JL Stealthbox & a/d/s/ amplifier installed. Comments & questions... (long) - AudiWorld Forums

JL Stealthbox & a/d/s/ amplifier installed. Comments & questions... (long)

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Old 05-08-2000, 06:07 PM   #1
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Default JL Stealthbox & a/d/s/ amplifier installed. Comments & questions... (long)

Last month I picked up a used JL Audio Stealthbox (thank you Alex), and a new a/d/s/ P440.2 amplifier from Soundhabit.com.

FINALLY, I got it all installed today by a reputable installer here on Staten Island.

The amplifier is 40w X 4 channels, and 120w X 2 bridged into 4 ohms. The system sounds quite nice. I am pleased with the combination. It is not terribly loud. 120w for bass is not a heck of a lot. And the stock speakers are bottoming out with that much power at loud levels (I crossed them over at 80Hz).

But I don't listen to music very loud in the car, and this amplifier adds plenty of dynamic headroom, which I did not have with the headunit powering the front speakers. In fact I found myself listening to the music a few dB louder, only because I could, and it was still clean.

I also heard some detail in the music which I haven't even heard before on my high-end home stereo -- probably because of the close proximity of the speakers to the driving position.

As for the bass, it is quite nice with the Stealthbox. A 400w amp bandbass box it certainly is not. But it is very tight and clean. I'm sure if I gave it a more powerful amp than the a/d/s/ 120w, it would sound even better. But this is certainly sufficient for my needs.

I do have a very important question about the installation however...
The system sounded great in the installer's shop.
(Actually I adjusted the X-overs to my liking.)
But when I started the car and pulled out of the shop, I noticed a high-pitched whine coming from the speakers.
It is quite faint, and when the music is playing, I don't hear it.
Also, the frequency seems to correspond to the RPMs of the engine -- higher pitched as the RPMs increase.
As a matter of fact, it sounded like the frequencies correspond to the number of RPMs.
i.e. 1000 RPM (idle) = 1 Hz
2000 RPM = 2Hz
3000 RPM = 3Hz etc...

THe installer ran power lines down the driver's side of the car, and grounded the amp one of the bolts holding the luggage tie-down hooks.

Signal & speaker lines were run down the passenger's side.

I also got the Blaupunkt pin-out adapter, in order to get RCA outputs from the stock headunit.

The high-pitched whine does NOT get louder as I turn up the volume of the radio. So the music easily masks the sound. But nonetheless, I want to get rid of it.
Furthermore, and this is most confusing, the noise is still there even when the radio is OFF.
(Apparently the amplifier stays on until I turn off the car.)

I am working late in the day tomorrow, so I plan to take it back to the installer tomorrow morning.
But if anybody can point me in the right direction, I'd certainly appreciate it.

One other small note...
With the amplifier driving the front channels, I now hear defined "clicks" through the speakers when I adjust the volume, or even change CDs or tracks on the CD. It is not really invasive at all. Heck, my old Sony in my Saab would beep whenever I adjusted the volume. That drove me nuts. I just mentioned the clicks as an observation. If the clicks go away with the same fix for the high-pitched whine, I'll be happy.
If not, I'll be content with the clicks.

Some other small notes...
The Stealthbox is a PERFECT fit in my 98.5 car.
And the Blaupunkt pin-out adapter (bought from Crutchfield) works great.
I also got a set of Hella air horns while I was there, wired to the horn and also the factory alarm. Also a dash mounted switch so I can turn them off and just use the stock horn. (I plan to get a second fog light switch, so it looks stock.)

Any questions about the installation, or if anyone has any advice on how to get rid of that whine, drop me an email !

98.5 A4 1.8tqms GIAC 1 bar, ITG filter, Neuspeed shifter, Valeo E-code projectors, JL Audio Stealthbox, ADS P440 amplifier, Hella air horns
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Old 05-08-2000, 07:54 PM   #2
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Default Problem solved...

I just went outside and tweaked the amplifier some more.
I also managed to get rid of that annoying high-pitched whine by employing a little trick that I often use when I am working with a noisy PA system: I turned the amplifier gains way down, and turned up the volume on the head unit.
Problem solved. No more whine.

There is still the issue of the clicking when turning the volume ****, but it doesn't bother me.

Also, the amplifier "thumps" when it turns on and off. I know that some amplifiers have anti-thump circuitry, but I got this one real cheap. So c'est la vie. Hope it doesn't damage the JL Audio drivers.

I'm happy now. :-)

I must say too -- the stock speakers sound pretty decent when they get some real power. There is actually imaging in my car !
The speakers are quite bright (moreso than MB Quarts), but that is easily fixed with the tone controls.
BA Pro 5.5 to be installed in a few months.

-- Peter
98.5 1.8tqms...
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Old 05-09-2000, 03:17 AM   #3
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Default Some comments.

There is no reason why an A/D/S amp should thump when turning off and on. Quite frankly, I've never experienced that with a car audio amplifier. I wonder if it has more to do with the way it's wired than with the amplifier. Usually, I believe the delayed power on for the amp, which removes the thump is part of the circuitry from the head unit. If your amplifier is not controlled this way (like from the ignition instead) then perhaps that is what is causing the instant power on thump. Also, a bad connection somewhere might cause something like that and also your whine.

How was your amplifier wired into the car? You should probably have quality 8 guage wiring to the amplifier (kept away from any speaker or signal wires) and quality 8 guage wiring to ground. If your ground wire is too long or too thin, then this can cause whine also.

The clicking you mention sounds like what you might get when an RCA connection grounds out on metal somewhere, but I think you wired into the rear speaker wires right? Not knowing more about how this system is wired makes it difficult to diagnose (it's hard enough as it is! ) Hopefully Foo will read this and help out. He's very knowledgeable on this stuff!

You will absolutely LOVE the BA Pro's! :-) My favorites are BA Pro's, Diamond Audio, A/D/S, and Focal. I will be doing Pro 5.5's soon in my Xterra. I can't wait! See my reponse to anil for more details on the up and coming project. Good luck!<p>Charles
2000 Nissan Xterra SE V6 4x4
'98 A4 2.8 Q-Tip (employer owned)
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Old 05-09-2000, 08:04 AM   #4
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Default Peter, BA Pros 5.5s?!?!?! You're a bad man. :-)

You'll love them. I just had the RC51 Rally's replace the Quarts in mine
and they sound much better. I think that the 5.25" mid helps a lot.
Surprisingly, the tweets aren't much softer than the ones on my quarts.
Maybe if I compared the BA Pros tweets vs. the Quarts I'd see a greater
difference. Anyways, I listen to more energy music so the Rally's suit me

How does Stealthbox sound? Are you getting a rattle that you were concerned
with earlier?

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Old 05-09-2000, 08:57 AM   #5
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Default About a/d/s/ turn on thump . . .

<center><img src="http://www.sounddomain.com/images/shopping/products/STISPSON.jpg"></center><p>My trusty old a/d/s/ PH15.2 amp (circa 1992) has the same turn-on (& turn-off) thump. It's actually a common phenomenon associated with a/d/s/ PowerPlate amps. However, the newer a/d/s/ amps aren't supposed to do this!

When I install it in my TT, I will try an amp turn-on delay (see link). Perhaps this will help with your problem, Peter.<ul><li><a href="http://www.sounddomain.com/shopping/product_details.cgi?sku=STISPSON&sidebar_type=bran ds&selected=Stinger">http://www.sounddomain.com/shopping/product_details.cgi?sku=STISPSON&sidebar_type=bran ds&selected=Stinger</a></li></ul>
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Old 05-09-2000, 09:30 AM   #6
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Default I have the BA Pro 5.5s and the Stealthbox...

You won't be disappointed with the upgrade to the fronts! I ran my stock front speakers for a while with the stealthbox and it sounded good. However, I felt that it was lacking some mid range in the fronts. When I switched to the BA Pros, there was a huge improvement and the overall sound of the system was more complete and full. Good luck, and nice setup!

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Old 05-09-2000, 10:35 AM   #7
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Default Really? A friend of mine had a PowerPlate amp back in...

...'92 that didn't thump, that I can remember. I know they had a model or two at that time that were known to catch on fire, but his was not one of those models, happily! All I know is his was a 50Wx6 unit. I'll have to ask him about the thumping.<p>Charles
2000 Nissan Xterra SE V6 4x4
'98 A4 2.8 Q-Tip (employer owned)
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Old 05-09-2000, 11:38 AM   #8
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Default Yep, Chuck, my PH15.2 is a 6x50 unit--it's probably the same model as your friend's. (more)

The thump is a small price to pay for the pure sound of a/d/s/ amps, though. It's only prevalent if you don't turn off the receiver before turning off/starting the car.
-John P.
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Old 05-09-2000, 08:24 PM   #9
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Default More about that pop...

My amplifier is hooked up to the factory Concert headunit using the Blaupunkt pin-out adapter.
The adapter supplies front & rear RCA connectors and also remote-turn-on.

Apparently the Concert headunit triggers the remote-turn-on with the ignition, instead of with the radio power. Because I've noticed that the amp turns itself on (and has that popping sound through the sub) when I turn the ignition key -- even with the headunit off.

Is there a better way to get the remote turn-on ?

Thanks again,
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Old 05-13-2000, 09:34 PM   #10
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Default What installed in Staten Island did you use? I've been thinking of getting a JL Stelthbox myself?

<p>1999 2.8 Q.
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2001, a4, ads, amp, b7, box, connector, head, horn, installed, p4402, ph15, ph152, plate, power, rca, stealth, unit, work

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