Originally Posted by alan s
What if a single parallel resistor (for one channel only) were to fault. I'm thinking of the HE adapter box configuration. In that case the entire circuit wouldn't be broken.
Would that result in the corresponding side of the headphone (the right or the left) becoming louder ?
If I understand you correctly:
assume this is a solid state amp with a very low output impedance (this is a fair assumption!)
assume each channel has an 8 Ohm resistor in parallel with it's output
assume each channel is also loaded down with a 100 Ohm resistor in series with a 60 Ohm headphone
now if in one channel only the parallel 8 Ohm resistor fails so that it looks like the resistor is removed (this is called open circuit), then the difference in volume should be negligible.
your power amplifier probably has an output impedance of approx. 0.05 Ohms, maybe 0.1 Ohms (basically a very low value)
so if you remove or delete one of the 8 Ohm resistors, you may not even notice the difference in volume from channel to channel (i.e. right versus left). The channel without the 8 Ohm resistor MAY sound very slightly louder.
However, if the 8 Ohm resistor faults so that the resistance is now 0 Ohms (this is called short circuit)................well, let's hope we didn't destroy the corresponding amp channel!
If the power amp is a tube amp with a relatively high output impedance, if one channel has the 8 Ohm loading resistor and the other one does not, then the one without the loading resistor would probably be noticeably louder.
BTW, I'm not trying to talking anyone into using or not using a loading resistor.
Edited by Chris J - 4/17/13 at 9:40am