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View Full Version : Bucking Transformer - Lower Mains Voltage by 20v


swampy
23-06-2018, 10:27
This is useful on most vacuum tube amps from China. Most are rated 220V even though they state can be used on 240V UK. Measure your internal heater voltage and it will be typically 6.8v for regular tubes and if you are running something like 845's much higher. This shortens the life of the tube a lot and stresses the other components leading to failure.

This was made for a 845 china made amp to drop the UK voltage 20V. It is suitable for any pre-amp and even the big 300B/ 845 power amps etc. It works different to a step down isolation transformer so don't let the size fool you. You can make your own quite easy if you have a suitable transformer. UK plug and regular iec on the end.

Clearing out some bits...

£15 + parcel2go postage

Image :-

https://drive.google.com/open?id=1r4mTBvjVOHf9Mu7CHfW6yedWwVwI9LEV
Lawrence001
23-06-2018, 11:21
PM sent!
swampy
23-06-2018, 15:32
Sold I think to Lawrence.
If you want to make one and why you should...

http://www.dms-audio.com/bucking-transformer-diy
Lawrence001
23-06-2018, 22:39
Thought there'd be a high demand for this. I've just bought a Chinese pre so buying this in case..
montesquieu
23-06-2018, 23:02
Thought there'd be a high demand for this. I've just bought a Chinese pre so buying this in case..

Yes I was beaten to the draw ... this would have been handy to have kicking around. Sadly I don't have the skills to put one together.
Lawrence001
23-06-2018, 23:13
Ah sorry Tom, I've been after one for a while since I read some threads on here a while ago, I've had 4 Chinese valve integrateds over the years and was always worried about the strain put on them.

Ps haven't had a chance to try the Gate pre yet, were you very keen on it?
struth
24-06-2018, 06:56
Can also use a variac to do same job. It has other uses too of course Got mine on end of my Japanese market amp. It's worth more than the amp most likely
Firebottle
24-06-2018, 07:20
Yes I was beaten to the draw ... this would have been handy to have kicking around. Sadly I don't have the skills to put one together.

I can put one together for you Tom when you need one, at minimal charge.
Cheers, Alan