Older Hi-Fi equipments and the 120V, 220V & 240V voltage selector.

Hello and welcome to whatishifi blog.

A few months ago something was not sounding “right” at my Hi-Fi. I couldn’t get the usual pleasure I get when I listen to my system. When something like this happens, I always have the same dilemma: do I need psychotherapy or something is indeed going wrong in my Hi-Fi? (Of course, I never come to a clear conclusion so let me limit myself by saying that up to now I haven’t visited the psychotherapist).

After a lot of checking and listening, I got the idea that there was something wrong with my mains supply. So I thought about measuring it and I saw that it was at 233VAC and during the night it could climb up to 237VAC.

I have 233VAC, should I choose 220VAC or 240VAC voltage selector position at my Hi-Fi?

Now, my pre and power amp come from the early 90’s so they have a voltage selector switch that you can choose between 120VAC, 220VAC & 240VAC. No 230VAC position!

Like many of you, I thought that my country supposed to be 220VAC so I had all the selectors at 220V position. But after some reading I found out that in EU they try to make a mains voltage harmonization, so the countries that were supposed to have 240VAC they should drop it at 230VAC and the countries that were supposed to have 220VAC they should increase it at 230VAC.

At some older Hi-Fi equipment the voltage selector switch has no 230V position!

But now what? I mean I actually have 233VAC so where should I put the voltage selector, at 220VAC or 240VAC?

At the beginning, I thought about leaving them at 220V position. I believed that the machines will be happy to be feed with a few volts more.

But then I thought to do some more reading and a listening test.

The reading led me to the fact that the previously existing tolerances of supply standards were the ones below:

• 220VAC tolerance: -6% and +10% (that is 206.8VAC min, 242VAC max)
• 240VAC tolerance: -10% and + 6% (that is 216VAC min, 254.4VAC max)

So, when a machine was designed for one of the voltages above, it should deal with these tolerances.

Since I actually have 233VAC at my home, it looked like the 240VAC voltage selector position is the optimum choice. So I unplugged everything from the mains, I changed the voltage selector at the 240V position, I double checked that I did not by mistake choose the 120VAC position (that would be a bad mistake), I plugged everything back and started a listening test. Please, if you decide to give it a try at your equipment, take extra care to follow those steps above.


The voltage selector inside a Luxman M-03 power amplifier. To find the same switch at the paired Luxman C-03 preamplifier, turn it upside down.

Now, I don’t trust very much the listening tests that you can not quickly change the two things you are comparing. However, I strongly felt that the music was coming out of the speakers in a better way: just a little bit sweeter and calmer than before. The low end was still strong and solid. Yes, everything was sounding again like it should.

So, my proposal to you is to do the same thing. Measure for a week the actual voltage at your socket. Observe min and max values during the day, the night and the weekends. According to your measurements, see where you stand better regarding the tolerances of the old 220V and the 240V and make the change if necessary (always with the equipment unplugged from the mains – double check that you will not by mistake chose 120VAC at a country with 230VAC grid!). Then plug everything back and listen.

Out of curiosity I also measured the effect that changing the voltage selector from 220V to 240V has on the bias of my power amps – I prefer my power amps to work with the bias a little above manufacturer max. value (don’t do that if you don’t know what you are doing!). So, for a given actual supply voltage (in this case 233VAC), moving the selector from the 220V position to the 240V position caused a slight drop of the bias, so I readjusted the bias to my personal preferred value. However, I have to note that this drop was small and well within the manufacturer allowance of +/- 0.5mv. I also assume that a power amp that has the bias calibrated with the selector at the 220V position at a 220V grid will have the same bias value when the selector is moved at the 240V position and the amp is connected at a 240V grid. In other words, do not consider this bias thing a problem if you do not know how to adjust it, just go ahead and put the voltage selector switch at the position you consider optimal.

You can read more regarding the differences between 220VAC, 230VAC and 240VAC mains supply here.

Happy listening as always.

Chris