final impedance of the stock premium sound mids+tweets?

[paulkeith]

What is the final effective impedance of the stock premium midbass drivers + tweeters strung off the backside of them?

My goal is to run the stock premiums off a new headunit's internal amp, just want to make sure they're not an effective 2ohm or something before I hook them up to my headunit.

Also, which connector on the back of the premiums is positive? The wider or narrower spade connector?

Just quick background, currently stock 1989 premium sound.

Upcoming configuration:

Alpine headunit
new wires run to stock premium speakers
Alpine MRP-M500
EDesign 11Ov.2 in .5cf sealed

Eventual 4 channel amp and new components up front, coaxes rear. I'm running the 4 additional channels of RCA to the trunk in anticipation, but I'm hoping the headunit amp + stock premium speakers will hold me over for now.

Thanks in advance,
Paul

[Jean]

They'll be fine. No speaker is ever a static 2, 4 or 8 ohms. It changes with frequency.

[paulkeith]

really? did not know that. I looked tonight and see that the mid is rated at 4 ohms and the tweeters are rated at 8. They're wired in parallel so that comes out to 2.667 ohms, but does the "crossover" affect that any?

Whatever, doesn't really matter as long as the HU internal amp won't go into protection or overheat.

Thanks for your help.
Paul

[Jean]

Doesn't work that way with speakers. You are measuring DC resistance, and when speakers plays audio it's impedence is variable (the graph actually looks like Air to Fuel ratio if you ever looked at that, well it looks different for every speaker and every speaker combination, and yes crossovers have a lot to do with that as well). I wouldn't worry about it :)

[paulkeith]

I mean, i read those impedances off the stickers on the back of the speakers, I didn't sit there and measure DC resistance with a multimeter.

How is this situation different from wiring up a 2 ohm DVC sub in parallel to get a 1 ohm load on the amp, etc?

I'm not arguing, I want to understand.

Thanks,
Paul

[Jean]

http://www.mmxpress.com/technical/re..._impedance.htm :)

Wiring a 2 ohm DVC in parallel get's you a 1 ohm load yes, and wiring it in series get's you a 4. But still depending on what freq. it plays it's not a constant 1 ohm.

[paulkeith]

When a speaker is measured at 4 ohms, it is measured using a device that puts out DC current to do the measuring. The only other time the subwoofer will have anything near 4 ohms is when it is at resonance. The rest of the time, the voice coils impedance is very high. My 10" subwoofers reach a peak of 45 ohms, and they have a 6 ohm voice coils.

Cool. Thanks for the article.

So...which terminal is the positive one, the wider or narrower connector?

Thanks,
Paul

[woodisgood]

The positive is the wide blade that has the capacitor and the coil connected to it. The signal for the woofer goes through the coil and is already connected. The signal for the tweet goes through the capacitor and out to the tweet from the other wide blade connector on the same side of woofer as the input. The narrow post on the other side is ground for both woofer and tweet..

[paulkeith]

bonus. that's what I thought, just wanted to confirm. out of town for the 4th until sunday, but by that time the headunit, amp, and wiring should be waiting on me. shaping up to be a sweet sunday night....

[netcsk]

Doesn't work that way with speakers. You are measuring DC resistance, and when speakers plays audio it's impedence is variable (the graph actually looks like Air to Fuel ratio if you ever looked at that, well it looks different for every speaker and every speaker combination, and yes crossovers have a lot to do with that as well). I wouldn't worry about it :)

You're getting way too technical for this forum. Hah.

The impedance on the back of the speaker is the lowest impedance in the frequency range of the speaker. It is most often taken just after the resonance frequency of the speaker (the spike that you see in the impedance curve). On the picture that I've attached, the impedance curve is the bottom line and the impedance of the speaker will be called 4 ohms.