jl500/1 input sens, multimeter issue

Hi Guys,

I am trying to tune the input sensitivty on my JL500/1 amp to 31.6v as recommended by JL Audio.   When I connect my multimeter, I am getting voltages <1V and it's always changing, never staying on one reading.   I am doing everything by the book.  Meaning I have been to JL's website and have followed their exact instructions.  I have also used their CD with a 50hz non-attenuated sine wave and bought a 2nd multimeter, thinking my original one was bad.   

Bascially, when I have the amp connected to my JL10w6, I have have the input senstivty set to a place where it sounds ok.  I just want to be by the book and get the 31.6v reading which is recommened by them.   What I am really concerned about at this point is that I can't even get a consistent reading.

By doing everything they recommend I mean,

- using their 50hz sine wave on their cd, I also burned a 50hz sine wave off the internet and get the same results.

-connecting the multimeter to the same locations they show in their online tutorial, the subwoofer output

-turning the volume on my OEM BMW non-dsp x5 headunit to 75%

-making everything "flat"

-adjusting the input sensitivty while watching the multimeter to see if I can get the output voltage to go above 1v or even just give a consistent output.

-have tried the multimeter in both the 20v and 200v settings, even tried the mv setting to see if I could get a consistent output

-tried both the dc and ac multimeter setting even though I know it's dc. 

-I have even connected wires to the subwoofer outputs and then used tape to connect them to my multimeter prongs to ensure good connectivity.

-Both mulitmetters correctly read the resistence (ohms) of my 10w6.

On fact that may or may not be important, I am including it becuase I am not sure.  I bought the car used and it had the wiring for a sub amp already done, I just had to by a mono amp and hook it up.   I am not 100% sure where the RCAs and the remote turn on wires are coming from, but I am 90% sure they are coming out of the OEM amp.   Like I said, everything sounds good when it's hooked up, it's just that I can't get a consisent output voltage on my multimeter and it's driving me nuts.  What am i doing wrong? 

I appreciate your help

Thanks,

Ted

hi,

is the 10w6 producing sound (cone moving well)?...lots of 50hz tone at the volume setting?

are the meter leads connected to the speaker output at the amp? (+ to + etc.)..yes it's a dumb question, just covering the bases.

the reading you're measuring will be an AC voltage...a 50 Hz sine wave is an AC signal...31.6V AC hopefully after you've adjusted everything.

i'd check where your input to the amp is connected to in the vehicle.  BMW actively crosses over the speakers vehicles with amplifiers.  you may have the amplifier connected to a source that has minimal output at 50 Hz.  if you set your meter on volts AC, what do you measure at the input rca.  if isn't more than   a few  volts at the 75% volume setting then i'd check exactly where it is connected.  you could also try connecting a small speaker temporaily on the rca input at listen to what is being produced by it (lower the volume setting)  and also watch the cone.  if it isn't producing much sound or moving much, you need a different input connection.

hope this helps

mark

Hi Mark,

1.  Yes, the sound cone moves well and produces great sound.   It produces the 50hz sound well.

2.  Yes, the meter leads are connected from + on meter  to + on speaker output.  Similar for negative

3.   You may have solved my issue by telling me to use the AC, not DC setting.   I could have swarn I tried both, but will double check in the morning.  I will let you know.   If this turns out to be the solution, I will feel like the biggest idiot!!!  :)

Thanks,

Ted

Guys,

Thanks, switching to AC worked.   Duhhh.  I may get the stupidest post award. 

-Ted

Nah, you'd be surprised how many people make the same mistake.