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RMS Ratings

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RMS Ratings

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I have an Alpine MRP-F300 4 channel amp that pushes 50RMS per channel. Which speakers would give me the best sound and let me crank the stereo as loud as I want? A speaker set rated less than 50 RMS per speaker or on rated over 50 RMS per speaker. I have 4 Alpine SPS-507 speakers installed now but one has busted and before it busted I was never able to go more than 2/3rds on the volume and they were rated at 50RMS per speaker.

Verified Answer
  • pearisburg

    It was installed professionally by a well known company.

    doesn't mean they didn't screw something up, but 2/3 volume may have been where they decided to set the gains for full-power.  that's fairly typical, actually, so seems like they set the gains spot-on based on what you stated.  would have been nice if they explained that to you, tho.

    you could back off on the amp gain and be able to turn the volume up higher, but you'd likely reach the same SPL prior to the onset of clipping, and may start distorting the signal. 

All Replies
  • Just because you have speakers that rate as high or higher than the rms or your amp doesn't mean you can turn the volume all the way up. Most head units will distort long before they reach their maximum volume.

    Read up on clipping and distortion and learn how to properly set all your levels or take it to a REPUTABLE shop and have them do it.

  • pearisburg
    Alpine MRP-F300 4 channel amp that pushes 50RMS per channel

    I have the exact amp. It has been tested to do ~63 watts X 4. I agree with Namosh. You must have your gains set correctly. Search the forums for setting gain. At the very least, find the maximum number you can turn your head up to without distortion with the amp gains turned all the way counterclockwise, then turn the gains clockwise, 1 at a time using the fader to switch between front and rear, until the sound just begins to distort then back off until no audible distortion. This should be done with your EQ set the way you listen to music most.

    GLH Geeked

  • Also - ratings are somewhat voluntary.  35W speakers from a "good" company might handle more wattage than 500W ones from a flea-market brand.

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • It was installed professionally by a well known company.

  • Go back and re-read the earlier responses.  I was not referring to the installation company and also was not meaning that Alpine was not a good audio company.

    Anyone else have suggestions?

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • pearisburg

    It was installed professionally by a well known company.

    doesn't mean they didn't screw something up, but 2/3 volume may have been where they decided to set the gains for full-power.  that's fairly typical, actually, so seems like they set the gains spot-on based on what you stated.  would have been nice if they explained that to you, tho.

    you could back off on the amp gain and be able to turn the volume up higher, but you'd likely reach the same SPL prior to the onset of clipping, and may start distorting the signal. 

  • pearisburg
    Alpine SPS-507 speakers rated at 50RMS per speaker

    Those speakers are rated 75 watts RMS each. With the head set just below it's distortion volume, the amp gains should be set using 50 watts x 4 ohms = 200. Square root of 200 is ~14 volts AC.

    GLH Geeked

  • In your post you mentioned needing to replace one pair of the Alpine speakers. Before we can give you a good recommendation we'll need to know what vehicle you have.

    Anyone else have a suggestion?

  • GLH
    Those speakers are rated 75 watts RMS each. With the head set just below it's distortion volume, the amp gains should be set using 50 watts x 4 ohms = 200. Square root of 200 is ~14 volts AC.

    this is the voltage reading when using a digital multi-meter (DMM) to set the gains, in case that wasn't clear.

  • Still haven't heard from you on the vehicle for the speaker recommendation. It looks like all your other questions were answered, and if you still need a speaker recommendation let us know.

    Anyone else have a suggestion?

  • pearisburg

    I have an Alpine MRP-F300 4 channel amp that pushes 50RMS per channel. Which speakers would give me the best sound and let me crank the stereo as loud as I want? A speaker set rated less than 50 RMS per speaker or on rated over 50 RMS per speaker. I have 4 Alpine SPS-507 speakers installed now but one has busted and before it busted I was never able to go more than 2/3rds on the volume and they were rated at 50RMS per speaker.

    Given the installation dimensions that the Alpine SPS-507 speakers need, you can install the Polk Audio DXi570 into the same opening. They can also work with the power output of your Alpine amp.

    Although, you should get a more powerful amp and speakers to match so you can get louder output from the system. If you have been clipping the sound trying to get the volume from the speakers you have, then more power and matching speakers should do the trick. The most powerful speakers that can fit into the same opening your current models do are the Alpine SPS-517 and they handle 75 watts RMS. A matching amp for those that will help you keep away from the clipping level is the JBL GTO-804EZ model.

    Anyone have other recommendations?

     http://www.crutchfield.com/bio/Paul