Matching Amp to Preamp?

Discussion in 'AV Receivers' started by Troy R, Apr 2, 2003.

  1. Troy R

    Troy R Stunt Coordinator

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    What do I need to know to make sure a pre amp is compatible with an amp? I'm looking to buy my first set of seperates and I would like to know if all pre's will work with all amps? What kind of specs do I need to know so that they will work properly together (electronically speaking)? This will be for two channel only.

    I'm currently looking at used McCormack DNA 1 or DNA 0.5, with the TLC-1 pre, or some used Audio Research (SS) gear, but am not limited to this gear. I have Dynaudio 1.3mkII speakers, if that helps...

    Any help would be greatly appreciated!
    Thanks!
     
  2. Yogi

    Yogi Screenwriter

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    Most solid state designs are cross compatible but the one thing to keep in mind is the sensitivities. Make sure your preamp's output impedance is lower by an order of magnitude compared to the input impedance of your amp. That way you will be assured that your preamp has enough juice to drive your amp to full power.

    For example if the input impedance of your amp is 33Kohms then make sure your preamp has an output impedance of 3.3 Kohms. Most of the preamps that I have experience with have an output impedance of less than 1K ohm and most of the amps I have experience with have an input impedance of more than 10K ohm. So in my experience there would never be a problem mixing any ss preamp with a ss amp. When you are mixing tube preamps with ss amps or vice versa you should take special care to match them. Otherwise for the most part you would be fine.
     
  3. Troy R

    Troy R Stunt Coordinator

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    Thank you very much Yogi!

    That's what I needed to know!
     
  4. Chu Gai

    Chu Gai Lead Actor

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    I concur with Yogi. Generally speaking the output impedance of a preamp is an order of magnitude or more lower than that of an amp. The bigger the difference, the better so to speak, but don't take that as putting yourself on a search for the lowest output impedance preamp and the highest input impedance amp.
    Having this large disparity surprisingly enough is referred to as 'matching'. Almost oxymoronish isn't it?
    The reason for maximizing this disparity has to do with maximizing the voltage transfer from the preamp to the amp. If you were to match the loads of both devices, i.e. equal impdances, then you'd actually wind up with a 3 dB loss.
    If you want equations, ask.
     

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