Quote:
Originally Posted by Compelica
My understanding is that the HU amp sees a 2 ohm load based on the parallel wiring configuration on the tweeters and midbass. Both stock tweeters and midbass are at 4ohm, so if the tweeter is bypassed the circuit basically becomes a single sided speaker wired in series, hence that replacement speaker has to be 2ohm to match the impedence seen by the HU amp.
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That would be true if there were no passive filtering separating the frequencies to the tweeters and mid-range speakers underneath your dash grilles.
You have separates in the dash and although they are both 4-ohm drivers and indeed wired in parallel like you have discovered, the addition of crossovers in the circuit, i.e. the capacitors acting as a 6 db filter, make the sets act as a single 4-ohm speaker, and the head unit amp sees both as two 4-ohm loads. One right, one left.
Most factory head units, as well as almost all aftermarket units are not designed to run at 2-ohm loads and will get hot and eventually start distorting and cutting out as the volume is increased.
Coaxial speakers will also normally have capacitors mounted on the tweeters doing the exact same thing as what the capacitors in the separates are doing. And if you were to read the individual resistances of each driver of the coaxial speaker with an ohm meter, you would find that the readings are also approximately equal to each other, presenting a single-speaker load to the head unit approximately equal to the ohm-reading that you read of both the tweeter and mid-range drivers. It would not be half of what you read.
So what you basically will be doing is removing the factory tweeter from its spot next to the mid-range in the dash and adding another tweeter directly on top of a new mid-range driver that you are installing as a new set of coaxials.
Does this explain it a bit better for you?
P.S. I've never seen a set of two-ohm aftermarket coaxials. Not saying that they don't exist, I just haven't ever seen any.