Amp for 2 12w7's

 

Bronze Member
Username: Markd

UK

Post Number: 28
Registered: Apr-04
hi, i'm either going to get 2 10w7's or, if i have enough boot space, 2 12w7's. i'd use a jl 1000/1 for the 10's, as they only need 500w each. however, the 12w7's require 750w each, total 1500w. i'd like to get the most spl i can out of them, and the amp needs to have very good sq. can anyone recommend a good amp?
 

Silver Member
Username: Jmloughrey

Farmington, CT

Post Number: 169
Registered: Jul-04
even though i'm not a huge JL fan, i for some reason beleive the rule of thumb was something like 500/1 for 1 W7 and the 1000/1 for 2 w7's, it seems to make sence in my head, i do know the amps do put out a little more then 1000watts...someone wanna feild this question a little better?
 

Bronze Member
Username: Ffxdevilarms

Post Number: 65
Registered: Jul-04
a 12w7 does not require 750, it is just a rating. The jl 500.1 puts out way over 500, i would say close to 700 maybe. 1000 will be overkill for just one 12w7
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 1231
Registered: May-04
500/1 typically puts out 650-700W RMS
1000/1 benches between 1300-1400W RMS.
I'd do a 1000/1 for 2 12W7's personally. Power ratings are thermal, you can push any sub to it's limits below the rated power if your enclosure allows it.
 

Bronze Member
Username: Markd

UK

Post Number: 29
Registered: Apr-04
if jl design their amps that much underrated, wouldn't their subs be designed to take higher than their rated power also?

jonathan, what do you mean by 'Power ratings are thermal, you can push any sub to it's limits below the rated power if your enclosure allows it.'? i'm going to be using them in a sealed enclosure.


 

Robert J
Unregistered guest
Say the recomended box size for a 12w7 is 1.6 if you are putting the most power the company recomends then this is the box size to use and it will push that sub to it's peak ecusion. Now say you have a amp that is a couple hundred under that recomened power rating but you still want the sub to hit it's full ecursion. well all you need to do is make the box bigger. with the box being bigger there is less power need to compress the air in the box.
 

Bronze Member
Username: Jessejames

NB, PA USA

Post Number: 81
Registered: Aug-04
The JL subs have been known to take a lot more power than rated for, though they can also blow up too...
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 1250
Registered: May-04
If you use a ported enclosure and you set the subsonic filter below the tuned frequency (not by a lot, just 5-10 hz), the sub will unload (doesn't see the box anymore) and will reach full excursion much easier. At the tuned frequency the excursion is actually at it's least. Ported boxes actually have more sub control above tuning than sealed boxes do, but anywhere below the tuned frequency excursion will rise dramatically. Larger sealed boxes allow more excursion than smaller ones. The JL subs are equally underrated usually, I will say that the 12W7 may be a notch underpowered, but with a ported box you can easily reach full excursion if your subsonic filter is set to do so. What I mean about thermal ratings is this, a subwoofer's power rating is merely a thermal rating, not a power requirement, it measures how much heat the voice coils can withstand long term without failure. For example, an Adire Audio Brahma can handle 1600W RMS thermally, but typically will reach full excursion in a 1.0 cu ft. sealed box with about 800-900W RMS. Ported is even less than this if you're below the tuned frequency.
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