الموضوع: Speaker FAQ

o-axial vs Components

What's the difference?

Co-axials are speakers that have the tweeter permanently mounted in the middle of the midwoofer. Co-axials typically do not have external passive crossovers.....only a capacitor in-line with the tweeter to highpass the tweeter. They are generally much cheaper than components, and will work well off of headunit power (but will perform well off of external amplification aswell).

Components have separate midwoofers and tweeters as well as an external passive crossover. The midwoofers and tweeters are separated for a number of reasons.....for example, to allow optimal speaker placement. The passive crossovers are usually quite complex (for more advanced than what's used for co-axials) and are designed to optimize the performance of the speakers (by way of crossover points, crossover slopes, tweeter attenuation, tweeter protection, impedence compensation [zobel network], etc etc). The speakers used in component sets are typically of much higher quality and better performance that those used in co-axials. Typically components are best used with external amplification only.

2-Way vs. 3-Way

In a perfect world, we'd have a single speaker that could reproduce all frequencies perfectly, 20hz to 20khz. Unfortunately for us, such speaker does not exist…..so, we need to break the frequency spectrum down and play it through multiple speakers (mids, tweeters, subs, etc). This is where we get "2-ways, 3-ways, 5-ways, etc" from.

In co-axials, a 2-way speaker is a speaker that contains only a midwoofer and a tweeter…..the midwoofer playing the lower frequencies (down to around 80hz or so), the tweeter playing the higher frequencies (around 3khz or 4khz and up). 3-way co-axials typically have a midwoofer, tweeter and "supertweeter", with the supertweeter being designated to handle the very, very high frequencies only. Co-axials can go as high as 5-way (midwoofer, midrange, smaller midrange, tweeter and supertweeter). For all intents and purposes, anything more than 2-way in co-axials is a marketing gimmick. Going with 3-way co-axials or higher usually does not increase performance much, if at all.

For component speakers, a 3-way system includes a dedicated midbass (generally plays around 60hz-350hz), a dedicated midrange (generally plays around 350hz-6500hz or so), and a tweeter (generally 6500hz and up). Whereas a 2-way system is only a midwoofer (playing around 60hz-4000hz or so) and a tweeter (4000hz and up). Ideally, for a 3-way system, you'd want to put the midbass in your door, and have kicks built for the midrange & tweeter. For a 2-way component set, kickpanels or door mounting will suffice with generally good results.

General advantages of a 3-way component set:

1) There isn't a crossover point in the middle of the midrange frequencies (which are generally the most important to imaging and tonality), and they aren't being split up between drivers like they sometimes are in a 2-way setup. In a 3-way, they will be played by mainly one speaker, which is the dedicated midrange.

2) In a lot of cars, the mids will need to be flipped out of phase to help correct some midrange frequency phasing problems. In a 2-way system where one speaker plays midrange & midbass, running one of them out of phase will decrease the midbass impact. By running a 3-way, the midrange can be flipped out of phase and it has no effect on the midbass since it is being played by a separate driver.

3) The midrange and midbass frequencies in a 3-way may sound "cleaner" since each speaker has more of a limited bandwidth to play.

Disadvantages of a 3-way component set:

1) Tuning and aiming the speakers can be a much bigger pain the ass with 3-ways. Installation, tuning, phasing and aiming speakers will be much easier/quicker to perfect with 2-ways.

2) Room. It can be much more difficult find the room to fit all of the speakers. In some cars, kickpanels are simply out of the question.

3) Money. 3-ways are normally considerably more expensive than 2-ways.

As you can see, 3-ways aren't necessarily better than 2-way. It's more of a personal preference. Some ppl would rather have a 3-way (for the advantages above), some ppl would rather have a 2-way (easier to tune, less room is occupied, etc).

rossover Points I am sure you have heard the term 20 to 20 in refering to audio. Sound is just pulses of air pressure our ears can pick up. Frequencies are measured in cycles per second (Hz) which is just the number of pulses which happen each second. If your speaker moves back and forth 80 times in a second it is playing an 80Hz tone. It is generally acepted that the range of human hearing is 20Hz to 20KHz. KHZ is KiloHertz or 1000Hz. If you know piano, the fundamental tone for middle C on a Piano is about 263 Hz. You will not find any speaker anywhere which can produce 20Hz all the way up to 20KHz (that will fit in your car or that you can afford). That is why you use some combination of tweeters and woofers to reproduce sound. A typical 2 way component set will have the tweets covering notes from 3KHz-20KHz and the midbass covering from 80Hz-3KHz. The sub covers 20Hz-80Hz. In the system I just described the crossover points would be 80Hz (where the sub gives way to the midbass) and 3KHz ( where the midbass gives way to the tweeters)

Crossover Slopes In the above example I listed a midbass/tweeter crossover point of 3KHz. If I were to unplug my midbass speaker and play a 1.5 KHz tone I should not hear anything, right? Wrong. The hand off between two speakers is very gradual. If you take two speakers playing the exact same note at the exact same db, the result would be 3db higher than one speaker. Since the falloff of a speaker is gradual, the crossover point is the tone where both speakers are down 3db. There are a few common crossover slopes: 6db, 12db, 18db and 24db. These are know respectively as 1st order, 2nd order, 3rd order and 4th order. What does this mean? In my example from above, if the crossover slope was 3rd order (18db) it means that for every octave below the crossover frequency the sound fades off at 18db. So if we were to unplug our midbass and play a 1500Hz tone (one octave below 3KHz) it would be 18db below a 3KHz tone played into the tweeter.

tweeter attenuation In most car audio environments the tweeters end up very close to your ears while the mids end up further away. Since the tweeters and mids are playing at the same level it would make the tweeters sound louder than the mids since they are closer. This is why many crossovers will have tweeter connections for 0db, -3db, -6db etc... This allows you to lower the power to your tweets so you can match them to the volume of your mids. This is known as tweeter attenuation. FYI since every 3db drop is half power if you have your tweets set to -6db and running off a 100watt RMS amplifier you are actually only sending 25watts to your tweeters.

tweeter protection Like any speaker, if you stress them too much they will break. Some crossovers will have fuses installed between your amp and tweeters that will blow at a predetermined wattage to prevent you from blowing a tweeter.

impedence compensation [zobel network] This one is a bit harder to explain without getting into crossover design theory. Basically in order to design a crossover you need to know what the impedance of the speaker is. The components for a 3Khz, 6db slope crossover are totally different if you are using a 4ohm speaker rather than an 8ohm speaker. The problem comes into play near the resonant frequency of the speaker. As a speaker aproaches it's resonant frequency it tend to resist electricity more. For example, in a common 6ohm tweeter with a resonant frequency of 1Khz, the amplifier may see a 12 ohm load at 1Khz rather than a 6ohm load. This REALLY messes with crossovers because they suddenly see a 12ohm load and their crossoover point changes for that moment!!! A zobel network is normally used when you are driving tweeters down to a point near their resonant frequency. It is a set of components which divert power through a resistor near a particualr frequency (normally tuned to the resonant frequency of the tweeter) so as to show the crossover and amplifier a more consistant resistance.

rossover Points Cont'd - now you all know that a crossover point is meant to limit each speakers 'bandwidth' so that each speaker can only play that certain range of frequencies, and retain a higher volume and better clarity. this is the reason we use components with passive corssovers, or an active crossover that we can select the exact points.

you should also understand that a crossover WILL NOT act as a 'brick wall' and stop the speaker from playing that frequency. a crossover is meant to limit the extenstion of the speaker so that it will not play frequencies it was not designed to play at loud volumes. this means that there will be an 'overlap' of frequencies.

for example (and this is ONLY for example, i highly doubt you will see this kind of crossover and respose curves... ever) this is a subwoofer (a GREAT subwoofer mind you ) and a midbass speaker, lets say an 8" speaker.



as you can see, the point where they 'dip' together is the crossover point (please correct me if im wrong). this point (by looking at the graph) is 80hz. this is normally where people set thier subwoofers and midrange - its practically a 'rule of thumb' to try about 80hz on your frist try, and go up or down from there depending on if YOU LIKE IT OR NOT. because noone can tell you what you like and what you dont like. this is 100% subjective.

now, as the speakers 'roll off', or start to play the frequencies below\above their crossover points, that frequency will get lower. here is the tricky part. since the other speaker is picking up that frequency as its companion drops it, the music wont sound like there is a giant hole (or it shouldnt if the points are set well).

Refrence Level - this is somthing that people usually dont comprehend eaither. a 'refrence level' stereo system- is a system that can FULLY REPRODUCE, at any volume level that it is capable of, 20hz->20khz with no distortion. now, it may sound easy by reading all this stuff we are teaching you, but its not qute that simple. the '0db' setting most of you see on your home theatre recievers, or stereos, refers to the *CURRENT* volume, or the standard volume, or whatever volume it will produce with how many watts the amplifiers are producing, if you turn the knob down from 0db, you will be ATTENUATING the signal through the amplifier - and thus, your system will more than not, be below 0db. for example, we have a single 10" speaker playing a 50hz tone (in and out 50 times per second), about the middle of the 'sub bass' frequencies. we are feeding it 500 watts of power in whatever box, and whatever car. when we put a microphone in the car, the car reads 100db. that is the pressure level of the air as the speaker moves in and out, its a way to measure volume (as most of you SHOULD know). now, REFRENCE LEVEL, means that EVERY FREQUENCY (or **** near it) should be able to play 100db. so our tweeters playing a tone of 5631.245hz should be able to play 100db, and likewise, the midrange should be able to play 235.654hz at 100db. this is the '0db' mark. say the system is at a volume of 20, and its hitting 96db, ALL FREQUENCIES should be able to play a 96db note. this is refrence level - all your frequencies have a 'FLAT' response curve. and this is what that looks like;

flat response (good)


versus a peaky and valley response curve (not good)


now, some people LIKE peaks and valleys in certain spots. this is fine. this is why stereos are subjective. some people cant hear distortion (sure ) - and thats fine too. but 0db means at whatever volume that knob is at, an entire 20hz-20khz sweep should mic evenly. it wont be exact. but you get the point.

Round Speakers VS Oval Speakers
The subject goes as follows: A 5.25" speaker can fit in a stock 5x7" location, and a 6"-6.5" speaker can fit in a stock 6x9" location. So which should you use? It's quite simple. A round speaker is more likely to have weight evenly distributed against the Voice Coil and VC Former. This means that you can achieve clearer sound with a round speaker that with an oval speaker. On the flipside, an oval speaker will obviously have more cone area. With the same excursion as the round speaker, the larger oval cone produces more sound. An oval speaker is capable of getting louder and usually producing more mibbass than a round speaker.

There are a great many exceptions, more and more as the quality of your speakers goes up, but this is the general overview.

oing 'active'
A further improvement is the use of active crossovers. Unlike passive crossovers which are situated between the amplifier and the 'speaker drive-units, the active version is placed between the output of the preamplier and the input of the power amplifier.


Active set-up
Adding active crossovers is even better.
One of the major benefits of active crossovers is that the amplifier has more direct control over the 'speaker drive-unit and can therefore control it more accurately. Think of it like this. If you (the amplifier) sit in the back of your car giving directions to a chauffeur (the crossover), who is driving the car (the drive-unit), you may get on fine at slow speeds, relaying your instructions, but if you were in a race, it would be much better for you to have (direct) control of the car yourself. Click HERE for a fuller explanation of active crossovers.
Changing from passive to active control of your 'speakers will involve the following:

* A separation of the preamplifier and power amplifier stages. If you currently use an integrated amplifier you will need to know where the circuit for the preamplier joins the power amplifier section.
* One or more extra power amplifiers (you need one mono power amp channel per drive-unit ie one stereo power amplifier will drive two drive-units) These amplifiers need to have an identical specification as regards gain.
* An active filter (crossover) circuit. You can either build one from scratch, from a kit or buy one ready built.
* The removal (or disconnection) of the passive crossovers.
* The possible alteration of the cabinet size and port tuning.

I am a very big fan of active crossovers, having experienced the improvements they bring. Once you have an active crossover, it is also much easier to alter it to suit different 'speaker configurations than it is with a passive crossover.
On the negative side, an active system costs more than a passive set-up due to the cost of the extra amplification. However, as sound quality is our ultimate goal, I feel that this extra expense is well worth it. And remember that building your own amplification will keep the cost down. See the Build your own section for links to some of the good amplifier kits available.
There's only one thing better for 'speakers than an active crossover, and that is no crossover as I have discovered with my most recent 'speaker project which utilises some full-range drivers. (Click Here for details) However, even full-range 'speakers aren't perfect, often needing another unit to 'help' them cover the full frequency range.