# Stock Speaker Impedance???



## verkion (Sep 27, 2001)

Just curious what the stock speaker impedance is. And wondering whether they will handle whatever impedances aftermarket headunit, built in amps, are able to deliver. (4 or 8 most likely.) There seem to be some significant peculiarities with car audio stuff compared to live sound/studio stuff so I thought I'd check first. I was looking at the Kenwood Z828 Headunit.
verkion


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## verkion (Sep 27, 2001)

*Re: Stock Speaker Impedance??? (verkion)*

Bump...just a little








verkion


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## vwgtirob (Aug 16, 2001)

*Re: Stock Speaker Impedance??? (verkion)*

Amplifiers (in HU or otherwise) don't "deliver" impedances, speakers "present" impedances. Impedance is a function of frequency (speakers may have different impedances at different frequencies, and usually do), and the figure given on the speaker is the "nominal" impedance, or the standard impedance the speaker was designed to present.
Impedance is resistance generalized to AC (squiggly voltages), and can be used in place of resistance in Ohm's law equations. Ohm's law presents a relationship between voltage, current (in amps), and resistance/impedance (in ohms):
V=I*R, I=V/R, P=V^2/R, P=I^2*R, R=V/I, P=V*I
Amplifiers look like voltage sources, which means they try to keep their output voltage the same regardless of the load and the amount of current they need to source to do it. There are limits to this, of course, and this is where impedance starts to concern amplifiers.
Keeping voltage the same (lets say 10V), across a 4 ohm load (speaker), an amplifier (one channel) will develop P=10^2/4=25W. Across a 2 ohm load, it will develop P=10^2/2=50W. This is good, more power is a good thing, but it also means more current (the stuff that heats wires up, among other things) going through the transistors of your amplifier, and more current the power supply in your amplifier will have to provide. For the 4 ohm load, the circuit has I=10/4=2.5A of current passing through it. But for the 2 ohm load, the circuit has twice that: I=10/2=5A of current.
In cars, most stuff other than subwoofers is 4 ohms. This is because our source of power (the battery/charging system) is of low-voltage, and early stock sound systems used the 12V from the battery directly to power the amplifiers. Since you need less voltage to develop the same power across a lower impedance, we wanted lower impedances than the 8ohms of standard home speakers. Since the most the amplifier could output was 12V, so the most power you could get out of it was P=12^2/4 or 36W, versus with 8 ohm speakers P=12^2/8 or 18W, which is pretty measly for a car, which is a noisy environment.
Most outboard car amplifiers can handle 2 ohm loads, although many HU internal amplifiers will have trouble with such loads. 
Subwoofers come in many configurations, such as 2, 4, and 8 ohm single voice coils, and 1, 2, 3, 4, and 6 ohm dual voice coils. Dual voice coils allow you to wire them in series (for twice the impedance of a single voice coil), or parallel (for half the impedance of a single voice coil) to give you more flexibility when matching the speaker to your amplifier's capabilities.
If your car has the Monsoon system, there is a separate amplifier in the rear of the car which has amplifiers for all 8 speakers and crossovers (to direct the frequencies to the appropriate drivers). In the Jetta, Golf, and GTI, the tweeters are 4 ohms, the front mid-woofers are 4 ohms, and the rear mid-woofers (referred to in some places as "sub-woofers") are 2 ohms. The Monsoon amplifier is driven directly from the speaker-level outputs of the HU's internal amplifier (so if you were to replace the HU, there'd be no need to change anything else).
Without the Monsoon system, the HU is directly connected to all 4 sets of speakers, and they're all 4 ohms.
I hope I haven't confused you too much.


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## verkion (Sep 27, 2001)

*Re: Stock Speaker Impedance??? (vwgtirob)*

Ok...I understand the electronics aspect of it. I'm an electrical engineer. I just put it in "less correct" terms because that is how most people talk about this stuff...from what I've heard anyways. Ok, in any case, are the stock speakers 8, 4, or 2 ohms? Or are they different for the tweets and woofers? And, is there a crossover unit somewhere in the existing STOCK NON-MONSOON system? Like in the HU or seperately mounted somewhere? Lastly, there are seem to be quite a bit of disagreement between car enthusiasts about whether it is best to run amps at 2 or 4 ohm that is assuming the speakers in question have either 2 or 4 ohm coils. What do you think? 2ohm or 4ohm load and why? 
verkion


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## ytsejam (Oct 31, 2001)

*Re: Stock Speaker Impedance??? (verkion)*

According to the Monsoon site, the rear tweeters are 2-ohm, all of the other speakers are 4-ohm. I'm pretty sure the Monsoon does the crossover in the amplifier. I don't know how the non-Monsoon does the crossing over, but I'd be curious to find out as well since that's what is in my Passat (Monsoon style HU, w/ mid control, but no Monsoon amp). Sounds like the Monsoon does some EQ as well, because when I fade between F/R the response changes significantly. Sounds like the rear channel EQ'd to put out more bass.
edit....Delete repeat of what gtirob said.
External amps have to step up the rail voltages to get to the higher power. Lower impedence speakers means higher power output at a lower voltage. I guess the lower impedence loads make for a more efficient system as far as reducing the amplifers need to step up the volatage higher and higher to get to the ridiculous power levels people are after. Iguess that means for high powered subs 2-ohm is better, usually as 2x4-ohm, or 3x6-ohm in parallel








Just a guess

















[Modified by ytsejam, 8:49 AM 11-8-2001]


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## vwgtirob (Aug 16, 2001)

*Re: Stock Speaker Impedance??? (verkion)*

quote:[HR][/HR]Ok...I understand the electronics aspect of it. I'm an electrical engineer. I just put it in "less correct" terms because that is how most people talk about this stuff...from what I've heard anyways. Ok, in any case, are the stock speakers 8, 4, or 2 ohms? Or are they different for the tweets and woofers? And, is there a crossover unit somewhere in the existing STOCK NON-MONSOON system? Like in the HU or seperately mounted somewhere? [HR][/HR]​The speakers are crossed over with a capacitor on the tweeter and a coil on the woofer. I don't know the exact points, but it doesn't really matter. And like I had said in my earlier reply, the speakers in the non-Monsoon system (the Premium system) are all 4 ohms.
quote:[HR][/HR]Lastly, there are seem to be quite a bit of disagreement between car enthusiasts about whether it is best to run amps at 2 or 4 ohm that is assuming the speakers in question have either 2 or 4 ohm coils. What do you think? 2ohm or 4ohm load and why?[HR][/HR]​Depends upon the amplifier. If your amplifier has more output at the lower impedance, get the speakers with the lower-impedance coils. If not, go for the highest impedance that will get you full-output. That will minimize losses in the amplifier and decrease beta-droop distortion.


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## kas (Nov 2, 2001)

*Re: Stock Speaker Impedance??? (vwgtirob)*

Quote:
The speakers are crossed over with a capacitor on the tweeter and a coil on the woofer.
Is this true for the monsoon systems as well as the non-monsoon? So the crossover isn't part of the monsoon amp?

[Modified by kas, 6:57 PM 11-9-2001]


[Modified by kas, 6:58 PM 11-9-2001]


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## vwgtirob (Aug 16, 2001)

*Re: Stock Speaker Impedance??? (kas)*

quote:[HR][/HR]Quote:
The speakers are crossed over with a capacitor on the tweeter and a coil on the woofer.
Is this true for the monsoon systems as well as the non-monsoon? So the crossover isn't part of the monsoon amp?
[HR][/HR]​That was only regarding the non-Monsoon "Premium" system. The Monsoon does have crossovers at the amp.


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## verkion (Sep 27, 2001)

*Re: Stock Speaker Impedance??? (vwgtirob)*

Hehe. El Cheapo method for cross over. Oh well, it works I guess.







Yeah, I have the NON-Monsoon system. Figured I would probably be putting aftermarket stuff in anyways.
verkion


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## kas (Nov 2, 2001)

*Re: Stock Speaker Impedance??? (verkion)*

So I guess Monsoon & non-Monsoon vehicles have different speakers, huh. Any idea what the crossover point is on the rear speakers in a Monsoon-equipped car?


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