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  1. #1

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    Default C400.4 with MMC6500, crossover question

    First of, I just getting into car audio so plz go easy on the noobie :)

    I have two pairs of MMC6500s installed my my Durango w/ a Pioneer DEHP80MP (4V pre-out) and a C400.4 amp. The speakers were installed before I got the C400.4 amp and are still wired to the crossover that came w/ the speakers. Is the active crossover built into the C400.4 somehow superior, or is there any other advantage to using that over the ones that came w/ the speakers?

    I find that the MMC6500s tweeters sound well... too bright and too loud i guess :) I was told on other forums that over time as they break in this seems to disapate, but mine still sound too loud.

    The other issue I find is that the speakers seem to distort the bass at a volume level of around 30 on the HU, this seems somewhat strange to me since its not all that loud ( tho my wife would claim otherwise :). Now if I turn on the HU highpass filter at 80Hz obviously that fixes the problem, but the speakers sound tinny.

    Am I doing anything wrong? Should I be using the C400.4 crossover and then say adjust the highpass filter to the MMC6500s to prevent them from distorting the bass?

    Any suggestions or ideas would be appreciated.

  2. #2

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    The crossovers in your new amp are optimized for the MMC6500s I believe, so there should be no problem running with that rather than the supplied passives.

    If you don't want to use the passive crossovers, there are a couple of ways to tame the tweeter response to suit your tastes. You can bi-amp the front component set with all four channels of your amp, and adjust gains on the front/rear channels to balance the output, or use an EQ/bass and treble control in your head unit to sort things out. If you do want to keep your amp powering both sets of speakers (as-is), you can use the supplied passive crossovers and attenuate the tweeter level with the switch on the crossover to either -3db or -6db to balance the output of your components to your liking.

    As far as the mids distorting with bass at higher volumes, they are not meant to put out the lowest frequencies and would work better with a subwoofer doing that job. 80hz is actually a good crossover point for those MMC6500s. A modest sub playing 80hz and below would be an ideal upgrade for your system. If you are wanting some accurate sound in the lower frequencies, consider a matching MM2104 10" sub with an appropriate amplifier.

    The Momos are a very nice speaker and should really outshine the factory ones in terms of high frequency and midrange/midbass. Most aftermarket component sets are not really designed to play down in the lowest frequencies with any kind of volume, and manufacturers usually engineer them to be used with a compatible subwoofer to reproduce the whole music spectrum.

    The paper-cone specials that came from the factory are a big comprimise, in that they don't really reproduce any one frequency band all that well. They are designed to put out modest bass output that should keep most non-audiophiles happy, but don't really do for those expecting great sound.

    Compared to stock, it's not unusual to notice a little less bass out of your new components. They should loosen up and play lower with ease after they are broken in properly, but they are still not going to put out subbass the way a designated subwoofer can. After break-in, if the MMCs aren't sounding as good as you envisioned, go for a subwoofer. Compared to a lot of the competition those Momos actually do very well in the midbass department, so swapping them out for another brand could very well sound worse unless you spend huge money. Also- covering the mounting locations around your speakers with something like Dynamat may cut enough distortion that you may be happy with their bass output.
    Last edited by Greg Peters; 08-23-2006 at 03:14 PM.
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  3. #3

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    You can use the high pass filter on the amp instead of the one built into your head unit. You can then high pass as low as 50Hz, with a 12 or 24 db slope. I'd say high pass them at about 60 or 70 at 24db/ octave and see how that is. If the tweeters are too much, I second the passive crossover switch suggestion. I'd guess that they're on "0" now.

    Any chance the loud function is on? Or some EQ setting such as "powerfull" or whatever Pioneer puts in those things? That would lead to popping at higher volumes, too.

  4. #4

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    Quote Originally Posted by Greg Peters
    The crossovers in your new amp are optimized for the MMC6500s I believe, so there should be no problem running with that rather than the supplied passives.

    If you don't want to use the passive crossovers, there are a couple of ways to tame the tweeter response to suit your tastes. You can bi-amp the front component set with all four channels of your amp, and adjust gains on the front/rear channels to balance the output, or use an EQ/bass and treble control in your head unit to sort things out. If you do want to keep your amp powering both sets of speakers (as-is), you can use the supplied passive crossovers and attenuate the tweeter level with the switch on the crossover to either -3db or -6db to balance the output of your components to your liking.

    As far as the mids distorting with bass at higher volumes, they are not meant to put out the lowest frequencies and would work better with a subwoofer doing that job. 80hz is actually a good crossover point for those MMC6500s. A modest sub playing 80hz and below would be an ideal upgrade for your system. If you are wanting some accurate sound in the lower frequencies, consider a matching MM2104 10" sub with an appropriate amplifier.

    The Momos are a very nice speaker and should really outshine the factory ones in terms of high frequency and midrange/midbass. Most aftermarket component sets are not really designed to play down in the lowest frequencies with any kind of volume, and manufacturers usually engineer them to be used with a compatible subwoofer to reproduce the whole music spectrum.

    The paper-cone specials that came from the factory are a big comprimise, in that they don't really reproduce any one frequency band all that well. They are designed to put out modest bass output that should keep most non-audiophiles happy, but don't really do for those expecting great sound.

    Compared to stock, it's not unusual to notice a little less bass out of your new components. They should loosen up and play lower with ease after they are broken in properly, but they are still not going to put out subbass the way a designated subwoofer can. After break-in, if the MMCs aren't sounding as good as you envisioned, go for a subwoofer. Compared to a lot of the competition those Momos actually do very well in the midbass department, so swapping them out for another brand could very well sound worse unless you spend huge money. Also- covering the mounting locations around your speakers with something like Dynamat may cut enough distortion that you may be happy with their bass output.
    Thanks for the quick reply. Just to help me clarify some stuff :

    "You can bi-amp the front component set with all four channels of your amp, and adjust gains on the front/rear channels to balance the output"

    What does bi-amp mean? Drive the front speakers w/ all four channels from the amp? Using the front to drive the midbass say, and the rear channel to drive just the tweeters? I'm assuming this would then allow me to use the crossover adjustments on the amp itself to tweak settings, correct?

    And I do have a sub w/ a seperate amp already, two 12" Rockford Fosgate Punch3 w/ a RF amp. I was just trying to tune the component speakers a bit more to reduce that slight distortion I sometimes get.

    Lastly, so using the passive crossover for the speakers is not a bad thing right? I was somehow under the impression that i could remove that passivecrossover and run the speakers somehow straight out of the amp, but I guess as you pointed out ( and if my understanding of bi-amp is right on ) I'd need more channels to drive each of the speakers.

  5. #5

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    Quote Originally Posted by Thom
    You can use the high pass filter on the amp instead of the one built into your head unit. You can then high pass as low as 50Hz, with a 12 or 24 db slope. I'd say high pass them at about 60 or 70 at 24db/ octave and see how that is. If the tweeters are too much, I second the passive crossover switch suggestion. I'd guess that they're on "0" now.

    Any chance the loud function is on? Or some EQ setting such as "powerfull" or whatever Pioneer puts in those things? That would lead to popping at higher volumes, too.

    I made sure the loud setting was off on the head unit :) What is the significance 24db/octave vs 12db ? I very much confused of what the "practical" result of changing that setting would do.

    Also I didn't realize you could adjust anything in the passive speaker crossover, I shall have to take em out and have a look! Thanks for the info!

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    Quote Originally Posted by rniedzial
    Thanks for the quick reply. Just to help me clarify some stuff :

    "You can bi-amp the front component set with all four channels of your amp, and adjust gains on the front/rear channels to balance the output"

    What does bi-amp mean? Drive the front speakers w/ all four channels from the amp? Using the front to drive the midbass say, and the rear channel to drive just the tweeters? I'm assuming this would then allow me to use the crossover adjustments on the amp itself to tweak settings, correct?

    And I do have a sub w/ a seperate amp already, two 12" Rockford Fosgate Punch3 w/ a RF amp. I was just trying to tune the component speakers a bit more to reduce that slight distortion I sometimes get.

    Lastly, so using the passive crossover for the speakers is not a bad thing right? I was somehow under the impression that i could remove that passivecrossover and run the speakers somehow straight out of the amp, but I guess as you pointed out ( and if my understanding of bi-amp is right on ) I'd need more channels to drive each of the speakers.

    Biamping is a good thing for fine adjustment of the levels that each tweeter/midrange produce. It does require all four channels for one component set however. Your amp is designed so it can replace the MMC6500 passive crossovers with the electronic versions built in to the amp. Some say the sound quality is better when doing so. If that's something you want to try, your manual for the Momos spells it out pretty clearly.

    Biamping may not be necessary in every install. You do lose the ability to dial the tweeter attenuation up and down at the crossover itself- you have to do that with the gain settings on your amp instead. If tweeter attenuation is important to you, along with the ability to power two sets of Momos with one four channel (as it sounds like you want to do), try to use the supplied passive crossovers and see if it gives you enough control when trying to turn down your tweeter levels.

    As far as distortion in the lower midbass from your Momos, it could be from a couple of different things. If the speakers are not perfectly sealed where they attach to each door, you'll get some distortion. If your door (the speaker's "enclosure") is not sealed up well, some sound pressure from the speaker's back wave will leak out of the door and interact with the wave produced at the front of the cone, causing cancellation (and distortion) at certain frequencies.

    The Momo components are capable of moving a fair bit of air with their cones at higher volume, so its important to deaden the speaker mounting surfaces with something like Dynamat, Second Skin, etc. if you notice the panels buzzing at higher volume levels. It is also a good idea to treat the rest of the inner door panel the same way. The plastic water barrier in most car doors doesn't do a really good job of sealing the door and giving your speakers a proper enclosure to play in. Improving that seal will allow cleaner and tighter midbass response.

    Lowering the gains on your amp may also be an option if the speakers are simply seeing too much cone excursion (and are bottoming out in their baskets) at the volume levels you prefer.
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  7. #7

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    Quote Originally Posted by Greg Peters
    As far as distortion in the lower midbass from your Momos, it could be from a couple of different things. If the speakers are not perfectly sealed where they attach to each door, you'll get some distortion. If your door (the speaker's "enclosure") is not sealed up well, some sound pressure from the speaker's back wave will leak out of the door and interact with the wave produced at the front of the cone, causing cancellation (and distortion) at certain frequencies.

    The Momo components are capable of moving a fair bit of air with their cones at higher volume, so its important to deaden the speaker mounting surfaces with something like Dynamat, Second Skin, etc. if you notice the panels buzzing at higher volume levels. It is also a good idea to treat the rest of the inner door panel the same way. The plastic water barrier in most car doors doesn't do a really good job of sealing the door and giving your speakers a proper enclosure to play in. Improving that seal will allow cleaner and tighter midbass response.

    Lowering the gains on your amp may also be an option if the speakers are simply seeing too much cone excursion (and are bottoming out in their baskets) at the volume levels you prefer.
    Thanks man, that the best explanation/reasoning I've read thus far on why one should Dynamat the doors :) I'm almost certain the buzzing and "distortion" I'm hearing is due to poor mounting and unsealed enclosure.

    Is Dynamat the best way to go? I've seen it sold online and it looks fairly pricey :(

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    I've heard that 2nd Skin presents better value, but Dynamat Xtreme has never let me down. I buy it when I can afford it (and still need a couple hundred bucks worth).
    Last edited by Greg Peters; 08-25-2006 at 02:16 AM.
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  9. #9

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    It is the more expensive brand out there but it is also one of the best. Ive been using it for years with very good results, and check your local shop for deals.

    I can get a 4 square foot wedge pack for less the $30 at my local shop. You can get it for like $15 on Ebay but after $15 shipping you aint saving much.
    polkaudio sound quality competitor since 2005
    MECA SQ Rookie of the Year 06 ~ MECA State Champ 06,07,08,11 ~ MECA World Finals 2nd place 06,07,08,09
    08 Car Audio Nationals 1st ~ 07 N Georgia Nationals 1st ~ 06 Carl Casper Nationals 1st ~ USACi 05 Southeast AutumnFest 1st

    polkaudio SR6500 --- polkaudio MM1040 x2 -- Pioneer P99 -- Rockford Fosgate P1000X5D

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    Quote Originally Posted by rniedzial
    The other issue I find is that the speakers seem to distort the bass at a volume level of around 30 on the HU, this seems somewhat strange to me since its not all that loud ( tho my wife would claim otherwise :). Now if I turn on the HU highpass filter at 80Hz obviously that fixes the problem, but the speakers sound tinny.
    Quote Originally Posted by rniedzial
    And I do have a sub w/ a seperate amp already, two 12" Rockford Fosgate Punch3 w/ a RF amp. I was just trying to tune the component speakers a bit more to reduce that slight distortion I sometimes get.
    Just a question- what frequency do you have the low pass for your subs set for?

    While I can't speak from experience regarding your exact sub/sub amp combo, you may want to try to set the low pass around 80hz for the subs (if you cross your components over for 80hz and up). This may alleviate the "tinny" sound you describe if you've been running your subs crossed over lower than 80hz.

    A lot of settings depend on your equipment, enclosure size, and the frequency response you actually see in-car due to characteristics of your vehicle. Sometimes it takes a great deal of time and fiddling to get right.

    You could also low pass your subs at 100hz to allow for some overlap in the frequencies, but that might make the sound muddier in the lower midbass area. Some cars and systems need some overlap between sub and component crossovers, and some (like Mac's setup) need a gap to account for the vehicle's specific peaks in frequency response. It wouldn't be a great idea to run your subs above 100hz.

    As far as crossover slope, i.e. 12db/octave or 24db/octave...the steeper the chosen slope, the less high frequency (in a low pass) or low frequency (in a high pass) filter setting sneaks through past the chosen crossover point. A steeper crossover slope will tighten up your comps if you choose a lower crossover point for them. A steeper slope on your subs will also tighten up their upper bass response if you find they tend to get muddy playing the higher bass notes when crossed over higher.

    The professional (and most costly way) to set up your system would be to visit a quality shop that has a Real Time Analyzer and have them fine tune your system. An RTA shows peaks and valleys in your system's frequency reponse and does so by playing "pink noise" through your system and then measuring anomolies in the playback with a microphone. An RTA is the most exacting way to go, but most experienced car audio types can set things up pretty good by ear with music and test tones.
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