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Factory Speaker Impedance

26K views 41 replies 7 participants last post by  1stJeepGC 
#1 · (Edited)
Alpine System. I was messing around with my meter and decided to check the resistance value. Here is what I got.
Center speaker appears to be 2 ohm ( 2.1 )
Front 6x9's tested at 2 ohm (2.1 )
Front Tweeter tested at 6 ohm ( 6.1 )
Factory Sub tested at Dual 2 ohm ( 2.2 )
 
#5 ·
Dual 2ohm means it has two sets of positive and negative to the voice coil. When ran in parallel it would be at 1ohm. Yes, a single 4ohm would work as that's what I installed the first round ( JL Audio W3v.3 ). I would look for DVC 2ohm or DVC 4ohm. The factory enclosure is a joke...so if you use it, you will need to stiffen it up. I used several...several layers of bedliner spray.
 
#7 ·
I actually like my factory Alpine system. I think my sub has quite a bit of bass. I actually had to turn the bass down -3 in the factory EQ settings. This is with the 430N. Now my friend has the 730N. We did a side by side comparison and his bass was non-existent. How can two factory systems be so different?
 
#9 ·
Probably in the settings. I've noticed that if you fade towards the front, that you will lose some bass output. I've also noticed that if you raise the Treble that it also loses some bass output. Probably something designed into the amps. My guess is that it pulls the bass region from the rear channels of the factory head unit. As you fade it towards the front you lose output to the rears which affects the sub. Just guessing though.
 
#10 ·
The factory Alpine system is decent considering. If I decide to go all out, I'm keeping the head unit and using a processor ( Audison BitOne, Arc Audio PS8, Rockfords 3sixty.3 ) or something similar. You can then de-equalize the system and start from scratch. I've done it multiple times.....best way to IMHO. This way you won't lose any factory functionality from the system.
 
#14 ·
The only way to do it right is start checking connections. I would start at the subwoofer if that is the only issue that you both notice. Are you sure it has the sub back there? Can you actually see it when you look into the grille? Hell, maybe they forgot to put it in....I had that happen on a Titan pickup. The sub was never installed from the factory even though I had it optioned that way.
 
#17 ·
What you are measuring is the speakers resistance, not its impedance. They are not the same thing. A speakers impedance changes with frequency and cannot be measured by just connecting up a multimeter to the terminals and taking a reading.

As a rough and ready guide to get somewhere close to knowing the actual impedance from the measured resistance you need to multiply the result by 1.3. Even so, this is not really that accurate.

For a more concise description take a look at epanorama.net/Speaker impedance
http://www.epanorama.net/documents/audio/speaker_impedance.html
 
#18 ·
No, I understand it's DC resistance, but it still close enough that you can figure it out. DC Resistance is fairly close to the actual average impedance of the driver. You're correct about impedance changing through out the frequency. Just figured it was easier for most to understand.
 
#19 ·
So in reality from your measurements all but the tweeter are nominally 4 ohm speakers. Compatible with 99.9% of replacement speakers.

Tweeters are often a higher impedance as the greater value works as an attenuator and allows the tweeter to cope with a much higher input power than is actually needed. Typically an average tweeter with an actual 4 ohm impedance would only need a tenth of the power that an average bass speaker does (yes, I know that efficiency can also have a large bearing on this). By making them a higher impedance it does away with the need for a proper crossover.
 
#24 ·
I'm having trouble understanding that statement. Your own measurements show the DC resistance to be 2.1 ohms, the rough guide multiplication factor converts this to 2.73 ohms (which is only a rough guide but still well above 2 ohms) so I have no doubt at all that if the impedance was measured properly at the standard 400Hz the true value would be far closer to 4 ohms than it would be to 2 ohms.
 
#27 ·
Ok, fair enough but I am a (UK) degree qualified electroincs engineer of some 30 years experience, 10 years of which were spent in car audio design and installation. I've had a passion for domestic and PA loudspeaker design since I was a teen (I'm now in my 50's!!). Not professing to know everything about the subject by a long way but I have done a lot of measurements of car audio systems - and with the correct equipment. I had a look at the Madisound web site but can't find any useful information on there. Any chance of a link?
 
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