Aurora Audio GTM822-2GN User Manual
Page 5
As can be seen in the chart above, the power dissipated into headphones depends
on their impedance.
For a given output voltage… in this case +20dBu = 7.75 volts at 1KHz… the
power is given by Voltage (squared) / load impedance. Thus 600 ohms headphones
will produce around 0.08 watts while 150 ohm headphones will produce 0.30
watts. The power available increases up to 0.75 watts at 22 ohms but then
diminishes to around 0.65 watt with consumer 8 ohm headphones and down to 0
(no output) at a zero ohm short circuit.
Even around 0.1 watt is pretty loud a signal with a pair of headphones clamped to
your ears but, in the case of drummers or musicians in a noisy environment, I’d
recommend using lower impedance headphones…
e.g. Sony MDR-7509 and MDR-V300 are 24 ohms
Fostex T40RP are 50 ohms
AKG K240 are 55 ohms
Sennheiser HD280 are 64 ohms
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