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should my amps have the same power rating?

Discussion in 'AV Receivers & Amplifiers' started by JonLeach, Apr 1, 2004.

  1. JonLeach

    JonLeach
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    Hi

    After recently changing my 985 MK 11 power amp. to the following ....


    Rotel RB1080 200w Fronts
    Rotel RB981 130w centre and if i find the right speaker centre back
    Rb981 130w surrounds

    .......i have calibrated my amps and found that the 130w amps need -4 to -6 db less. which i thought would be the other way around, the more powerfull amp would need "stepping down" a few db.


    have i made a mistake and the amps ar'nt compatible!!!

    Jon
     
  2. cmo

    cmo
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    JonLeach,

    The RB1080 is generally classed as a different range to the RB981s.
    The fact that the smaller amplifiers sound louder is probably down to their input sensitivity being slightly higher - it shouldn't be a concern.

    Alternatively you don't mention what speakers you are using, maybe the fronts have a lower sensitivity meaning they need more power to reach a certain volume.

    In general the Rotel sound is similar throughout their range although the RB1080 should sound better.
     
  3. Reiner

    Reiner
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    For matching different amps you need to ensure that the (internal) gain is the same. Usually this applies only to units of the same make/series.

    Nope. No matter how powerfull an amp the setting does not directly relate. Given you have amps with the same gain but different power ratings the level to be set would be exactly the same (assume same speakers and distance).
    During normal operation an amp just runs on a few Watt (<20 W). The higher power comes only into play when you want it really loud (party, disco) or in case of high dynamics (aka headroom). It's a kind of reserve - just like your car with 100hp doesn't run at the max. all the time.
    In other words under 'normal conditions' a 50 Watt amp and a 200 Watt amp provide the same power output. Of course the 200 Watt amp can go louder and provide more dynamics when needed.

    If you can adjust the volume levels to match I don't think it's a problem.

    Different gain could however mean that the amp with the lower gain would not increase it's volume synchronous to the amp with the higher gain, i.e. in reference to the higher gain amp the volume of the lower gain amp would become lesser as you increase the overall (system) volume.
     
  4. JonLeach

    JonLeach
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    Thanks for the replies, havn't had access to a pc till now.

    so to confim, the input impedence has to be the same.

    RB 1080 32k ohms / 1.5v

    RB 981 33k ohms / 1v

    is this the gain your talking about.

    Means nowt to me so can some one explain please.

    Jon
     

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