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Thread: mm120 spl/sq??

  1. #1
    Kkii9
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    Default mm120 spl/sq??

    I was wondering if the mm120 is more of a sq sub then spl?
    It seems to lack a lot in the "feel" of the bass. i have 500w rms going to each 12 and i thought it would be very loud. But instead they are pretty mild and not giving much spl.

    anyone have more specs/experience on this?

  2. #2

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    polk has yet to produce a sub that is anything but geared for sound quality.

    the momo line was an attempt (and i believe success more or less) to move from SQ to "high power SQ" --- bordering on what some would call "SQL" (very loud, high power sound quality subwoofers).

    If you're 12's aren't bumpin your vehicle you might need to look at a few things...

    1- is youre 500 watt amp really 500 watts?
    2- is it tuned / set properly

    3- how big is your vehicle? if you've got a Ford Expedition or a Chevy SUburban, you may need 3 or 4 subs to get the extreme BOOM that you are looking for.
    4- what kind of enclosure are they in? are they in the proper 0.88 sealed cubic foot box each or otherwise designed iso-push pull BP box? porting them or having incorrect box design can cause crap-o-la sound.

    5- are they directed in the right manner -- sometimes facing a sub forward versus backward, or up versus down can cause a dramatic change in the bass that you both feel and hear.

    as far as specs -- the momo 12 is rated at 500 -- can handle 600 - 650 rms with no problem... as long as its good clean power. sensitivity is like 87 db's so they are at least mildly efficient on power.
    "With your own attitude it is hard to survive here... But who gives a damn, we are here to change the world, and we dont need a password for that."
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    Lack of the "feel" of bass...would normaly mean the loss of low end extension. Though we dont hear much towards the 20hz we usualy feel it... If your running the subs in .88 you are probably loosing some low end...even though that is the proper size enclosure. I wont recomend going to band pass....I just wont.

    If you can run some test sweeps using bass mechanics..that might give you an idea of where your at as far as what your sub is producing..and at what level...

    after that is done..I'm sure we can help further..

    Good luck..
    thomass A.
    Peace sells, but who's buying?

  4. #4
    journey
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    I have the same problem. I have 2 Polk Momo mm120's(the old style 12"), powered by a jbl 1200.1 D-class amplifier. The subs definatly have some punch in the higher bass( 50-120(xo point)), but when playing sweeps below 50 i can see the sub moving, and moving quite a bit, and it makes the rear-view mirror move alot, but i can't actually feel a whole lot of the bass.

    The subs are in a custom dual box, prob more like .90ft^3 to each sub, facing straight up into the hatch of an 89 RX-7 (really tiny car, not even a back seat).

    I actually managed to blow one of my two momo's yesterday, and i was curious if people had any experience with the adire line of subs. I was thinking about keeping my current polk momo for the sq of the higher end bass, and getting possibly an adire tempest in a sealed box(for size reasons) as well, with a 50hz crossover on it, and 120hz on the momo. Would this work well? I would probably be wiring both subs up to the same 1-channel amp, just with a crossover between the amp and the tempest

    I mostly ask because my first system was made of cheap subs in a bandpass, and it was loud, but i wanted something that sounds good so i bought the momo's, being told they were some of the louder SQ subs out there. I don't want to loose my sq(definatly not going jl, i've heard the 10w6's, and 12w3's, both in sealed boxes, and am incredibly un-impressed with the quality of sound), but i would like some more of that real pounding-feeling you get from a sub that hits low.

    Thanks

    Erik

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    Erik, sorry to hear that you blew the momo -- you might wanna think about finding a replacement old school style momo on ebay for like 100 bucks before you go mixing brands / sizes / styles of subs.

    as far as why you dont feel the bass? -- they're pointing up (my best guess). if its shaking your mirror, and the woofer is really MOVING but you dont feel it, chances are, they're directed wrong. I had 4 DX 12's pointed forward and i swear i couldn't feel a damn thing -- head hurt, but i coldn't FEEL bass... pointed them backwards... i felt a lot. you may want to try pointing them toward the back, forward, or if all else fails, get a couple of wooden blocks and point the box down (putting the edges of the box on the blocks so that your woofers are like 4 inchs off the ground (if it works u can then build a new box to suit the new pointing or just craft some "feet" for your current one)... if you STILL dont feel it after that then I really don't know... the JBL does not have a sub sonic filter, so you are getting "true" full bass bandwidth there... ntohing's cut out.

    normally ppl lose low end when the box is too small.. but if you're at 0.9 each, you're golden.

    adire makes a good product.. the Brahma sub is an SPL wonder, but i've yet to see or hear about the tempest (that's a reflection of my own lack of knowledge, not the sub's quality).

    try redirecting the one sub you've got left (assuming your box has separate chambers and you disconnect the blown one first) and then decide exactly what it is that you want in a sub / how you want it to perform, and how you will be pointing it in the future... it'll be easier to pick a sub after that.

    also -- 120 hertz? that's a bit high... is there a reason you're pushing them into such a high freq range? --- usually, on a momo or similar sub you're aiming for the 80 - 100 hertz range... the 80 being the preferable...
    "With your own attitude it is hard to survive here... But who gives a damn, we are here to change the world, and we dont need a password for that."
    - Anurag

  6. #6

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    correction...the Adire Brahma is an SQL sub... much like the IDMAX is.. Excellent sq while hitting higher DB's. .... very efficient sub.... hehe.. A real sub :) sorry polk

    BTW...stay clear of the "one note wonders" JL subs. I'd by polk momo's before I'd buy JL's again. The W7 is the only thing they have going right now..however...at an extremely high price.. Heck..you could get 3 momo's for the price of 1 JL W7...lol:o
    Peace sells, but who's buying?

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    Just a thought I had concerning the lack of punch coming from teh speakers.

    Did you wire the subs out of phase of each other? Meaning, did you reverse the polairty of the leads on one sub? That would cause lots of movement but very little sound because the two subs would be firing oppositely. When one was pushing out the other would be pulling in. It would cause the two subs to cancel each other out. Reversing polarity causes a 180 degree phase shift. If one is operating at normal polarity and the other is 180 degrees out of phase then the frequency map would end up looking like a DNA helix profile and not a single sine wave like it should. So every valley on one sub's map would be met with an equal and opposite peak on the other sub's map. You know, physics, an object in motion tends to stay in motion unles acted upon by an equal and opposite force, or however it goes. It works the same way for sound waves. Although that analogy isn't 100% accurate, it gets the point across with the same general idea. Two speaker wired out of phase of each other will cancel each other out.

  8. #8
    journey
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    The subs were wired to the same polarity, and its not that the bass didn't hit, it did. It hit alot harder than my friends pair of 12w3's, getting power from an mtx 6500D in a passat, although not as hard as my other friends kicker L7's powered by a 1000W alpine amp in a jetta.

    For the upper bass, especially 50-80, if i parked in the driveway and had it up loud, you could hear the bass in both bedrooms at the front of the house, upstairs.

    The subs definatly hit, i guess the easiest way to describe would be an analogy i saw somewhere else on this board, its the difference between being punched in the head, and kicked in the stomach. There was definatly bass there, and alot of it, but down into the lower bass it just didn't hit.

    Anyone have some suggestions for where to find some good bass tracks for tuning, as opposed to listening to? I used to have a track that had 300-20hz, in 10hz increments, with a voice telling you what frequency it was switching to, but i dont have it anymore. Perhaps if i can find a program to generate it that would work too.

    I grabbed a couple tracks off of mp3.com that claim to be bass-test's, and even with just 1 sub the higher bass hits realy well, but the sweep will get to a point, and then after a few more hz it will be there, but only at a fraction of the volume it was with the higher bass. The sub is still moving, and i've tried with the box facing back, up, and forward(might try and find a way to have it down-fire to test that).

    Its almost hard to test though, because i'm so used to listening to 2 12"s getting 1200W, instead of 1 getting 600W, probably arround a 5-6db difference from what i've been told.

    Once i figure out exactly what i'm going to do with my second blown sub(replace, just run 1 for awhile, try to fix, etc.) i'll do more, although if i can figure out how to position the box and get good bass out of the one sub, that would be nice too.

    Erik

  9. #9
    Kkii9
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    Ok, i figured out what was wrong, i guess it was the box. I bought a new box and put the subs in there, made sure it was air tight and the bass sounds so much better. i figured it was the box from the get go, but wanted to see other options before i did it.
    Now it sounds so much better, but i dont know how to tune properly my amps to get the best possible sound from the Momos.


    Would anyone know what the proper levels i should adjust my amp settings for sub? I have 1 JL 500/1 to Each of my Momo mm120.
    i just wanna know how high i should turn the "Q" , Center Freq, Boost, Filter Freq, 12/24db slope, etc.
    THanks .. i appreciate the help im getting on the board.

  10. #10

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    Most those options are personal taste. You dont need the bass boost on though... distortion..distortion..and the q is in requard to the bass boost..so dont even worry abou them...

    gains... if no o'scope is used or meter...just turn your hu to 3/4 volume...amp gain to 0- increase amp gain till it starts to distort.. and then back off a bit.. you just set it .... basically

    xover...you can set at 24db or 12db..wich ever you like.. 24db more likely the ideal setting though...
    and as far as cut off..usually 80hz is ideal for subs

    think I covered everything

    <Thomas the Grey-Master Cap Hater>
    Peace sells, but who's buying?

  11. #11
    kkii9
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    Thanks, ill try it out

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