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This is a discussion on Need opinion on amplifier within the Interior Mods forums, part of the Tech & Modifying & General Repairs category; Hey guys. I've got two 12" Rockford P2's in a slot ported enclosure. The subs put out 250rms. My amp ...

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    Registered User scoobyroo's Avatar
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    Need opinion on amplifier

    Hey guys.
    I've got two 12" Rockford P2's in a slot ported enclosure. The subs put out 250rms. My amp only puts out 200rms (I'll double check when I go to my car). The subs are 2ohm and the amp is mono. Now, if I were to upgrade to something that put out say 500rms (2 channel) or 250rms (mono) would I notice a signifigant difference? What would you suggest in my situation?
    I'm sorry if what I'm saying doesn't make sense I don't have much experience with car audio.

    Thanks.

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    He simply abides. SD_GR's Avatar
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    Quote Originally Posted by scoobyroo View Post
    I've got two 12" Rockford P2's in a slot ported enclosure.

    The volume and port dimensions are important to figure out how the drivers will sound in any enclosure.



    The subs put out 250rms.

    I disagree. Drivers are rated for input in terms of power, output in terms of dB across a frequency range.



    My amp only puts out 200rms (I'll double check when I go to my car). The subs are 2ohm and the amp is mono. Now, if I were to upgrade to something that put out say 500rms (2 channel) or 250rms (mono) would I notice a signifigant difference?

    Nobody can give you a meaningful response without having modeled those drivers in that specific enclosure. There are freeware modeling applications available. These will allow you to figure out at what power/volume/frequency the drivers will bottom out, and what their output will be with a given power and enclosure volume at any given frequency.

    Failing that, you'd have to find someone with a similar setup and listen. I'd recommend finding an audio forum with more info on driver modeling.
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    Resident meany-rator 06wrx4me's Avatar
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    Its hard to say. As an ex audiophile with now permanent upper range hearing loss as per my last hearing test a year ago, I must say......"You'll shoot your eye out kid."

    My opinion is sell the subs and buy a DP.

    But to answer your question, not necessarily. You might just be wasting your money.
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    Registered User scoobyroo's Avatar
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    Thanks for the response.
    They recommend 1.85 cu. ft. from Rockfords website. My box is 1.9 cu. ft.
    The subs are rated at 250rms and 500 max.

    Should I look for an amp that better suits the subs (power wise)? What would you recommend to get the best output possible?

    Thanks!

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    Registered User scoobyroo's Avatar
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    Quote Originally Posted by 06wrx4me View Post
    My opinion is sell the subs and buy a DP.
    I own an '88 Vw Cabby haha
    Subey is coming in 6 mo.

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    No offense, but i don't think you know enough about stereo operation to do this task on your own. No one here can answer your questions because they don't really make sense.

    Number 1, the subs don't "put of 250 rms". It means that they can be powered with 250 watts forever without blowing up. Thus, if you want to run both of them with potential for full power, you will need an amp that will supply 500watts rms in some 2 channel configuration.

    Number 2, you need to know the impedence of the amplifier and sub woofer (ohms). You need to make sure that in the final configuration, the impedance of the amplifier matches that of the speakers, or one or the other will melt. Usually, the amplifier will give you options on how to set the stereo up, and will usually provide diagrams.

    Number 3, I dont tend to like ported boxes, as they are very "boomy", and not as clear as a sealed box. However, you need to find the manufacturers website for the subs, and see what size of ported box they recommend for those subs.

    Hope i helped at all. If you have any specific questions after this, i'll be glad to help you out.
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    He simply abides. SD_GR's Avatar
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    Quote Originally Posted by scoobyroo View Post
    Thanks for the response.
    They recommend 1.85 cu. ft. from Rockfords website. My box is 1.9 cu. ft.
    The subs are rated at 250rms and 500 max.

    Given the internal volume taken up by the sub baskets and any stuffing, you may be spot on regarding volume. However, you still need to figure out the optimal port size for tuning to a specific frequency response.

    Should I look for an amp that better suits the subs (power wise)? What would you recommend to get the best output possible?
    This can be answered one of four ways:

    Yes/no by someone that does not understand loudspeakers -- meaningless.

    Empirically, by trying out different amps and/or different enclosures -- could be fun, could also be expensive.

    From examples, by someone with the same setup that's measured or modeled it -- now we're getting somewhere.

    By modeling the enclosure, port, and drivers and seeing what response is available at what volumes, port sizes, and power levels -- winner.

    The manufacturer would be able to recommend a port size and power level to adequately drive their woofers and provide you with rough frequency response and output curves given enough info about your situation. I don't know that they will, but they certainly can.
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    Registered User scoobyroo's Avatar
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    Quote Originally Posted by nocturnal_wrx View Post
    No offense, but i don't think you know enough about stereo operation to do this task on your own. No one here can answer your questions because they don't really make sense.

    Number 1, the subs don't "put of 250 rms". It means that they can be powered with 250 watts forever without blowing up. Thus, if you want to run both of them with potential for full power, you will need an amp that will supply 500watts rms in some 2 channel configuration.

    Number 2, you need to know the impedence of the amplifier and sub woofer (ohms). You need to make sure that in the final configuration, the impedance of the amplifier matches that of the speakers, or one or the other will melt. Usually, the amplifier will give you options on how to set the stereo up, and will usually provide diagrams.

    Number 3, I dont tend to like ported boxes, as they are very "boomy", and not as clear as a sealed box. However, you need to find the manufacturers website for the subs, and see what size of ported box they recommend for those subs.

    Hope i helped at all. If you have any specific questions after this, i'll be glad to help you out.
    Thanks. I realize the Sub does not "put out" 250 rms. My mistake, bad choice of words.

    The subs are 2 ohm and the amp is 2 ohm.

    I posted above the specs of my box and the recommended cu. ft. from Rockford Fosgate's website.

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    Registered User scoobyroo's Avatar
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    Quote Originally Posted by SD_GR View Post
    Given the internal volume taken up by the sub baskets and any stuffing, you may be spot on regarding volume. However, you still need to figure out the optimal port size for tuning to a specific frequency response.



    This can be answered one of four ways:

    Yes/no by someone that does not understand loudspeakers -- meaningless.

    Empirically, by trying out different amps and/or different enclosures -- could be fun, could also be expensive.

    From examples, by someone with the same setup that's measured or modeled it -- now we're getting somewhere.

    By modeling the enclosure, port, and drivers and seeing what response is available at what volumes, port sizes, and power levels -- winner.

    The manufacturer would be able to recommend a port size and power level to adequately drive their woofers and provide you with rough frequency response and output curves given enough info about your situation. I don't know that they will, but they certainly can.
    The recommended tuning frequency of the subs is 38hz. My box is tuned to 39hz (If that makes sense ).

    I'm just wandering what amp would best power my subs with my setup

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    He simply abides. SD_GR's Avatar
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    OK it seems you have a box of the correct volume with the correct tuning. At this point, if the amp can drive your speakers to adequate levels, you can call it a day.
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    The world breaks everyone and afterward many are strong in the broken places. Ernest Hemingway
    I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damning thing of all... I think I can live with it. And if I had to do it all over again - I would. Benjamin Sisko
    DISCLAIMER: Opinions expressed are the author's alone and are inherently worthless.

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    Registered User scoobyroo's Avatar
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    Quote Originally Posted by SD_GR View Post
    OK it seems you have a box of the correct volume with the correct tuning. At this point, if the amp can drive your speakers to adequate levels, you can call it a day.
    That's good news!
    So, would you get a mono amp at say 600 rms and wire paralell? Go with a 2-channel amp? What's the best route in your opinion?

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    Registered User scoobyroo's Avatar
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    Anyone

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    Registered User scoobyroo's Avatar
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    So a guy at a store recommended this amp:
    http://www.rockfordfosgate.com/produ...9&locale=en_US
    How would I wire this set-up to have 300 going to each sub? Positive from amp to positive on one sub, neg from sub to pos on other sub, then neg from last sub to neg on amp?

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    COME ON!! I NEED HEEEEELP

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