Hooking up external amps - volume level change?

Discussion in 'Archived Threads 2001-2004' started by Len Cheong, Jan 2, 2002.

  1. Len Cheong

    Len Cheong Second Unit

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    I'm wondering when I hook up external amps, does the volume of my system change relatively since the amps have more power than the receiver amps? or does the system just change in terms of the quality of the sound? Thanks.
     
  2. Chuck Kent

    Chuck Kent Supporting Actor

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    Len: The output wattage of any amp is not the only thing responsible for relative volume level (especially at normal listening levels.) Output wattage does come into play in determining the final, ultimate loudest output. Besides output wattage, there are at least 2 other concerns. They are gain and sensitivity.

    Gain is the amount of amplification (expressed in decibels) between the input signal and the output signal. A common number I've seen is around 29 decibels. (As an example, no matter what the incoming pre-amp volume level is, the final ampification stage delivers it to the speakers 29 decibels higher.) For nearly all amps, gain is fixed (of course there are a handful of exceptions.)

    Input sensitivity relates to the amount of input signal needed to run an amp at it's designed levels. (An example would be an amp that it rated to deliver it maximum output wattage (say 100 watts/channel) when supplied 5 volts to it's input terminals. Anything less than 5 volts would mean that the amp would put out less than 100 watts/channel.) Some amps come with controls on them to allow the user to adjust the input sensitivity.

    To answer your questions...

    The volume of your setup after the amp may be different than before. It would relate to the gain/sensitivity issue more than watts per channel capability. If you want to check on this stuff before you buy the amp, check the gain and sensitivity specs on your receiver and the amp you're going to buy. Then you'll have a better idea of where you stand.

    Will the sound be different? Possibly, but not just because of adding an amp. There are a lot of things that are part of the whole package. Connecting cable quality, impedence matches (or mis-matches) between the receiver and amp, quality of the added amp itself, etc. In this case, nothing can take the place of personal listening experiences. Your ears will help you to decide whether the extra investment is worth it.
     
  3. Len Cheong

    Len Cheong Second Unit

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    Voltage gain: 23 dB (balanced)

    29 dB (single-ended)

    Input sensitivity: 2.4 V for full rated output (balanced)

    1.2 V for full rated output (single-ended)

    These are the specs. Thanks for the info, Chuck. The input sensitivity is not at 5v but the amps are rated at 150 w/ch at 8, 250 at 4 ohms.
     

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