JL Audio HD900/5 Review

[gunz4me2 10+ year member]

Review of Amplifier: JL Audio HD900/5

After growing tired of dedicating 12.5” x 40” to three amplifiers over my rear axle hump, I decided that it was time to purchase a JL Audio HD900/5 and see if it would meet or exceed my expectations. I finally have the amplifier installed, and I must say that I was a little leery about giving up a little power here and there to run the 900/5. Well, now that it is in there, and tuned the way I liked it, I must say that my power deficit concerns were irrelevant. Just in case anyone wants to know, here are my system specifications: Alpine CDA-9887 source; Tang Band W4-1757SB (500 Hz on up); Mach5 Audio MLI-65 (80 to 500 Hz); Subwoofer – 13w6v2 Mustang Stealthbox (80 Hz on down).

Thus far, I performed more critical listening with the car NOT running than with any other setup I have owned since re-entering this hobby in 2007. I’ve been trying to expose those alleged full range class D flaws by trying to pick out something that does not sound right, and I just can’t do it. Pink Floyd - Dark Side of the Moon sounds GREAT and I really love Echoes off of Meddle. I also listened to a few tracks from Nine Inch Nails - The Fragile, and I was impressed. The imaging in Somewhat Damaged is spot on and the midbass in We’re In This Together is most certainly there. A Perfect Circle’s Thirteenth Step also sounds awesome and is on par with my old ab/gh setup. For kicks, I cranked up the volume on Killasound by Freestylers vs Wizard just to see if I would notice the 350 watt power deficit on my subwoofer. I must say, the theoretical 2.55 decibel loss in subwoofer output by going from 850 watts to 500 isn’t as noticeable as I thought it would be. If anything, the subwoofer appears to blend better at all volume levels versus being overpowering at times.

Any concerns I once had about full range class D are now moot. Granted, it was tough to get past the stigma of the Alpine PDX-5 that I tried in 2008, but this amplifier literally smokes it. My complaints about the Alpine were lack of midbass, lack of subwoofer output, and noise. I am happy to report that the JL Audio HD900/5 has NONE of these issues! If you are tired of dedicating a whole bunch of real estate to multiple amplifiers and are on the fence about purchasing a 900/5, my advice is to purchase it!

Lastly, other options I considered were the Kenwood XR4s with a XR1; Alpine PDX F4 with a PDX M6; the JL Audio 600/4 with a HD750/1; and the Audison LRX 5.1k. The reason the HD900/5 won out was due to the fact that I get everything in one amplifier with a small footprint!

Just to give you a size perspective, this is how big the amplifier is compared to a CD Jewel Case:

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[gunz4me2 10+ year member]

Here is the RTA with my old setup, a Lunar L450 and Clarion DPX1851:

Unfortunately, I had it on peak hold and managed to capture the HU beep around 5kHz //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif Also, I tested with the subwoofer maxed out instead of at a reasonable level on the HU.

Here is the setup with the 900/5:

And here is old versus new:

All measurements were taken with a calibrated Dayton EMM-6, TrueRTA, USB Mic Mate, and the same pink noise CD.

 

[Shinju 10+ year member]

There is a IASCA/Team Hybrid pro class maybe even extreme class competitor here in WA state that runs 4 of these HD amplifiers in a older T-bird and let me tell you it was probably one if not the best sounding car I have ever heard since I have been doing this hobby.

Anyone who can say they can hear a difference between class D on a front stage vs A/B is lying, These HD amps do just as good if not better then those old school magic watt amplifiers.

 

[The_Grimy_One 10+ year member]

I want one or 2 of them now. Haha.

 

[VWBobby 10+ year member]

Excellent review!

Good choice of NIN CD too //content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif

 

[tipptop 10+ year member]

This will definately be my next amplifier. Almost double the output of my RA50 with much better mounting options and extremely efficient. Seems to be very easy to set-up and tune too. I like the wiring plugs too, great idea. If I can believe what I read about it, sq is amazing. However I love my RA50 its just a beautiful amplifier.

 

[thevolunator 10+ year member]

Great review! I have the XD700/5 and like you I don't want have multiple amps. I had this amp in a Ford F-150 powering (2) 6w3v3 subs under my back seat and it rocked. But, I wrecked the truck and am now kind of starting over. From my sig. you can see what I have at the moment, my local dealer say's(and I agree) that my 6's aren't going to be near enough to get the SQ that I'm looking for and suggested the JL Audio "Stealth Box" with a 12w3v3-2. But, he also said that I would need to buy another amp(suggested XD 600/1) Basically another $1000. Now, after doing a little research, I noticed that MY amp(the 700/5) has a RMS rating of 300w @2ohm and that hits right in range of the "optimum" range of the sub in the Stealth Box.

Now, I said all of that to ask this. In your review, you said... "see if I would notice the 350 watt power deficit on my subwoofer. I must say, the theoretical 2.55 decibel loss in subwoofer output by going from 850 watts to 500 isn’t as noticeable as I thought it would be. If anything, the subwoofer appears to blend better at all volume levels versus being overpowering at times."

So...you couldn't tell a "noticeable" difference from 850w to 500w. Yet, they're telling me that my (300w@2ohm) XM700/5 won't be enough power?

Doesn't make sense to spend (basically) another $500 for another 150wrms? Am I missing something here?

 

[gunz4me2 10+ year member]

The difference wasn't as bad as I thought it would be when listening to music at normal levels. Now, when I cranked it, the Mustang didn't rattle as much from the bass as it had before with the Clarion DPX1851 powering my sub. Then again, it is time to start over with a new system because I traded my Mustang in on a 2012 WRX three days ago!

In your case, that is a tough call. If that 12w3v3 is going to be in a sealed enclosure, you may want to opt for more power. Worst case, you can try what you have first, then purchase more power later on. Unless matching amplifiers is an issue, there are plenty of ways to achieve 500 watts RMS at 2 ohms on a budget outside of the JL Audio brand.

Finally, my general rule of thumb when upgrading in the past was to only upgrade if I was doubling the power. I ended up modifying my general rule slightly to save on space.

 

[thevolunator 10+ year member]

Thanks, that makes sense. And, yes. I think that the "stealth box" is a sealed enclosure. Like you said though, I can always add the other amp later if the sub is starving for power. On another note, how did your stealth box sound? I noticed that you upgraded to the w6 over the w3(the one they spec for my Xterra)

And, good luck on your new build...

 

[gunz4me2 10+ year member]

Thanks, that makes sense. And, yes. I think that the "stealth box" is a sealed enclosure. Like you said though, I can always add the other amp later if the sub is starving for power. On another note, how did your stealth box sound? I noticed that you upgraded to the w6 over the w3(the one they spec for my Xterra)

And, good luck on your new build...

I tried all kinds of subs and always came back to the Stealthbox. There are other subs if you want louder, but the Stealthbox was the easiest to get a smooth frequency response with in the Mustang. Finally, the Stealthbox for the 2005-2009 Mustangs came with the 13w6v2. There was a slight body revision in 2010 that required a change in Stealthbox. In other words, mine wouldn't work in a 2010+ Mustang.

Thanks for the luck on the build... I have an idea of what I want to do, but I want the new car smell to wear off before I start tearing it apart.

 

[Alex81 10+ year member]

I want one or 2 of them now. Haha.

Ha. Exactly what I was thinking

Can you buy the Mustang Stealth boxes without the subs in them