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How Would You Wire This Up?


shawndoggy

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I'm struggling on how to wire up my cabin speakers. Amp is a jl xd600/6. Speakers are all Polk mm651um's. These speakers are 3 ohms. Can I safely run parallel on a single channel?

Layout is four speakers in the cabin, two speakers on dash, two in bow. Thought was to wire cabin speakers to their own channels and then run the dash and bow speakers parallel, so I could bring down the gain on those to balance the sound in the cabin (bow sound is of no significance to me).

Help me smart guys!

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Interesting on Polk's page they say they are 4ohm.

http://www.polkaudio.com/caraudio/specs/6-1-2/speakers/mm651um/

"Normally" JL is conservative and could take a slightly lower impedance (ie rated for 2ohm, you are probably okay at 1.5ohm) but in general I'd avoid that if I could. In particular in a boating environment where you may run things a bit "hot".

As for how to wire them. You can run 2 on one set of channels and the rest on their own. The question becomes what do you want to fade/balance between from the headunit and what can you balance only from the amplifier gains. Personally I'd probably run the 4 cabin speakers on their own channels and the bow/dash on their own...but an awful lot of my high level listening is done sitting still when I'd actually fade out the dash and bow.

Your other option is to run the bow off the headunit or pick up an uber cheap used small amp for them. I literally just threw away a couple old school 30w amps that would be fine and could be had for $30 used. *feeling like an idiot now btw*

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If it is a silver 'UM' version then it is a 4-ohm impedance even though the DCR may read lower. In that case you can run two speakers in parallel on one channel.

If it is the black non-UM version then the impedance is 2.7-ohms in which case you cannot run two speakers in parallel.

Even if the amplifier will drive 1.35 ohms (two 2.7 in parallel) without a thermal shut down it would be because the smart protection circuitry cuts back on the rail voltage in self preservation which would impact all channels and cut back on the overall output power in the process.

So if it is the 4-ohm version you are okay but if it is the 2.7-ohm version then you need to add a two channel amplifier for a total of eight channels to drive eight speakers.

David

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I am pretty sure the upside down horseshoe under the work polk audio is the 3 ohm sign which could be 2.7 ohms rounded up to 3????

Edited by Bozboat
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Here is the tricky part. Polk rates that speaker (MM651UM) as a 4-ohm model in its own manual yet the sticker states 3-ohm. Polk is an absolute mess in ME. They even have a non-UM 2.7-ohm model which normally has a black grill with a silver grill made just for Nautique OEM. So alot can depend on the origin or channel of distribution for the speaker.

So here is what I recommend.

Calibrate your meter and check the DCR. The DCR will almost always be well below the nominal impedance. It is possible to have an narrow impedance dip below the DCR but fairly rare in a basic speaker. If the DCR reads above 3-ohms consider it a 4-ohm impedance. If the DCR reads below 3-ohms consider it to be a 3-ohm impedance. And let that dictate your amplifier configuration.

David

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I'm struggling on how to wire up my cabin speakers. Amp is a jl xd600/6. Speakers are all Polk mm651um's. These speakers are 3 ohms. Can I safely run parallel on a single channel?

Layout is four speakers in the cabin, two speakers on dash, two in bow. Thought was to wire cabin speakers to their own channels and then run the dash and bow speakers parallel, so I could bring down the gain on those to balance the sound in the cabin (bow sound is of no significance to me).Help me smart guys!

That's how I would do it.

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