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Old 07-10-2002, 10:56 AM   #1
judgegavel
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I was planning on getting a new HU and speakers Piece by piece for my wrx. I believe the HU I will be getting is the Alpine CDA 7893 with the built in mosfet60 hybrid amp. I donot plan on adding an additional amp or a sub for that matter. My question is will this have enough power to run quality component 6 1/2s front and quality 4's (comp) from the rear or should I just stick with excellent speakers. Any recomendations, I really want to keep the cutting and wireing to a minimum. In fact according to cruthchfield they claim the only comp 61/2s that will fit without are RF fanatic Ps true or false, Other options? I'm looking for quality sound not base pumping noise.


Oh has anyone tried a single din MD player/reciever, with an ad on single din cd. I was looking at a Kenwood option, the add-on cd is like 199, not bad, and they have two MD/recievers, but the cheap one looks like garbage and the eXcelon one is like 500, Thats alittle rich.
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Old 07-10-2002, 11:05 AM   #2
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It really depends on the speakers that you get. Some require more power and you'd need an amp to get the best sound you can get from them. As for the speakers, almost all aftermarket speakers will require that you make a spacer and drill some holes. Wiring isn't too bad as long as you get the proper harnesses and connectors for the speakers.

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Old 07-10-2002, 11:24 AM   #3
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Well the fanatic P's for example have an rpr of 8-50 watts, while the HU above 27w RMS/ 60 peak x4, so it seams like it would work fine would I be correct, if anything it could blow at 60 so may be a little higher.
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Old 07-10-2002, 12:23 PM   #4
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judge,
I have been considering this also, but a CDA-7894 (also 27W RMS x4). From what I have read, a speaker that is rated at less than 8W RMS can be powered by a stock head unit, and will sound good off a high power head unit like the one you listed. I'd be worried if it was rated at 8W and up, but your head unit is pretty much a small 4-ch amp. Just be careful in your selection and look for a sensitivity level that is high (90db+) and also the RMS power that is recommend.

I had BA components (50W RMS recommend) and they would not play off my Pioneer head unit (22W RMS). Based on that experience, I am going to be looking at speaker specs more close.

I find the Infinity Kappa Component sets have a very high sensitivity, and also a RMS power rating of 2W-80W or something like that, so I am considering them.
http://www.crutchfield.com/cgi-bin/S...cs&i=108K605CS

Also look here:
http://www.sounddomain.com/sku/INFKAPPA605CS
They come with a free dynomat extreme door kit ($89/value).

Now I just can't decide if I want to buy the headunit, or an external amp instead, and just keep the stock head unit.


Paul G.

Last edited by paultg; 07-10-2002 at 12:28 PM.
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Old 07-10-2002, 12:33 PM   #5
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Some speakers blow due to lack of power as well
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Old 07-10-2002, 03:57 PM   #6
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Quote:
Originally posted by Nacan_5
Some speakers blow due to lack of power as well
This is one of the biggest myths in the car audio world. Think about it for a second, this is the same as saying your speakers can blow if you dont keep the volume cranked all the time.... 99.999999999999% of the time your speakers will be seeing less than 20 watts. Most speakers have a sensitivity in the range of 92ish which means that when listening at 92 db you are using ONE watt from your amp/head unit. every time you want 3 db more (percieved as twice as loud) it takes twice the power, so to get 95 db it takes 2 watts, 98 takes 4 watts etc.

The only reasons speakers fail is due to either defects, overheating or pushing the speaker past its mechanical limits. The latter two are caused by too much power, plain and simple. Saying speakers blow from to little power is kinda like saying your engine will blow if you only drive around at 3000 RPM's, not gonna happen.
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Old 07-11-2002, 12:30 PM   #7
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The reason why speakers get blown from too little power is the unit(amp,HU) gets cranked beyond its ability. What happens then is the amp clips and the sinewave goes square and becomes DC current instead of AC wave. The speaker extends and waits to go back but the inverse wave never appears. That burns the voicecoil and blows the speaker. Yes underpowering wont blow speakers but, driving amps into clipping will.
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Old 07-11-2002, 01:27 PM   #8
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cranking you radio factory or aftermarket will clip its amp so you may blow your speakers and shops will say from underpowering it and try to sell you an amp... trust i do it everyday lol im an installer... in reality an external amp is best if you can always use more power than you need keep the amp turned down and it wont clip lol

its like you can never have too much HP in your car you just dont have to use it at all times but you know that you have it when you need it....

paultg --- the kappas have big magnets on them... you will have fun trying to install those speakers into the front doors lol let me know how that works out if you go with them

im still looking for a nice set of components that will fit with minimal drilling spacing cutting right now i have a alpine cda 7893? i think not sure lol anyways its the 60x4 peak 27x4 rms and it is driving my factory speakers great

ive also used a toyota aftermarket pocket instead of another cd or casset deck, gives me a nice storage for a cd or remote

judgegavel ---
doing the kenwood set up make sure you match up the brands/series aka excelon... makes it look better that way...

you may also want to look at a MD changer and a cd up front with the pocket that may work nice also..
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Old 07-11-2002, 04:01 PM   #9
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Quote:
Originally posted by rexecutioner
The reason why speakers get blown from too little power is the unit(amp,HU) gets cranked beyond its ability. What happens then is the amp clips and the sinewave goes square and becomes DC current instead of AC wave. The speaker extends and waits to go back but the inverse wave never appears. That burns the voicecoil and blows the speaker. Yes underpowering wont blow speakers but, driving amps into clipping will.
It is impossible for an amplifier to output dc voltage. The "square wave" is simply multiple sine waves compressed. If broken down thats exacly what makes up a square wave. The only things that break speakers is abuse (pushing byond mechanical or heat limits) or defects.
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Old 07-11-2002, 04:12 PM   #10
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Quote:
Originally posted by Usacjudge


This is one of the biggest myths in the car audio world. Think about it for a second, this is the same as saying your speakers can blow if you dont keep the volume cranked all the time.... 99.999999999999% of the time your speakers will be seeing less than 20 watts. Most speakers have a sensitivity in the range of 92ish which means that when listening at 92 db you are using ONE watt from your amp/head unit. every time you want 3 db more (percieved as twice as loud) it takes twice the power, so to get 95 db it takes 2 watts, 98 takes 4 watts etc.

The only reasons speakers fail is due to either defects, overheating or pushing the speaker past its mechanical limits. The latter two are caused by too much power, plain and simple. Saying speakers blow from to little power is kinda like saying your engine will blow if you only drive around at 3000 RPM's, not gonna happen.
I believe the rationale behind that story is that with such little power available, distortion is an issue at a relative low volume. That is where the whole "not enough power blows speakers" thing comes from.

CHad
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Old 07-11-2002, 04:17 PM   #11
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judgegavel -
No matter what components you're looking at, you're not going to come close to realizing their full potential off head unit power. One big reason is the passive crossovers used in components. Dont waste your $ on components if you can't get a decent amp to run them. I love Alpine heads (I have a 7949) but no head unit power is going to do components justice.

Chad
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Old 07-11-2002, 04:34 PM   #12
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Actually, it's the peak of the wave getting clipped off. This is very apparent if you input a sine wave into an amplifier, connect a scope to the output, and watch the waveform as you turn up the gain. The sine wave will get bigger and bigger (more and more amplitude) until the output voltage cannot go any higher (lower). Then, as you turn up the gain, the top (bottom) of the wave is cut off and it looks like a square wave where the output increases (decreases) like a normal sine wave, it reaches the maximum (minimum), then stays at that maximum (minimum) until the output falls (rises) below (above) this maximum (minumum) voltage when it looks like a sine wave again. This is a clipped signal and you can actually hear the ringing (easily demonstrated if you have the Autosound 2000, Disk one, I believe...either 1 or 2). During the time that the output is supposed to be above (below) the maximum (minimum) voltage the amplifier can produce, the output will be the maximum (minimum) output voltage. This is DC. And, the more this happens during a song, the more DC you are pumping through the voicecoil (either + or - voltage).

For example, lets take a simple sine wave. The signal from the head unit (it's a good head unit with a pre-out voltage of 4V) is maxed out, with no clipping. So, if you connect a scope to the output from the head unit, you would see a nice sinewave with a peak-to-peak voltage of 8 volts (4 volts above ground, 4 volts below).

Then, let's say you have an imaginary amplifier, and the gain is turned way up and is 10. So, if you connected a scope to the output of the amplifier, you should see a nice sine wave with a peak-to-peak voltage of 80 volts (10x8 volts from the head unit). However, due to the load (speaker) of the amplifier and the current capacity of the amplifier, it can't do 80 volts p-p. It can only do 40 volts p-p. So, what you would see on the scope is the signal increasing up until it hits 40 volts, then the output stays at 40 volts (the max) until the signal starts down the other side of the wave and gets to 40 volts again. Then, it will go down, past 0 volts (ground) until it gets to -40 volts and it will stay there until the wave start back up the other side of the wave and it hits -40 volts again.

During the entire time that the output of the amplifier stays at 40 volts and -40 volts due to the clipping of the amplifier, you will have a DC current flowing through the voice coil with a value based on the resistance of the voicecoil (this is not impedence, which is frequency dependent, but close to it). So, if the speaker has a 4 ohm voicecoil, you would have 10 amps (I=V/R = 40/4 = 10) flowing through this little voice coil wire. And this current would be flowing through this coil for both the + and - voltage, just in different directions.

If this happens a lot, the voice coil gets hot, and eventually burns out.

Hard to explain without pictures.
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Old 07-11-2002, 05:22 PM   #13
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If a square wave truely is DC current, would you mind telling me how it can travel trough a transformer, or even a capacitor for that matter (of which all amps have and are integral parts of the amplifier circuit)? Square waves cannot hurt speakers UNLESS they contain too much power, and if thats the case a perfect sine wave of equal power will be just as harmful to the speaker. A square wave is in fact multiple sine waves packed together. More specifically it is the fundamental (since wave) plus all harmonics of lesser amplitude and higher frequency.
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Old 07-11-2002, 08:41 PM   #14
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I'm not saying that the square wave itself is DC, but the flat part of the top is. If you look at a square wave on a scope, and zoom way in on it, the top of the wave is DC since it doesn't cross zero. Yes, I know we are really zooming in on the wave itself to get this "DC" part, but my point is if you are playing a track, and 75% of the track has the amplifier clipping, then you have the amplifier outputting this max voltage more of the time.

You are right. A true square wave from a frequency generator is a sine wave with harmonics to "sharpen" the corners. But someone started that a sine wave clipping is a square wave and I was just saying it "looks" like a square wave, but is just a sine wave with the top cut off flat.

I think we are both saying the same thing here...just in different ways. Although, an amplifier CAN output a DC voltage, if that is the signal inputted.
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Old 07-11-2002, 08:55 PM   #15
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WHOA!

This whole topic is completely blowing my mind!!!

Can we go back to kiddie terms!!!

Bryan
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Old 07-11-2002, 11:07 PM   #16
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I think you will get good sound out of good speakers and that HU, however it's nothing you'd get compared w/ an amp!
I just made the upgrade -- I put in an Alpine 7995 H/u (the one without the amp) and an alpine HV340 amp which is 60x4 RMS.
The power coming out of that amp is so much cleaner than that from a head unit it's silly.
Right now I still have the stock speakers in, as mine new ones havn't arrived yet, and the sound improvement from the H/U and amp is incredible. Lots more clean bass, and clarity. I can really crank up the volume even w/ stock speakers and its still clear.. Granted, they still don't have nearly the range I'm looking for, but I was impressed considernig they're made of paper!
At any rate, my rec. is to spring for an amp.. If you want to do it yoruself, it is a decent amount of work.. I spent two straight afternoons getting it set up.. ended up running all new speaker wire, which was a complete PITA, but glad I did it.
As far as speakers, I think w/ any upgraded components you will atleast need spacers.. You will need to do a little bit of re-wiring because the stock speaker wires connect via harness to the stock speakers, and they run a crap setup to the tweeter, which needs to be replaced w/ a crossover.
Its really not hard stuff to do, just time consuming.
Ts
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Old 07-12-2002, 09:30 AM   #17
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2000vfr800-

I agree we are kind of taking different approaches to explaning the same thing. Although I still disagree with the statement that an amplifier can output dc voltage. Every component in the output side of an amplifier requires ac voltage. I dont think any of them would let a dc voltage pass or even output a dc voltage, thats just not how they operate. This is one case where "If it looks like a duck and quacks like a duck it must be a duck" isnt quite true... It does seem to "act" like dc voltage, but I dont think it really is.
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Old 07-12-2002, 10:29 AM   #18
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I guess it depends on what type of amplifier we are talking about here. But I guess we can agree to disagree on this point...no biggie.

Good thread though. Brings back a lot of memories on research I did involving IGBT's for dyno controllers.
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Old 07-12-2002, 10:33 AM   #19
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In any case...back to the question.

I don't think you will get anywhere near the sound quality you can out of those speakers with the head unit power. Just get any kind of small amplifier, throw it under the seat, and it will sound very nice.

But, I have not heard the HU you are looking at, so I don't know for sure. But, HU amplifiers will have to have changed a LOT for my above statement to not be correct. Just my $.02...

Good luck.
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Old 07-12-2002, 10:38 AM   #20
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Then comp are out, cause I hate insatlling amps, Can anyone recomend a good 6.5 speaker that will fit with no problems, Kappas are obviously out cause of those huge magnets. Crutchfiels only lists one and I forget what they were, plus there has to be other options. they list like 11 for the 4"s.
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Old 07-12-2002, 11:11 AM   #21
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Quote:
Originally posted by judgegavel
Then comp are out, cause I hate insatlling amps, Can anyone recomend a good 6.5 speaker that will fit with no problems, Kappas are obviously out cause of those huge magnets. Crutchfiels only lists one and I forget what they were, plus there has to be other options. they list like 11 for the 4"s.
Go listen to the Boston Acoustics RX57's and RX67's. They are 5 1/4" and 6 1/2" respectively...but the 5 1/4's sound better I think...and they will most likely fit easier depending on depth issues. You should be able to get a pair for around $160-170.

Chad
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Old 07-12-2002, 11:38 AM   #22
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2000-

Thats cool, this thread would probably end up being 30 pages long if we didn't agree to disagree

About the speaker question, I listened to a set of Eclipse 82641 6.5's off of deck power and was actually really impressed. Best of all they are under 2" deep so they should fit no problem. I would suggest finding and Eclipse dealer and taking a listen.
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Old 07-12-2002, 04:40 PM   #23
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vfr800, didnt think this thread was going anywhere and check a day later to see this. Great job at explaining that, knew I read the specifics somewhere a long time ago. I am still pretty certian that the clipped wave is DC voltage, just for the simple reason it is not changing in amplitude. It remains constant, hence the Direct Current. Once it becomes a wave again it is Alternating or at least starting to be AC.
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Old 07-13-2002, 12:10 PM   #24
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Do you know of any large stores that carry BA speakers, I know they're great quality but havent seen them in awhile (even the home stereo var.)
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Old 07-13-2002, 02:01 PM   #25
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check out www.bostonacoustics.com they ahve a dealer locator
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