Hello. Hope someone can help answer my question.
I live in a country where the voltage is 230. My tube amps (monos, class a) is rated at 220v. Have gathered from reading up that a 10% allowance (above rating) is ok. However, I have heard that the voltage does occassionally go slightly above 240v especially in the night time. Sometimes it's 245v, which is above the 10% allowance...🙁
Would appreciate some advice as to what could happen to my amps. I am also curious if this could affect the electrical circuitry of the house...ie...from breaker box--->electric cable--->wall socket--->power distributor--->hifi system. Or would any problems,that could surface, be limited to my amps>
I am a total novice and I hope someone can help. Any EE in da house? Thanks...🙂
I live in a country where the voltage is 230. My tube amps (monos, class a) is rated at 220v. Have gathered from reading up that a 10% allowance (above rating) is ok. However, I have heard that the voltage does occassionally go slightly above 240v especially in the night time. Sometimes it's 245v, which is above the 10% allowance...🙁
Would appreciate some advice as to what could happen to my amps. I am also curious if this could affect the electrical circuitry of the house...ie...from breaker box--->electric cable--->wall socket--->power distributor--->hifi system. Or would any problems,that could surface, be limited to my amps>
I am a total novice and I hope someone can help. Any EE in da house? Thanks...🙂
Good question 🙂
What will happen with a valve amp is that filaments get over run. If you have a 220 to 6.3 vac filament supply then the ratio is approx 35:1 meaning 220 volts gives 6.3 volts. 245 volts would give nearer 7 volts.
Does that exceed a typical valve filament tolerance ? (that's something I don't know)
Also, the HT supplies will rise by a similar percentage. That's likely less of an issue provided the voltage rating of any caps are not exceeded. For example a nominal 430 volt DC rail that had only 450 volt caps would find them pushed over the limit by the higher mains voltage.
The problem is likely much less of an issue for any other equipment. CD players and so on have stabilised supplies. As long as the basic unregulated supplies were not pushed over any limiting capacitor voltage then there would be no problem. Same goes for power amps. If the rails were 60 volts and the amp used only 63 volt caps (an unlikely scenario) then you could have a problem.
Anything with a switch mode PSU is probably good for 90 to 265 vac with no worries.
No problems with the house wiring and the higher voltage. Bulbs (filamant type) and elements rated for 220 vac will burn brighter/hotter and have a shorter life.
What will happen with a valve amp is that filaments get over run. If you have a 220 to 6.3 vac filament supply then the ratio is approx 35:1 meaning 220 volts gives 6.3 volts. 245 volts would give nearer 7 volts.
Does that exceed a typical valve filament tolerance ? (that's something I don't know)
Also, the HT supplies will rise by a similar percentage. That's likely less of an issue provided the voltage rating of any caps are not exceeded. For example a nominal 430 volt DC rail that had only 450 volt caps would find them pushed over the limit by the higher mains voltage.
The problem is likely much less of an issue for any other equipment. CD players and so on have stabilised supplies. As long as the basic unregulated supplies were not pushed over any limiting capacitor voltage then there would be no problem. Same goes for power amps. If the rails were 60 volts and the amp used only 63 volt caps (an unlikely scenario) then you could have a problem.
Anything with a switch mode PSU is probably good for 90 to 265 vac with no worries.
No problems with the house wiring and the higher voltage. Bulbs (filamant type) and elements rated for 220 vac will burn brighter/hotter and have a shorter life.
Line voltage variation is common. The tube amp power supply design should already be able to accept this range (+/-10%) of line voltage, since 220V x1.1 = 242V.
What is the voltage rating of the supply capacitors in the amp?
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buy a variac or build a small 'bucking transformer using a spare filament transformer.
both work on the autotransformer principle. use a fixed 12.6 volt transformer to knock off that many volts on the line.
seems a common problem for the UK's adoption of the EU standards just on paper alone 230 VAC =/= 220 VAC.
both work on the autotransformer principle. use a fixed 12.6 volt transformer to knock off that many volts on the line.
seems a common problem for the UK's adoption of the EU standards just on paper alone 230 VAC =/= 220 VAC.
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@Mooly and Rayma.
Thank you so much for your response. I really really appreciate it. As stated in my first post, I am a total novice. To be honest, I bought these amps new from a store and I assumed that they were 230v. A year has come and gone and to my shock and horror, I have discovered that the amps are actually 220v (just noticed it at the back of amps). I have put in about 900 hours so far in the past year without break down. The store I bought them from has since gone under.
It's a relief that any issues would be limited to the amps, not anything else esp house wiring etc etc.
If I could trouble you again. How would this voltage issue affect the amp's sonic performance. Oh...I forgot to mention...I am getting transformer hum (vibration) from one of the monos.
Thank you so much for your response. I really really appreciate it. As stated in my first post, I am a total novice. To be honest, I bought these amps new from a store and I assumed that they were 230v. A year has come and gone and to my shock and horror, I have discovered that the amps are actually 220v (just noticed it at the back of amps). I have put in about 900 hours so far in the past year without break down. The store I bought them from has since gone under.
It's a relief that any issues would be limited to the amps, not anything else esp house wiring etc etc.
If I could trouble you again. How would this voltage issue affect the amp's sonic performance. Oh...I forgot to mention...I am getting transformer hum (vibration) from one of the monos.
10% of 220 is 22, 22+220=242. I think you should be fine, as stated the only thing I would be concerned for in a normal valve amp would be capacitor rating and heater filaments as mentioned. If you are comfortable with high voltage, you could do some data analysis by waiting for the line voltage to get up to 245 and then measure the various voltages around the amp to see what the heater voltage is at and if it is exceeding the datasheets specifications, and to see if the voltage rating on the capacitors is exceeded.
I like to see a little lower voltage on my heaters because they work about the same and last a lot longer.
I would like to note that if the valves were biased hot to begin with, then they could also be exceeding the max plate dissipation if the amp is unregulated and the B+ has increased.
I like to see a little lower voltage on my heaters because they work about the same and last a lot longer.
I would like to note that if the valves were biased hot to begin with, then they could also be exceeding the max plate dissipation if the amp is unregulated and the B+ has increased.
Try tightening the transformer mounting bolts and cover, if present (with the power disconnected). Watch out for slipping and damaging a tube.
classic symptom of a transformer running closer to saturation.
is it getting hotter n louder at off hours ( highest line)?
Sonics... well a higher supply voltage would theoretically raise the maximum power output the amp could deliver but the effect would be marginal and certainly not audible as a power gain. Depending on the amps circuitry it should ideally have no change in sonic character with these variations in supply.
My experience of valves is limited but I do have a lot of experience with CRT's (TV tubes) and a 10% increase in filament voltage would certainly alter the emission. On a good CRT the effect would be minimal. On a failing low emission one that increase would bring a remarkable improvement in emission... for a limited time until the cathode succumbed.
Having over run (if it really is doing) the heaters then to bring them back down after all these hours of use could see a drop off in emission.
There are a lot variables and ifs and buts. I think you have to look at it realistically and say that you have been using it for many many hours with no issues and as such it is likely to be fine. You can worry over things that aren't a problem in practice.
The same applies to the solid state amp. A little more power and no change in sonics.
I could make a killing selling 240> 220 adapters over there.
audiophiles worry and Mooly says if-n-aint broke.
audiophiles worry and Mooly says if-n-aint broke.
Does the amp has a rectifier valve?
People sometimes replace it with a type that has a bigger voltage drop to lower the HT.
People sometimes replace it with a type that has a bigger voltage drop to lower the HT.
There are a couple of aspects that others have missed.
My comments here apply to tube based equipment. Solid state equipment is usually more tolerant due to technology change and due to world marketing in teh semiconductor age.
1. The EU standardised on 230 V. They put pressure on the UK to drop their 240 V back to 230 V - they saw 240V as an impediment to trade. That would cost power authorities big money, so they didn't. The Pommy polticians solved the problem by declaring the country's voltage to be 230 V, but with an increased tolerance that allows them to keep delivering 240V. Then Australia did the same thing. Maybe other countries, I don't know. Yes, I know it is technically silly - that's politicians for you.
In such countries, measure what you are getting. If you are getting mostly 240V, use the 240 V tapping on the power transformer. Or if its imported 230 V stuff, use a 240/230 autotransformer.
2. If equipment is made for 220V, it is also probably made for 60 Hz, not the 50 HZ used in Europe. Using 60 Hz equipment in a 50 Hz country is often a serious affair. The power transformer will have 20% less primary reactance and at best draw 20% more current. It may saturate - that makes for much heat and humming noise.
Fortunately, the better US and Japanese manufacturers specified their transformers for 50 Hz - so they will work anywhere in the world - voltage permitting. But you can be caught. If the power transformer is hot and huming badly this will be the cause.
Unfortunately the only real cure is to replace the transformer or rewind it for 50 Hz.
My comments here apply to tube based equipment. Solid state equipment is usually more tolerant due to technology change and due to world marketing in teh semiconductor age.
1. The EU standardised on 230 V. They put pressure on the UK to drop their 240 V back to 230 V - they saw 240V as an impediment to trade. That would cost power authorities big money, so they didn't. The Pommy polticians solved the problem by declaring the country's voltage to be 230 V, but with an increased tolerance that allows them to keep delivering 240V. Then Australia did the same thing. Maybe other countries, I don't know. Yes, I know it is technically silly - that's politicians for you.
In such countries, measure what you are getting. If you are getting mostly 240V, use the 240 V tapping on the power transformer. Or if its imported 230 V stuff, use a 240/230 autotransformer.
2. If equipment is made for 220V, it is also probably made for 60 Hz, not the 50 HZ used in Europe. Using 60 Hz equipment in a 50 Hz country is often a serious affair. The power transformer will have 20% less primary reactance and at best draw 20% more current. It may saturate - that makes for much heat and humming noise.
Fortunately, the better US and Japanese manufacturers specified their transformers for 50 Hz - so they will work anywhere in the world - voltage permitting. But you can be caught. If the power transformer is hot and huming badly this will be the cause.
Unfortunately the only real cure is to replace the transformer or rewind it for 50 Hz.
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Newbie,
what is your typical Mains voltage while you are listening?
How much does that voltage vary?
Have you asked your supplier what their contracted range of supply voltage is?
Not many Countries actually have a nominal 230Vac mains system.
They are usually 100Vac, 110/120Vac, 220Vac & 240Vac, all having a tolerance of roughly +-5% to +-10%
what is your typical Mains voltage while you are listening?
How much does that voltage vary?
Have you asked your supplier what their contracted range of supply voltage is?
Not many Countries actually have a nominal 230Vac mains system.
They are usually 100Vac, 110/120Vac, 220Vac & 240Vac, all having a tolerance of roughly +-5% to +-10%
1. Stating that the EU 'put pressure' on the UK is a bit one sided view. It was a compromise: the UK 10V down and the whole of the continent going 10V up.
2. In the Netherlands we used to have 220V (+/- 10%) @ 50Hz and the expression '2-20' is still synonymous for mains.
There is still a lot of equipment out there based on this old standard. Why should we assume that 220V trannys are for 60Hz only? I associate 60Hz only with 100/110/120V.
is not correct, because it misses the error of Keit's assumption.
Keit stated
That is where Keit went wrong.
The EU did not standardise on 230Vac.
The EU adopted an harmonised voltage for the EU.
That is a requirement for manufacturers' of equipment to be used/sold in the EU.
The equipment that is SOLD for use in the EU must operate properly and safely over the whole range of voltage available in the "harmonised" region.
i.e. safe to use with a supply voltage from 216Vac to 253Vac
and operate properly over that same voltage range.
I'm sure the EU regulations that are written down are being paraphrased by you.
what is on topic is what is the definition of "operate properly"
cutting an unregulated tube filament (and other parts too_) ,operating lifetime by a major amount may not meet a reasonable expectation in my sense of the word. but an audiophiles tube amp owners concerns will be a whisper in the woods. will 'it' last beyond the basic warrantee re 'laws in your country' might be enough for some / most consumer advocates.
its all just words ...any gear using a unregulated supply will either be over specced at higher prices OR its not going to make spec and /or stressed at either ends of the " harmonized" widened voltage spectrum.
the OP doesn't really know until he digs deeper.
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Another small correction: it is not the EU that standardized the mains. It was CENELEC, a non-EU organisation.
Always thought that it was another EU scheme 'though.
Well, this is unexpected (by me anyways):
I quickly checked several valve datasheets and most don't mention the tolerance of the heaters.
Some (US) datasheets do mention 5 or 10% tolerance but they seem to be the exception.
Perhaps the effect of the mains tolerance on the HT is more important.
Say an amp is designed for 400Vdc operation and a 230V mains.
The European norm states +/- 10% (-15% for short periods), so the HT can be 360-440Vdc.
It's clear that you have to watch your cap rating.
For the valves however, I wouldn't worry too much about lifespan. Suboptimal operating points, maybe.
Now the OP is about a 220V design running on a 230V normalized mains.
So the 400V from my example will be a nominal 418V spanning from 376-460V.
Still not that extreme. A bias adjustment might be in order.
Now back in the 220V era, I had a customer that complained that his output valves wore out so quickly. We gave him a spare amp for the time that we were checking out his own amp.
Next week he returned the amp: the HT caps had exploded!
Upon my inquiry he admitted that the mains in his house rose to about 260V when the nearby industrial area shut down at night. 😱
I guess his lightbulbs had a short life as well.
Moral of the story: measure what you actually have (on different times of the day)
I quickly checked several valve datasheets and most don't mention the tolerance of the heaters.
Some (US) datasheets do mention 5 or 10% tolerance but they seem to be the exception.
Perhaps the effect of the mains tolerance on the HT is more important.
Say an amp is designed for 400Vdc operation and a 230V mains.
The European norm states +/- 10% (-15% for short periods), so the HT can be 360-440Vdc.
It's clear that you have to watch your cap rating.
For the valves however, I wouldn't worry too much about lifespan. Suboptimal operating points, maybe.
Now the OP is about a 220V design running on a 230V normalized mains.
So the 400V from my example will be a nominal 418V spanning from 376-460V.
Still not that extreme. A bias adjustment might be in order.
Now back in the 220V era, I had a customer that complained that his output valves wore out so quickly. We gave him a spare amp for the time that we were checking out his own amp.
Next week he returned the amp: the HT caps had exploded!
Upon my inquiry he admitted that the mains in his house rose to about 260V when the nearby industrial area shut down at night. 😱
I guess his lightbulbs had a short life as well.
Moral of the story: measure what you actually have (on different times of the day)
I live in AU and our mains power run from 230v to 245v if you are close to the main transformer you get 242v, now I run on standalone solar the pure sine wave inverter runs out at 230v 50hz and I fine no problem running my main transformer in the valve amp with the inverter at 230v the only problem I can see with using "mains power" is that it is never a constant "240v" there is a lot that plays in what you get out of mains electricity the age of the line the age of the transformer outside your home and how many people are sucking power out of the line well that is what I have found here in AU and given the fact that we has less Mbps download speed then Romania our electricity is the bloody same crap!!
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