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#### Butcher78

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Hello, I'm a noob looking for some help. I can't seem to find the answer to the question - How many watts does each speaker receive wiring them in parallel or series. Lets say I have an amp RMS 90 watts x 4 channel @ 2 ohms with 2 - 4 ohm speakers wired in parallel dropping the resistance to 2 ohms, how many watts will be driving each speaker? I assume 45 watts is the answer, but I would like to confirm before staring my system. Also, is the answer the same for running them in series? Last question. Is it necessary to match the resistance of the circuit of speakers with the amp? Thanks

#### Jepalan

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Here is a good reference for you to read -> Series Parallel Speaker Impedance

Also this one -> How to Match Subwoofers and Amplifiers

Lets say I have an amp RMS 90 watts x 4 channel @ 2 ohms with 2 - 4 ohm speakers wired in parallel dropping the resistance to 2 ohms, how many watts will be driving each speaker?
In this ^ specific example, as long as the speakers are of identical type, they each would get approximately half the delivered power.

Is it necessary to match the resistance of the circuit of speakers with the amp? Thanks
Yes, it is necessary to provide the amplifier with a load impedance that falls within the range the amp was designed for. In most cases the amp specs provide the lowest stable load impedance. Higher impedance loads are generally OK to use.

For example: an amp that is rated for a 2-ohm minimum load should not be connected to a 1-ohm load, but it would work just fine with a 4-ohm load.

#### Butcher78

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#### Butcher78

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So, I have an amp rated for 60 watts x 4 @ 4-ohm / 90 watts x 4 @ 2-ohms / 175 watts x 2 @ 4 ohms. I am running 4 speakers RMS 75 watts, 225 watts peak & 4 ohm each . Should I wire home runs for each speaker with 60 watts onto a 4 ohm load or run 2 sets of speakers wired into series with 175 watts onto an 8 ohm load? Amp would be rated @ 4 ohms for both scenarios.

#### squeak9798

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To obtain 175w from that amp, you would have to wire the two sets of 8ohm speakers in parallel not series.

Anyways...what speakers are you talking about ? If they are, for example, front and rear speakers, you would not want to wire them together in either series or parallel because you would lose your ability to fade front-to-rear. There are very few instances where it would be recommended to wire them together.

#### Jepalan

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So, I have an amp rated for 60 watts x 4 @ 4-ohm / 90 watts x 4 @ 2-ohms / 175 watts x 2 @ 4 ohms. I am running 4 speakers RMS 75 watts, 225 watts peak & 4 ohm each . Should I wire home runs for each speaker with 60 watts onto a 4 ohm load or run 2 sets of speakers wired into series with 175 watts onto an 8 ohm load? Amp would be rated @ 4 ohms for both scenarios.

If you wire each 4-ohm speaker to it's own channel then you have 60 watts per speaker available for a total of 240 Watts of music power into your car.

The amp can put 175 WRMS into a 4 ohm load when bridged. It will only put about half of that into an 8 ohm load when bridged. So if you run a pair of series sets (8 ohms) on the bridged outputs, you will have about 175 WRMS of total music power available in the car.

You cannot run your speakers as parallel sets because the amp cannot handle 2 ohms bridged.

I would run each speaker on its own amp channel. This will get you the cleanest, loudest output for this amp & speakers

#### Jepalan

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Another option:

You could run the amp bridged to 2 channels and *only* connect the 2 front speakers (4 ohms each). Then you would have 90 watts available for each of the front speakers (where it matters most).

I would just connect the rear speakers directly from the speaker outputs of the head unit (since these should only be turned up slightly for rear-fill anyway).

#### Butcher78

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Yes, it is necessary to provide the amplifier with a load impedance that falls within the range the amp was designed for. In most cases the amp specs provide the lowest stable load impedance. Higher impedance loads are generally OK to use.
Sorry, I read this and thought I could get away with running an 8 ohm load on a 4 ohm rated channel. I'll stick with matching the amps rated resistance with the speaker/s resistance for now. I should have mentioned earlier this application is for a boat and the speakers are 4 - 6.5" Infinity Kappa model 612m powered by Kicker ZX350.4. They are located on the tower pictured. I will also be adding 4 - 6X9 Infinity Kappa model 9612m inside the boat before winter ends (still shopping for an amp to power these). I have a 12" MTX 7500 Thunder already installed powered by a MTX Thunder Amp bridged to 340 watts @ 4 ohms. Wiring the tower is a real pita and I don't have a lot of room in the access holes for more than 2 12 gauge wires. Can I get away with 14 gauge for the tower speakers? Will the speakers perform well with only 60 watts? thanks

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#### miniSQ

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60 watts is about all i would feel comfortable running to those speakers so you should be fine. 14ga wire is also fine. Are you able to High pass them so they dont have to play freq below say 90hz

#### Butcher78

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Looks as if I can adjust the freq from 50-200 Hz. Is this what you're referring to on the high pass question? Please inform me why you wouldn't want to run these with more than 60 watts? Is there a spec on them worries you? I'm still learning so your insight is greatly appreciated. Especially since I still need to by 4 more 6x9s and an amp to drive them.

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#### miniSQ

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Looks as if I can adjust the freq from 50-200 Hz. Is this what you're referring to on the high pass question? Please inform me why you wouldn't want to run these with more than 60 watts? Is there a spec on them worries you? I'm still learning so your insight is greatly appreciated. Especially since I still need to by 4 more 6x9s and an amp to drive them.
RMS: 150 watts per pair / 75 watts each

that and figuring you will be out on a boat...trying to over driver them to get loud music while drinking beer

They will last longer with 60 watts.

and yes...set that XO to about 80-90hz.

#### Butcher78

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I forgot to mention that I did some resistance testing on the speakers and came up with some interesting ohm loads. The infinity 6.5" 4 ohm speakers showed 3.19 ohms each, 2 speakers wired in parallel showed 1.67 ohms, 2 speakers wired in series showed 6.35 ohms. Is it normal for the factory specs to be off like this?

#### Butcher78

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that and figuring you will be out on a boat...trying to over driver them to get loud music while drinking beer
Ha! You're good at reading people. I like what you're saying here about getting more life out of them. :beerchug:

#### YukonXL04

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Just to get this out of the way... your not going to hear those while wake boarding lol. Hanging out behind the boat and wake surfing should be fine though. Have you already bought the speakers and amp in question? Also being on the tower you would be just fine bridging the amp. However in your application with those speakers, it won't do you any good.

#### miniSQ

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Just to get this out of the way... your not going to hear those while wake boarding lol. Hanging out behind the boat and wake surfing should be fine though. Have you already bought the speakers and amp in question? Also being on the tower you would be just fine bridging the amp. However in your application with those speakers, it won't do you any good.
i do not think the amp is stable to 2ohm bridged, i was going to suggest that earlier to save wiring hassle. But no need to melt the amp if it is not stable.

#### YukonXL04

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What I meant was being on the tower wiring pairs of speakers together doesn't pose a problem because you usually won't notice whether they are stereo or not like you would in a car or even in the cabin of the boat.

You are correct that amp isn't 2 ohm stable bridged. Even if it was I wouldn't do it because it would get too hot on a boat lol.

#### Butcher78

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Just to get this out of the way... your not going to hear those while wake boarding lol. Hanging out behind the boat and wake surfing should be fine though. Have you already bought the speakers and amp in question? Also being on the tower you would be just fine bridging the amp. However in your application with those speakers, it won't do you any good.
I'm fully aware these will not through sound 70 feet behind the boat over the noise of the engine. We need music while anchored or at the dock. The 4 - 6.5" tower speakers were purchased last month & I already had the amp. I would love to go with a Wet Sounds system, but it's a little beyond my budget. Do these speakers & amp suck? Please don't entertain me straight talk is appreciated. I have thick skin. Thanks

#### squeak9798

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I forgot to mention that I did some resistance testing on the speakers and came up with some interesting ohm loads. The infinity 6.5" 4 ohm speakers showed 3.19 ohms each, 2 speakers wired in parallel showed 1.67 ohms, 2 speakers wired in series showed 6.35 ohms. Is it normal for the factory specs to be off like this?
What you are measuring with the DMM is called the DC Resistance, or DCR (referred to in thiele small parameters as Re). This is different than the nominal impedance of the speaker, which is the 4ohm as rated by the manufacturer. DCR is the resistance of the coil at DC (direct current, like your car battery) as if the coil were acting as a resistor. However, music and test tones and sine waves are all composed of AC (alternating current). With AC, due to inductance and the motion of the coil and other various factors, the impedance of the speaker will vary with frequency. That 4ohm nominal rating is sort of the average impedance of the speaker over the intended operating bandwidth. Sometimes it will be higher (from a little to a lot), sometimes it will be lower (not much, but a little lower)...but the "average" impedance while in use will be around 4ohm.

So, in short, the manufacturer spec wasn't off...you measured resistance not nominal impedance. For your purposes you can ignore your measurement. You want to use the 4ohm rating.

#### Butcher78

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What you are measuring with the DMM is called the DC Resistance, or DCR (referred to in thiele small parameters as Re). This is different than the nominal impedance of the speaker, which is the 4ohm as rated by the manufacturer. DCR is the resistance of the coil at DC (direct current, like your car battery) as if the coil were acting as a resistor. However, music and test tones and sine waves are all composed of AC (alternating current). With AC, due to inductance and the motion of the coil and other various factors, the impedance of the speaker will vary with frequency. That 4ohm nominal rating is sort of the average impedance of the speaker over the intended operating bandwidth. Sometimes it will be higher (from a little to a lot), sometimes it will be lower (not much, but a little lower)...but the "average" impedance while in use will be around 4ohm.

So, in short, the manufacturer spec wasn't off...you measured resistance not nominal impedance. For your purposes you can ignore your measurement. You want to use the 4ohm rating.
Thanks for schooling me on this Squeak. Is there a way to test for nominal impedance? I'm assuming you would have to tap into the speaker loop while in use?

#### squeak9798

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There are ways, but it's really unnecessary for most hobbyist purposes. If you search the net for methods to measure a speakers impedance curve there are many methods available depending on the level of equipment and resources you have access to. But unless you really need the curve for some specific design reason, it is perfectly acceptable to just accept the manufacturer's impedance rating at face value. Unless you have a fair understanding of what is going on, beyond a novice level, an impedance curve is just going to confuse the hell out of you

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