new Box for momo10 inch?

[Aimen RG]

i have polk momo 10inch in a sealed box as per polk recommendation
about .66 cu ft i think, around 15x13x9 outsides

the quality is nice, but im missing the lower freqs,
i ran a freq sweep, in car, i have cont drop from 50hz below

i was thinkin of using ported box, tune at 45hz, the polk site says i would get abt 10more dbs in 40-60hz range, which isnt a bad thing :D

but what abt quality? how much does that suffer? i dont want loud, but clean low base.

im runnin it off 150 rms amp
will be upgrading to 300+ one, but wt first? amp of ported box??

[MacLeod]

Something else is wrong, probably with your crossover settings.

I too have a MM2104 in a sealed box about .68 ft3 and mine has no problem hitting the 18 Hz note on the IASCA disc or the 21 Hz note on the MECA disc. Plus, I only cross mine over at 40 Hz.

Check the crossover settings on the amp and/ head unit and make sure theyre not set to HIGH PASS.

[Aimen RG]

i burnt my own disc with 10 20 30 .. 100 hz sine waves
20-30hz range is almost non existant. :(
it picks up from 40hz, from thr own, around 100hz, the response is pretty decent.
no the amp is not on HPF, its on LPF, crossed at abt 80hz, usin freq tones, i could hear the effect of crossover, its not the LPF which is at fault.
the amp doesnt have a subsonic filter button so i cant think its the problem
maybe it has internal prefixed subsonic filter ^o) i think not.

im using the sealed box, sized same as the one on polk page
i did add some foam in it to absorb some boominess. is it absorbin the lower octave aswell? i think i will try removing it.

the woofer is placed in trunk facing upwards, :D because it keeps fallin if i face it inside the cabin near the rear seats. :(

should i try a bigger amp first?

[Aimen RG]

here a pic :D:D

[MacLeod]

I dunno dude. Mine is in a .68 sealed box sitting in the front of the trunk firing forward into the cabin and Im only using 300 watts and itll play sub 40 Hz notes with authority all day long and twice on Sunday.

How much power are you running?

It could be cancellation but I wouldnt think so at least not that low in the spectrum. Try facing the sub in different directions.

[Aimen RG]

im pumpin 150 rms into them :D, i will remove the dampin material and move it around.

[MacLeod]

Ya may need a little more power.

The lower the frequency, the more power required to reproduce that frequency. 150 watts is pretty small for a sub, especially a quality sub like the MM2104.

[Greg Peters]

I dunno dude. Mine is in a .68 sealed box sitting in the front of the trunk firing forward into the cabin and Im only using 300 watts and itll play sub 40 Hz notes with authority all day long and twice on Sunday.

How much power are you running?

It could be cancellation but I wouldnt think so at least not that low in the spectrum. Try facing the sub in different directions.

^^^Definitely. Try facing the sub's cone towards the license plate.

[GLN305]

^^^Definitely. Try facing the sub's cone towards the license plate.

x2 definitely

[Aimen RG]

sub now facing the plate
using kicker amp, 300watt @4 ohms
with 6db boost at 40hz,
im feeling more clear base.
my gain is at 75%, i feel its becasue of my crappy pioneer entry level pre outs.
i think if i upgrade my pre, i will get out more music and sound from my current setup.

[Greg Peters]

Bass boost + gains set too high = blown sub :(.


If you're trying to extract more than your sub and amp can produce, you'll drive your amp into clipping (much earlier on the volume dial using high gains and bass boost) and eventually cause damage to your sub. Sealed enclosures typically allow higher power than ported, but sending the sub a clipped signal routinely with either will probably cause failure, as amps can double their power when clipped.

http://www.resnet.trinity.edu/areynol1/gain.htm

Set your gains properly, lower bass boost, and if you don't get the output you desire you should think about upgrading your equipment.

[Aimen RG]

i do not own an o-scope. cant use method one

checked the output of the amps using multimeter, but cant set the gains accordin to them as speakers/subs are of not same sensitivity. setting them to thr max at a given headunit volume is of no use. need a flat responce.

i actually used something like method two. thou i didnt use 1khz tone, but fixed the head unit volume to 20 of 30max, than turned the gain up with no base on the speakers till i heard clean tones to me required level, than adjusted the sub, using 30 40 50 60 70hz sine tones. had to boost at 40 to flaten up the response to my ears. didnot hear any clipin or bottomin out at my required levels

gain at 75%, u must be worried abt that, as i mentioned, its the crappy pre outs, im sure they aint making more than .5volts. ill run 50hz tone and check them aswell.

[MacLeod]

Greg is right. Bass boost with the gain at 75% and youre cruisin' for a blown sub.

Remember, a single 10 with 300 watts aint gonna blow your windows out. For that youre going to need more and bigger subs and a much more powerfull amp. Dont try to force your Polk 10 to put out that kind of output cause it physically cant and youre gonna fry it in the process.

[Aimen RG]

dunno how u r saying lookin at the gains that im gonna blow the speakers out
as far as i know, its the sensitivity. need to match it with my head unit out
ive done that, my system max out at volume 20 of 30 total. i usually listen at 15 or lower. i still havent gotten time to tune the system, busy with studies. will do it. i know my amp at the momemt is too sensitive, which isnt letting me use full range of head unit volume, its getting louder quicker. nothing like blowing up.

even if i keep the gain at max, one cant say im gonna blow the speakers, as i can stop myslef from rotating the volume knob too much.

[MacLeod]

Yup, then the first time somebody gets in your car and decides to crank the volume up to 20 cause they like the song thats playing - your amp clips, sending more than double its rated power to your speaker which could then rip it a new one.

Or the first time you stick in a CD thats not recorded at a high level like anything much from the early 80's or 70's and want to crank on the volume to get some more output - your amp clips and there goes your speaker even tho the output was never that loud due to the crappy recording, but the amp still clipped and your speaker is still dead.

I suppose youre right that you could set your gains too high and then use extreme caution with the volume so that you never turn it over 1/4 up.....but I just think its better to just set the gains right at the start and then you dont have to worry about it. But thats just me.

[Aimen RG]

good valid point.
i;ll make a 1k tone, see whr my HU clips. and then adjust the amp accordingly.