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4x4x4dr
GenIII
 
3/07/2005
22:07:16
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 Subject: 2 ohm amp wiring question - good 8" sub?
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I have the following:
00' QC
Panasonic CQ-C330U HU
MTX MXA 4004 amp
Infinity Ref. 6000CS's in the front
Infinity Ref. 6002i's in the rear
Amp specs:
50W RMS x 4 channels @ 4 Ohms
100W RMS x 4 channels @ 2 Ohms
200W RMS x 2 channels bridged @ 4 Ohms
Questions:
First, how would I wire the speakers to get the 100W RMS x 4 channels @ 2 Ohms? Second, what are the drawbacks of doing so, if any? Third, I'm considering putting an 8" sub behind the driver side rear seat and would like opinions on what would be a good match with the amp that I have.
Any specs on a sub box would be great appreciated also.
Thanks
~Tracy
'00 4x4 SLT QC 4.7 Auto Mods:My Dak
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GraphiteDak
GenIII
3/07/2005
22:58:24
|  RE: 2 ohm amp wiring question - good 8
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If the speakers are 4 ohms each, which most are, they will get 50 watts each from the amp unbridged.
The amp is rated to have 2 ohms per channel unbridged, so if you put two 4 ohm speakers on one channel each speaker would get 50 watts but the amp would see a 2 ohm load and powering 100 watts through that channel.
Not really a way to get any more power to each speaker unless you BRIDGED each two channels and only ran two speakers total on that amp. Then you would get 100 watts to each single 4 ohm speaker and only be able to run 2 speakers.
Funny thing is you could run 8 speakers total all getting 50 watts each. But it's hard to get more than that to a single speaker while running more than two speakers.
You can try hokking two speakers per each bridged output and hope it doesn't overheat or worse, so you are basically stuck with running 4 speakers at 50 watts each. And if they are door speakers, that will be plenty!!!
I only bought a 2 channel amp and am running two speakers on each channel. It's more than enough for my factory speakers.
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Lurkin
Dodge Dakota
JOIN HERE
3/08/2005
09:12:47
| RE: 2 ohm amp wiring question - good 8
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I put a Q-logic QLT-.3508 behind the drivers side seat of my QC. The box fits with no wiggle room left over. You can look up the measurements on Crutchfield's site as I can't recall them.
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rhibo
Dodge Dakota
JOIN HERE
3/08/2005
12:33:08
| RE: 2 ohm amp wiring question - good 8
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Lurkin how does that sound?
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4x4x4dr
GenIII
3/08/2005
23:14:57
| RE: 2 ohm amp wiring question - good 8
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GraphiteDak, thanks for all the info. I've decided to go with 8" 4-ohm Rockford Fosgate Punch Stage 2 in the Q-logic box. Hopefully it will sound decent. I'm going to run the front components from the front 2 channels @ 50W each, the sub @ 200W bridged from the rear 2 channels and the rear speakers from the HU as filler at 25W each.
I'm still having problems with the alt whine. I have grounded the amp directly to the battery, but no help. I'm 99% sure the problem is the HU ground, but it is still a mystery to me, because I don't know how it is getting a ground. The black wire coming out of the universal adaptor is not connected to anything and the HU still works. I'm going to ground the HU to the battery as well tomorrow, but I'm not confident that it is going to help since it is definitely already getting ground from somewhere else. Any ideas?
~Tracy
'00 4x4 SLT QC 4.7 Auto Mods:My Dak
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GraphiteDak
GenIII
3/08/2005
23:33:10
| RE: 2 ohm amp wiring question - good 8
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4x4x4dr, I'd say if you run two channels in stereo mode (un bridged) for your front speakers that you could just put both the front and rear left speaker on the left channel of the amp and both the front and rear right speakers on the right channel of that amp. That would give 50 watts to each speaker and the amp would see a 2 ohm load thus running it's rated 100 watts per each of those two channels which should be with in it's rated limits. You probably wont even have it maxed out.
Then bridge the other two channels like you said and get the 200 watts to that one 4 ohm subwoofer.
That's how I have my two channel amp on my door speakers. Two speakers on each channel. You just can't FADE the speakers from front to rear, but who does anyway?
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4x4x4dr
GenIII
3/09/2005
08:11:37
| RE: 2 ohm amp wiring question - good 8
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Message:
GraphiteDak, thanks again! You have any thoughts on how the HU is getting ground from what I said above or any tests that I could run to try and figure it out?
~Tracy
'00 4x4 SLT QC 4.7 Auto Mods:My Dak
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Lurkin
Dodge Dakota
JOIN HERE
3/09/2005
08:35:42
| RE: 2 ohm amp wiring question - good 8
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rhibo, it sounds pretty good. I have a Kicker S8L7 in the box. It's the square sub, so the box had to be cut. It sounds pretty good. I had an Infinity 10" sub in the last truck I had, and the 10" had better sound quality, but the L7 keeps up reasonably well, given my install restrictions. Just power it well, I have an RF 301s driving a 2ohm load.
Since I did not want to lose any interior room, make, or pay, for a custom box, or modify seat brackets (like Graphite...), this was the best way forward for me.
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Lurkin
Dodge Dakota
JOIN HERE
3/09/2005
08:40:24
| RE: 2 ohm amp wiring question - good 8
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4x4x4x4x4x4..... :-)
...an install tip. When you install the box, just remove the driver's side seat back, not the entire seat. Remove the 2 Torx bolts from each side of the seatback frame, and the back lifts out.
I think it's easier then taking the entire seat out, then getting it pushed into place after the sub box is put in.
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4x4x4dr
GenIII
3/09/2005
14:49:33
| RE: 2 ohm amp wiring question - good 8
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Thanks Lurkin. I'll definitely keep that in mind when I install the box. Actually, I have already had that seat out once before whenever I was installing the amp. It is not difficult to remove, because there are only 4 bolts that hold it on and they are fairly easily accessed.
~Tracy
'00 4x4 SLT QC 4.7 Auto Mods:My Dak
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Lurkin
Dodge Dakota
JOIN HERE
3/10/2005
09:46:53
| RE: 2 ohm amp wiring question - good 8
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You are right, getting the seat out is not a problem, but getting the box positioned, putting the seat in, then getting it pushed back while trying to put the bolts in can be an unnecessary pain. Definitely your call though.
Oh yeah, another reason I removed the seatback was that I put the amp under the seat bottom, so removing the seat back allowed me to move the seat bottom up and down when positioning and adjusting the sub and the amp.
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GraphiteDak
GenIII
3/10/2005
23:25:09
| RE: 2 ohm amp wiring question - good 8
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The alt whine could be form the deck if the HU has some internal broken ground.
Try taking your amp(s) and run a strap from the metal ground of the truck to the outer connector of one of the RCA jacks on your amp. That usually does the trick.
As for the rear seat. I cut out the padding behind the seat and sinched my carpeted box up to the metal on the back of the cab by using straps and screws. I've got over an inch in between the box and the rear of the seat.
With my seat mods I can either lift the seat bottom up to adjust the amp(s) or I can lift the bottom up, then unhook the back from the brackets, and then fold the back down onto the bottom to access the sub or computer behind my seat.
You can see what I'm talking about in my pix.
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