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View Full Version : help with my system! no bass in speakers??



6a12tt
09-27-2005, 09:18 PM
hi, my head unit is an Alpine 9833 and i bought the new Polks MMC690 component.
As everyone knows, the Alpine HU comes with its own crossover, and isn't it redundant
to have two crossovers, and so is it why i have no bass at all coming out of my Polks?
(my OEM speakers has more bass to them w/ the HU's crossovers!)

I tried changing the crossovers on the HU, no good. I figured.. wait a minute, i'm on a
2way crossover so try the 3-way, same thing! Or do i need an amp to run the comps?!
sorry, i'm a newb here, so bare with me, tia!!

$$mok3d
09-28-2005, 12:32 AM
are you running the components off of your head unit? that could be the problem

6spdcoupe
09-28-2005, 01:49 AM
It isdefinately recommended to use an external amp. Although if your getting NO bass at all, check your wiring, very good chance theyre just out of phase.

6a12tt
09-28-2005, 02:39 PM
are you running the components off of your head unit? that could be the problem
yes i was... not enough power to run the comps right?



It isdefinately recommended to use an external amp. Although if your getting NO bass at all, check your wiring, very good chance theyre just out of phase.
i think i do need an external amp (reading from the stickies in the speaker section of the forum)


however, i need a good powerful amp to match the comps output right? but i get confused looking at amps power outputs, especially the multi channels since some of them around around 68-80watts at 4ohms, then it goes higher from 2ohms to bridged channels. i know the rule of thumb is better to have the amps overpowering the speakers than the other way around, but w/c amps though? thanks!

Decado
09-28-2005, 02:50 PM
i know the rule of thumb is better to have the amps overpowering the speakers than the other way around, but w/c amps though? thanks!

Correction, it is not better to overpower the speakers, if you don't know what you're doing overpowering can blow your speakers. And also, you said that you aren't using the crossovers that came with the set or am I reading wrong, i don't really understand? Use them, they are made to get the best out of your components. And also, your HU isnt going to stop low frequencies that can damage your tweeters.

6a12tt
09-28-2005, 07:01 PM
Correction, it is not better to overpower the speakers, if you don't know what you're doing overpowering can blow your speakers. And also, you said that you aren't using the crossovers that came with the set or am I reading wrong, i don't really understand? Use them, they are made to get the best out of your components. And also, your HU isnt going to stop low frequencies that can damage your tweeters.

let me take that back, it's better to overpower your speakers a little than to send them too little power, now am i correct? i know my HU's crossover won't stop low frequencies, but it'll limit a range of frequencies being sent to my speaker, in this case the comps. i was using the crossovers that came with the Polks (read earlier post)


but anyway, that didn't really answer my question, but thanks for the input though!

Xekutr
09-28-2005, 07:23 PM
no the whole overpowered/underpowered thing is dealing with having too little power in the amp which causes it to clip if you try to drive it hard past its limit. So the rule of thumb is to have not neccessarily a more powerful amp but make sure your gains are set right. Just turn off the h/u's crossover? I think that it would be more suited to a person that has say, stock speakers where you need to limit, like low bass to keep them from distorting. But in your case, you already have the crossovers in the comp's so the h/u crossover isn't really needed. And I agree with 6spd, you should try switching the polarity on one set of the comps going into the xover and see if that makes a diff in bass, or you might just be expecting alot out of a 6 1/2 with little power and a door that usually isn't sealed too well.

bikejunkie223
09-28-2005, 07:33 PM
I would run about 75 watts rms to those, if you have little midbass, check that one of the midbass speakers isn't wired backwards. The other thing, is that the speaker needs to be sealed to the door (uses the door as an enclosure) for good midbass, but it also needs to be sealed to the backside of the door panel (if behind factory grilles), otherwise the sound isn't projected well into the car, but some into the car and some into the space between the door panel and the actual door metal. I had this problem with the Polk db 6500 components in my civic si. Sound deadening/sealing the doors + sealing the speaker to the door panel cured my midbass woes without a new amp. HU power is not the best for components in my opinion, get a 2 channel that gives them 75-100 w rms into 4ohm. You should be able to run those speakers down to 63hz or so without a problem, that's where mine are set. Just remember the lower you want them to play, the more power it will take to get them to perform, and most Polks play loudest @ 80hz (resonant frequency) which means output will roll off fairly rapidly much below that. At least that's where my 6.5's measured.As for the crossovers that came with the speakers, they are there to divide the signal between the mid-driver and the tweet, so set your deck @ 63hz or so, and let the passives do their thing.

6a12tt
09-28-2005, 07:47 PM
no the whole overpowered/underpowered thing is dealing with having too little power in the amp which causes it to clip if you try to drive it hard past its limit. So the rule of thumb is to have not neccessarily a more powerful amp but make sure your gains are set right. Just turn off the h/u's crossover? I think that it would be more suited to a person that has say, stock speakers where you need to limit, like low bass to keep them from distorting. But in your case, you already have the crossovers in the comp's so the h/u crossover isn't really needed. And I agree with 6spd, you should try switching the polarity on one set of the comps going into the xover and see if that makes a diff in bass, or you might just be expecting alot out of a 6 1/2 with little power and a door that usually isn't sealed too well.

quick note: the Polk comps are 6x9's (MMC690) and installed in the rear deck; no the MMC650.

i tried switching the polarity on the comps and no changes or difference in bass.


I would run about 75 watts rms to those, if you have little midbass, check that one of the midbass speakers isn't wired backwards. The other thing, is that the speaker needs to be sealed to the door (uses the door as an enclosure) for good midbass, but it also needs to be sealed to the backside of the door panel (if behind factory grilles), otherwise the sound isn't projected well into the car, but some into the car and some into the space between the door panel and the actual door metal. I had this problem with the Polk db 6500 components in my civic si. Sound deadening/sealing the doors + sealing the speaker to the door panel cured my midbass woes without a new amp. HU power is not the best for components in my opinion, get a 2 channel that gives them 75-100 w rms into 4ohm.

the comps were fully installed on the rear decks. i did try switching the wires just to be sure but no changes on the output. but you're right (and everyone else too), i do need an amp to run my Polk MOMO comps but just didn't knew the minimun specifications to get the most of them, thanks!

Raven
09-28-2005, 09:15 PM
Try changing the polarity on just one of the speakers. Doing both just wires them out of phase again. =p