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JL HD900/5 Review
I did not send this one in, but this is from Audio Science Review
JL Audio HD900/5
https://www.audiosciencereview.com/f...plifier.27808/
Below is copied and pasted from ASR
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:
https://www.audiosciencereview.com/f...io-jpg.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:
https://www.audiosciencereview.com/f...io-png.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:
https://www.audiosciencereview.com/f...io-png.163129/
Crosstalk at high frequencies is about average but not as good as it could be at low frequencies:
https://www.audiosciencereview.com/f...io-png.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):
https://www.audiosciencereview.com/f...io-png.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:
https://www.audiosciencereview.com/f...io-png.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:
https://www.audiosciencereview.com/f...io-png.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%:
https://www.audiosciencereview.com/f...io-png.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:
https://www.audiosciencereview.com/f...io-png.163135/
Stepping through various frequencies shows one, highly well-behaved class D amplifier design:
https://www.audiosciencereview.com/f...io-png.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:
https://www.audiosciencereview.com/f...io-png.163137/
Subwoofer Amplifier Measurement
I tested the subwoofer amplifier by itself for power and once again got the company specified power:
https://www.audiosciencereview.com/f...io-png.163138/
https://www.audiosciencereview.com/f...io-png.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.
