2 JL Audio HD900/5 amps! Build me a system! 1800 watts RMS in a Grand Cherokee...

[Ijcobra 10+ year member]

I took each of my JL Audio HD900/5 amps out of my Mustang and Bronco and put them in my 2006 Jeep Grand Cherokee SRT-8.

I also have a set of Boston Pro-60SE components up front. Tweeters in the factory 3.5" dash speaker location. The left woofer is blown and rattles especially on acoustic guitar. These are using a bridged set of outputs and are getting 150w each (3 ohm).

Have a set of Boston SR-60 components in the rear doors, but am not using the tweeters. Woofers only.

Subs are 2 JL Audio 10w3v2 in a sealed box. I've had them for about 9 years now. Gains are set pretty low because they are rated at half what each of my amps put out (500w each RMS).

Headunit is a Pioneer double DIN with 4V pre-outs.

I listen to everything, but mostly metal.

I'm thinking of getting 2 JL 12w6v3's or 13w3v3's. Sealed.

Looking at CDT Audio 6x9 woofers up front running bridged at 200w each. 3" in the dash at 100w each. Then 1 or 2 set of their 1" silk tweeters at 100w each. I'll need an active/electronic crossover to run bi-amped like this. Then I'll adjust each channel's gain/crossover to make the subs/mid bass/midrange/and highs work together nicely.

What do you think?

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[bbeljefe]

There's no need to run 100 wpc to tweeters in a bi-amped system with only 200 wpc to the midrange drivers. I'm running 300 wpc to my midrange drivers and 75 wpc to the tweets and at that I have to have the tweeter amp's gain turned almost off. And two sets of tweeters doesn't sound like a good idea with the midrange and sub stages you're describing... unless you have them buried somewhere that they can't be heard. But even then, poor imaging can't be helped by more poor imaging played louder. I would run the upper mids on ~75 wpc and the tweets on ~50 wpc with those midwoofers.

I get that you listen to a lot of metal... I do to. But you do realize that a high quality low compliance sub in a ported box or a t-line will sound just as good and about 2-3 times louder than any woofer that's relegated to the acoustical imprisonment that is a sealed box? I mean seriously, I don't mean this to be insulting but you might as well run some cheap woofers if you're locking them away in sealed boxes and only feeding them 500 watts each.

And you have a Grand Cherokee so it's not like you have no room for a quality subwoofer box. ;-)

 

[trumpet 5,000+ posts]

Here's what I would do with 2 900/5s, with the intent of having a lot of extra power that is only going to be used a small percent of the time.

CDT aluminum tweeters with ES-03 3" mids wired to MX-1000SX passives, 2 channels bridged per side

CDT HD-690CF 6x9 subs with 2 channels bridged per side

CDT QES-1220 x 2 on the sub channels in sealed boxes.

With good tuning and the right sound deadening this would absolutely kill on all kinds of music. Tweeter placement would depend on the choice of tweeter and auditioning in various locations. My personal favorite tweeter is HD-1A/BL, and it requires a fairly large flat surface to mount it.

 

[Ijcobra 10+ year member]

Here's what I would do with 2 900/5s, with the intent of having a lot of extra power that is only going to be used a small percent of the time.
CDT aluminum tweeters with ES-03 3" mids wired to MX-1000SX passives, 2 channels bridged per side

CDT HD-690CF 6x9 subs with 2 channels bridged per side

CDT QES-1220 x 2 on the sub channels in sealed boxes.

With good tuning and the right sound deadening this would absolutely kill on all kinds of music. Tweeter placement would depend on the choice of tweeter and auditioning in various locations. My personal favorite tweeter is HD-1A/BL, and it requires a fairly large flat surface to mount it.

Why aluminum tweeters?

Why the mid & high with a passive crossover instead of driven by individual channels through an active crossover (bi-amp)?

Why sealed instead of ported?

Thanks for the advice!

 

[trumpet 5,000+ posts]

Why aluminum tweeters?

In my experience they make metal recordings really come alive compared to soft dome tweeters. This is a personal preference.

Why the mid & high with a passive crossover instead of driven by individual channels through an active crossover (bi-amp)?

You can go either way. It's a bit easier in several regards to have the mid and tweeter together. Less wiring. With these crossovers you can do the bulk of your level matching, and then the rest is done in EQ. Keeping the mid and tweeter very close together on each side of the vehicle helps them sound as though they're one speaker with a wider frequency response. You might ask, "why not use one speaker that plays higher?", which is a fair question. You might be able to use a 3.5" coaxial. Then you're restricted to whatever sound you can get out of available 3.5" coaxials. With a separate mid and tweeter you have a lot more options.

Why sealed instead of ported?

It's more foolproof to get great bass response in both a wide bandwidth and fast response to changes, like what you get with metal music. The box size can be much, much smaller as well than some ported designs. The box size depends on the sub and what you want out of it. Ported boxes in general are always going to be louder than the same sub in a sealed box on the same amount of power. I personally prefer the way a good sealed sub sounds on metal. It's a compromise as overall output suffers.

 

[Jroo 10+ year member]

I think trumpet is getting you in the right direction. I would say always start with less and see how it sounds and add where you are missing. If you end up active, just do a set of tweeters, a set of mids, and a set of midbass. Trumpet is right that sometimes a good coax can end up sounding better than a componet set.

I also wouldnt rule out sealed. I have never used or like ported boxes, but thats me. There are auguments for both, but IMO a sealed box always sounds better than ported. Ported boxes can sound good, but realistically guys on the street use them because they are louder. I have never cared about being loud, so sealed always worked better for me. The reality is you pick the box based on the woofer.

 

[trumpet 5,000+ posts]

Thank you for the order. I'm happy to help over the phone. These kinds of systems can be a lot easier to sort out verbally than over a discussion forum.

 

[Ijcobra 10+ year member]

Ok I went with the CDT MX series 3-way components with a 6.7" midbass, 3" midrange, and silk dome tweeters. Also got a Rockford 3Sixty.3 sound processor. I'm running the tweets and miss with the crossover off 2 channels and the 6.7" midbass bridged. Also got a set of CDT 6.5 coaxials in the rear.

Initial impressions after some tuning of the crossovers and processor:

Midbass is way better than with my Bostons. Midrange and highs- not so much. It may have to do with the midrange speaker location (shooting up into the windshield and reflecting off) and I'm not sure about the tweeter location either. They are high in the corners of the windows aimed at the center of the windshield (as recommended in the instructions).

I'm going to disconnect the coaxials and run the fronts fully active (no passive crossover at all) and do some more tuning and see what I can come up with.

The sound processor seems to have decreased the volume of my system substantially, and I re-gained my amps after configuring it too. Weird.

Also ordered 2 JL 13W3V3 subwoofers which should match my amps output better and be a big improvement over 10W3V2s. Getting a sealed box made.

 

[trumpet 5,000+ posts]

Midbass is way better than with my Bostons. Midrange and highs- not so much. It may have to do with the midrange speaker location (shooting up into the windshield and reflecting off) and I'm not sure about the tweeter location either. They are high in the corners of the windows aimed at the center of the windshield (as recommended in the instructions).

How did you set the switches on the MX-1000SX crossovers? I would like to at least document this for future reference even if you will be removing them from the system. The crossovers offer a lot of adjustments, and while I don't recommend hopping back and forth between the processor and the crossovers to tune the system, I do ask that you give them a bit more time.

 

[Ijcobra 10+ year member]

We'll after A LOT of tuning and changing from running fronts bridged, rears/no rears and my sub through the DSP or not, I'm pretty much done, and it sounds awesome!

Here's my system:

Pioneer AVH-P3300BT headunit with F/R/Sub RCAs going to the

Fosgate 3.Sixty-3 DSP

2 JL 900/5 amps

2 JL 13w3v3 4 ohm subwoofers in a sealed box with 1.5 ft3 airspace each chamber

CDT HD-M6 6.7" midbass woofers (bridged channels)

CDT ES-03 3" midrange speakers

CDT WS-100i tweeters

Crossovers settings and gains:

Subs: 80 Hz low pass, -6 dB don't know slope (HU forces low pass Sub out)

6.7": 80 Hz - 350 Hz band pass, -6 dB 24 dB/Oct

3": 350 Hz - 4000 Hz band pass, -8 dB 36 dB/Oct

Tweet: 4000 Hz high pass, -15 dB 48 dB/Oct

I used a program called True RTA and the microphone that came with my head unit to do some equalization using uncorrelated pink noise. I evened out some of the peaks in the midrange a bit.

I used test tones to figure out the time alignment, and think I got it right on. The numbers were a bit different than simply measuring speaker distances, but that provided a good starting point.

The midbass sounds way better bridged and with time alignment. Very full sound which I have been missing.

Things I don't like:

The output from the DSP to my amps is some weird in-between low level and high level. RF claims it is 8v out. With my amps set to low level, I have to set the gains all the way down and still have to set more - dB through the processor in order to get the required gain/voltage out. And in high level mode, the amp won't gain enough to get anywhere the voltage needed for the subwoofers. Ugh. So I'm running low level.

My subs don't seem to be as loud and crazy as you'd think 2 13.5" subwoofers should at 1000w (44.7 volts). I increased the gain from -12 to -6 dB in the DSP today. I'll have to "play it by ear" with my remote sub gain control knob, which is fine since we have to do that anyways since all music is mixed so differently, especially anything older than 1988 with their severely lacking bass.

My midranges are in the dash and point up right at the windshield, where the sound bounces off, scatters and refracts across the dash (I assume). I'd like to have pods made into the A-pillars pointing them directly at me.

The tweeters are meant to be imaging tweeters, mounted directly to the upper corners of the windshield and facing towards the center of the dash. I did not like this arrangement, and mounted them in the very bottom corners of the windshield/A-pillar/dash facing me. But they look like crap there, literally taped to the glass. I'm trying to exchange them for CDT DRT-26S tweeters, which I believe are the same thing but with different mounting options (angled).

Has anyone reduced the gain of speakers closer to you slightly to compensate for the 6 dB sound loss per doubling of distance? For example, if my right tweeter is twice as far as my left, would I reduce the gain of my left tweet 6 dB? Not sure how this equation gets screwed up in the enclosed car environment.

 

[T3mpest 10+ year member]

What curve did you shoot for with your rta? Generally you can't tune subs using an RTA. The pressure modes in the car just don't make a good correlation between the mic and your ears. Generally though, a flat response on an RTA will sound very weak in a small location like a car. A 6-12db rise below 80hz as you approach 20 is generally better, as you go lower, more gain.

Midbass best thing for time alignment is bandwidth limited pink noise, using midbass, my old tone was 80-300hz.. If you get that pink noise to sound like it's front and center, so will all your music.

RTA flat is great for your upper midrange. Very high treble though, above 6k or usually needs a few db's of rolloff as you head to 20khz.

 

[trumpet 5,000+ posts]

To EQ the speakers tune one side to eliminate peaks and nulls varying more than 3 dB from flat. Switch to the other side and try to get the curve to mimic the side you previously tuned. Then center it and tune the speakers together until you get the curve you want. Yes, you do generally need to attenuate the closer speakers.

On the RTA you should sit in the car and move the microphone in front of your face while watching the display. You'll want full range pink noise playing at this time, and then watch the display for peaks and nulls that don't go away as you adjust the EQ. That's how you identify acoustic phase issues that you can't fix with EQ.

One thing about your microphone is your RTA software should be matched with a microphone that includes a calibration file. If True RTA doesn't know the curve of your mic your measurements can't be trusted to be accurate against another calibrated RTA setup.