240v stereomour on 220v?

[franklin]

Hi, I just order a 240v stereomour but then I realize it seems to be running AC filament ?
The power here is 220v so my question is the filament voltage will drop too much ??
 

[triode]

Hi Franklin,
I would try it first. If the filament drop more than 10% (2.3V for 2A3 and 5.7V for 12AT7) then definitely you need to increase the line. You could do this using a bucking transformer, just google it for information.
I made one, but in my case it's lower the line from 240V to 220V.

Hope this helps

[Doc B.]

We should have a new 120-240v variac arriving today or tomorrow that will allow us to work up some numbers.

[Paul Joppa]

The most common EU standard is "230v +/-8%" I think, and as in the US the actual voltage is most often higher than the nominal. Thus the median voltage is about 240v - why they chose a standard that is not the most widely-used actual voltage is beyond me! But if you haven't already done so, the first thing is to measure the actual voltage with a good digital meter of 1% or better precision. Be sure to measure aat the time of day that you are likely to listen to music, and re-check as the weather varies!

[franklin]

Thanks Triode,
I just googled the bucking transformer.
I didn't know a low voltage transformer can be wired like an autoformer.
It is quite useful because only 1/10 of the va rating is needed for 1/10 of the voltage step-up/down.


Hi Doc and PJ,
I just have a check and asked a electrical worker here, I measured 217v in the socket and the worker told me
we usually have 214v ~ 218v, never excess 220v.
If these number is too far for the 240v PT, I don't know is it possible , can I custom order a 220v PT from your supplier?