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Thread: Memphis Belle 5 channel amp + Infinity Perfect 12" DVC - not sounding right

  1. #1
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    Memphis Belle 5 channel amp + Infinity Perfect 12" DVC - not sounding right

    I finally got my fiberglass enclosure finished and temporarily installed the car so I could test everything and make sure it sounds the way you'd expect. Unfortunately, it does not sound like you'd expect a 12" sub to sound. I currently am using a m10000 setup (using an external soundblaster usb sound card). From the carpc, audio is going to my Memphis Belle 5 channel amp which i have Diamond Audio Hex 6.5" components, Diamond Audio M3 5.25" in the rear, and lastly the 12" Infinity Perfect DVC subwoofer.

    The primary problem is: I am getting bass, but not on the magnitude I would expect from a 12" subwoofer getting power from the 5th channel of the Memphis Belle. I have wired the subwoofer as per Infinity's specifications, and have built the fiberglass enclosure just over 1 cubic foot as per Infinity's specifications. There is one thing to note. I haven't sealed up the hole for the wires in the enclosure yet. However, I'd think that wouldn't make THAT much of a noticeable difference. Anyway, it basically sounds like an 8" sub; if that.. No shaking of the rear view mirror, no heart pounding bass, I can feel it, but it sure doesn't feel like my 12" kicker that i had my old dodge neon in a standard sealed enclosure.

    If anyone has any suggestions I should try; I would be most appreciative.

    Also to note, I have fooled around with the memphis belle's settings but don't think I've made any noticeable enough changes, so if anyone with this amp can suggest proper settings. It could be settings on the computer? For whatever reason, plugging the subwoofer channel coming from the soundblaster external sound card into the memphis belle sub channel completely cuts out the sub, unplugging it allows the sub frequencies to come back through.

    I was considering changing out my carpc setup completely, but I'm just concerned that I may have this same problemw ith any pc hardware setup that I go with. Do I possibly need a line driver or something else completely?

    Thanks again!

    Pictures of the subwoofer enclosure and trunk setup can be found here:
    http://www.flickr.com/photos/smesser/sets/1096066/

  2. #2
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    There may be a setting in the software to turn the sub on. I'm not sure on that.
    Also, I read elsewhere on this site that the usb soundcards don't transmit the full frequency range.
    As for the speaker setup, it sounds good. But from expierience, the Infinity subs are really power hungry. How much power are you running to the sub? What impeadance are you running the sub at?

  3. #3
    Variable Bitrate StrataG's Avatar
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    Keep in mind that setups from car to car can vary significantly. Also one 12" sub setup can be much different from another. You can make a 12" sound like 2 15"'s or a 10" sound like 2 12"s, etc. The power going to sub is obviously a key factor. Depending on what ohm load you have, the Memphis Belle may only be putting out 300 watts.

    Setup is an often overlooked factor. First off, any unintentional holes will definately have a big factor on the box's efficiency. Having a hole in a box isn't like having a ported box. Ported box's are built and tuned very specifically. If you screw up the specs, a ported box can sound like complete crap. This also goes for your not quite sealed box. It throws off the entire harmony of the woofer's excursion and pressure inside the box. I've seen woofers in boxes with unsealed corners sound like someone farting. Not only does it not sound good, but it's not as loud as it could be if properly sealed.

    Also another key component is the same exact setup in 2 different cars can be dramatically different. A Neon, no offense to those who have them, is not built all that well. It is a cheap car which is why it is built and bought, but you get what you pay for. A better built car with a more sealed cabin will have a drastic loss in audible bass vs your neon. I have 600 watts rms going to one 12" in my hatchback and it pounds. Throw that same setup in a Lincoln Town Car (with self-sealing trunk) for example and it wouldn't sound nearly as loud because there are obviously firewall, seats, and a rear deck in the way. I use the Lincoln Town Car as an example because my buddy had to throw 3 12" with more than double my wattage to sound as loud as my car does.

    Bottom line, seal your box and see how it sounds. Make sure you are wiring your sub properly. The Memphis Belle can put out 1100 watts down to 300 watts to the sub depending on the load it sees. Contrary to what defsquad says, it appears that your sub is rated at only 400 watts rms. Most likely you are running a dual 2 ohm wired in series to produce a 4 ohm load. 300 watts in the trunk of a Maxima in a sealed box is not going to pound that hard. I would suggest one of four things:

    1. Go with a dual 4 ohm sub wired in parallel capable of 600 watts.

    2. Add a second sub of the same type. Run both speaker's voice coils in series producing 4 ohms each and then each sub in parallel to produce 2 ohms. This will yield 600 watts from your Memphis Belle. Problem with this is it will be hard to build another fiberglass box with the same interior volume, which would produce the best result. Best bet would be to create a single box for the two in this case.

    3. Redo your box. Make it larger and port it. The sound quality won't be as good, but it will most definately be noticeably louder if done correctly.

    4. Make a hole in your rear deck and cover it with speaker cloth or a grille. This will allow more bass into the cabin.

    Any one of the above or a combination there of will produce get you more bass. I personally would suggest going with #1 as you already have your box built and you wouldn't need to modify anything else. Just keep an eye on the mounting depth and volume of the sub you choose to make sure it fits in your current box and yields the appropriate cubic volume.

  4. #4
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    Quote Originally Posted by defsquad
    For whatever reason, plugging the subwoofer channel coming from the soundblaster external sound card into the memphis belle sub channel completely cuts out the sub, unplugging it allows the sub frequencies to come back through.
    Here's my guess as to what is going on here: The MB amp has some sort of detection (either mechanical or electrical) on the sub jack. When you plug something into the sub jack, that's the signal that drives the sub. When the sub jack is left empty, the MB amp automagically uses an internal crossover to generate the signal to the sub amp from the L+R signals.

    Now, I'd be willing to bet that you've either got a bad sub cable from the soundboard to the amp, or the soundboard drivers are not actually sending the signal out the sub channel. In my experience, the audio configuration software is terribly confusing and poorly documented and best tested with known gear, say your home audio system. In many cases, you'll need to go into some speaker setup where you tell the drivers just what speakers you have connected and often what size they are as well. You could try plugging the sub out into one of the other channels to see if you are actually getting something on the sub-out line.

    -p.

  5. #5
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    Troubleshoot.... Hook up an ipod, or a walkman to your front speaker inputs and the sub (look for settings on the amp for a single input source). Test sound quality. If its fine, than its a setting in your computer.

    Did you run through the speaker selection settings in the sound card apps?

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    Thanks guys for all of the replies. Yeah, i've been round and round with various speaker setup settings in Creative's appliation that comes with the soundblaster 24bit usb sound card.

    I have been considering upgrading to an MII12000 or SP13000 and getting a PCI based audigy 2, supposeldy the software is different and a lot more refined.

    I like the idea that maybe my RCA's are bad, they I think, are also the source of some alternator whine problems I've had off and on.

    I'll give that shot. Hopefully that works because I'm going to be disappointd if I can't hear that sub for all its worth. (a buddy has the 10" svc version and it sounds incredible.)

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    StrataG,

    Thanks so much for that long explanation and suggestions. I will most definitely look into all of your suggestions.

    I appreciate, once again, everyone's comments and suggestions. This arms me with enough knowledge and suggestions to go forward and do some more testing, etc.

    I'll definitely keep everyone updated on my progress.

  8. #8
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    First I gather you have the lower power Memphis Belle amps There are only two one puts out 200 watts to the sub at 2 ohms
    The other 600 watts at two ohms.

    The DVC is a dual 4 ohm Sound Quality SUB. This means it can be wired to 8 or 2 ohms.

    First off a SQ sub in a sealed enclosure of only 1 CU ft. Is not going to slam no matter what you do. Second depending upon which Belle you have and How the sub is wired (series vs parallel) 4 or 8 ohms will also effect the output. and finally it also depends on location and what type of vehicle. a 1 cube box for even a SQ sub is tight. And because of that it will not extend down to the lower freqs. That box is probably rolling off at 100 hz or so.

    If you are a computer geek then may I suggest you google for a program called winISD it is a free speaker design proggy. Plug in the Woffer specs, and desired freaquency range and you can find the optimal box dimensions. It handles bot sealed and vented type enclosures.

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