[jules]

Many types of equipment offer a choice of settings for input AC voltage, such as 110, 120, 220, 240V

Here in Australia the nominal figure is 230V so I'm wondering, if there's a choice between 220V and 240V, which is going to be kinder to our gear and why? Would some components be stressed by a lower voltage where others might be stressed by higher voltage?

There might not be a simple answer to this as supply voltages vary from place to place and time to time, so I understand there can be short term variation between 215V and 250V with grid supplies generally erring on the high side.

edit: I'm thinking mostly about long term durability rather than sound quality.

Jules

[Elizabeth]

The general rule: Motors are stressed by LOWER than expected voltages. Electronics are stressed by HIGHER than expected voltages. Good luck. 
Added: so you would want to set/buy the expected AC 240v nominal in electronics if your AC is 230volts. If you are buying say an air conditioner, or refrigerator, you would want to buy the 220V one for your nominal 230v. And actually 10 volts out of 230 or so in only 4% and well within the standard range of acceptable.

((You don't have to worry about things like the motor in CD player, as that motor is run from a power supply inside the CD player. But a freestanding motor on a turntable.. yes, UNLESS you have a motor speed controller. then no.))

[jules]

Yes, thanks. I'm thinking of an amp that has optional voltage settings. In terms of the motors v electronics I guess the relative parts to consider might be the transformer v the rest. The transformer would presumably run a little hotter for the same output if the voltage was lower than the chosen option.

I would guess, as you say, that for the electronics the extra 4% or so is well within tolerances.

Maybe it comes down to taking care not to push the amp on hot days if it seems to be putting out significantly more than normal heat.

I would not want to have to source a large transformer for an out of production amp.

Jules

[andyr]

Yes, thanks. I'm thinking of an amp that has optional voltage settings. In terms of the motors v electronics I guess the relative parts to consider might be the transformer v the rest. The transformer would presumably run a little hotter for the same output if the voltage was lower than the chosen option.

No, the traffo will get a little hotter if the mains voltage is higher than the chosen option.

It will also get hotter if it was designed for 60Hz operation - rather than our own 50Hz.

I would guess, as you say, that for the electronics the extra 4% or so is well within tolerances.

In terms of the increased voltage from the DC power supply driven by the power traffo - yes ... an extra 4% is neither here nor there.

But in terms of the extra load on a designed-for-60Hz traffo ... I would suggest it is not desirable.

Maybe it comes down to taking care not to push the amp on hot days if it seems to be putting out significantly more than normal heat.

Or simply not using it, in summer.   

If that's unacceptable, given the mains supply is more like 240v than 230v in Oz ... buy a power amp which has a 50Hz traffo in it.  (Which excludes amps made in China or Japan.)