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Quick CAR AMP Question......

E

ECE

Member
MTX amp rated at 12.5Vdc
60w x 4 @4ohms
120w X 4 @2ohms
240w X 2 bridged @4ohm

currently i have 4 4ohms component speakers on each channel, each getting 60w. Can i pair them up in parallel to get a 2ohm load at 120w and bridge the other 2 channels for my new sub to drive 240w through it? Trying to maximize my amp before spending more money!! TIA!
 
yeah i realize that but my choices: buying 2 new subs, a new box, and a new amp over just getting 1 sub and losing fader control...hmmmmmmm
 
amp the front speakers 60 x 2, bridge the other 2 for the sub 240 x 1, power your rear speakers with the headunit, or disconnect them.
 
why cant i put 2 speakers in parellel at 2ohms so that i'll get 120w x 2 at 2ohms? is it because of the fader control ability? the HU only supplies about 20W rms and i have all mb quartz component speakers and 20W through them wont be as good. 🙁
 
Originally posted by: ECE
why cant i put 2 speakers in parellel at 2ohms so that i'll get 120w x 2 at 2ohms? is it because of the fader control ability? the HU only supplies about 20W rms and i have all mb quartz component speakers and 20W through them wont be as good. 🙁
Click to expand...
Heh heh...that's what they want you to think 🙂
 
With a 2 ohm load on the first 2 channels, plus bridging on the remaining 2, the amp will get much hotter, and won't actually produce as much power (volume) as before.

The two ways to "do it right," according to all my research and many conversations over the years:

1. Keep your existing setup as is and get another amp for the sub.

2. Don't get another amp, ditch the rear speakers, and run the amp as a three channel. (You can also run the rear speakers off the HU, but that's kludgy, IMO. If you're going to do that, you'll need to re-set the front gain on the amp so that one pair doesn't start to distort at a lower volume setting than the other, and I think a passive crossover, like a "bass-blocker," might be a good idea for the rears, since the sub will provide the lower frequencies.)
 
now that was the answer i was looking for! thanks gonagle! kinda hard to ditch the rear speakers as i drive an suv and with that taken out, there would be a 'sound gap' in the back. decisions, decisions....
 
Originally posted by: Howard
There's only a small difference in SPL between 60W of input and 120W.
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What do you mean? I am currently powering one speaker with 60W and i was wondering if i can power both of them with one channel by putting 2 in parallel to drop resistance to give me 120W for both speakers.
 
Originally posted by: ECE
Originally posted by: Howard
There's only a small difference in SPL between 60W of input and 120W.
Click to expand...


What do you mean? I am currently powering one speaker with 60W and i was wondering if i can power both of them with one channel by putting 2 in parallel to drop resistance to give me 120W for both speakers.
Click to expand...
I mean that it won't get that much louder with 120W as opposed to 60W.
 
Originally posted by: Howard
Originally posted by: ECE
Originally posted by: Howard
There's only a small difference in SPL between 60W of input and 120W.
Click to expand...


What do you mean? I am currently powering one speaker with 60W and i was wondering if i can power both of them with one channel by putting 2 in parallel to drop resistance to give me 120W for both speakers.
Click to expand...
I mean that it won't get that much louder with 120W as opposed to 60W.
Click to expand...


exactly, but now i would have 2 speakers being powered by one channel as oppose to using 2 channels.
 
When I first installed my AMP, I had a similar question.
Mine is:
80x4 @ 4 ohms
120x4 @ 2 ohms.

I too had 4 4 ohms speakers and I was trying to get all four running at 2 ohms to get the extra power but thats not possible. Only way for me to run all 4 at 2 ohms is to get 4 2 ohms speakers.

Anyway....sure you can do that but
1) as someone said....it would run much hotter.

2) Yeah, the first 4 speakers would be running at 2 ohms, but it wouldn't be running at 4x120. Think about it.....4x120w and the other 2 channels bridged at 240w...wheres the extra wattage come from ???
The AMP is rated 4x120 OR 2x240...if you're going to run 5 speakers total, you won't be getting 4x120 and 1x240.

3) as someone said, ditch the rear speakers....do you drive alone most of the time ??
If you truely have a good system.....you would have the fronts driving the highs and the woofers in the back driving the low...its a wonderful combination.
When you have the front with the highs and then also the back producing highs....it doesn't sound right at all.
I was messing with my car the other day and I came to the same conlcusion as everyone been saying all along. You're really just distorting the sounds when amping the back speakers.
 
Originally posted by: CTrain

2) Yeah, the first 4 speakers would be running at 2 ohms, but it wouldn't be running at 4x120. Think about it.....4x120w and the other 2 channels bridged at 240w...wheres the extra wattage come from ???
The AMP is rated 4x120 OR 2x240...if you're going to run 5 speakers total, you won't be getting 4x120 and 1x240.
Click to expand...

actually i would be using only 2 of the channels to run 4 speakers at 120w X 2 @ 2ohms (2 4ohms in parallel) and the other 2 bridged to give me 240w X 1 @ 4ohms for the new sub. no?
 
You can parallel the right speakers (2 4ohm coils = 2ohm final load, you already know this) and parallel the left speakers, and have them goto the corresponding front channels. You'll still have left/right fader control this way. Bridge the rear channels to your sub for a 240w @ 4ohm load. All of this is can be handled pretty well by your amplifier.

Also, the outputs given are at 12.5 vdc. You'll most likely see 13.5-13.8 volts realistically. But I can't remember if MTX runs regulated or unregulated power supplies in their amplifiers. If its unregulated, you'll see a bit more power. Not anything that will even be noticeable, most likely.

Also to those above:

Double power or cone area ~ 3db gain. 10db = double in loudness.
 
Originally posted by: ECE
Originally posted by: CTrain

2) Yeah, the first 4 speakers would be running at 2 ohms, but it wouldn't be running at 4x120. Think about it.....4x120w and the other 2 channels bridged at 240w...wheres the extra wattage come from ???
The AMP is rated 4x120 OR 2x240...if you're going to run 5 speakers total, you won't be getting 4x120 and 1x240.
Click to expand...

actually i would be using only 2 of the channels to run 4 speakers at 120w X 2 @ 2ohms (2 4ohms in parallel) and the other 2 bridged to give me 240w X 1 @ 4ohms for the new sub. no?
Click to expand...

Your going to drive 4 speakers with 2 channels so your statement of "4 speakers at 120w X 2 @ 2ohms" doesn't make sense although I know where you're coming from.
Don't know how exactly the numbers but maybe you will get 60wx4 instead of the 120x2 by driving 4 speakers.

I thought you thought you were going to get 120x4 @ 2 ohms when connecting the 4 speakers to the 2 channels.
 
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