was just lookin through the settings on my in dash dvd player for subs, and it has frequency. Ive never been good with tuning so ive always left it alone but what frequency do people usually run the subs on? mine has always been on 80mhz, it goes down to 50 and up to 120 im pretty sure

Generally, people set it to 80Hz or 100Hz. But the best idea is to put it on each setting and see which sounds the best.

Just set it to 120hz, then adjust it on the amp to what sounds best.

It depends on what other speakers you have as to what will work.
If your other speakers are larger or good quality the sub will usually sound best at a lower frequency (80hz and under).
If the other speakers are smaller or crappier, you might have to have the sub doing some higher tones (above 80hz) to help compensate.

on that note, as I said, not very good at tuning.. to tune the amp so it isnt too bad, this is what I heard to do

-turn the settings (gain) right down on amp
-on head deck turn all base settings up to the highest
-turn the volume up on head deck as loud as u can stand, about the loudness u would possibly listen to it in then
-turn the gains right up and its done?

Well normally and mainly when your tuning speakers a general rule of thumb before touching any EQ settings etc is to turn the headunit volume to 0. The balance to full of where youd like to tune so say all the way to the front for tuning front speakers...bass control to zero and the gains right up.

Then crank the volume until you start to hear distortion...crackles and so on....do the turning up slowly u dont wanna just crank it to the end and cook something....

Then gradually reduce the gains until you are able to turn the system to MAX volume or at a level your comfortable to be the max and leave the gains....with more advanced tuning when you start with equalisers etc this will effect this and gains etc will need to be tweaked again...so all this will apply to subwoofer tuning..

Balance leave in the normal position, all subwoofer settings on - bass enhancement options like bass bossters etc left off. But the actuall subwoofer level to full.

But gains for the sub channel onthe amp to max....headunit volume on 0....gradeually increment volume til it either distorts...start to hear wobbling sort of noises or too droney etc....then like speakers...gradually reduce the gains while trying to get the volume near the max....since the bass control is left on max you wont have to worry bout it distorting when you increase/decrease this later...remeber also if you do run other boosters such as Alpine MX mode...then you will need to tune again as this will effect the audible output.

It dpeends on what size and type speakers your running in the rest of the system and their freqneucy response.

I would not normally go higer than 80htz, unless using 4" front speakers.

Mine runs at 45htz but that is lower than most people run.

I find 63 works quite well with a steep slope of 24db.

What front speakers are you running what size?

Whoa man if your speakers can reproduce 80mhz your are probably transmitting radio signals all over the place....
If you run 120hz you will find that the sound stage will be pulled back towards the rear of the car.
The higher the crossover point the worse it gets.
I tend to run my system at around the 50-60hz region but that depends upon what sort of front speakers you are running.
When I had my 10 inch 3 way front stage I used to run the fronts full range and the subs to 50hz and that worked very nicely......

Mines at 80 aswell

Who said 80mhz?
Thats the end of Bat hearing range?

80htz is a suggestion to try.

Mine is csossed at 45htz but it depends on how well set-up your front stage and sub intergration is and the type and size of the drivers

Original poster accidently type 80mhz

I just have 6.5" fronts, which can play reasonably low, and 12 subs so I set mine at 63Hz for everyday listening and change it to 80Hz when I want to turn it up LOUD.