[Grewe02]

Originally Posted by Crashnburn80

I just went and poked around on the ROF. The stock amp is 2ohm, most car stereo stuff is 4 ohm. Most seem to hunt down a 2 ohm sub (such as the JL 8W3V2 2 ohm sub) and use the facotry amp. If you use a 4 ohm sub on a 2 ohm amp you will loose 1/2 the power.

From this thread ----> HERE

Ok, after my trip to the car audio place, I'm slightly confused. From what the guy at the store was saying, I got the impression that the stock amp is using 1 Ohm, and the dual voice coil speaker is using 2 Ohms per coil. Is this correct? From my limited speaker / amp knowledge, I thought that a 1 Ohm amp was freakin gigantic. This stock thing is puny. Looks like a dang boomerang with a heatsink.

So, my question: In order to retain the stock amp and still utilize both voice coils, what kind of speaker do I need? I want to run an 8" woofer, mainly because I know there is a greater market for them than there is for the 6.5". Is the JL subwoofer mentioned in that thread a good one to use?

Thanks!

[Exparrot]

Jeep designed that amp to squeeze whatever power they could (hence, 1 ohm) out of a little footprint. Unfortunately, lower impedence = lower quality sound.

The factory amp is putting out only about 75 watts or so at 1 ohm, which means that even at 2 ohm, which is the lowest impedence I've seen on a sub, it'll be pushing 37.5 watts at peak performance. WAYYYYY too little for any aftermarket sub.

99% of the people who post in this forum say if you upgrade the factory sub, upgrade the amp as well. It opens up a lot of options and sound 300x better than just using the factory amp and/or sub.

[Grewe02]

Well ****.


I couldn't wait, and went and bought the JL sub in the link above... I'm going to install it, and just hope for the best. Worst comes to worst, I'll have to buy an amp to power this beast. $119 for the sub and grille, after tax and with a 10% Military discount.

[SirGCal]

Originally Posted by Grewe02

Well ****.


I couldn't wait, and went and bought the JL sub in the link above... I'm going to install it, and just hope for the best. Worst comes to worst, I'll have to buy an amp to power this beast. $119 for the sub and grille, after tax and with a 10% Military discount.

Getting in a hurry is why most aftermarket systems don't work or end up costing more than expected... 1) always plan out the full system in advance. 2) never change your system to take advantage of a 'deal' unless it's the items you wanted that fit your plan anyhow. 3) never listen to salesmen.. 90% or more of them are ignorant and have no real idea what they are talking about and how to properly match up equipment. Do your own homework and plan the system properly. Heck, half of their 'amp & sub specials' aren't even properly matched... It's sad really...

Also, it won't work well... (And don't try to break the outside forum link filters again or you could be banned...) Anyhow, if you got an 8W3v2-D2, you're going to also have a difficult time finding a proper amp for it... Your best bet is to look for something that puts out 100Wx1 @ 4-ohms and wire it up in series. Because finding an amp that puts out the tiny 125W or less at 1-ohm is going to be near impossible...

The stock amp (according to the FSM) only puts out 40W... If we even assume it can squeze out 75W as some have been tested... it's going to be at 1-ohm only... 2-ohms would result in less than 33W, 4-ohms less than 17W... And remember, RMS is all that matters... Plus the stock amp's design is less than optimal anyhow...

If that was the sub you ordered: a few amps that would work:
Clarion APX2120, half of an Alpine MRP-F250 (two channels bridged.. other two channels used for something else...), same with Pioneer GM-4300F... and that's about it for one JL 8W3v2-D2... It wasn't what I would have purchased for a single 8" sub setup... Also, a sub that strong would also need the cheap plastic box replaced with a proper MDF box or at LEAST reinforced properly with more fiberglass. Or you're going to get pinging, yucky sound.

As I've said once before, people that do something like this without the proper power or box rigidity and think it sounds great, I feel sorry for them because the only possible answers are 1) they don't know what they are missing 2) they don't know what they are listening for 3) they don't understand what the ping, echo, distortion, clipping, etc sounds like to know it's bad... And on top of all that, they can cause damage to their newly improperly installed equipment.

Lastly, what that guy did on 'that' forum scares the pants off me.. I can't believe he's content with it.. The sub box isn't sealed (notice the huge crease in the lower left of the second picture), it's not reinforced, etc... I can't believe he likes the result, espically with that sub... It's only about (at best) 6.5% of it's expected power level or 200W RMS...

[mylt1]

Originally Posted by Exparrot

The factory amp is putting out only about 75 watts or so at 1 ohm, which means that even at 2 ohm, which is the lowest impedence I've seen on a sub, it'll be pushing 37.5 watts at peak performance. WAYYYYY too little for any aftermarket sub.

a 2ohm DVC sub is either 1ohm or 4ohms. so there are a lot of 1ohm subs out there.

if your gonna change the factory sub you will need to build a box to fit inside the console.

[SirGCal]

Originally Posted by mylt1

a 2ohm DVC sub is either 1ohm or 4ohms. so there are a lot of 1ohm subs out there.

if your gonna change the factory sub you will need to build a box to fit inside the console.

Ya, but none that run on that low of a rated power as the stock amp... So it's pretty pointless..

[Grewe02]

Well as I expected, and as SirGCal predicted, I should've waited. The stock amp is NOWHERE near strong enough to pump this thing. I got the interior of the box gutted, and magled some of the screw clips to fit on there, and now I need to wire up an amp.

Question time: I've already got an amp lying around that I was going to use for my interior speakers, until I figured out that I'm an idiot, and bought a completely wrong type of amp. Here's to hoping that it'll work for this!

It's a Power Acoustik PS2-300 (300 Watt). I don't have the manual or anything for this right in front of me, but it says "Mosfet, Bridgeable, Crossover, HPF/LPF, BassBoost, 2ohm Stable" on the top cover. I know you said either 1 or 4 ohms, so I'm pretty sure this isn't going to be my lucky day. Is there any way I can hook this up and have it not sound like crap?

Thanks!

[SirGCal]

Well, bridged it will take 4-ohms and is rated for 170W RMS. While this is significantly more than the sub can handle on it's own, and therefore I can't recommend it legally, I will say it's a better choice than running it grossly underpowered. And if you set it up properly, shouldn't be the end of the world. To do it, wire the sub in series to get back to 4-ohms at the amp, bridge the amp to a mono output, and be sure to use my DMM instructions to properly setup the amp and it will help.

[USCGTWEET]

not to hijack but going the other way with this thread, if I want to uninstall the factory sub and amp how can I do it. And what I mean is if I wanted to remove it from my system by installng the tuffy console with out the sub how would affect things and could I expect a degradation in sound quality and what to do with extra wiring from the head unit? I have the Alpine head unit and I was just curious as to how this would affect things.

[SirGCal]

just remove it and unplug the wiring harness and you're fine...

[Exparrot]

Originally Posted by SirGCal

Ya, but none that run on that low of a rated power as the stock amp... So it's pretty pointless..

Thanks for clearing that up. That's pretty much what I was trying to say.

Saved by Sir again

[Grewe02]

Originally Posted by SirGCal

Well, bridged it will take 4-ohms and is rated for 170W RMS. While this is significantly more than the sub can handle on it's own, and therefore I can't recommend it legally, I will say it's a better choice than running it grossly underpowered. And if you set it up properly, shouldn't be the end of the world. To do it, wire the sub in series to get back to 4-ohms at the amp, bridge the amp to a mono output, and be sure to use my DMM instructions to properly setup the amp and it will help.

You are the MAN!!!!!Eleven!!!!!111!!!


Sounds good (to my untrained ear), and all I have to do now is cut the center console to let the speaker grille protrude from it. After 2 years, I've finally got some real bass in my Jeep. Thanks!!!

[Grewe02]

Ok, time for some pictures.



300 Watt amp is under seat







Thanks SirGCal!!! I'll let you know when the time comes for the rear seat box.

[mike_dippert]

back from the dead b/c i'm excited that grewe did what i did, but mine didn't come w/ a subwoofer to begin with.

[bman9089]

woah, nice work. No storage space left though, right?