Complete system upgrade final question
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Joined: Dec 2007
Posts: 63
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From: Mannheim
Complete system upgrade final question
I have a 2005 coupe with Bose no On Star. I have been reading all of the posts from everyone and have picked out all of the parts for my stereo:
I currently have sitting in my living room:
Pioneer AVIC-Z2 w/ bluetooth adapter
JL Audio 500/5 amp
Polk MMC6500 components for the front
Polk MMC525 Coaxial for the rear
antenna adapter
Metra install kit
Speaker plates
Peripheral GMCO and GMAHCM.
I am getting ready to order the driver and passenger side sub box from madvettemotorsports and I am planing on using the JL Audio 10W1V2 in the boxes.
My question is with the 500/5 should I get 2 4-ohm subs and parallel them to 2 ohms on the sub channel? The specs for the amp are:
Rated Power Sub woofer Channel: 250 W RMS @ 1.5 ohm-4 ohm (11V-14.5V)
Does that mean that I need to put 1.5 ohms on the amp to get the full250W?
It's been about 10 years since I have dome a complete stereo so sorry if this is a dumb question. Just want to make sure it all sounds good
for the $$$ it's costing me. 
Thanks in advance for your help.
I currently have sitting in my living room:
Pioneer AVIC-Z2 w/ bluetooth adapter
JL Audio 500/5 amp
Polk MMC6500 components for the front
Polk MMC525 Coaxial for the rear
antenna adapter
Metra install kit
Speaker plates
Peripheral GMCO and GMAHCM.
I am getting ready to order the driver and passenger side sub box from madvettemotorsports and I am planing on using the JL Audio 10W1V2 in the boxes.
My question is with the 500/5 should I get 2 4-ohm subs and parallel them to 2 ohms on the sub channel? The specs for the amp are:
Rated Power Sub woofer Channel: 250 W RMS @ 1.5 ohm-4 ohm (11V-14.5V)
Does that mean that I need to put 1.5 ohms on the amp to get the full250W?
It's been about 10 years since I have dome a complete stereo so sorry if this is a dumb question. Just want to make sure it all sounds good
for the $$$ it's costing me. Thanks in advance for your help.
Melting Slicks
Joined: Aug 2003
Posts: 2,786
Likes: 7
From: Iowa
the impedance of the sub is the resistance on the circuit for that speaker, the lower the resistance, the more power output you get. I don't see how they could have designed an amplifier which would output the same wattage over such a wide range of 1.5-4 ohms. at 1.5 ohms the amp will put out over double the wattage that it will with a 4 ohm load. the only way I can see that JL could get away with that would be to have the amp automatically throttle back at lower impedances...and that makes no sense whatsoever.
Thread Starter
Advanced
Joined: Dec 2007
Posts: 63
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From: Mannheim
That's what I was thinking and why I had to ask. I have always seen the amps advertise the wattage at each impedance. I would say then running 2 ohms will get me as close as possible to the 250 they advertise.
Melting Slicks
Joined: Aug 2003
Posts: 2,786
Likes: 7
From: Iowa
just in case the formula for calculating the overall resistance when wiring in parallel is:
1/R = 1/r1 + 1/r2 +...
for series its much easier
R = r1 + r2 + r3 etc
where R is the final resistance, and r1, r2 etc are the individual resistances of the drivers.
remember also that the B+ voltage will affect amplifier output as well. the spec says 11V-14.5V, well the amplifier is going to make more wattage at 14.5V than it is at 11V. how much more depends on the efficiency among other factors of the amplifiers circuitry.
Le Mans Master
Joined: Jun 2004
Posts: 9,289
Likes: 16
From: Skippack PA
St Jude Donor '13
You guys are thinking in analog terms, and from that approach you are correct. But the Alpine PDX, and I suppose looking at those specs this JL amp in question, are digital amplifiers. Whatever circuits they use delivers the same output over that specified resistance band.
The old rules don't apply once you get to class D.
The old rules don't apply once you get to class D.
Burning Brakes
Joined: Feb 2004
Posts: 1,229
Likes: 0
From: Kansas City MO
Here is a little info about JL's RIPS power supply in that amp.
http://mobile.jlaudio.com/products_a...php?page_id=46
http://mobile.jlaudio.com/products_a...php?page_id=46
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Thread Starter
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Joined: Dec 2007
Posts: 63
Likes: 0
From: Mannheim
Yes that is very cool! Thanks for the help. My how things have changed since my last stereo install. Now I just need to stuff all that gear into the car and see about some premature hearing loss!