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Help, I designed a speaker problem

Old 05-20-2008, 06:33 PM
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Default Help, I designed a speaker problem

I am moving my standard issue radio/cd player from my console to my t-top electronics box.
I carefully measured all the wires, got good marine connectors, drilled the t-top legs to run wires and put the rubber grommets in place so eveything is very snug..... (so far so good...)

But I'm two wires short of what I need, and to add additional wires I need to redrill the post and to do that i need to remove the wires i fished through today (PITA!)

Any way can I "power' my speakers in a different way to use the wires i have?

Currently I have two sets of 4 ohm, 100 w speakers (bow and console mounted)
I have a power wire, a ground wire,and four speaker wires (two pair- 4 total) running through my top (not connected on either end).
To match what i had peviously i need three wires for each speaker set (left, right and common) at this point i only have two.

How can I rig this with what I have? I am not really concerned with left / right balance or front / rear for that matter... If i remember my EE classes correctly i can run each set in series (or parallel??) without reducing power but I figured I would ask some of you guys that know.

I know the correct way would be to remove and start over but the music is not a big deal to me and i only play it when the wife is on the boat...so anyone got an easy fix?

Thanks. ;?
Old 05-21-2008, 05:03 AM
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Default Re: Help, I designed a speaker problem

If you have a seperate amp, most will hold a 2 ohm load (but no radio's can), you can parallel the pairs of speakers if the are the same (i.e. - 4 Infinity 602's), which means you only need 2 pairs of wires total.
Old 05-21-2008, 05:24 AM
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Default Re: Help, I designed a speaker problem

why do you need the common wire? your speakers should just need a positve and negative connection.

what speakers do you have?
Old 05-21-2008, 05:43 AM
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Default Re: Help, I designed a speaker problem

You should be able to ground your speakers to any ground, does not have to go back to the amp or radio.
Old 05-21-2008, 07:44 AM
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Default Re: Help, I designed a speaker problem

If you use a vessel ground for the (-) of the speakers, you will likely pick up a lot of noise.
Old 05-21-2008, 07:52 AM
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Default Re: Help, I designed a speaker problem

Proline3250 - 5/21/2008 8:43 AM

You should be able to ground your speakers to any ground, does not have to go back to the amp or radio.
that is incorrect. most head units use a floating ground for the speaker outputs, so 2 wires are required for each speaker.

very old stereos (and those of poor quality) use the common ground system that you are referring to.

if he wired his stereo the way you suggested, it would probably cause damage to the internal amp.
Old 05-21-2008, 09:35 AM
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Default Re: Help, I designed a speaker problem

OK, so if you put two 4 ohm speakers in parallel, you end up with a 2 ohm speaker load on your stereo output, to low for a standard radio/CD player, so that will not work.

If you put two 4 ohm speakers in series you end up with am 8 ohm speaker load on your stereo output, that will work with a standard radio/CD player, but you will have less output power from the stereo amplifier than you did with a 4 ohm speaker load. The lower the speaker impendence the higher the output power, the higher the speaker impendence the lower the output power.

So try putting the two left speakers in series and hookup to the left front output, and put the right two speakers in series and hookup to the front right output. If you still have enough power you are all set. Remember when putting speakers in series connect the positive of one speaker to the negative of the other speaker, than connect the remaining negative and positive speaker leads up to the negative and positive stereo output leads.

Jim
Old 05-21-2008, 09:49 AM
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Default Re: Help, I designed a speaker problem

i misunderstood, nevermind my question about the common wire.
Old 05-21-2008, 10:48 AM
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Default RE: Help, I designed a speaker problem

To try and clear up some confusion. The radio is an older Jensen model (it actually has a cassete deck slot -- I'm very "old school")

The wires out of the back indicate :
L Front Gnd R Front
L Rear Gnd R Rear

Power (+) and Neutral (-)

If this doesnt contradict the previous advise I'll try the Left in series and Right in Series suggestion and check the sound production.

I probably just need to get a new radio and rewire though... (but thats like three gallons of HD100 oil !)
Old 05-21-2008, 11:01 AM
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Default Re: Help, I designed a speaker problem

Wiring's relatively cheap. Can you just pull what your stereo really requires through with the wires you just installed, or attach a temporary wire to pull through with the existing cables, add the 2 wires and pull all back through?
Old 05-21-2008, 07:44 PM
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Default Re: Help, I designed a speaker problem

I think thats what I will wind up doing. My problem is, I carefully bundled the wires and measured the total wire bundle diameter and drilled a 1/2" hole so the wires would fit snugly in the rubber grommett. Its not big enough for an extra set of wires so I have to remove all of them and re drill the hole larger. I still have the pull string in place.

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