How to find 80hz on my mono amp?

hi guys,

i'd like some advice or help with this as im lost as to how and where 80hz is on my amp.

firstly, here is the 12inch sub woofer enclosure im using and its specs:

JBL GTO-1260BR 300mm Bass-Reflex Subwoofer Box Subwoofer

GT4-12/300mm Enclosure: bass-reflex

Power handling, RMS: 250W

Power handling, Max: 1000W

Sensitivity (2.83V/1m):

92dB Frequency response: 35Hz – 200Hz

Impedance: 4 ohms

Dimensions (L x D x H):460mm x 437mm x 360mm

and here is my amp and spec's, its a pioneer gm-7200m mono :

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ok guys,

the amp is installed, is getting plently of power ( i dont think its a demanding amp anyway ) and i can hear it playing along with the music.

only problem is that it doesnt sound right at all. its as almost as if it misses the timing of the beat by a fraction of a second, or im thinking

the problem is that its not tuned properly ( seems more likely as it sounds really flat and not impressive ).

i have a pioneer p80mp headunit with 3 pre-outs feeding it the music and each pre-out has 6.5v going to it and it matches my amps perfectly.

my thinking was to buy both amps from the same range/model line up from pioneer.

anyways, i have my hpf on the headunit set to 80hz, and the lpf is also set to 80hz.

however, my mono amp has a frequency knob and this goes from 40 - 240hz.

i have it currently set up like this : ( its a very simple amp with not much tweakability )

you can see from the photo where the knobs are currently set to by the green arrows. my thinking is that if the amp frequency starts out at 40hz,

well then all i need is another 40hz, so i just gave a guess at this and raised the knob to where i think 80hz would be.

am i correct in my method or completely off the mark altogether?

where exactly would 80hz on this amp be ?

if you know where it is, could you please save the above photo, open it up with paint, and mark where it is with a green arrow and repost.

thanks for your time guys ,

dave, ireland.

hi,

thanks for the reply :)

ya, that was my thinking also.

but i could be wrong too. if i have 80hz for my high pass and my low pass, should i be looking at setting the amp to 80hz too or do i need

to set it closer to the highest range of the subwoofer, which is 200hz?

i saw an article on this while googling earlier, where the guy said you should start off by upping the frequency on the amp to match the spec of the woofer.

i'll go look and repost it.

hi again ,

i found the info i googled earlier :

http://answers.yahoo.com/question/index?qid=20081204131556AARPM0R

basically,  the guy looking for help is asking where he should set his frequency knobs to. kinda like me. here is the answer he got :

Set the LPF on the amp to just below the highest range in the frequency response of the subs. Example, if the subs are 20-200Hz, set the LPF to about 180 Hz.

Source(s):

A.A.S. degree in Electronics/Industrial Electronics with 25 years in the mobile audio/consumer electronics field

live by the ford,die by the ford.

this is the thing,

i dont trust pioneer headunits when it comes to setting the filters from the menu of the cd player.

i think once the signal is fed out from the cd player in the form of the 6.5v pre-out, i think its up to the amps to do the filtering.

because the 4 channel amp i have , which is also pioneer, has a 80hz hpf switch which automatically  cuts to 80hz.

if i turn this switch to normal, all the bass goes to the front door components, which tells me that the cd menu hpf doesnt affect the pre-out signal.

i think i should really contact pioneer in fairness.

its their fault anyways.

if they were any good, they would have a switch on the mono amp also, which is auto tuned to 80hz for simplicity.

but no, they have to be awkward in order for the customer to bring his/her car to the audio dealer and get " set - up " or " tuned " for an extra price. its like buying a tv and having to call the dealer to tune it in. except the fact that you know when youve got the right channel with tuning a tv. with car audio, its all guessing unless you know what your doing.

im sad now :(   lol.

maybe i need a 10" sub then , which would have tighter bass .

its a possibility that the 12" i have just doesnt sound good. its ported so possibility goes too low and resonates the car. giving bad vibes.

it gets very boomy, sloppy boomy that is. nothing is tight or accurate.

you think a 10" would sound better?

its probly the ported box im guessing you mean the round ports every sub i have heard in a round hole ported box sound that way. try a vented box that has a long rectangle hole they seem to be right on and hit hard if built to the right specs.