110V/240V Transformers...

stickyfiddle

Me again in the amp section...

Hypothetically speaking, if I wanted to run a USA-spec amp in a 240V country I'd need a transformer change - either in the amp itself, or from an external transformer rated to a high enough wattage to output whatever the amp needs. Can these be small enough to mount inside the amp itself? I feel like I've seen it done but can't work out the right google search to find it.

ecc83

Yes, could be done in a combo but I wouldn't recommend it. "Auto" transformers as these things are known are notorious for a large stray hum field and there is every chance it will couple into the existing OP transformers or/and other wiring. It would also make the amp quite a bit heavier.

Use an external traff of about 10% higher rating than the amplifiers MAINS CONSUMPTION! Not the rated power output. Plaster the amp with "110 VOLTS ONLY!!!" stickers. In fact if other bods are likely to plug up your kit, take the mains fuse out and sort it yourself on site. That said, a Yanky VALVE jobby usually just blows a fuse on 230V and suffers no ill effects. This is NOT the case for solid state gear!

Bloody 60Hz Imericans!

Dave.

ToneControl

stickyfiddle said:

Me again in the amp section...

Hypothetically speaking, if I wanted to run a USA-spec amp in a 240V country I'd need a transformer change - either in the amp itself, or from an external transformer rated to a high enough wattage to output whatever the amp needs. Can these be small enough to mount inside the amp itself? I feel like I've seen it done but can't work out the right google search to find it.

Look inside the amp first
Many have  extra outputs on the mains transformer to allow you to rewire to  240v
In fact this would be possible for most  of the  amps I've owned

I have had a Victoria, a Badcat and a Fuchs rewired for 240v, it's a 30-60 min  job
There are some amps where you are supposed to use more capacitors on 50Hz,  Matchless I think

I think almost all Matchless can be rewired to  240v

stickyfiddle

Cheers chaps. The amp in question would be a Badcat; just trying to work out all my options

ToneControl

yep, my Badcat just needed a bit of soldering work, and a changed fuse

ICBM

ecc83 said:

Yes, could be done in a combo but I wouldn't recommend it. "Auto" transformers as these things are known are notorious for a large stray hum field and there is every chance it will couple into the existing OP transformers or/and other wiring.

I've done loads of them and it's never been a problem. It may be worth experimenting with position and orientation to be absolutely sure before fixing it permanently though.

The advantage of mounting it properly in the amp - aside from stopping anyone plugging a 110V amp with an IEC socket directly into the UK mains, which I have seen done several times, occasionally blowing the PT - is that you can wire it properly so the stepdown transformer is on the downstream side of the power switch.

It might be tricky in a head though, unless it's something where the box is miles too big for the chassis.

DJH83004

Just a general point when using step down 'auto-transformers' just make 100% sure you have earth continuity from the earth pin of the 13amp (BS1363) mains plug of the transformer and the chassis, 

stickyfiddle

I think that plan is out as Coda will do me a Badcat without VAT, which means the saving from buying a US one is bugger all next to the hassle of messing with extra transformers.

migabobo

Hi, Tone Control,

I also want to rewire a Bad Cat Mini to 240V. I put the Black and the Brown/White cable of the main transformer together, to get both coils serial, but it doesn't work (the 1 Amp fuse (240V) broke). Can you help me? I saw a scheme of the amp with a 220uF/350V instead of a 22uF/350V and a picture of an European Version with a "240" handwritten by Bad Cat even on this Electrolytic Capacitor. Could this be the Problem?