Question Advice on running a 220v amp on UK 230/240v mains

caoleuk

Active Member
I'm looking to buy a valve integrated amplifier from an EU supplier (Germany) it's a great little amp but I have heard that due to the UK's high and variable voltage (anything from 216v to 260v)
I'm worried that this may shorten the life of the transformer valves and as you know valves are very expensive and run very hot.

"The nominal voltage in the UK is currently stated as 230V+10%-6% (216-253V) - although it used to be 240V±6% (225-255V) here and 220V±6% on the 'continent' (now they're 230V+6%-10%) - with a view to converging on 230V±6% all over at some unspecified point in the future.
The 230V+10%-6% is only a fudge to allow the voltage not to actually be changed but remain within specification - means your light bulbs burn brighter (and burn out faster) and your kettle boils faster than your continental neighbours"

Is there a way that I can transform the UK voltage to a steady 220 volts? I have look all over the web for a transformer to do the job but they all seem to be dedicated to convert from 110 to 220 or 220 to 110.

have read the EU agreement to "normalise" power supplies across Europe to make manufacturing and the flow of equipment easier and fairer, the trouble is all they have done regarding the UK is allow wider and wider percentages of fluctuation which is not helpful if you are running audio equipment.
Can anyone help please, even a diy solution could be helpful?
 

larkone

Distinguished Member
Why don't you ask the manufacturer of the amp if it would be an issue before assuming that it is?
 

DT79

Well-known Member
Why don't you ask the manufacturer of the amp if it would be an issue before assuming that it is?
Exactly. I doubt there’s any manufacturer of anything that’s making different versions for UK and EU because of the slight voltage difference.

All audio devices have to be able to turn a slightly variable AC into a fixed and steady DC voltage, so if it doesn’t have a reasonable tolerance built in for fluctuations in the incoming AC, then it’s a bit of a chocolate teapot.
 

bogart99

Well-known Member
You can go down the route of buying a good 240v AC to 12 or 24v DC converter. The AC input can vary widely well within your limits and still give 12 or 24V. Then use a good full sine wave inverter to get back to a steady AC voltage. Mind you I think is all over the top a bit as the amp will probably be okay
as is.
 

noiseboy72

Distinguished Member
Valve amplifiers can very fussy about input voltage, but it depends if they are "true" valve or a hybrid design with a more modern fully regulated silicon diode rectified supply.

The heaters are less of an issue than the 300v HV supply, as +10% on a 7v supply really doesn't make any difference.

Older valve amplifiers often had multiple taps on the mains transformer at 10v intervals so that you could match them to the local supply voltage. If the amplifier you are looking at doesn't have this, the chances are its a regulated power supply design and all will be fine.
 

caoleuk

Active Member
Why don't you ask the manufacturer of the amp if it would be an issue before assuming that it is?
The manufacturer say's that 230v should be OK but as I said 240v or even 250v is what we actually get in the UK, We almost never get 230v but that is the stated standard for the UK.
Also if a valve that is designed for 220v has to convert 240v instead in stands to reason that like any other transformer it will get hot and heat is a killer (in the end) for valves.
 

caoleuk

Active Member
Thank you for all the replies, I think what I'm really saying is that Harmonisation of power supply is a myth and and the reality is that the power supply in the UK has never changed.
having said that it is no wonder that we have problems with hum and other power associated issues.
 

larkone

Distinguished Member
having said that it is no wonder that we have problems with hum and other power associated issues.
Be interested to know what the science is behind that statement because it eludes me
 

caoleuk

Active Member
Valve amplifiers can very fussy about input voltage, but it depends if they are "true" valve or a hybrid design with a more modern fully regulated silicon diode rectified supply.

The heaters are less of an issue than the 300v HV supply, as +10% on a 7v supply really doesn't make any difference.

Older valve amplifiers often had multiple taps on the mains transformer at 10v intervals so that you could match them to the local supply voltage. If the amplifier you are looking at doesn't have this, the chances are its a regulated power supply design and all will be fine.
It is a Hybrid amp but like most it is made in China and china is dedicated to mainly selling to the USA (due to the easy route to the USA) They do also make some compromises for the EU but there it is again "compromises"
The only thing that is on the amp is the ability to switch from 110 to 220 so I would say that the transformer would only have the two taps.
 

caoleuk

Active Member
I'm no electronics expert however, It is something that I nave been told on other electronic forums.
I assume if you want to reduce an input voltage from 240v to 220v that you will need to get rid of 20v and in doing that you create heat, in other words you burn off the volts as heat much the same as switching on a light bulb.
 

DT79

Well-known Member
I'm no electronics expert however, It is something that I nave been told on other electronic forums.
I assume if you want to reduce an input voltage from 240v to 220v that you will need to get rid of 20v and in doing that you create heat, in other words you burn off the volts as heat much the same as switching on a light bulb.
The only way you’ll ever be completely certain either way is to speak to the manufacturer and ask them this specific question.
 

noiseboy72

Distinguished Member
In this instance, we don't need to "burn off" the 20V, but it will affect the biasing of a push-pull amplifier and this will increase heat, non-linearity and distortion.

The problem with valve amplifiers is that the anode voltage is INCREASED from the mains rather than decreased as you would normally find in a transistor amplifier. This means that any change or instability in the input voltage will be magnified to the Anodes.
 

DT79

Well-known Member
In this instance, we don't need to "burn off" the 20V, but it will affect the biasing of a push-pull amplifier and this will increase heat, non-linearity and distortion.

The problem with valve amplifiers is that the anode voltage is INCREASED from the mains rather than decreased as you would normally find in a transistor amplifier. This means that any change or instability in the input voltage will be magnified to the Anodes.
The lesson therefore being that valve amplifiers aren‘t a very good idea?
 

noiseboy72

Distinguished Member
No, I wouldn't say that, but a stable,ripple free supply certainly helps with longevity of the valves and keeping distortion low.
 

caoleuk

Active Member
I have sent the manufacturer an email but being in China I'm not sure if they will be able to understand me but fingers crossed.
 

caoleuk

Active Member
This is the amp BTW
s-l640.jpg
 
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larkone

Distinguished Member
You don't hear other valve amp owners complaining about this issue so is it really an issue?

Edit: If there were complaints then the snake oil manufacturers would have invented a 'quantum entanglement voltage de-organiser' to protect valves at £1500 a pop
 
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caoleuk

Active Member
Finally made the leap, went for the Cayin cs 88kt. Managed to get it from a UK supplier who was a great deal of help (Audio Emotions) I have to say it is the best thing I have bought ever!
The sound is so rich and the music is almost in 3D sit's well with the Monitor Audio golds
All i would say is make sure you match it well with your speakers for the perfect sound. if it helps and you are interested Audio Emotions offered me a 14 day home demonstration so you can't make any mistakes.

Thanks for all the help and a happy new year to you all.
 

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