Urgent:Wrongly order 220V Power supply for 230V enviroment

[Avico]

I just recived my amplififer ,
Its 221/845 mono blocks amplifiers and i just discover an unbelievable mistake
that I request 220V power supply version where the area i live it's 230V.
The power transformer Tango MS-UVD-H (220V)

current outlet measure show 227V at night it's can get up to 233V .

Following the manufacturer - it's meaningless and explain he have order for area where there are 10% voltage difference and the amplifier can absorb such differences with no issue - In addition he said i can send the power transformers to him and he will replace it with the amount difference + shipping.
But the shipping price is very expensive ,
I trust the guy in 10000% but i want to be sure before spending more money for replace the power transformers.

I talked with Koji (Tango Transformers distributer from EIFL and he said i don't need to worry and it's very small difference.

I have worried the tubes working life will reduce due to the higher voltage
And also from any noises .
I haven't plug the amplifiers (Waiting for the tubes).

The amplifier Scheme :


What do you think?

[toprepairman]

He's probably right.
But if you're really worried you could always run it off a 'bucking' transformer.
Ie one with 230V input and, say, 12V output, then connect the 12V secondary in series with the live supply, but in antiphase and it will safely drop by that amount.

[Charles Darwin]

Can't help you with the schematic but when the EU harmonized the voltages which were 220, 230 or 240V nothing really changed: In Germany there are still 220V and in UK 240V coming out of the sockets.
They just increased the allowable error percentage so that all are nominally covered by the 230V tag.

[Tony]

i wouldn't be too concerned if your filaments do not go beyond 6.9 volts when your line voltage reaches 233volts..... your heaters are fed dc with resistance in series, that should keep you calmer........

[simon7000]

That is less than a 6% difference! Normal design values are 10%, but more importantly what is the peak of the AC sinewave. These get squashed by other loads so it is almost always less than theory says it should be.

But the best solution is an adjustable buck transformer. That way you can set the voltage for what sounds best to you.

[kevinkr]

Buck transformer is an excellent solution, do place a fuse in series with the input to your buck box.. The buck transformer should have a secondary current rating at least 50% greater than the current requirement of your amplifier, and I usually go for 100% - quieter, cooler running, and better regulation under varying load (since this is a class A SE amp variations will be small or non-existant) - and in the event of an eventual amplifier fault the transformer won't fail..

Before going to all of this trouble I would measure the filament voltages with all tubes installed and the amplifier operating and make sure there is an actual problem. Just be careful making the measurements given the very high voltages present in the driver and output stages. While you accidentally specified 220V the transformer may actually be wound for the harmonized EU line voltage of 230V - you'll know for sure once you check this - hopefully not wound for 100V which has happened to me..

[Avico]

A buck transformers is good idea - but it's also an expensive invesment and it's more warm and will take more place (and those ampflifier are big already)
Not sure this is a practical solution .... I guess replacing the transformers to 230V would be easier ,
But as suggested only after measureing the filament voltage...

[simon7000]

Originally Posted by Avico

A buck transformers is good idea - but it's also an expensive invesment and it's more warm and will take more place (and those ampflifier are big already)
Not sure this is a practical solution .... I guess replacing the transformers to 230V would be easier ,
But as suggested only after measureing the filament voltage...

A buck transformer is cheap and small!

[Vinylsavor]

Hi!

Since you are building this amplifier yourself, you have everything under control. Adjust the series resistances in the DC filament supplies to get the correct voltage with the mainy at your place. If the heater voltage of the input tube is a bit high, just insert a little series resistance there as well.

The B+ voltages willnot be an issue. If plate dissipation of some tubes get a bit high, increase cathode resistors a bit.

This is a much better and cleaner solution than adding a buck transformer on the primary.

Best regards

Thomas

[Lavcat]

I'm old enough to remember when some sockets were AC and some sockets were DC. That does make a difference. I suspect you will be OK with what you have, but to be safe you could get an isolation transformer with about a 10% stepdown. Such things exist in the 110V world at least. A ferroresonant (I think that's the right term) transformer would also provide some line voltage regulation, though at the cost of making noise.