Hello, in the past, in Europe the standard main voltage used to be 220 Volts. This mains power voltage has been increased over the years and at the moment it appears that the standard is 240V, raised again from 230V that used to be the standard in recent years.
When I measured my mains power voltage where I live, it is at times even 245 V, partly due to solar generated excess power when the sun shines brightly.
Now, the potential problems I face with these elevated voltages is with my older equipment. I use a diy tube amp with a power transformer (ex-Lafayette from the seventies) that is rated for 220V, and an older Rotel RB-850 power amp that is also rated for 220V. Besides that, I also use a Rotel RB-980BX amp that is rated for 230V. All according to the labels on the back. For the 220V tube amp it became obvious, that the B+ tension is too high when connected to 240V mains power and I use a variac (1000W) to bring the voltage back to 220V and the working voltage for the EL84 tubes back to 300V. I do have more tube amps from old times, when the mains power used to be 220V.
I would like to know what the (long term) consequences could be if older gear is exposed to elevated mains voltage. Is there a difference between solid state and tube amps? Does solid state amps may also "wear out" quicker or would it affect sound quality? What would be a good work-around besides a variac (may be bad for sound quality?). It is mostly not possible to rewire the power transformer because the needed taps are simply missing.
Thanks for the advise!
When I measured my mains power voltage where I live, it is at times even 245 V, partly due to solar generated excess power when the sun shines brightly.
Now, the potential problems I face with these elevated voltages is with my older equipment. I use a diy tube amp with a power transformer (ex-Lafayette from the seventies) that is rated for 220V, and an older Rotel RB-850 power amp that is also rated for 220V. Besides that, I also use a Rotel RB-980BX amp that is rated for 230V. All according to the labels on the back. For the 220V tube amp it became obvious, that the B+ tension is too high when connected to 240V mains power and I use a variac (1000W) to bring the voltage back to 220V and the working voltage for the EL84 tubes back to 300V. I do have more tube amps from old times, when the mains power used to be 220V.
I would like to know what the (long term) consequences could be if older gear is exposed to elevated mains voltage. Is there a difference between solid state and tube amps? Does solid state amps may also "wear out" quicker or would it affect sound quality? What would be a good work-around besides a variac (may be bad for sound quality?). It is mostly not possible to rewire the power transformer because the needed taps are simply missing.
Thanks for the advise!
I've seen - might even have, buried somewhere in my Google Drive - an article (from 50s or 60s) that detailed tube life related to filament voltage. IIRC a modest decrease helped extend tube life, while an increase definitely shortened it. I may be wrong (won't be the first time) that a 10% increase in B+ won't, typically, have a deleterious effect on the tubes, or circuit, while it might well have on the filament supply.
It is 230 volt (+6%/−10%) since at least 4 decades so a maximum voltage of 253V. Since solar and wind energy have been introduced inverters of those push that voltage to the higher regions as they can otherwise not deliver energy back. The most recent EU proposal is to raise the maximum to 264V for a period of 15 minutes maximum as the supposedly green aspect of solar and wind energy is a laissez-passer. This will practically be the end of transformer fed classic devices.
When one notices to be in an area where mains voltage always fluctuates at the higher side it maybe it best to give in and use SMPS as these don't have any issue with fluctuations. Sad but true. About every new source device will have SMPS anyway.
For classic 220V tube devices a solution is to have regulated DC filament voltage buy then preferably with high efficiency so with either LDO or uLDO regulators. Filaments are sensitive to continuous overvoltage and the more often occurring failure mode that they will go open when switched on at the wrong time of the mains voltage sinus so at power on (AC, so no DC soft start). The fluctuations in the B+ will not be as detrimental but regulating B+ also is a possibility. However, even when thinking to have adapted stuff to 250V (so all is good) one will notice one day when there is no wind or sunshine that the mains voltage then is 217V and the regulators may become unstable as their input voltage is now too low. Such fluctuations are normal today. Again, SMPS usually will not have an issue with those fluctuations. If you are into old devices you will have work to do. KiCAD/JLCPCB are your friends. Make sure to implement overdimensioned filter capacitors to cater for fluctuations and have less ripple voltage.
It is a good thing to check every older device in possession for higher mains voltage taps and choose 240V primary taps. This also with oscilloscopes, bench equipment etc.
When one notices to be in an area where mains voltage always fluctuates at the higher side it maybe it best to give in and use SMPS as these don't have any issue with fluctuations. Sad but true. About every new source device will have SMPS anyway.
For classic 220V tube devices a solution is to have regulated DC filament voltage buy then preferably with high efficiency so with either LDO or uLDO regulators. Filaments are sensitive to continuous overvoltage and the more often occurring failure mode that they will go open when switched on at the wrong time of the mains voltage sinus so at power on (AC, so no DC soft start). The fluctuations in the B+ will not be as detrimental but regulating B+ also is a possibility. However, even when thinking to have adapted stuff to 250V (so all is good) one will notice one day when there is no wind or sunshine that the mains voltage then is 217V and the regulators may become unstable as their input voltage is now too low. Such fluctuations are normal today. Again, SMPS usually will not have an issue with those fluctuations. If you are into old devices you will have work to do. KiCAD/JLCPCB are your friends. Make sure to implement overdimensioned filter capacitors to cater for fluctuations and have less ripple voltage.
It is a good thing to check every older device in possession for higher mains voltage taps and choose 240V primary taps. This also with oscilloscopes, bench equipment etc.
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Well, supposedly the actual voltage levels in Europe and the UK were not changed, just the allowable ranges; see below (*). So in principle your old equipment should work, if it was in compliance with the full 220V range. This of course doesn't help you, if your local electricity supplier allows fluctuations above the 242V upper edge of the old 220V+/-10% range that your equipment was designed for.
The cleanest option might be to get a 240V to 220V step down transformer, if you can find someone willing to ship to you. Apparently those were quite the rage in Australia.
Another commercial option would be a UPS with AVR (automatic voltage regulation). I have not found any adjustable AVRs, so you might have to select one with tight enough specs for 230V.
Alternatively this link has two great ideas for homebuilt AC adjusters. In particular, for a constant offset a relatively low power mains transformer with a 20V secondary could be used, with the secondary connected out of phase to the incoming mains voltage, to reduce the output voltage by a fixed amount. The author also presents a second, regulated, solution, with a variable inductance in series with the load. He builds the variable inductance from two identical mains transformers, with the primaries connected in parallel, and the secondaries connected out of phase, so that he can feed a variable DC current through the secondaries, which can saturate the cores and thus allows to adjust the inductance.
Apparently it helps if you have old PDP-11 parts laying around.
(*): My wisdom comes from this Wikipedia article, and specifically this section:
"Until 1987, mains voltage in large parts of Europe, including Germany, Austria and Switzerland, was 220±22 V while the UK used 240±14.4 V. Standard ISO IEC 60038:1983 defined the new standard European voltage to be 230±23 V. From 1987 onwards, a step-wise shift towards 230+13.8
−23 V was implemented. From 2009 on, the voltage is permitted to be 230±23 V. No change in voltage was required by either the Central European or the UK system, as both 220 V and 240 V fall within the lower 230 V tolerance bands (230 V ±6%). Usually the voltage of 230 V ±3% is maintained. Some areas of the UK still have 250 volts for legacy reasons, but these also fall within the 10% tolerance band of 230 volts. In practice, this allowed countries to have supplied the same voltage (220 or 240 V), at least until existing supply transformers are replaced. Equipment (with the exception of filament bulbs) used in these countries is designed to accept any voltage within the specified range."
The cleanest option might be to get a 240V to 220V step down transformer, if you can find someone willing to ship to you. Apparently those were quite the rage in Australia.
Another commercial option would be a UPS with AVR (automatic voltage regulation). I have not found any adjustable AVRs, so you might have to select one with tight enough specs for 230V.
Alternatively this link has two great ideas for homebuilt AC adjusters. In particular, for a constant offset a relatively low power mains transformer with a 20V secondary could be used, with the secondary connected out of phase to the incoming mains voltage, to reduce the output voltage by a fixed amount. The author also presents a second, regulated, solution, with a variable inductance in series with the load. He builds the variable inductance from two identical mains transformers, with the primaries connected in parallel, and the secondaries connected out of phase, so that he can feed a variable DC current through the secondaries, which can saturate the cores and thus allows to adjust the inductance.
Apparently it helps if you have old PDP-11 parts laying around.
(*): My wisdom comes from this Wikipedia article, and specifically this section:
"Until 1987, mains voltage in large parts of Europe, including Germany, Austria and Switzerland, was 220±22 V while the UK used 240±14.4 V. Standard ISO IEC 60038:1983 defined the new standard European voltage to be 230±23 V. From 1987 onwards, a step-wise shift towards 230+13.8
−23 V was implemented. From 2009 on, the voltage is permitted to be 230±23 V. No change in voltage was required by either the Central European or the UK system, as both 220 V and 240 V fall within the lower 230 V tolerance bands (230 V ±6%). Usually the voltage of 230 V ±3% is maintained. Some areas of the UK still have 250 volts for legacy reasons, but these also fall within the 10% tolerance band of 230 volts. In practice, this allowed countries to have supplied the same voltage (220 or 240 V), at least until existing supply transformers are replaced. Equipment (with the exception of filament bulbs) used in these countries is designed to accept any voltage within the specified range."
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Post #3 has link to perfect solution of this issue. I had same problem and one 200VA transformer with 18V output solved it completely. Mains PS is about 220V again
Thanks again for the many useful tips. I may switch over to an off-grid battery solar system I already have as a backup (pure sinewave, premium brand, functional but not in use) to be immune of mains power fluctuations and noise. That is less convenient however, I am in favor of plain old mains power in general. I will dive into the above tips also. Meantime a variac will do the duty but it has a slight buzz. I also think there must be (commercial) active power filters that can also regulate the mains voltage but I would guess they are pretty expensive. The UPS solution also may be a good idea.
So the standard voltage appears to be still 230V in Europe, but it can fluctuate plusminus 10% so that is a stretch for older equipment. As stated, transformers in generic devices will be phased out in the end. Saves a lot on copper anyways. Old tube equipment may experience out-of-spec circumstances that can short the lifetime of tubes and probably capacitors. If you are not aware and you f.e. use your special and rare 300B tubes in old equipment in a region with 240+ voltage (lots of "green" energy in the region f.e.) you may feel sorry after some time for not taking care.
So the standard voltage appears to be still 230V in Europe, but it can fluctuate plusminus 10% so that is a stretch for older equipment. As stated, transformers in generic devices will be phased out in the end. Saves a lot on copper anyways. Old tube equipment may experience out-of-spec circumstances that can short the lifetime of tubes and probably capacitors. If you are not aware and you f.e. use your special and rare 300B tubes in old equipment in a region with 240+ voltage (lots of "green" energy in the region f.e.) you may feel sorry after some time for not taking care.
Exactly. You may not be very enthusiastic when using consumer grade UPSes. For stable voltages you need a double conversion UPS. Synthesized sinusses and added complexity plus noise may not be your thing either 😎
If you like simplicity this is all far away from what once was.
If you like simplicity this is all far away from what once was.
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That counts for a lot of other things in our lives today..🙄
Regarding the solar/battery/inverter option, I already tested this in my previous home and it actually sounded a little better. The inverter can deliver 1200VA pure sine continuous, at most I need one third of that for audio. Saving some energy this way is a side benefit with power hungry tube gear.
I have a mains conditioner that constantly monitors the incoming voltage. Here in rural Surrey I have had as high as 252v and no lower than around 239v. I have not found this ti be a problem with any of my amps.
Measure the B+ and filament voltages. Use a bucking transformer to reduce the applied voltage to proper levels.
Some North American equipment had marginal filter capacitor ratings. Our mains have risen over the years from 117 VAC to 125 VAC. Doesn't sound like much, but it is.
Some North American equipment had marginal filter capacitor ratings. Our mains have risen over the years from 117 VAC to 125 VAC. Doesn't sound like much, but it is.
I had a similar problem with high mains voltage here in the USA.
Mine was 2-3 volts above the limit so I called the power company and they came out to check within a few hours.
They checked the voltage at many houses in the neighborhood that were fed from a few different transformers and all were high.
It was fixed the next day and the repair crew told me the cause was a bad pole mounted capacitor bank.
These are used for power factor correction on the 13 KV transmission lines throughout the grid.
So call the power company and let them know what you measure.
Since the problem can be limited to a small area they may not know unless someone speaks up.
Can't hurt.
Mine was 2-3 volts above the limit so I called the power company and they came out to check within a few hours.
They checked the voltage at many houses in the neighborhood that were fed from a few different transformers and all were high.
It was fixed the next day and the repair crew told me the cause was a bad pole mounted capacitor bank.
These are used for power factor correction on the 13 KV transmission lines throughout the grid.
So call the power company and let them know what you measure.
Since the problem can be limited to a small area they may not know unless someone speaks up.
Can't hurt.
I wish. This is a commonly measured AC voltage across most of south Ontario. It was a trend where it slowly went up over a couple decades. I'm pretty sure they are aware, but I'll put in a call.
Not yet, but I will soon. I did measure the filament voltage at the tube rectifier however, and it was approx. 4,6V (5V spec.) when using the variac at 220V output.
Fantastic!,
lucky if anyone looks at anything here unless you send them some thing from a power analyser trace from £xxxx piece of monitoring equipment!
I looked at these five years ago, some of these are nearly £10K now!
e.g.
Megger MPQ 1000 Power Quality Analyzer.
Chauvin Arnoux CA8336/ CA8345 Power Quality Analyser.
Chauvin Arnoux PEL115 Power Energy Logger
Fluke 1775/1777 Three-Phase Power Quality Analyser.
We had dire triplins harmonics that was parasitically raising the main voltage to close to 250VAC,
caused havoc, thanks to insufficiently filtered SMPS throughout the network.
I went as far as seeing if they could be hired. The longer the time lo,g the more accurate the 'picture'. One might have as well bought the unit!
I second that. It a cheap and effective solution.
Take a 230V~ / 10 V~ or 12 V~ (or whichever secondairy winding you want the mains to be lowered with ) transformer of appropriate VA rating, and you're set.
Unless the voltage is at the lower side the next day. If it would always be at the higher side it would be easier.
This could be from the growing number of residential "grid tied" solar installations, since they must produce a voltage slightly higher than the grid to return excess power to the grid.
However, they are designed to not exceed the specified voltage limits.
That's how I found out about the high mains voltage.
My grid tied solar system started to report it was periodically not producing power on sunny days.
After the power company replaced the capacitor bank, the problem went away.
The solar company later confirmed my suspicions of the high voltage shut down.
If the voltage is that variable, there is little you can do but monitor and adjust with a variac. Most can be wired to both decrease and increase the output voltage.