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How to choose an amp?

Discussion in 'Audio' started by RingMaster4x4, Aug 22, 2003.

  1. RingMaster4x4

    RingMaster4x4 1/2 ton status Premium Member

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    Well I have 2 Rockford Fosgate HX2 15's and they are rated for 600 watts RMS and 1200 watts Peak. I will be running the subs at 2 ohms. I was thinking about two Rockford Fosgate 401S amps brided(one per Subwoofer). The amps are rated for 400 watts RMS @ 4 ohms and 1200 watts peak.

    Do I have the right train of thought or am I going about this all wrong? /forums/images/graemlins/thinking.gif
     
  2. Z3PR

    Z3PR Banned

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    In my opinion, you're paying more for the name then anything else with RF now adays. I recomend MMATS . I've ran MMATS amps befor and they put RF to shame. /forums/images/graemlins/eek.gif My first choice is MMATS. /forums/images/graemlins/deal.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif [ QUOTE ]


    When only the loudest, deepest thump will do, choose one of MMATS competition crushing, ultra efficient Class D amplifiers and see why Autosound 2000 Test Labs was quoted as saying "one of the best, if not the best, dedicated subwoofer amplifiers we have ever tested."

    [/ QUOTE ]
     
  3. 3car

    3car 1/2 ton status

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    theres nothing wrong with fosgate amps,and they are reasonably priced.you can get killer deals on them on ebay.also,jbl power series are great amps for the money,powerful,clean,and run super cool.there mono sub amps are stable down to 1 ohm,and mine dosent even get warm at 2 ohms.
     
  4. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    [ QUOTE ]
    Well I have 2 Rockford Fosgate HX2 15's and they are rated for 600 watts RMS and 1200 watts Peak. I will be running the subs at 2 ohms. I was thinking about two Rockford Fosgate 401S amps brided(one per Subwoofer). The amps are rated for 400 watts RMS @ 4 ohms and 1200 watts peak.

    Do I have the right train of thought or am I going about this all wrong? /forums/images/graemlins/thinking.gif

    [/ QUOTE ]


    Well presumably, when you bridge those 400W amps you will end up with something close to 800W per channel for each sub.

    So in terms of matching amp to speaker, you seem fine. The main thing with amps is making sure you get an amp that's truly high quality and is producing the advertised power levels in "real life" applications.

    That MMATS link is actually pretty good at showing some relevant specs.....I like the fact that when they give a power rating they also give the frequency range that it is tested for (in the case of their amps it's 10Hz to 230Hz)... which is fine for a subwoofer amp.

    I also like that the crossover is really STEEP on those amps (24 db/Octave)....for subs, you want to be able to roll off VERY quickly as you get up to where the mid-basses start to play. An amp that only does 12dB/Octave isn't going to be as easy to get a good "blending" between the different speakers.
     
  5. RingMaster4x4

    RingMaster4x4 1/2 ton status Premium Member

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    ok well I did some more resuorce and found out the that the 401S is not 2 ohm stable when bridged. So i have been looking and I found an other one. The main thing that I worried about it running to much wattage. The RMS and the peak wattage is what confuses me. /forums/images/graemlins/confused.gif What would ya'll say is a safe range too look for? /forums/images/graemlins/thinking.gifThanks for all everyones help.

    P.S. I will look in to MMATS amps Paul. /forums/images/graemlins/thumb.gif
     
  6. HarryH3

    HarryH3 1 ton status Author

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    RMS (Root Mean Square) is a true measure of power and what matters most. Peak power is Marketing Bull$h!t that is used to hype consumers into thinking they're getting more than they really are. Also look at THD (Total Harmonic Distortion) at the power level claimed by the manufacturer. I've seen cheap crapola amps that claim to be 500 watts per channel. But when you look closely at the specs you find that it's really 500 watts of peak power with some absurdly high THD number like 5% or higher. So at clean (read useful, non-distorting) power levels you might really be getting an amp that can kick out 75 watts RMS at .010% THD. /forums/images/graemlins/angryfire.gif
     
  7. RingMaster4x4

    RingMaster4x4 1/2 ton status Premium Member

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    So basicly I just need to be between the RMS rating and the peak for the sub? /forums/images/graemlins/ears.gif
     
  8. Z3PR

    Z3PR Banned

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    One MMATS DHC1400.05 could run both your DVC RF subs. [ QUOTE ]
    DHC1400.05 - 1400W @ 0.50 Ohm

    [/ QUOTE ] Remember, you can always turn a amp down so it doesn't blow your subs apart. /forums/images/graemlins/deal.gif
     
  9. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    [ QUOTE ]
    So basicly I just need to be between the RMS rating and the peak for the sub? /forums/images/graemlins/ears.gif

    [/ QUOTE ]


    I don't think focusing on the RMS and Peak Power so much is really the important thing. I am willing to bet that you NEVER get the amp to put out it's RMS wattage for anything more than a few seconds at a time.....unless you are playing test tones instead of music..!!!

    The key is really to be "in the ballpark" with the amount of power the subs are rated for. If you go WAY under (like putting a 50 WATT amp with speakers rated for 500 WATTS) you are probably overspending on the subs and won't get the benefit from them.

    Overpowering a speaker (if it's CLEAN power) is not usually a problem....again, it goes back to the fact that music has a lot of "transient" demands for power, but not really SUSTAINED demands. I ran 200W to every speaker in my K5 system......Woofers, MidBasses and Tweeters.... It was probably overkill for the tweeters because they don't need THAT kind of power to work, but the overall system just sort of worked out that way. The tweeters were fine, they got CLEAN power and went as loud as I could stand....


    /forums/images/graemlins/thumb.gif
     
  10. RingMaster4x4

    RingMaster4x4 1/2 ton status Premium Member

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    I can't find any prices on that website am I blind? /forums/images/graemlins/thinking.gif
     
  11. Z3PR

    Z3PR Banned

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    You have too go through one of thier authorized dealers. In Tx. the only dealer I found is [ QUOTE ]
    Radicals Tint & Alarm
    3009 Blanco Road
    San Anton, TX. 7821209
    (210) 732-3277

    [/ QUOTE ]
     
  12. RingMaster4x4

    RingMaster4x4 1/2 ton status Premium Member

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    I found a Hell of a deal on a pair of these. [​IMG]

    /forums/images/graemlins/thumb.gif
     
  13. Z3PR

    Z3PR Banned

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  14. RingMaster4x4

    RingMaster4x4 1/2 ton status Premium Member

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    I looked at MMATS but since they are going in my blazer I thought these would do nicely. I have also been told that the older style Rockford amp were cleaner than the new ones.

    BTW They are the Power 1000A2 amps. /forums/images/graemlins/thumb.gif
     
  15. Rebel88

    Rebel88 1/2 ton status

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    The older style than the one pictured were actually the nice amps...they had a gold and silver version...but that version you got is the last generation of the nice powerful amps

    Later
     

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