I hate cars

I almost posted this in my "getting out of car audio thread" since this amp "failure" triggered that thread but I figured it might get more exposure here. Skip to the Cliffs Notes at the end of you don't want to read a bunch of useless crap.

Well luckily a JL tech helped me out on DIYMA and we figured out the problem which turned out not to be the amp.

Back to the problem... If I had the key in the run position listening to music and then started the engine, the system would come on minus the sub channel. My tweeters are run off of the same amp. I did this once late at night, had no subs, did a bunch of troubleshooting and determined it was the amp and then made the post that I hate everything about car audio. I was correct but if I had stuck around and cycled the ignition again I would have found the real problem.

According to the JL tech, the early run of 900/5s are sensitive to low battery voltage. If the board detects a problem (there's a name to this feature but I can't think of it), it mutes the sub channel. Low battery voltage makes it think there's a problem. The sub channel is the only one with this feature so it make sense why channels 1&2 of this amp and the entire HD600/4 work fine.

The one thing I changed that night was going straight from the run position to the start position. If I'm listening to the radio I'll usually cycle it to the off position, wait for the MS8 to shut down and then start the car. I did this because I got a nasty pop from the tweeters when doing it the other way. So what's happening is everything is running in the run position pulling the battery down. I've been meaning to replace this crappy Optima for years now. It's been scaring me all winter barely turning the engine over.

Cliffs Notes: If your HD900/5 randomly loses the sub channel, it's probably low battery voltage, not the amp.

TmaX

iTrader: (1)

Are you running a Red or Yellow top Optima battery?
I've always heard good things about the Yellow hence my concern.

I hate cars

Optima hasn't been a good brand in many years, since it changed ownership. The technology has been surpassed by many but the real problem is the quality control is just awful. Many, many failures in under a year, some in a month. If you already have one, I wouldn't worry but if you're looking at buying one, you can spend your money on better batteries at that price point. That goes for the red and yellow top.

The Sears Die Hard Platinum is a good one. It's a re-badged Odyssey for a few bucks less than it sells for under the other name. Much better than the Optimas for about the same price.

djtsmith007

iTrader: (1)

So are you getting rid of the JL HD900/5?

I hate cars

No, I'm replacing the battery.

MOS805

Wow crazy stuff, I remember reading the post of you getting out of the car audio game because of the 900/5 problems, it is good to hear that the sub channel is not dead but it sucks it took that much frustration and work to figure it out. Good luck with your set up and from reading some of your recent posts on diymobileaudio cant wait to see what you are going to do next.

jda123

So the HDs don't adjust input rail voltage like the Slash do?

I hate cars

They do, it's the very low voltage spike when the starter is hit along with a weak battery. Apparently it causes the processor to lock up which mutes the output by default. Once the sub is on, it never shuts off but sometimes when the car barely turns over, the sub channel never comes on. My battery has needed replacing for over a year now and I keep putting it off. It doesn't help that my daily driver is 5 minutes or less each way so there's just not enough time to fully charge it. I take it for at least a 30 minute drive at least once a week to help charge the battery and burn off any condensation in the oil and exhaust.

TmaX

iTrader: (1)

I picked up the Yellowtop last year and its been reliable thus far.
It's CCA abilities haven't left me stranded in the Canadian winters as yet.

Both the Red and Yellowtop appear to have a 3 Year Warranty.
So hopefully if anything goes wrong with mines its within that period.

Thanks for your insight about the battery and the JL 900/5.

Nick337

iTrader: (2)

so Matt, its safe to say your not getting out of car audio?

I hate cars

Unfortunately, you're correct lol. Not yet anyway. I just found and fixed another issue, going to start a thread right now. I was having bad cancellation of my kick panel mounted mids. The temporary cure was removing the under dash covers. Weird.

Nick337

iTrader: (2)

Lol I knew it. Welcome back. I'm supposed to be headed that way in a month or two again matt. We Definately need to go get beers

I hate cars

For sure. My phone has been trouble free for nearly 2 months, I think it's a record. You have both of my phone numbers, right?