Midwest Car Audio

HERE I WILL COPY AND PASTE THE INFO.

This is what we uesd to do for our SPL vehicles.
The first thing we did was use an O-scope to set all of the gains.
Unforfunetly you can't do that unless you have an O-scope.
So just set your stuff up the best you can by ear.
Next take your DMM hook the positive up to the positive speaker wire at the amp so your positive speaker wire and positive wire from the DMM are connected to the positive speaker terminal on the amp.
Now do that with the negative also. Do the negative the same way you just did the positives.
and set the DMM to AC voltage.
Now take your clamp meter and clamp that only around the positive speaker wire comming out of the amp.
Set the clamp meter to AC amperage.
Now the install part is done.
Next you need a test tone disc.
Set the volume on the head unit to were you feel everything is as loud as you think it shoud be.
Or if you have an O-scope set your volume rite at clipping. Just a hair less so your not running a clipped signal and remember that volume number becuase you will need to do all your testing at those same settings to get an accurette Idea of whats going on.
Now with the DMM set to ac voltage and the clamp meter set to ac amperage take the test tone disc and find a frequency to start with, burp your system and write down the results from the DMM and clamp meter.
Both those numbers need to be writen down at the same time or you won't get propper results.
then go up 5 hertz burp again and write it down.
then go up another 5 hertz and do it again.

Example:
start at 30 hertz burp then 35 burp 40 burp and keep doing that until you have gotten to 80 hertz.
Now the physical work is done.
Alright now you need a calculator and a place to sit down and relax and you want to well im going to write it for you the way I've got it wrote down in my notes.

AC voltage from the speaker outputs divided by the amp draw on the positive wire from the amp.
That will give you your impedance at each frequency.

Heres some thing extra for you do you really want to know how much power your amp is really making do this.
Multiply the AC voltage by its self then divide that number by the ohm loads you just came up with.
thats a heck of alot more realistic than just use 4 ohms or 2 ohms becuase you just did the work to find out what your amp is really seeing. so the wattages you come up with are alot more realistic.
I'm going to post this then I'll have another post for you that shows you how I set up my paper.
After my next post if you don't get it PM me and I'll try to help but I would like to have any question you ask to be posted in this thread so it can help others.


Heres an example of a kicker ZR360 running to 2 10 inch solo L7 tens with a nominal 2 ohm load.

Volume-----Frequency-----AC voltage----AC amperage-----ohms------watts
31 --------------20--------- ----41.4------------10.7 -----------3.87------- 443
31---------------25--------------44.1-------------9.6------------4.6---------423
31---------------30--------------44.3-------------9.7------------4.56--------430
31---------------33--------------48.3-------------7.4------------6.53--------357
31---------------40--------------48.9-------------3.75---------13.04--------183
31---------------50--------------38.4-------------3.15---------12.19--------121
31---------------60--------------42.9-------------9.22----------4.65---------396
31---------------70--------------33.5-------------9.16----------3.66---------306

Do you get the idea.
Do you see that even though I am running a nominal 2 ohm load I never hit 2 ohms
but my amp did put out rated power.
Its supposed to put out 400 watts at a nominal 2 ohm load and if you look at the numbers I averaged 400 watts.
Do you see the impedence rise at 40 hertz and 50 hertz and look at the wattage.