact may be way off.

The sensitivity of a loudspeaker is the medium sound pressure between 125 Hz to 4 kHz using a constant voltage at a specific distance; measured in dB per watt and meter. Usually 2.83 volts is used as this corresponds to 1 watt @ 8 ohms, with the SPL measured at 1 meter.

For instance the sensitivity of an 8-ohm loudspeaker might be listed as 92 dB / 2.83 volts / 1 meter. In this case the power (P = V squared / R) = 2.83 X 2.83 / 8 = 1 watt. In a 4-ohm loudspeaker 2.83 volts will generate 2 watts. To get the actual reference value at 1 watt, you have to subtract 3 dB (power cut in half) from the sensitivity measured; if the speaker was measured at 2-ohms, you subtract 6db, etc. Many car audio manufacturers fail to include this correction. Some cheat it by measuring at 0.5 meter. Some intentionally fudge the numbers or the test voltage. Also since the value is measured at frequencies higher than normal subwoofer usage bands, it may or may not be 100% accurate below 80Hz. Good manufacturers will do it right and give you accurate numbers, and often will include specifics about the test such as if a subwoofer was measured using standard frequency sweeps or using sub-woofer sweeps below 80Hz.

But there are other factors contributing to the overall system efficiency and resulting output levels in a car. The speaker enclosure adds several SPL components, especially using a ported system. The vehicle has whatís called ďcabin gain,Ē or the many resonances set up as the closed vehicle functions as a resonance chamber similar to what happens inside a loudspeaker enclosure. These items might increase the system sensitivity value by as much as 6db or even more, and increase the overall system efficiency from the lowly speaker averages of 1 or 2% to 50 or 60% or more.

So a simple calculation beginning with the speakerís sensitivity rating and working up by adding 3db for every doubling of input power will only tell you part of the story. (BTW, the raw SPL difference between 1 watt and 1000 watts is +30db.) It only indicates what the speaker would do in a free air anechoic test chamber at 1 meter away. A better method is to test the system after installation and determine the overall system sensitivity. Then a calculation to determine required wattage to achieve a particular db SPL value will have much more meaning. Also realize that SPL decreases with distance at a rate of -6db for each doubling of distance. So if the output is 87 db at one meter, at 2 meters the output will be 81 db. It is critical to know where the test mic will be positioned in relation to the speakers to calculate a predicted output level.

By the way, loudspeaker efficiency is a measure of how much incoming electrical energy is converted into acoustic energy. Often speaker manufacturers will not give you this value, but for good quality loudspeakers a typical value might be between 0.2 % and 2 % and means that only 2% of the amplifier signal is actually being converted into sound, the rest is being wasted as heat. Some high efficiency subwoofers might get as high as 10% or 15%, but high efficiency speakers like compression drivers designed for pro audio can be almost 100% efficient (100% efficiency is 112db/watt-meter.) You can convert the listed sensitivity number into an efficiency using this formula: Efficiency = 10E(Sensitivity in dB - 112)/10
http://www.the12volt.com DYohn



Sounddeaden great read
http://www.sounddeadenershowdown.com/
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Old 02-16-2006, 09:12 AM   #3
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Default Re: FAQ

Subs

Subs are a good complement to just about any audio system. And they can serve many purposes. Some people add them to fill in some of the low end they fell is missing in thier current system. You have many different sizes ranging from 8", 10", 12", 15", and 18". You also have various self powered subs (meaning they don't require an amp) along with bass tubes.

Q: How do I wire subwoofers?
A: Like any speaker, a subwoofer can be wired in parallel or series. So long as the final resistance is in the range the amp needs to work then youíre all set. See- What is series and Parallel wiring? Above

Wiring options:
http://www.crutchfieldadvisor.com/S-...rs_wiring.html

Q: What's the best enclosure to use?
A: There is no "best" enclosure. An enclosure type should be chosen based on musical tastes, power available, and space available. Sealed enclosures are known for having deep, precise bass. Ported enclosures are known more for their harder hitting, take your breath away bass. Bandpass enclosures are known for being very loud, but typically don't sound as good as ported or sealed. Sealed enclosures require the least designing and calculations. Ported requires a few more. Bandpass, especially 6th and 8th order require extensive calculations; otherwise they will not sound good.

Type of Enclosures.

Free Air - subwoofers are either mounted under the rear deck or behind the rear seat of a car. This configuration will not work very well for hatchbacks. Holes have to be cut where the woofers are to be mounted. Since the woofers use the whole trunk as a box, the trunk has to be as sealed as possible from the cabin. Trunk can be isolated usually by putting particle board under the deck and behind the seat.
The drawback of free air subwoofers is that bass will not be very accurate (especially at lower frequencies), and more amplifier power will be required than with a regular box, but then again, you still have a full trunk.



Sealed - is the most common box and easiest to build. These boxes will give the flattest frequency response, and best overall sound quality (especially at lower frequencies). The box internal volume should be as close as possible to the recommended by the manufacturer. If a box is smaller than what it is supposed to be, the sound will be tighter, but more amplifier power will be required. If the box is too big, then the sound will be muddy.



Ported - boxes are usually bigger in size than sealed and have a "tube" (port) that lets some air out of the box. The idea of a ported box is that the speaker port pushes (or pulls) air at the same time as the woofer, reinforcing bass. The box itself acts as an amplifier, yielding to more bass than a sealed enclosure (3 to 4 dB). Ported boxes do not have a linear frequency response. If the box is not built according to specifications, it will not sound good. The box design acts as a filter, cutting off lower frequencies.



The most common type of port is a round tube. These are typically made of black plastic and look like a section of thin-walled pipe with a lip on one end.



The second most frequently used type of vent is a square port. The advantage of this design is that you are not limited by availability of only certain diameter tubes. You can also build the port out of the same material you are using to fabricate the enclosure.



The last type of vent is called a slot port. It is created using one wall of the enclosure as a wall of the vent. This can be very useful for bandpass enclosures which can be very hard to tune to a low enough frequency due to the small size of the front (vented) chamber. Friction created by the air flow in the enclosure traveling along the enclosure wall makes this type of port effectively longer than it physically is - which tunes the enclosure to a lower frequency so a slot port will be shorter for the equivalent vent area when compared to a simpler square vent.



Porting tips:

Keep the port(s) as far away from the enclosure sides and back as possible except for the slot type port.

Make sure the inside end of a tube or square port is at least the equivalent of one vent diameter away from the back of the box or any bracing materials.

Keep the vent free from anything that may affect air flow through it.

The port should also be placed as far away from the speaker cone as practical.

Band Pass - enclosures consist of a woofer between a sealed and ported box. Bandpass boxes will yield more bass than sealed and ported boxes (especially at lower frequencies), but over a narrower frequency range. Since the box acts as a filter, mechanically blocking lower and upper frequencies, a crossover is not needed in most cases. These enclosures are usually big, and very unforgiving when precise volumes and port sizes are not followed. Bandpass boxes also tend to mask distortion. If you can't hear distortion and turn your stereo down in time, you could damage your subs.




That should help out a little bit. And if you decide you wanna build a sealed box. Heres a calculator to help you figure out the dimensions..

http://www.carstereo.com/help/Articles.cfm?id=45

www.tccustomz.com

What are some good brands of subs?

Treo
JBL
Alpine
JL Audio
eD
HiFonics
Rockford Fosgate
Brahma
Resonat Engineering
MA Audio
Eclipse
Orion
Infinity
Audiobahn
Xtant
Kicker
Pioneer
Arc Audio
Ascendant Audio
Image Dynamics

http://forum.realmofexcursion.com/fo...play.php?f=103

Capacitors

Q: Whatís a Capacitor?
A: A capacitor is a passive device that stores electricity until it is needed. Capacitors can store a large amount of power that an amp will need and when the amp can't get the power it needs from the cars chagrining system, the capacitor will release its power to the amp. Capacitor can also discharge and recharge extremely quickly.

Q: Will a capacitor help my system?
A: Capacitors will only help your system if your car's electrical system can already support your system. In that case a capacitor will help for the split second it takes the alternator to react to the draw from your system, and kicks the output into high gear. Some people swear by capacitors and there have also been tests that show capacitors do not improve the sound quality of a system, or a systems SPL level. If you want to get a group of car audio people arguing, bring up capacitors.

Q: Will a Capacitor help my lights from dimming?
A: Yes, a capacitor can be used to smooth out some head light dimming. I suggest 1 Farad of capacitance per 1000 watts RMS your amps can draw. However a capacitor installed by an amplifier will only smooth head light dimming caused by the amplifier drawing power. It will not stop head light dimming caused by the A/C system or the fans kicking on.
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Old 03-10-2006, 02:37 PM   #4
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Default Re: LOOK BEFORE POSTING==> Aftermarket Audio F.A.Q

A helpful site for beginners: Basic Car Audio Electronics

Info sites.
Adire Audio's Technical Section
JL Audio's Tutorial Section
Momentum Magazine
MTX Audio's Education Section
DIYSubwoofers.org
Soundstream's Tech Support Section

Calculators ...

Rockford Fosgate's Wiring Wizard
Electronics Calculators

Equipment Reviews ...

Car Sound & Performance Reviews
Performance Auto & Sound Reviews
Car Audio Magazine Reviews
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Old 08-10-2006, 03:57 AM   #5
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Default Re: LOOK BEFORE POSTING==> Aftermarket Audio F.A.Q

CAP INFO

[quote author=El Ropo link=topic=46976.msg728591#msg728591 date=1148053090]
More information on caps quoted from another forum:

After studying a little history on large 1 Farad capacitors in car audio, you'd be amazed that they even sell at all. How useful are they? What do they really do? Will a Cap 'improve' my sound quality? Will it Prevent my lights from dimming? Will it audibly affect my audio system in any way?

Before you get the truth to any of the above questions, chances are, you've probably spent $100 or more on one of these devices. However, let's study a little history regarding this issue.

A long time ago, in a land far away, 2 elves...Ok, Richard Clark & Wayne Harris (Carsound magazine and the inventor of DB Drag, respectively) separately came up with a solution to preventing their lights from dimming.

WHO WERE THESE GUYZ?

As you may know, Richard Clark is one of the founders of autosound2000 Tech Briefs, Carsound magazine, and a published author of the industry of mobile electronics. In SQ competitions, he posted a record of 1234 1st place finishes, and only ended up NOT 1st in his first event. I've heard that he had minor system problems, but judging by his record, he must have corrected it. (evidently, he needed a Capacitor )

Wayne Harris was previously a leader at Rockford Fosgate in their development. Later, in his free time, he created the organization we call DB DRAG. Wayne was the first SQ World Champion from the organization we know as IASCA (International AutoSound Challenge Association).

Both of these gurus are both legends, and considered the leading experts in the field. During their competition days, both guyz came up with a way to assist in the prevention of voltage drops. In SQ competitions, the look of your system is actually more important than the sound, and having your lights NOT dim under high playing levels is a competitive advantage.

As you may know, amplifiers are made up a bank of little capacitors, resistors, etc. What has been common engineering knowledge is that capacitors store energy, and more or bigger ones assist in balancing the power supply.

Wayne came up with the idea of putting several dozen 'little' (approx 100uF) capacitors on a circuit board to 'extend' the power supplies storage. At about the same time, or shortly afterward, Richard came up with the idea of one huge mondo capacitor (I believe it was 800,000uF or 0.8F) to do the job.

Eventually, Richard won. The large cylindrical tubes won over the complicated 48 caps strapped to a circuit board. However, what did this really accomplish? Let's start here:

WHAT IS A CAPACITOR?

Basically, capacitors are an energy storage device. Large, 1 Farad or more
capacitors store energy (electrons) between their plates. Capacitors differ
from batteries because batteries store energy in the form of chemical
energy--and rely on acid and lead plates, as the place of storage. For a more detailed
description of a capacitor, go here:

http://www.eatel.net/~amptech/elecdisc/caraudio.htm

Then on the right hand side, scroll down to CAPACITOR. Keep in mind the use
of capacitors in an audio system.

WHY DO PEOPLE BUY CAPACITORS?

The number 1 reason would have to be because their lights dim when their
system is playing HARD. In car audio, we are told that a capacitor is
designed to prevent the voltage drop associated with your lights dimming.
The number2 reason is that it is rumored to 'improve' sound quality or
'stiffen' the power supply/source.

WHY DO MY LIGHTS DIM?

Headlights brightness is in direct proportion to the source voltage. For
instance, if your car is running, system voltage is ~12.5 -14.4 VOLTS. Your
lights will be much brighter than when your car is turned off--where battery
voltage is ~12V. Most car alternators put out between 75 to 120 amps of
current. When this current draw threshold of the charging system is
exceeded, system voltage will drop as power demands are now shared by the
alternator and the storage devices (battery & cap). We are using battery
reserves beyond this point until the demand lessens

When playing your system really hard. Your lights dim because your
alternator can't keep up it's charging voltage (around 13.5V) and therefore,
demand exceeds output. When this happens, your electronic devices are
dipping into the power storage of the battery. Since the battery stores
power at ~ 12-12.5V, there is a 1.3 to 1.8V drop in voltage available. This
in turn is why your lights dim down.

HOW MUCH POWER DOES A CAPACITOR STORE?

1 Farad = 100 joules or 100W/second
850cca battery = ~2,200,000 farads

For storage purposes, you'd need ~2,200 1 Farad capacitors to equal the energy of your battery.

Due to its impedence (ESR & ESL), a cap's energy is only 50% available. What's worse, is that in order for a 1 Farad cap to discharge, first the alternator output must have maxed out, and the voltage must have dropped around 1.5 volts. But I thought a cap was supposed to prevent that (voltage drop)!!!!!????? Yep, you got the point.


IF A BATTERY = 2,200 CAPS, THEN WHY BUY A (PUNY) CAP?

My question exactly. Marketing is the reason why people buy caps. In many cases, upgrading wiring will help your system get the maximum transfer of current. Once that has been reached, adding a capacitor may have a minor effect on your system. 50W over the course of a second is not a lot of power considering an amplifier may draw 2000W to put out 1400 watts. Let's look at the situation from a resources standpoint.

Alternator 80 amps
Car accessories (minus stereo) 40 amps
A large Car Audio system (DRAWS ) ~200 amps AT FULL OUTPUT

In this case, you have 240 amps of draw, but only 80 amps of current from the alternator. In your case, you need 160 amps x 12 volts or or let's say 1920 watts of energy. Since a cap stores 50W, how much of a difference do you think it's going to make? A cap is basically a peashooter. W+e need a Howitzer cannon here, to do the job well.

Also, Once a cap is discharged, where does it get it's power from? The alternator, which is already overloaded. Once a cap is discharged, it's worthless. Like SWEZ says, ・.The cap already shot its wad, an does limp til recharged・ I知 not so certain I will allow him to babysit my kids, but you get the drift. (I never said it quiet like that... and oh...I'm great with kids!)

SO, WHAT IS A CAPACITOR GOOD FOR?

1. Audio Jewelry- impress chicks with large cylindrical shiny thingy
2. Extra weight in winter time
3. A very POOR... BUT expensive distribution block
4. A projectile in the event of a crash
5. Rolling pin--for cooking purposes
6. A neat thing to tell your friend, "..Hey man, lick the top of this..


Please do not try # 6. New hairstyles are always refreshing, but if you are wearing railroad tracks across your teeth, you might have one big filling after it痴 over.

HOW CAN CAPACITORS IMPROVE SOUND QUALITY?

They can't. Sound quality is not dependant upon the presence of large bulky 1 Farad capacitors. How many 1 Farad Capacitors do you think the Boston Pops, Aerosmith, or Snoop dog use in the recording studio?

IN A NUTSHELL.......

When Richard, our fearless inventor, became World renown for winning every competition under the sun, people began copying what he did. Soon, every 'serious' competitor had a 'stiffening' capacitor--not to be confused with the 'loosening' capacitor.

WHY?

In the late 80s, people began sticking out their tongue when dunking the basketball because Michael Jordan did. Did sticking out your tongue improve your dunking ability? Same here with adding a capacitor to your electrical system.

STILL A GLUTTON FOR MORE PUNISHMENT?

Here's the Original Cap Debate.

http://www.audiogroupforum.com/csfor...ead.php?t=5010

Phoenix Gold's marketing guru had just posted information on how their Powercore (basically the Alumapro CAP15 in a Phoenix shell) had both stabilized their voltage and improved the sound quality. Richard called him on it (all in another post) and the marketing geek was unable to quantify any of the conditions that resulted in the voltage being HELD at 14.2V and the 'improved' sound quality.

Please do not read every stinking post as valid. There are a lot of people that have had the efficacy of capacitors inbred to their minds, and were not (and still not) convinced in the futility of a 1 Farad storage device.

In a final note, Richard relayed a quote regarding battcaps ( www.battcap.net ) as, "..The audio industry is the only place i know of where you can publish specs that show your product is useless and still be able to sell them------and whats worse is that technically ignorant people will argue against the math!!!!!!!..............RC.." when referring to the product. This also relates to most digital readout capacitors, and I wish my Archie Bunker skills could have said it better myself.
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Default Re: LOOK BEFORE POSTING==> Aftermarket Audio F.A.Q

Purchasing Info

Q: how come I bought something off e-bay, it said it had a warranty, but the manufacturer won't fix it?
A: most every major audio company does not support online sales. There are certain sites that are authorized dealers for certain companies, and you will get a factory warranty with them. However be wary and read all the fine print. Some sites warranty the products through themselves, so if you have a problem, you have to pay to send the product back to them, then pay to have them ship it to the manufacturer, and pay to get it back. Reading the fine print can pay off in the long run. If you don't care about warranty, then don't be upset when that great deal you got off e-bay dies on you.

Q: where's the best place to buy JL online?
A: nowhere. JL is one of the best companies when it comes to unauthorized sales. They do not allow any of their products to be sold by unauthorized people, and any place online is unauthorized. You can buy their products online; however you will get no warranty work from JL.

Q: How do I get some bump in my car?
A: there are many ways to get "bump" in your car. First you need to analyze what type and how much "bump" you want.

if you are not willing to give up trunk space, a good set of front components, possibly even 3 ways, and some 6.5" dedicated midbass drivers in your rear doors. The kicker resolution RMB6 in a door that has been sound dampened with dynamat or like metal insulation will add to the low end output of the system without taking up space or adding too much weight to the vehicle. Note that you still have to run them off an amp. another option would be to get a nice set of 6x9's for the rear deck, however not all 6x9's will fit under the rear deck. For example the blaupunkt overdrive dual voice coils 6x9ís that are capable of a lot of lower frequency output will not fit under the rear deck.

If you are willing to give up trunk space, you must decide how much space you are willing to give up, and how much you are willing to invest. Proper planning of a system will yield much better results than just picking something out because you've heard it is good, or it looks cool. To pick out what will work best for you, you need to prioritize different aspects of the system:
a) how much do you have to invest. It might seem straight forward; you want a $150 sub and a $200 amp. A system is much more than that. Youíll need an enclosure, wiring, possibly a line output converter, and are you going to install it, or are you paying to have it installed. There are so many small details that add into the price of your system. take the enclosure for example, a simple sealed wooden box might not cost very much, but say you want a sealed box made of fiberglass, if you don't know how to fiberglass, plan on spending several hundred on labor. You should plan on spending more on the enclosure than the sub itself. The enclosure can tailor the sound to just what you like. A good enclosure can make a poor quality sub sound good. A poor enclosure can make a good quality sub sound poor.

b) How much weight are you willing to add to your car? a sheet of 3/4" MDF (medium density fiberboard, which is pretty much the standard for audio enclosures) weighs in at 95 lbs. a basic sealed enclosure won't need a full sheet, but if you start working with slot ports and more complex enclosures you will be using closer to a full sheet. An 18" sub in a complex ported enclosure required nearly 2 full sheets of MDF. A 10" sub in a more complex 6th order bandpass enclosure required a sheet and a half of MDF. If you are worried about weight, look into fiberglass. It will cost more, but it will be lighter, in most cases. Also when thinking about weight, look at the equipment you are interested in. some of the really beastly 10's on the market weigh over 40 lbs. there are subs that weigh in over 100 lbs. don't forget about the amp(s). Some of them can get quite heavy.

c) Looks. Do you want to open your trunk and people think it looks absolutely awesome? Do you not care how it looks as long as it's loud? The nicer you want it to look, the more time will have to be spent building and finishing the enclosure. If you are paying someone to do it, that will add up quickly. If you are doing it yourself, that can add up to some serious frustration from time spent and possible problems.

d) How loud and at what frequencies. Musical listening tastes tend to dictate the subwoofers chosen as well as enclosure type. If you like rap, you'll want to use a ported box tuned low. Some subs don't perform as well when they are tuned lower, so that will need to be taken into consideration. Do you prefer flatter, more consistent output? Sealed would be the choice for you. Sealed enclosures are also easier for first time builders to try. They are not so picky about design flaws, and making an error in the volume as long as it's not a huge difference, will not cause an audible difference. Change the volume of a ported box, and it will totally change the tuned frequency. That brings us to picking a tuned frequency that is right for you. If you want the best sound quality out of a ported system, you'll want a very low tuning frequency, typically below 30 hz. If you aren't so concerned with flat response, and you really want everyone to hear it, tuning between 35 and 40 hz would be a wise choice. Depending on the sub, you'll still be able to play down to around 25 hz, but you will have to use an amp with a subsonic/infrasonic filter on it. Really low frequencies and higher tuned ported enclosures do not mix. The sub will not have enough resistance behind it, and too much power will easily damage it.

Now you have to consider how much power you want to run. Higher powered high quality amps are going to cost quite a bit. But can your car handle it? Running several thousand watts with a stock electrical system can be a very bad thing. It has to be closely monitored, otherwise you'll be replacing your battery every month, and possibly your alternator. A high quality 10 with 500 watts is more than enough for most people. If you are starting out, start small. Research things, and listen to other peoples systems. Decide what you'd want to upgrade. Just because someone down the block has four 15's doesn't mean you need that, let alone want it. Look at it as a learning process. Say you do go with four 15's. For most people that would be way too much and they'd take it out and maybe just run 1. For others, four 15's would be plenty for them, and they'd never want to change it. And for the really sick individuals, four 15's is not enough
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