Home > Consumer Reviews > JBL L8400P 12-Inch Powered Subwoofer with 600 watt Digital Amplifier (Black)

I was tryin to debate whether to get this $450 600 watts RMS subwoofer or the $175 JBL SUB12 with 300 watts RMS. I decided to go all out and get this one received it very quickley(3 days) thanks to PRIME shipping. Hooked it up and the clarity was amazing. Its actually not as powerful as I thought it was going to be but still very clear. If I had the choice to do it again I would just get the $175 SUB12 but its not worth the shipping to send it back so Im keeping it and very pleased with it. Had to play around with the positioning for about two weeks. I have a small room and tried 2 different positions in my walk in closet and it was louder in the next room than it was in my room so I eventually placed it at the front near the TV(only option). Big difference...It was alot louder in my room from the listening positions once i got it to the front I was very pleased.

Got mine yesterday and out of curiosity after reading another review I put a kill-a-watt on it and tested it out.

Yes there is a "chirp" sound when it turns itself on from sleep mode. It doesn't border me however since it is not that loud and it only does once. In sleep mode, it draws about 20w. Awaked but not playing any big sound, it draws about 25w. Basically the sleep mode is really pointless.

I have other JBL Studio L series speakers and I can tell the big difference over those home theater speakers. But this sub I really don't hear or feel any difference. A boom is just a boom.

I purchased 2 of the L8400Ps as upgrade to my existing AV system and I am very pleased with the results as also reviewed by others. I enjoyed the upgraded sound system for the evening watching a dvd movie. The next morning I was curious and reached behing the subs to feel the rear panel and it felt unusually warm. It takes power to heat that much metal. I measured the current drawn by the subs and it came to be .3 ampere each which translates to 36 watts of power. Two subs would add up to 72 watts and that is too much power to be wasted continously.

The other negative comment I have with the subs is the "chirp" sound they make when they automatically turn on upon receiving a low note from the AV receiver. I find the "chirp" annoying while I am watching a tv program or movie when the "chirp" suddenly come on.

I contacted JBL and they replied:

1)The standby power drawn by the subwoofer is the way it is. The solution if I do not want to wast electricity would be to manually turn on and off the main power switch at the rear panel. Because of the way my subs are situated, I had to move the subs everytime in order to operate the switch.

2)The "chirp" sound is caused by a resistor in the electronics module which have to be replaced. JBL customer service said I should go to JBL.com and locate the nearest service station to have it done. I did that and the nearest station is over 100 miles away. Considering the size and weight of the subs in the box, that would be next to impossible. The box would not fit into my car.

AND SO I am giving Zero Star (one being the minimum) rating for the power wasting and the chirp. I still must give a full 5 stars for the quality of the audio to be honest. I am so much disappointed that such a good sub would be spoiled by poor design on 2 points.

May 17, 2009. After re-thinking I believe a 3 star rating would be more appropriate, but I can not change it by clicking the stars, so this have to do