Too much power

Discussion in 'AV Pre-Amp/Processors & Power Amps' started by stephenbarnes, Jan 30, 2014.

  1. stephenbarnes

    stephenbarnes
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    I'm looking at ATI power amplifier, the lowest rated multi channel is 180W x 7 into 8ohm, 270W into 4ohm

    Mains 4ohm, 50-200 W
    Center 4ohm, 30-200W
    Sides 6 ohms nom., (3.2 min.) 10W-125W
    Rears, 8 ohm, 10 - 200 watts per channel

    Would there be a problem with too much power, if that is even possible? Also read something about gain on the power amplifer it has to match or something like that.
     
  2. HAWK-EYE

    HAWK-EYE
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  3. stephenbarnes

    stephenbarnes
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    input impedance too?
    28K for ATI
    Voltage gain 28dB for ATI

    My amps
    Gain: 29.0 dB at1kHz
    Total Harmonic Distortion: Less than 0.05%
    Signal to Noise Ratio: Better than 95 dB
    Input Sensitivity (RCA): 1V rms for 100W into 8
    Input Impedance (RCA): 50kΩ

    Thing is pre isn't a fixed item, I may change that in a while so then have to make sure pre matches power amplifiers..I do remember using Arcam Alpha's the difference in gain meant pre needed quite a bit of channel adjustment.

    Pre
    Output Level • 150mV Rms typical,6V Rms maximum (RCA connectors)
    • 300mV Rms typical, 12V Rms maximum (XLR connectors,
    MC-8 Balanced only)
    • Maximum value with full-scale input signal and volume
    at +12dB
    Output Impedance • 100Ωin parallel with 150pF (RCA connectors)
    • 50Ωin parallel with 150pF (XLR connectors, MC-8
    Balanced only
     
    Last edited: Jan 30, 2014
  4. KelvinS1965

    KelvinS1965
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    IIRC 29dB gain is what is refered to in my Arcam power amp's manual as 'THX' standard setting, but there is a switch which allows 26 and 31dB (approx as I'm going by memory). When I ran this amp for my front speakers I just used the 29dB setting and it worked fine (my AVR powered the surrounds). Since the channel levels were all around 0dB I could have used the 26 or 31 dB options and still had enough range in the adjustments.

    I think if you're going to use a power amp for all channels it would be less of a problem as the gain would be the same anyway. You're not going to have a problem going from 29db to 28db as you'd just need 1dB extra trim to match what you have now which will be taken into account when you do the set up (if your processor has an auto EQ/setup routine, if not you'd set to 75dB on your SPL meter and should need 1dB more than now).

    The input impedance needs to be a factor above the output impedance of the preamp. I can't remember off hand what is generally recommended as a minimum (maybe x10 or more), but the 100ohm output of your pre amp will work fine into 28Kohm of the ATI.
     
  5. stephenbarnes

    stephenbarnes
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    ATI's are too deep anyway..16" would stick out on the racking
     

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