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JL Audio HD900/5 Review (Car Amplifier)

theshakomaster

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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.
Here's the guts:

@amirm - maybe this is a dumb question, but is there any benefit to running a test with all channels driven at the same time? I'm curious if there is any performance dependency when it's all tested together. Perhaps its performance does not equal the sum of its parts.
 

Doodski

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Here's the guts:

@amirm - maybe this is a dumb question, but is there any benefit to running a test with all channels driven at the same time? I'm curious if there is any performance dependency when it's all tested together. Perhaps its performance does not equal the sum of its parts.
Wow! The size of that car amp compared to the power output is sooper. I specialized in warranty service high end car audio repair in the 90s and the car amps where much bigger for that kind of power output and they required big batteries and sometimes 2 batteries. I think it is a major job to disassemble so a teardown is maybe not a good idea for @amirm :D
 

jhaider

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I’m not at all surprised that JL Audio offers the performance they claim. The perceived build quality of their products is always top notch too.

I am pleasantly surprised to see the flat FR into multiple impedances in a fairly old class D implementation. These may have been updated, but I remember using the marine version of this amp (MHD900/5) ca. 2009 or so. (Why marine? Don’t remember. Maybe I liked the colorway better?)

I believe the HD series use technology from a company called PowerPhysics. I assume they are bespoke versions, but that is the origin. I do not know many home audio uses of this company’s amp modules, aside from the old NHT Xd-series active speaker controller. They've been around for a while so I assume they have a niche in pro audio.
 

Labjr

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I was fortunate to know and be able to work with JL's amplifier designer for a few years. I always had a great curiosity to learn about audio and amplifier design. At the time, before the internet, it was hard to find resources to learn about audio. He patiently spent time showing me more practical, hands-on knowledge than I ever learned from reading books. Very humble guy. Good to see they're doing well.
 

preload

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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).
+1 on the VXi. The ability to add a per-channel PEQ, time delays, and a digital crossover along with high quality amplification all in one compact box is a game changer.
 

Matias

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I''ve used a PDX-V9 for almost 10 years now and it's been a great amp. Zero regrets.
Mine is from 2014 and being used daily. So far so good, love it.
 

SEKLEM

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Maybe this has been discussed in one of these car audio amp review/threads, but is it possible the reason why these amps perform so well because of the exclusion of a integral or included subpar power supply? I imagine Amir's power source is incredibly clean compared to what is found in most home audio amplifiers. I'd theorize that these amplifiers wouldn't behave as well when installed in a vehicle, contending with added noise from the alternator and misc electronic components of typical automobiles.
 

AVKS

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Maybe this has been discussed in one of these car audio amp review/threads, but is it possible the reason why these amps perform so well because of the exclusion of a integral or included subpar power supply? I imagine Amir's power source is incredibly clean compared to what is found in most home audio amplifiers. I'd theorize that these amplifiers wouldn't behave as well when installed in a vehicle, contending with added noise from the alternator and misc electronic components of typical automobiles.
You're probably right, but IMO Amir's method shows the quality and true performance the amps are capable of, plus in the mobile environment there are so many other factors destroying sound quality that the power supply quality won't make an appreciable difference. In an SQ contest the car will be parked and power source will be optimized for that use case, but in regular use the ambient noise (road, passengers, etc), lack of ideal speaker placement, and harsh interior conditions (glass everywhere...) IMO and IME have way more negative impact.
 

JRiggs

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DSP, especially in car audio, is so important. I’m still running big class AB amps, Zapco Z LX and a Mosconi Aerospace 6to8 DSP.
 

Rottmannash

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DSP, especially in car audio, is so important. I’m still running big class AB amps, Zapco Z LX and a Mosconi Aerospace 6to8 DSP.
As an aside what is an outboard DSP I could use with old AB amps if I chose to dive back in?
 

hyfynut

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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
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:
View attachment 163125

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:
View attachment 163127

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:

View attachment 163129

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

View attachment 163130

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):

View attachment 163131

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:

View attachment 163132

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:
View attachment 163133

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%:

View attachment 163134

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:

View attachment 163135

Stepping through various frequencies shows one, highly well-behaved class D amplifier design:
View attachment 163136

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:

View attachment 163137

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


View attachment 163138

View attachment 163139

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.

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

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
I’m not seeing where this lands on the SINAD graph compared to other amps? Also providing the manufacturer’s specs in the review would be helpful.
 
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JRiggs

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As an aside what is an outboard DSP I could use with old AB amps if I chose to dive back in?
There a quite a few on the market these days that will work with any amplifier, old or new. Mosconi, Helix/Brax, MiniDSP, JL Audio, Alpine, Zapco, Arc Audio to name a few. These modern DSP's can process anywhere from 8-16 channels, a few offer autotune functions. The flagship MiniDSP uses Dirac Live technology.

For connecting high resolution signal sources, look for a DSP that has optical digital input and coaxial digital input. My music source is the Fiio M15 connected directly to the DSP via coaxial digital cable.
 
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Xyrium

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Glad to see JL doing well here. I've used their subs in car audio, and they've always been stellar. Of course, they never cost me as much as their home audio models do, but still quite good nonetheless.
 

cletus3x

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JL amps always sounded better to me when I was building car audio systems in the late 90’s and early 2000’s. I imagine they were well engineered back then as well. Thanks for testing this guy Amir!
 

spectral85

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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.
amirm, Did you mean that it ranks above the average of all the domestic amplifiers analyzed?
 

avanti1960

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Nice test. I have been running this amp in my car since 2012 and it continues to impress me (so does my modest car!)
Running a DIY ScanSpeak discovery sealed subwoofer and two-way actives in the front and the sound is clear, dynamic and excellent. Good to see sound quality reinforced by measurements. Keep up the excellent work.

pmPgF5QFj
 
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