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JL Audio HD900/5 Review (Car Amplifier)

amirm

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This is a review and detailed measurements of the JL Audio HD900/5 four channel amplifier plus subwoofer amp. It is on kind loan from a member and costs US $1,290 on Amazon.

This is a hefty amplifier packed in a small and dense package:
JL Audio HD900 5 Review class D car amplifier audio.jpg


There are the usual filters and such, all of which I left defeated for my testing.

JL Audio HD900/5 Measurements
I powered the unit using my custom Lithium battery pack (100 amps continuous/300 peak). Nominal voltage was around 13.3 volts. Here is our usual dashboard just driving stereo front channels:
JL Audio HD900 5 Measurements car amplifier audio.png


Distortion rises to 80 dB in the "bad" channel which sets the SINAD for that to 79 dB. Averaging the two at 81 dB would put it slightly above all amplifiers tested to date (vast majority home units). Considering this is a car audio amplifier, this is very good performance.

I was very impressed that the feedback loop includes the output filter in the class D amplifier as to eliminate its impact on frequency response:

JL Audio HD900 5 Measurements frequency response car amplifier audio.png


Crosstalk at high frequencies is about average but not as good as it could be at low frequencies:

JL Audio HD900 5 Measurements Crosstalk car amplifier audio.png


Multitone test shows typical performance in car audio where distortion rises at both low end (due to power supply likely) and highs (typical of all amplifiers):

JL Audio HD900 5 Measurements Multitone car amplifier audio.png


In the middle, performance is excellent, far exceeding the noise floor of 16-bit/CD content you are likely to play on this.

Signal to noise ratio and dynamic range is quite respectable:

JL Audio HD900 5 Measurements SNR car amplifier audio.png


Even at 5 watts, you are almost at noise floor of CD/16 bit content.

Name of the game is power in car audio so let's run our power tests starting with 4 ohm load:
JL Audio HD900 5 Measurements power into 4 ohm car amplifier audio.png


Distortion rises early on compared to home audio but still, this is pretty good. It produces 93 watts which is within a hair of company spec of 100 watts. But we can get that when we fix the distortion at 1%:

JL Audio HD900 5 Measurements max and peak power into 4 ohm car amplifier audio.png


Very honest spec.

Switching to 8 ohm we get much less power naturally although this is not a common impedance in car audio for speakers:

JL Audio HD900 5 Measurements power into 8 ohm car amplifier audio.png


Stepping through various frequencies shows one, highly well-behaved class D amplifier design:
JL Audio HD900 5 Measurements power into 4 ohm vs frequency distortion car amplifier audio.png


Very hard to get this in home audio let alone car audio. The noise level is high though due to ultrasonic components which we can see in FFT:

JL Audio HD900 5 Measurements FFT Switching Class D car amplifier audio.png


Subwoofer Amplifier Measurement
I tested the subwoofer amplifier by itself for power and once again got the company specified power:


JL Audio HD900 5 Measurements power into 4 ohm Subwoofer car amplifier audio.png


JL Audio HD900 5 Measurements max and peak power into 4 ohm subwoofer car amplifier audio.png


Spec is 500 watts and we are there. As noted earlier on the graph though, due to regulated power supply, there is no peak headroom. Continuous and peak are the same. This allows the amp to not care about battery voltage much.

Current consumption was about 76 amps at 13.4 test volt. That means 1000 watts consumption which seems high. I may need to look at the accuracy of my meter on my battery bank but I thought I share that anyway.

Conclusions
Clearly the JL audio HD900/5 is a very well design amplifier. It has specifications that match my measured performance that we can't get him home audio let alone the crazy world of car audio. With that, comes the very high cost which likely excludes it from most the market. I like the functionality of four amps at lower power and a higher one for a sub. Should cover a lot of common scenarios.

I am going to recommend the JL Audio HH900/5.

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As always, questions, comments, recommendations, etc. are welcome.

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Doodski

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Current consumption was about 76 amps at 13.4 test volt.
That's @ 500W4R? If so then I think that's fantastic compared to a big smoking hot class AB car amp. :D

A teardown to see what a new class D car amp does inside would be ace. It would be interesting to see the PCB, inductors, caps and layout etc.
 

GWolfman

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A 4.1 amp seems to make a lot of sense for car audio. Until we see more reviews, it's hard to know if this is money well spent (or not).
 

Webninja

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I’ve always run JL Audio amps and subs in my aftermarket car stereos. They have never failed in all sorts of extreme temperatures, freezing winters and hot summers.

Glad to see the test decently too.
 

RHO

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@amirm : Can you check your set-up? Maybe I'm imagening things but there seems to be a consistent ~4dB difference in SINAD in your most recent amplifier reviews. CH2 seems to be worse than CH1. Could be a coincidence.
 

DSJR

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I suspect the domestic audio market is too darned fickle to adapt these designs for domestic use. Mind you, we have Crown and Begringer making pretty decent power amps for very little and I'm hopeful the designers are watching the competition closely as well.
 

pma

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This one is really not bad. I like it much more than the 2nd one tested today:
 

Matias

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Thanks for the test. I was deciding between this one and the Alpine PDX-V9 and chose the latter, but good to know that both are solid choices for 5 channel car audio amplifiers.
 

AVKS

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@amirm Great to see you getting into the mobile audio space! It's perhaps worth noting in your reviews the voltage the car amp power rating specs are based on (typically 14.4V), so averaging 13.3 could be slightly handicapping the performance. Also, these amps bring different value propositions to the table such as the RIPS system of this JL amp that claims to produce the same power across a range of voltages and impedances. That's one of the features driving the price, so if it's falling short that's interesting to know.

Crossovers are also often integral to car audio use, so measuring their relative accuracy to frequency setting as well as claimed slope (this amp claims either 12 or 24 db selectable) could shed further light on how well the amp is made.

As a minor point, the product name is HD900/5, not /6.

Thanks for the test. I was deciding between this one and the Alpine PDX-V9 and chose the latter, but good to know that both are solid choices for 5 channel car audio amplifiers.
I've used a PDX-V9 for almost 10 years now and it's been a great amp. Zero regrets.
 
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Dogen

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I like these reviews of good car amplifiers, if only to shame manufacturers of home amps to do better. Does anyone use these in the home, and why not? The value proposition is pretty good.
 

sam_adams

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@amirm, the title of the review and headings are showing this as JL Audio HD900/6 when it should be JL Audio HD900/5.
 

Doodski

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I like these reviews of good car amplifiers, if only to shame manufacturers of home amps to do better. Does anyone use these in the home, and why not? The value proposition is pretty good.
Car amps are not used in the home for efficiency reasons. Running the amp requires a high amount of DC current and the supply needs to be either a battery or a expensive electronic DC power supply. A battery is "usually" not wanted because of outgassing of hydrogen if it's a sealed lead acid or in the case of @amirm he built a very nice well designed lithium cell power pack. I've seen the SLA batteries in a industrial setting cause hydrogen explosions in non-enclosed spaces so no damage was done but if in a enclosed space I would not want to see the damage. It smells acrid and then makes a big boom sound. Dangerous stuff.
 
OP
amirm

amirm

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GXAlan

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Does anyone have an Audiotec Fischer to submit? Available at Crutchfield.


These would be interesting to compare to the Lexicon DD8 since that DD8 is supposed to be similar to the BMW factory amps and Audiotec Fischer is a plug-in-play replacement with more power and EQ.

Factory Advertised Specs
1636050671113.png



Third party test
There is 5x65w and 2x160w which is what I think the two numbers represent

That SNR looks really poor -- but I wonder if it's because they had the wrong input. By default there is a potentiometer for adjusting the input level, but you can also configure it in software to skip the potentiometer setting
8bf842db-e4b9-4820-8da3-bf609042e58b.PNG





1636050483684.png

1636050519063.png
 

JeffGB

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These car amplifiers are interesting. Since purchasing an Aiyima a07 and researching power supplies for it I have found that high current power supplies of the voltages required for these amplifiers are easily available, cheap and reliable (Meanwell etc). I used a car amp with a 12v power supply years ago in a home installation but at the time the power supplies I had access to were poor.
 

JRiggs

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That's @ 500W4R? If so then I think that's fantastic compared to a big smoking hot class AB car amp. :D

A teardown to see what a new class D car amp does inside would be ace. It would be interesting to see the PCB, inductors, caps and layout etc.
The JL Audio HD series of amplifiers were first introduced in 2008. Still amazing technology. Their latest class D amps are the VXi line that combines JL Audio’s advanced class D amplifier technology with a powerful digital signal processor (DSP).
 

Doodski

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The JL Audio HD series of amplifiers were first introduced in 2008. Still amazing technology. Their latest class D amps are the VXi line that combines JL Audio’s advanced class D amplifier technology with a powerful digital signal processor (DSP).
Nice to see the DSP integrated into a good efficient amp. DSP in car audio is a game changer.
 

KaMiKaZeCATS

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Loving this car audio content, Keep it up! would love to see you test some of the car DSP's dac's. I can only imagine the horror stories there o_O

PS: Good on JL for matching/beating thier specs. Its such a crap shoot in the world of car audio!
1636061765075.png
 
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