Installing subs need amp advice

M

Maxamil

Founding Member

Feb 14, 2001

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Fresno, Cali

Jul 26, 2006

#1

• Jul 26, 2006

• #1

I have a JL audio power wedge system i bought for my car and they are 8 ohm and require 125W RMS each. When i look for amps i never see a 8 ohm measurement of RMS why?? What do i need to get my speakers to 4ohm or to get a 8 ohm amp?

 

blascrw

Member

Aug 19, 2004

191

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Opelika, AL

Jul 26, 2006

#2

• Jul 26, 2006

• #2

4 ohm is the usual for car 8ohm usual for home...

if you connect 2 4ohm speakers in parallel you get 4 ohm

the lower the ohm the greater the power until you reach the point of clipping of beyon the amps ability.

So if the wedge has 2 speakers at 8 ohm each you can wire them in parallel and run any bridgable amp in bridged mode...

a typical 100watt x2 channel amp will yield about 250 in mono or bridged mode...

You judt do not want to exceed 50% of their combined watt rating...unless you will be cautios with the volume...

Hope this helps.

 

blascrw

Member

Aug 19, 2004

191

1

16

Opelika, AL

Jul 26, 2006

#3

• Jul 26, 2006

• #3

addition

Sorry...

parallel is the +'s wired together and the -'s wired together

speakerA SpeakerB
+--------------+
|
|
|
+ terminal on amp

Same for - terminals

 

1

19stang66

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Apr 16, 2003

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Jul 26, 2006

#4

• Jul 26, 2006

• #4

OT but, Maxamil, your sig is kinda creepy. How does it know all of that stuff? I feel like i'm being stalked now...

 

T

tylerrocks

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Oct 13, 2005

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Big Spring, TX

Jul 26, 2006

#5

• Jul 26, 2006

• #5

hells yea

 

F

ForceFed70

That's why they call it "dope"

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Dec 6, 1999

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BC Canada

Jul 26, 2006

#6

• Jul 26, 2006

• #6

blascrw said:

if you connect 2 4ohm speakers in parallel you get 4 ohm

Click to expand...

I think this was just a typo, but so as not to confuse him... 2 x 8ohm speakers wired in parallel will have a net resistance of 4ohms.

Any amp will work... it's just that some will be louder than others. Some amps are capable of running bridged into a 2ohm load. Those amps will put out WAY more power if wired to a 2 ohm load vs a 4 ohm load (in theory twice as much power).

 

goom49

New Member

May 4, 2006

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Jul 27, 2006

#7

• Jul 27, 2006

• #7

Use these wiring diagrams. Pick out a setup that looks like yours. Sounds to me like you have "2 subwoofers"; "Single Voice Coil - 8 ohms". From that diagram you will be able to run your amp at 4 ohm, but if your speakers were 4 ohm you could run it at 2 ohms.

 

M

Maxamil

Founding Member

Feb 14, 2001

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Fresno, Cali

Jul 27, 2006

#8

• Jul 27, 2006

• #8

So if I have 2- 8 ohm subs hooked in a parallel configuration that require 125 watts each all i need for an amp is 250 watts @ 4 ohms?

 

goom49

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May 4, 2006

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Jul 27, 2006

#9

• Jul 27, 2006

• #9

if your talking 125 watts RMS then you should look for a amp that states a number closer to 500-700 peak watts at 4 ohms. What is the peak watts for your speakers? Look for an amp that does that added up.

 

goom49

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May 4, 2006

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Jul 27, 2006

#10

• Jul 27, 2006

• #10

Maxamil said:

So if I have 2- 8 ohm subs hooked in a parallel configuration that require 125 watts each all i need for an amp is 250 watts @ 4 ohms?

Click to expand...

Sorry doing too many things at once. Yes a amp that puts out ~250 watts RMS (or continuous power) is what you would need. Just remember that all these number are at near full volume, so if you dont turn it up you could use a bigger amp, but you dont need it.

 

F

ForceFed70

That's why they call it "dope"

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Dec 6, 1999

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BC Canada

Jul 27, 2006

#11

• Jul 27, 2006

• #11

Maxamil said:

So if I have 2- 8 ohm subs hooked in a parallel configuration that require 125 watts each all i need for an amp is 250 watts @ 4 ohms?

Click to expand...

That sounds about right. But the subs don't require that much.. that is the most they can take. Minimum requirement would be something closer to 50watts each.

Don't read too far into the ratings... there is no stereo equipment police out there. A 500W amp made by a quality name-brand manufacturere will often put out more power than a 1000W cheapy amp. Same sort of thing goes for subwoofers. Name brand stuff is usually pretty close (except the older sony explode stuff which was absolute crap).

 

goom49

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May 4, 2006

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Jul 28, 2006

#12

• Jul 28, 2006

• #12

BottleFed70 said:

A 500W amp made by a quality name-brand manufacturere will often put out more power than a 1000W cheapy amp. Same sort of thing goes for subwoofers. Name brand stuff is usually pretty close (except the older sony explode stuff which was absolute crap).

Click to expand...

Very good point, most quality companies will sent a test sheet with the amp that shows what that exact amp will output. For example I have a kicker that says 500 watts mono into 2 ohms, but the test sheets says more like 750 watts. The info for the model is a minimum, meaning they wont ship it unless its above that ratting.