Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Stereomour => Topic started by: franklin on October 15, 2013, 03:17:09 PM
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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 ??
:-\
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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
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We should have a new 120-240v variac arriving today or tomorrow that will allow us to work up some numbers.
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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!
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Thanks Triode,
I just googled the bucking transformer.
I didn't know a low voltage transformer can be wired like an autoformer. ;D
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 :P, can I custom order a 220v PT from your supplier?