Short backgrounder - here in Finland, and I guess most of mainland Europe, the old norm for domestic electricity was 220V AC +/- 5%. Some years ago (15-20, I believe) the norm was first raised to 230V, and recently due to EU harmonization and the laziness of the electric companies especially the upper limit was raised so that the voltage can deviate +/-10% before you'll have any luck complaining about it. For example at home, I typically measure 235V from the wall socket, and at the summer house it can be pretty much anything depending on whether the oven is on, etc.

This gets us to little older equipment, which usually only has voltage settings for either 220V or 240V. Which do you prefer if the nominal network voltage is 230V? I guess the 220V setting would product more heat at the power supply and so 240V would be preferable, but are we getting too close to margins if the kit is set to 240V and the network dips to 210 = almost -15%?

For newer kit with switched mode power supplies running at lower voltage might actually be worse, as peak currents in the power supplies will rise.

I don't think it makes a lot of difference! I would favour 240 but I have never had a problem and the UK supply is probably worse! Makes expensive power cables even more farcical really!

It makes a difference... the cooler the electronic, the longer the lifetime. Heat is the natural enemy of capacitors...

I have updated all B&O hardware that uses an oldfashioned transformer to 240V.

In the UK, we used to be nominal 240V supply and we changed to 230V to accomodate you Europeans when we all decided to get in bed together!

Most UK spec vintage B&O had and used a 240V tapping on the transformer and had different part numbers to the EU variant.

Hi Mika

Israel is specced at 220V. I have never seen anything lower than 222V, and normally see 236-238V at the wall outlet.

So I think it's all a lot of bureaucratic nonsense.

I always set my PSU's to 240V, if there is a possibility.

A brownout (lower voltage) is much easier on electronics than an overvoltage (I'm not saying that brownouts are healthy).

For that reason, I run all my lab equipment and stereo setups on APC UPS's which have AVR - automatic voltage regulation, which take care of both brownouts and overvoltage. Not all UPS's have these additional functions.

Menahem

Hi,

Interesting topic.

My view is that it may be an issue with unregulated amplifier power supplies. If the PSU was designed for 220V (France) then 220V it must be. It is important for all the settings of the amp (Beomaster 6000/8000 amp stages for instance). Serious manufacturers quote a maximum acceptable error percentage.  But some (over-complicated) circuits are specifically designed for dodging this, so it's a case-by-case problem, like always! You know, like impedance matching!

If the PSU is regulated (Beograms, Beocords) it becomes indeed an academic issue, provided the components can take the extra voltage... which is not always the case.

For what it's worth.

Jacques

Jacques,

I disagree with you.

If you set the selector to 240V, and there is only 220V coming in, there is less load on the regulator, and the system will still run perfectly (about 8% less AC reaching the regulator). On a typical 7805 5VDC regulator, you will find about 12-15V at the input. So, about 8% less is not critical at all.

If on the other hand, you set the selector to 220V and there is more than 220V coming in, the regulator will run hot - guaranteed.

I have a communique from B&O, which states explicitly to set the voltage selector to 240V to attempt to alleviate certain problems (on 1970's era equipment).

But even without that official word, it is good practice to do whatever is necessary to keep the regulators as cool as possible.

Menahem

Hello Menahem,

I can backup this.

Several of the BM901's I've got had blown output stages (Darlingtons, 0.39R safety Resistor, several driver transistors & diodes).

And all were set to 220V when I got them.

I saw one Power Stage blowing up while working on a voltage regulator in another area of the unit. And the only load the output transistors had was a 2000 Ohms headphone

Then I realized it was one unit where I did forget to set it to 240 Volt.

Would fit perfectly into the 70's equipment theory.

Power voltage was about 52 Volts instead of 48; Doesn't sound like a lot more but for example the caps are rated 50 Volts.

And those Motorola BD697/698 with their special housings are impossible to get as a replacement

    Gunther