The maximum voltage swing available would be about 4 volts rms with an A85. It could all be built into a small die cast box.
Headphone amp series#
However I am prepared to accept that some headphones will work optimally when fed from a very low impedance source - in that case why not build a simple external attenuator to drive a pair of headphones, and switch it on and off with one of the front panel speaker switches? Its difficult to suggest optimum component values without knowledge of the particular headphones and some experimentation, but a series resistor of say 47 ohms (rated at 20W or so) and a resistor to ground of say 6.8 ohms (rated at 2W) would be a good starting point. The sound quality of the A85 is outstanding (and certainly not lousy!) with very low distortion and the amplifier's headphones feed is derived directly from the main speaker outputs. The chosen values also ensure that the series resistors can be of a reasonable physical size as they have to dissipate heat when the amplifier is running hard. These values were chosen as a compromise that will work with all headphones from those with very low (say 4 ohm) impedances right up to 600 ohms ones or more, as one cannot tell in advance what will be used and we want all types to work OK and not inadvertently deafen the listener. This socket therefore has an output impedance of around 77 ohms.
✓ Texas Instruments TPA6120A2 headphone chip ampĮach channel of the headphones output socket on the A85 is fed via a simple resistive potential divider from the output of the main power amplifiers - 330 ohms in series and 100 ohms to ground. I see people still stress over amplifier output impedance as if it's the end all factor of amplification. Makes me think what all the NwAvGuy craze was about.
Therefore, not only integrated amps headphone output can be as good as a dedicated can amp, but if you have bat hearing to notice a 1db bass/treble boost, it can make your cans sound even better. Obviously tube amps have high Zout and more powerfull head amps need bigger resistors in the voltage potential divider, thus result in higher Zout. One guy wrote they benefit from higher output impedance amps, which is why people like them with beefier amps and tube amps. I often read how AKG K701/2, Q701, K712, K7XX are recommended with powerfull headphone amplifiers to sound more balanced.
0 kommentar(er)
