Component Speaker Impedance

[JoeyWelch]

 

 

So I put my soundbar for my Jeep together this afternoon which consisted of 4 8” coaxials and two 3” tweeters. All speakers are 4 ohm. The tweeters have a highpass filter on them of course. I was expecting to read something close to 2 ohms on each pair wired in parallel but to my surprise the DMM read 4.1 ohms on all 4 channels. What gives? Can someone explain?

Since I obviously don’t know what I’m doing, I’ll call this a theory. I’m thinking that the HP filter isn’t letting the DMM read the impedance on the tweeters but when the tweeters do play because the HP filter allows a frequency to pass, the impedance will the be the expected 2 ohms per say, on channels 3&4.

Am I on the right track or do I have something screwed up?

Thanks for any help

[Dafaseles]

If you can find the T/S parameters on the speakers you're using, what is the RE?

Basically, the manufacturer considers those speakers to be their 4 ohm speakers. That doesn't mean the voice coil is 4 ohm. I've seen brand new subwoofers read no where close to what they are considered by the manufacturer. 

I remember a pair of L7's I had that where dual 4's. Each voice coil read, if I remember correctly, read almost 6 ohms each. They where all the same, so it didn't cause any issues, but yeah. Just because they are listed by the manufacturer as their 4 ohm version, doesn't mean the coil will be 4 ohm unfortunately. 

[JoeyWelch]

RE (dc resistance) on the tweeters is 3.3 ohms.

RE on the coaxial is woofer 3 ohms and coaxial tweeter 3.6 ohms.

[Dafaseles]

Are those tweeters in the picture separate tweeters? Or the tweeters on the coaxials? 

[JoeyWelch]

They are separate.

 

Some else told me the HP filter is not letting voltage from the DMM pass through to read impedance on the tweeters there fore only the coaxial speakers are being included. 

[Dafaseles]

I've never heard of that, though I guess it's possible. 

By HPF, are you referring to caps soldered in line? Or the HPF on the amplifier? 

[JoeyWelch]

HP filter I’m referring to the caps soldered to the tweeters in line.

[JoeyWelch]

I removed one of the tweeters last night and checked impedance at tweeter terminal and it was 3.4 ohms. Checked it through the capacitor (HP filter) and could not get a reading.  So I’m pretty sure the cap is blocking the DMM. 

[Dafaseles]

Yep. You just verified it there. 

What amplifier are you using to power all this? 

The reason I ask is, would it be beneficial to wire the coaxials together, then leave the tweeters to have their own channel? I don't know if you have that option. Just throwing it out there

[JoeyWelch]

It probably would , I didn’t think of wiring it that way but I may just do that.

I could adjust the tweeter output separately then.