new battery

Quicksilversurf917 · **Posted:** Fri Jan 01, 2010 10:55 pm

I've noticed tonight that while I was driving that my driving lights flicker whenever my subwoofer hits. I still have the factory battery and I was wondering if I got a newer battery, like a optima red or yellow top, if it would stop flickering?

just throwing out there but I have a 450watt amp and kicker cvr sub

JL Rockies · **Posted:** Sat Jan 02, 2010 1:53 am

All energy to power the KJ and move the speakers comes from the alternator once the engine is running. That amplifier is not large enough to cause your charging system a lot of problems assuming the "gain" is set correctly and there's not copious amounts of bass boost. A 450 Watt amp driven into severe clipping will draw the same amount of average current as a 900 Watt amp that's not clipping. It's been my experience that 90% of professionals have no idea how to set the "gain" properly. It has also been my experience that 90% of end users (and professionals) have no idea what clipping sounds like mostly because recordings today are horrible.

Once the battery starts the car it immediately becomes a load on the charging system which now has less to give if someone is wailing away on their subwoofer system. If the battery is old and has been discharged many times, it may not charge up as quickly as a new fresh one. So replacing a battered battery with a new fresh one will help, but if the charging system is overwhelmed it will only buy you time. Have your battery load tested and if it's bad, it can be a source of the problem since a bad batt is a big load on the charging system.

Someone is going to recommend a "stiffening cap"; don't bother...... snake oil. I have a significant audio system in my KJ with an amp with regulated power supplies and I have no light-flashing issues. I do rock a Optima Yellow Top.

shaggy591a · **Posted:** Sun Jan 03, 2010 4:18 am

what is the best way to set the gain?

TexasRock · **Posted:** Sun Jan 03, 2010 11:39 am

JL,

What would be the best way to set the gain and boost on a sub amp?

Not to take this away from you shaggy... I'd like to know too!

Keith

JL Rockies · **Posted:** Sun Jan 03, 2010 1:17 pm

The "best" way it can be argued is to use an O scope on the outputs of the amplifier and adjust the "gain" until you see the wave form begin to clip. Since most people do not have access to one of these, there is another method that provides good results for a fraction of the expense and expertise. This is only "easy" if the manufacturer provides the information to the consumer; JL Audio is the only manufacturer that I know of that provides all the voltage numbers in the owners manual. Here's a Flash tutorial that illustrates the process: http://mobile.jlaudio.com/support_pages.php?page_id=143

You could download a 0dB reference sine wave, burn it to a CD and use Ohm's Law to calculate the output voltage. Or you can challenge the tech support people at the manufacturer you've chosen and ask them for the output voltage..... be prepared to be put on hold for a while though. JL Audio does sell a tuning disk if you don't want to search the internet for the deal.

As far as bass boost, the best setting is zero. If you find that you need to boost your bass more than 6dB, you're better off getting more output by adding woofers (or replacing them with real ones

). It's better to get output with displacement over clipping. You need to increase output by 3dB to get the minimal increase humans can hear easily. You need to double the average energy to achieve this increase.... physics can be a b*tch.

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