Which components are current / voltage specific?

PeterUK · December 21st, 2004, 01:58 PM

Buying an amp kit here in the UK seems a near impossible task as there are very, very few suppliers of actual kits like Marsh, Mojo, etc, so if I buy from the US, which components are current voltage specific? I've got a good amp book coming for Christmas so I should be able to educate myself, but in the meantime, I'm curious. Here's a sample parts list (not complete):

• Power transformer
• Output transformer
• Tone caps
• Filter caps
• Film Resistors
• Speaker
• Rectifier tube
• Preamp Tubes / Valves
• Power Amp Tubes / Valves

Now I'm guessing that both power and output transformers are current / voltage specific (e.g. 240v for UK & Europe) and everything else is OK.

Am I right or wrong. Advice please.

:D Peter

fullerplast · December 21st, 2004, 02:15 PM

If you are talking about just the differences due to 230/120 VAC input, just the power transformer, AC power switch, power cord, and fuses would be selected differently. After the power tranny, the voltages will be the same for either AC type. You should be able to find a power transformer that will handle either AC input with a tap.

Note that you also have a frequency difference (50Hz vs 60Hz) that will make the filtered AC have a slightly different ripple (and hum).

Dacious · December 21st, 2004, 09:28 PM

I have the same issue here in Oz with 240V power. I think the only change you need to worry about is the power transformer and mains (primary) fuse. With the fuse, if the schematic calls for a 115v 2A slo-blow fuse, use a 240 volt 1 amp slo-blo fuse. If you use a 2 amp, it may not blow as quickly as you'd like to save your transformer and other bits in event of a failure.

Because you're doubling the primary voltage, it is halving the current to supply the secondary circuit. Fender sold stuff all over the world with an export voltage switch, so I am sure this is not a major issue. First time it runs for any length of time just keep tabs on how hot the power transformer gets. If it rapidly gets too hot to touch, there might a problem. If everythig else looks right and sounds OK, probably not.

I have not found hum to be an issue here (55hz is Oz spec) but it may be.

December 21st, 2004, 01:58 PM	#1 (permalink)
PeterUK Friend of Leo's Join Date: Mar 2003 Location: . Posts: 2,830	Which components are current / voltage specific? Buying an amp kit here in the UK seems a near impossible task as there are very, very few suppliers of actual kits like Marsh, Mojo, etc, so if I buy from the US, which components are current voltage specific? I've got a good amp book coming for Christmas so I should be able to educate myself, but in the meantime, I'm curious. Here's a sample parts list (not complete): • Power transformer • Output transformer • Tone caps • Filter caps • Film Resistors • Speaker • Rectifier tube • Preamp Tubes / Valves • Power Amp Tubes / Valves Now I'm guessing that both power and output transformers are current / voltage specific (e.g. 240v for UK & Europe) and everything else is OK. Am I right or wrong. Advice please. :D Peter

December 21st, 2004, 09:28 PM	#3 (permalink)
Dacious Friend of Leo's Join Date: Mar 2003 Location: Godzone Posts: 2,623 35 Photos	I have the same issue here in Oz with 240V power. I think the only change you need to worry about is the power transformer and mains (primary) fuse. With the fuse, if the schematic calls for a 115v 2A slo-blow fuse, use a 240 volt 1 amp slo-blo fuse. If you use a 2 amp, it may not blow as quickly as you'd like to save your transformer and other bits in event of a failure. Because you're doubling the primary voltage, it is halving the current to supply the secondary circuit. Fender sold stuff all over the world with an export voltage switch, so I am sure this is not a major issue. First time it runs for any length of time just keep tabs on how hot the power transformer gets. If it rapidly gets too hot to touch, there might a problem. If everythig else looks right and sounds OK, probably not. I have not found hum to be an issue here (55hz is Oz spec) but it may be. __________________ My other Telecaster is a Thinline The Tele Bible, Ch 1, v 10 Love thy Telecaster, covet not thy neighbour's Strat!

December 21st, 2004, 02:15 PM	#2 (permalink)
fullerplast Tele-Afflicted Join Date: Mar 2003 Posts: 1,066	If you are talking about just the differences due to 230/120 VAC input, just the power transformer, AC power switch, power cord, and fuses would be selected differently. After the power tranny, the voltages will be the same for either AC type. You should be able to find a power transformer that will handle either AC input with a tap. Note that you also have a frequency difference (50Hz vs 60Hz) that will make the filtered AC have a slightly different ripple (and hum).