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Old 08-05-2016, 07:24 PM   #1
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Hey guys, my brain is stuck. I have a 4 ohm kenwood deck, want to wire in two sets of rear speakers, two speakers on each side. Speakers are 4 ohm, so will have 8 ohms total on each side. Do they need to be wired in series or parallel? I was thinking parallel so would total 2 ohms each side.....but audio guy mentioned series?
Please advise. Thanks!

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Old 08-05-2016, 07:54 PM   #2
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Hi Giller.
Just like you said. If you connect the speakers in parallel, resistance will be 2 ohms. If you will connect them In line, it will be 8.
Just to make sure we are on the same page, full shortcut, is 0 ohms.
So the lower the number is, the resistance is higher.
If you go with 8ohms configuration per side, your unit will have less load, but you will experience decrease in volume.
At the 2 ohms configuration, you will get more volume, but the unit will work harder (after all, more resistance on the output).
The question is, what is the unit specifications, and can it hold the loade?
As far as I know, there is no head unit that can handle 2 ohms.
You will just burn the outputs.
If you are using an amp, it depends on the amp specs.
Today, most amps can handle 2 ohms with no issue.
Subwoofer amplifiers (mono) can get down to one ohm easy. So is most modern 4&5 channels amps.
So to answer your question is, go with in-line configuration.
You are going to loose some volume, but you will not blow up the unit (unless specs specefi 2 Homs operation is no problem).

Last edited by Meir; 08-05-2016 at 08:01 PM.
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Old 08-05-2016, 08:37 PM   #3
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Perfect, thanks Meir. Sounds like I do want to go series - more ohms = less power draw on head unit. Might add an amp at some point, but right now everything is coming from the main deck, and it's at 4ohms, so need to stay above that. Great!
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Old 08-06-2016, 03:21 AM   #4
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you'll get 1/2 the power out of each leg that would otherwise be available out of that leg/channel if it were driving 4 ohms. If you found 2 2ohm speakers and wired them in Series then you would get full/max power out of each leg/channel. Head unit can't drive 2 ohms, amp chips will get hot and go into protect probably, but try enough times, and they will smoke.
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Old 08-06-2016, 04:49 AM   #5
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Hi Giller.
Just like you said. If you connect the speakers in parallel, resistance will be 2 ohms. If you will connect them In line, it will be 8.
Just to make sure we are on the same page, full shortcut, is 0 ohms.
So the lower the number is, the resistance is lower
If you go with 8ohms configuration per side, your unit will have more load, but you will experience decrease in volume.
At the 2 ohms configuration, you will get more volume, but the unit will work harder (after all, less resistance on the output).
The question is, what is the unit specifications, and can it hold the loade?
As far as I know, there is no head unit that can handle 2 ohms.
You will just burn the outputs.
If you are using an amp, it depends on the amp specs.
Today, most amps can handle 2 ohms with no issue.
Subwoofer amplifiers (mono) can get down to one ohm easy. So is most modern 4&5 channels amps.
So to answer your question is, go with in-line configuration.
You are going to loose some volume, but you will not blow up the unit (unless specs specefi 2 Homs operation is no problem).
Overall correct, just mixed up a bit. Lower resistance means more current.
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Old 08-06-2016, 08:11 AM   #6
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you'll get 1/2 the power out of each leg that would otherwise be available out of that leg/channel if it were driving 4 ohms. If you found 2 2ohm speakers and wired them in Series then you would get full/max power out of each leg/channel. Head unit can't drive 2 ohms, amp chips will get hot and go into protect probably, but try enough times, and they will smoke.
Agree, except it sounds like OP is talking small rear speakers, which are not going to be hard to drive, regardless of how they're wired.

I just did this...replaced the 4 rear speakers that had rotted with new aftermarket. Nothing fancy and I wired them like the factory. I'd have to look to see what impedance speakers I bought. 3" speakers are not going to be loud either way!
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Old 08-06-2016, 07:06 PM   #7
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You really can't wire speakers in series without it sounding like crap. The reason is that speakers don't have a simple resistance. They have an impedance which means that the resistance changes based on the frequency. This is because each speaker's windings are basically coils. Coils can be used to filter out high frequencies for subs.

If you want to keep your full spectrum of frequencies, you will have to wire each speaker pair in parallel. Then on one side of each speaker pair, you could add a 2 ohm resistor. Make sure the resistor can handle at least 1/4 of the amps output power, or pick up a speaker rheostat from Radio Shack and adjust it to 2 ohms.

Personally, I would try it without and just lower the output to the rears with your fader control. The worst that can happen is you burn out a fuse in the head unit, or start a fire and burn down your car
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Old 08-06-2016, 10:46 PM   #8
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Thank you NewB, for correcting that with speakers, it is impedance, not resistance. They are both measures in ohms, so it is often confused.

A trivia question....Does anyone know what conductance is measured in? Hint, conductance is the inverse of impedance

I did pro sound for 15+ years and as far as speakers wired in series sounding like crap, well I would have to disagree with you there. It really makes no difference to sound quality if they are in series or parallel.
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Old 08-07-2016, 09:09 AM   #9
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I did pro sound for 15+ years and as far as speakers wired in series sounding like crap, well I would have to disagree with you there. It really makes no difference to sound quality if they are in series or parallel.
You can wire subs in series, since you don't care about high frequencies, and passive filters for subs are basically coils anyway. But you cannot do that for full range speakers. The reason is that the frequency response that you will be sending to each speaker will be proportional to the inverse of it's impedance graph (or conductance as you pointed out). Just google some speaker impedance curves and see if that's the response curve you want to be sending your full range speaker.
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Old 08-07-2016, 04:18 PM   #10
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Well, the job is done. Subwoofer installed (Kenwood KSC-sw11) and it fits beauty under the passenger seat. Not going to blow the windows out, but adds some nice depth to the music. And the 4 JL's wired in series (2 and 2) in the rear really help fill out the cabin. System sounds very good - much better than before.

No audio expert - but can say the speakers in series sound just fine - certainly not 'crap' as posted they would.
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Old 08-07-2016, 05:20 PM   #11
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Well, the job is done. Subwoofer installed (Kenwood KSC-sw11) and it fits beauty under the passenger seat. Not going to blow the windows out, but adds some nice depth to the music. And the 4 JL's wired in series (2 and 2) in the rear really help fill out the cabin. System sounds very good - much better than before.

No audio expert - but can say the speakers in series sound just fine - certainly not 'crap' as posted they would.
And you own ears are what should always be the ultimate judge of an audio system, NOT the comments based on my ultra-anal compulsive perfectionism disorder!
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Old 08-07-2016, 06:38 PM   #12
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And you own ears are what should always be the ultimate judge of an audio system, NOT the comments based on my ultra-anal compulsive perfectionism disorder!
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Old 08-07-2016, 06:41 PM   #13
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Well, the job is done. Subwoofer installed (Kenwood KSC-sw11) and it fits beauty under the passenger seat. Not going to blow the windows out, but adds some nice depth to the music. And the 4 JL's wired in series (2 and 2) in the rear really help fill out the cabin. System sounds very good - much better than before.

No audio expert - but can say the speakers in series sound just fine - certainly not 'crap' as posted they would.
It ain't real without pictures

Did you have to modify anything to get the sub to fit under the seat?
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Old 08-07-2016, 08:12 PM   #14
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Is the sub in a box , and what model / type of JL s did you install I the rear ?
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Old 08-07-2016, 08:53 PM   #15
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The sub is super small, just slid right in, no problem. So yeah, while not the biggest sound, does quite fine in that small cabin.
I'll try to get a pic tomorrow.
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Old 08-07-2016, 08:55 PM   #16
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Put some JL TR350 CX's in the back. Nothing fancy - but for the money, good value I feel.
The sub is in an enclosure - google Kenwood KSC-SW11 for some pics. Fairly heavy, but quite compact.

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