Advise on System Set-Up / JL8w0

C

ChipG

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I have been putting together a simple system that includes a home built "Stealthbox copy" with a JL8W0, a new Alpine 9857,
and just ordered an Alpine MPR-F450 amp and JL XR650 speakers.
My idea is to run the front speakers ( XRs) off the amp @ 75 watts each and bridge the other 2 channels to run the 8W0. The
rear door speakers will be run off the head unit internal amp.
As I'm only running an 8" sub, What is the best way to cross over the speakers and sub to get as much clean bass as possible ? Should the sub box have fill in it ? Should the rear door speakers have some type of choke or bass blocker since there is no way to cross over thru the head unit ?

I'm really just trying to get some ideas of what settings HZ etc to consider as I haven't seen the XR cross overs or the Amp settings for bass boost and cross over ?

I'm currently running the 8 off an old Jensen amp with no controlls and the bass is pretty boomy rather than thumping.
I hope with the new amp and it's controlls, the bass will be more tune-able.
 
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I think your original plan will sound bad.

It would be much better to drive the four door speakers with your 4-channel amp (as that amp is probably designed for four 4ohm speakers) Then use a separate mono amp for the subwoofer. Your Alpine HU will have RCAs just for the subs (in other words only low frequency will be delivered to the mono amp)

When you start mixing and bridging speakers, you must make sure that the amp is not seeing any 2 ohm loads, if the amp is not 2 ohm stable!!

There may be a way to do what you want (maybe with external crossovers), but someone with better experience than I have should advise you.
 
The JL 8W0 is a 4ohm woofer

The JL 8W0 is a 4 ohm woofer. The Alpine MPR F450 has channels 3 & 4 bridgeable for sub applications.
 
I see, than it does look more promising, however the if you listen at high volume levels, the rear door speakers will clip much sooner than the amp driven ones
 
greasefingers said:

It would be much better to drive the four door speakers with your 4-channel amp (as that amp is probably designed for four 4ohm speakers) Then use a separate mono amp for the subwoofer. Your Alpine HU will have RCAs just for the subs (in other words only low frequency will be delivered to the mono amp)
Click to expand...

9857 has 3 pre-outs, along with an excellent sound qualtiy / EQ
 
It's a GREAT idea to amp the front pair and bridge the other channels for the sub. Nothing wrong with this at all. The rear speakers in any case is only for fill. Your primary speakers in front will set the main stage and is where the critical listening is at. I've done this in 3 of my cars and it works great. No point in amping rear fill as they will be crossed over anyhow. HU power is plenty to drive them loud. They don't clip before it becomes plenty uncomfortable to listen to. And you don't have to waste space for another amp.

Your 4ch amp should have 4 inputs. The crossovers will happen all in the HU as it has 3 pairs of RCA. My install is setup pretty much the same (search for my install thread for more info).

I have a premier 75x4 amp powering the front stage and the rear channels bridged powering the rear sub. The HU's front powered outs drive the rear door speakers. The HU's rear powered outs drive the rear-most fill speakers in the pillars. It is all nicely balanced with excellent imaging, loudness, and bass.
 
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Thanks Teck

Teck, thanks for the reply.....

Some how the thread became about using the 4 channel amp to drive the front channel and a sub. There was never a question as to wether this was a good system idea. I've been into car stereo since the cool set up was an FM converter on an AM radio and speakers stolen out of any appliance you could get your hands on.
The thread was about using a three channel set up and crossing over the front channel component speakers and the single 8" sub.
What freq. had others used ? Fiber fill ?

Guess I didn't spell it out.

I haden't thought about useing the HU front and rears like you discribed. I'll have to take a look at this type set up.
 
I had a JL8W0. It was a good sub for what it was worth, but I don't think you'll get it to hit "hard". I crossed it over high because I had 5.25's in soundbar of my jeep, I think around 100 or 120hz. But with 6.5's, I'd have the hipass Xover on the front RCA outs and the hi level outs to the rear speakers set to around 80hz on the HU and send everything under 80 to the sub RCAs. I think I had about .65 cu ft sealed, without polyfill. Build it to specs and you won't need any fill.

Don't know the specs of the HU or Amp, but you will probably want to build it like the others said: front pair of RCAs to channels 1 and 2 of the amp and the pair of Sub-Outs to Channels 3 & 4 of the amp. Highpass/lowpass filter adjustments can be made on the HU.

Sounds like you are on a space or $$ budget, but that setup will work for ya fine.
 
Pics of Psudo stealth install

If I can get these to load...
 

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  • sub sm.jpg
    sub sm.jpg
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Looks great! Full use of the DD shelf too. I think the 8W0 can only see 200w rms, so you won't get that to thump in the big cabin of a 4R, especially firing into open air and not into a side or real panel. Have you looked into retrofitting a 10" in that box? One with a shallow mounting depth and small sealed box requirements.. IDQ or ED, for example.
 
8"sub sound

Punk

I have used this sub because it was left from a Tacoma I had.
The box was built to the JL 8W0 spec and is right at .3 cuft.
This week, with any luck, I will be getting my new amp and front door speakers as well as some Raamat . When I get the whole system together and tuned up, I'll decide if a larger sub is needed. I have looked at the ED SQ10.
Buy the way, I'm not trying to blast myself out of the car, At 47,
I've done alot of head bangin and now I just want clean, correct reproduction of the music.
When the front Components & amp come in, I'll do some picture taking
and let yuns know how it all sounds.
 
Yeah, that's right..... forgot, I had 100wrms/200wpeak going to my 8w0 before I upgraded to a 10" JL and gave it 200wrms.
 
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