US 115V rated gear in 100V rated country?
solidstate
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#1
4th March 2012
Old 4th March 2012
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US 115V rated gear in 100V rated country?

Hi,

most of my gear is rated for 100-240. I have a couple of pieces, namely 1073 in VK racks and tubetech cl1b rated at either 230/115V.. I live in Japan an the main voltage here is 100V. 115V gear it has been working fine so far, I never had an issue with noise(well the 1073 isn't the quietest pre I've heard anyway) or headroom before.. Recently though, a tech i respect a lot told me that bringing the voltage down to 100V will give a better S/N and a fuller sound.. I guess i should get a voltage regulator like the furman 1AR 215 J? Or a step down transformer? Any suggestion on the brand?

Or maybe i should't care so much about it
#2
4th March 2012
Old 4th March 2012
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Hi
You should aim to get the 'nominal' voltage withing the rated voltage band. The main isues you would have would be power line frequency related 'ripple' (typically double the mains frequenct predminantly).
Valve gear that does not have 'regulated' supplies will change performance slightly. For example a TubeTech unit is mostly regulated but the HT for the final output stage is not so there is a possibility that you may 'lose' a dB or two OUTPUT headroom. Since this is well in excess of +28dBu into a load greater than 600 Ohms this is not exactly an issue.
Other kit such as a LA2a for example would also alter slightly as it's supplies are not regulated.
It should be relatively cheap to get a 'step up' transformer sorted out so that your supplied 100 Volts can be made up to 115 Volts. You may actually find that the '100 Volts' is actually 'high' so making conversion not worthwhile.
ALL gear is designed to tolerate a range of supply, typically around 10 percent so you are almost in the range anyway.
To be told that reducing the supply for gear that uses REGULATED internal supply rails is total £$^& for the simple reason that unless the mains is too low, the GEAR inside won't know what the actual mains supply is until it is so low that it drops out of regulation.
Matt S
solidstate
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4th March 2012
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Thanks Matt! So do you think I could get away with a standard step up transformer? I'm no expert, but won't it make worse noise-wise? Like hum o buzz? I do have a couple of furman power conditioner to prevent this kind of things though..
#4
4th March 2012
Old 4th March 2012
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Hi
You only need a decent 'step up' autotransformer. In essence it is a 100 Volt mains transformer with a 15 Volt (say) secondary at (say 10 Amps) which is wired such that the 15 volt secondary ADDS to the 100 Volt mains that is coming in. Thus this transformer only adds the DIFFERENCE which is 15 Volts as I propose, not the full power that an isolated step up transformer would give. In this scenario the transformer is rated at 15 Volts X 10 Amps which is 150 VA which are quite cheap. A transformer to provide 10 Amps at 115 Volts in a 'conventional' way would need to be 1150 VA, MUCH larger.
ANY big transformers must be placed at least 1 metre away from audio gear / cabling.
Power conditioners should not really be necessary in any half decently wired studio and they are a 'band aid' for sloppy design.
Matt S
solidstate
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4th March 2012
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Hey Matt,

thanks for helping me with this. You mean a "stepdown autotransformer" right?

I've found this: (sorry Japanese only, I used google translator and looks like this one might work)

SH (

Will it be ok to use it in the same room with my other gear? If not, do you have any suggestion?

Here a few more, I can't tell which one is good though!

http://www.soundhouse.co.jp/shop/Sea...ategory_cd=380
#6
4th March 2012
Old 4th March 2012
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If you live in an area with 100V available and the piece of equipment is designed to operate on 115V (newer equipment might be 120V or even 125V) then you need a step-up transformer to raise the voltage to a higher level.
But I think that most equipment (with the exception of power amplifiers) that are designed for 115/120V operation will work OK on 100V.

The bigger question is are you in a 50 Hz or a 60 Hz area. A transformer designed for 60 Hz will not be happy on a 50 Hz supply. But a 50 Hz transformer is OK with 60 Hz.
#7
4th March 2012
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Hi
You actually need to step UP as just posted above.
Japan is super technical and has lots of good egineers, if you can find them, to help with specific problems. You need to get talking to some guys near you.
Sorry I can't remember the name of one tech I was friends with who was at AMEK's dealer in Tokyo as it was about 14 years ago when I was last there (more's the pity as it was fascinating).
Matt S
solidstate
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5th March 2012
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Indeed I asked a tech to come over next week. I just wanted to get more educated on the subject meanwhile.. Now Except from 1 piece of gear(namely the UA dcs preamp) all my equipment is 50/60hz. As far as I understand there is no way to convert the input frequency. So I guess my only solution is ask to the tech to change the transformer(ua already say they don't have one for the Japanese market). Now, about that stepUP transformer can someone post a link just so I understand what to look for?

Thanks in advance!
#9
5th March 2012
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The link you posted is a step up. 100v in, 115v out. Presumably the bigger, chunkier and more expensive the transformer the better.

FWIW I contacted Furman's tech support recently asking them if it's ok to use their US power conditioners in Japan (which are rated to run on something like 90v~130V).
He said that the only problem might be that 50Hz mains would cause the unit would see a higher voltage than normal and this might trip the surge protection circuit.
If that's the case perhaps other equipment would also see a higher than 100v voltage and a transformer wouldn't be necessary?
I'm thinking aloud so someone please correct me before someone gets hurt.
#10
5th March 2012
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Hi
A transformer rated for 60 Hz will not produce a significantly higher voltage when run at 50Hz, in fact slightly the opposite.
The frequency MAY cause a problem if there is insufficient iron core (it may buzz, overheat perhaps) but the voltage out should be much the same, certainly within tolerance.
The Furman conditioners MAY have an issue and you HAVE to contact them directly for their comments. DO NOT use website / forum info for this as it could be dangerous.
Having a LOWER frequency mains will REDUCE the DC available slightly as the reservoir capacitors have LESS time to 'recharge' during the mains cycle.
I have not seen the link but 100 Volt in and 115 Volt out sounds good to me. Work out the power requirement for your studio (or at least the units that are to be fed with this transformer) and allow plenty for new toys you may get in the future.
If it is only the UA gear that is unhappy with 100 Volts but is rated for 50 / 60 Hz, you could use a much smaller step up transformer for that unit only.
Matt S
#11
5th March 2012
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The difference between 50Hz power transformers and 60Hz transformers is that the 50Hz have more iron in the core and are heaver. Many 60Hz transformer will have their core saturate (overload) when operated at 50Hz.

If you have a skilled technician, you may talk about using a buck/boost transformer to correct the voltage.

Bucking Xfmrs
#12
5th March 2012
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Hi
That 'Bucking transformers' link tells you practically all you need to know. As I said earlier a 15 Volt 10 Amp (output specification) transformer would give you about 10 Amps at 115 Volts which would power a reasonable amount of gear (1150 VA) and as they should be available as 'standard' transformers near you they should be cheap. You MUST of course have it put in a proper box of some sort with fuses included for safety.
Matt S
solidstate
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5th March 2012
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I guess I'll have the tech look into this.. It's waaaaaaaaaaaaaaay over my head

Thanks for trying folks
#14
18th September 2013
Old 18th September 2013
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How did you get on with this? I have recently moved to Tokyo and am struggling with the same issues? Would really appreciate any insights (or your tech's phone number ;-)
#15
18th September 2013
Old 18th September 2013
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Or maybe find a different tech... running 115v gear at 100v will not make it quieter, fuller, or fatter. It may cause it to drop out of regulation. Some areas of japan are 50 Hz, so a 115v 60Hz transformer will be even more challenged at 50 Hz.

A bump transformer is similar to an autoformer where 15v gets added to the 100v to make 115. In an autoformer the primary and secondary are not isolated, but any suitable isolated winding 15v transformer can be configured to bump 100 to 115.

Do not mess with dangerous primary voltage if you are not sure of what you are doing.

JR
#16
18th September 2013
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Most US AC I have measured is more like 120V...The average being more like 115V.
But, the drop on the primary will result on the same percentage drop on the secondary...
Plus that 120Hz pulse into the filter caps (60 Hz) will now be 100Hz (50 Hz)..Based on a full wave bridge..
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18th September 2013
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#18
19th September 2013
Old 19th September 2013
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Quote:
Originally Posted by JohnRoberts View Post
Or maybe find a different tech... running 115v gear at 100v will not make it quieter, fuller, or fatter.

JR
Hi John,

I think the tech recommended using it at the correct voltage for best performance ie using a transformer to correctly run the gear at 115v, not 100v as the OP had been doing. (I think the confusion lies in "bringing the voltage down to 100v" - the OP meant "bringing the voltage up to 115v").

Cheers
#19
19th September 2013
Old 19th September 2013
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One solution is a "Buck/Boost" Transformer.

Rod Elliott has a page on transformers.

Bucking Xfmrs
#20
19th September 2013
Old 19th September 2013
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Quote:
Originally Posted by Robo View Post
Hi John,

I think the tech recommended using it at the correct voltage for best performance ie using a transformer to correctly run the gear at 115v, not 100v as the OP had been doing. (I think the confusion lies in "bringing the voltage down to 100v" - the OP meant "bringing the voltage up to 115v").

Cheers
That would make more sense, I am inclined to read posts literally.

If the tech is advocating proper mains voltage he is back on the island.

JR
#21
22nd September 2013
Old 22nd September 2013
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Quote:
Originally Posted by solidstate View Post
I guess I'll have the tech look into this.. It's waaaaaaaaaaaaaaay over my head

Thanks for trying folks
Just purchase a correct transformer, set it for "step-up", plug it into the wall outlet, and plug your gear into the transformer's outlet(s). Safe and a "no-brainer".
There are a number of sources of inexpensive 100 volt to 115/117 volt step up transformers made specifically for this purpose. You can purchase one for less cost than adding a series 15 volt transformer with an appropriate case, circuit breaker or fuses, and cables.

This source has (6) sizes between 100 watts and 3 kW.
#22
23rd September 2013
Old 23rd September 2013
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Wouldent think you need to worry about a transformer. power company's have a 10% variation anyways.
Just pull the cover of your equipment and test the DC power supply if the voltage is within spec's just get on and use your gear.
#23
24th September 2013
Old 24th September 2013
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Quote:
Originally Posted by Format C: yes View Post
Wouldent think you need to worry about a transformer. power company's have a 10% variation anyways....
But so does the Japanese power company (have a possible +/- 10% variation). Japanese "mains" voltage can be as low as 90 volts. Some power supply designs are conservative and some are "borderline". As has already been said, for most contemporary solid-state audio gear using regulated power supplies, it will depend on how much the unregulated voltage supply is above the minimum "drop out" voltage of the regulator.

There are three likely possibilities:

1. The unregulated voltage is 25 or 30 % over the "dropout" voltage and the gear works as intended with no ripple noise and no headroom loss.

2. The unregulated voltage is 15 to 20% above "dropout" and there is ripple and hum when the voltage drops a few volts due to line loading changes, or when the gear is driven hard causing noise modulation on peaks and reduced headroom.

3. The unregulated voltage is 10 to 15% above the "dropout" voltage and running at a lowered line voltage causes the regulator to saturate and feed all the PS ripple through to the audio circuitry causing significant hum/buzz and headroom loss.

Simply measuring the static power "rail" DC voltages may not give an accurate indication of possible ripple and/or voltage fluctuations under peak load conditions. At a minimum, the power "rails" should be checked with a oscilloscope under operating conditions.

With older hardware , particularly vacuum tube gear and tube power amplifiers (usually built with unregulated power supplies), running at a 15% reduced line voltage will almost always result in reduced performance all the time.

Using an inexpensive transformer to restore the power line voltage the designer had in mind is a simple way to eliminate the issue. You can always try to "get away" with running your gear at 15% less line voltage, but unless you are sure (by measurement) that the voltage after the regulators will always stay within design range you are risking possible audible consequences of doing so.

For the cost of a good mic cable, why take the risk?
#24
25th September 2013
Old 25th September 2013
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Find a variac with a step-up option. For example, some Staco variacs have a switch to change the output from 120v to 140v to adjust for the situation you are describing. Of course, in 140v mode you will not get 140v in your situation but something closer to 120v. Then use a voltmeter to adjust the variac output to exactly 120v.
#25
26th September 2013
Old 26th September 2013
  #25
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Quote:
Originally Posted by Lotus 7 View Post
But so does the Japanese power company (have a possible +/- 10% variation). Japanese "mains" voltage can be as low as 90 volts. Some power supply designs are conservative and some are "borderline". As has already been said, for most contemporary solid-state audio gear using regulated power supplies, it will depend on how much the unregulated voltage supply is above the minimum "drop out" voltage of the regulator.

There are three likely possibilities:

1. The unregulated voltage is 25 or 30 % over the "dropout" voltage and the gear works as intended with no ripple noise and no headroom loss.

2. The unregulated voltage is 15 to 20% above "dropout" and there is ripple and hum when the voltage drops a few volts due to line loading changes, or when the gear is driven hard causing noise modulation on peaks and reduced headroom.

3. The unregulated voltage is 10 to 15% above the "dropout" voltage and running at a lowered line voltage causes the regulator to saturate and feed all the PS ripple through to the audio circuitry causing significant hum/buzz and headroom loss.

Simply measuring the static power "rail" DC voltages may not give an accurate indication of possible ripple and/or voltage fluctuations under peak load conditions. At a minimum, the power "rails" should be checked with a oscilloscope under operating conditions.

With older hardware , particularly vacuum tube gear and tube power amplifiers (usually built with unregulated power supplies), running at a 15% reduced line voltage will almost always result in reduced performance all the time.

Using an inexpensive transformer to restore the power line voltage the designer had in mind is a simple way to eliminate the issue. You can always try to "get away" with running your gear at 15% less line voltage, but unless you are sure (by measurement) that the voltage after the regulators will always stay within design range you are risking possible audible consequences of doing so.

For the cost of a good mic cable, why take the risk?
I've been emailing the manufacturers of the gear in my rig & some say in 115V mode their product will work down to 90V, but others say it won't. Which makes sense, depending on the gear & the design of the power supplies.

So, I'll be buying a transformer in the next few days.

But, I'm still left with the question of grounding, since most places here, including the space I'm converting only have unearthed power points. The standard here seems to be 15A unearthed two prong plugs.

The local Furman dealer said to me "There is no power problem because the Japan are grounded cold side (neutral side)." But, I'm not sure about this.
#26
28th September 2013
Old 28th September 2013
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Quote:
Originally Posted by fernmeister View Post
But, I'm still left with the question of grounding, since most places here, including the space I'm converting only have unearthed power points. The standard here seems to be 15A unearthed two prong plugs.
I had the same problem for a while. Eventually I found that my house had an earth/ground rod so connected all my equipments' earths to that in a 'star grounding' format. But I'm not sure if having an earth rod is standard in Japan, I may have been lucky. You could always get a copper earth rod and make your own earth (I've seen them in Unidy) but depending on where you live it might be a problem finding soil to hammer it in to!

I have a Kashimura TI-20 step up/down transformer and would recommend it. I use it in step UP mode to step up the voltage from 100v to 230/40v for my UK gear. It is pretty heavy duty and has worked perfectly and silently for years. I also think it naturally isolates from mains noise etc, and is recommended for audio use by a few sources.

I think you would need the TI-149 for 115v gear:

http://www.kashimura.com/goods/kaigai/TI15.html
????.com - ???? KASHIMURA TI-149 [?????????? 110-130V/1500W]??????

Cheers

Last edited by Robo; 28th September 2013 at 05:26 AM.. Reason: Misspelling
#27
24th November 2013
Old 24th November 2013
  #27
Gear interested
 

Quote:
Originally Posted by Robo View Post
I had the same problem for a while. Eventually I found that my house had an earth/ground rod so connected all my equipments' earths to that in a 'star grounding' format. But I'm not sure if having an earth rod is standard in Japan, I may have been lucky. You could always get a copper earth rod and make your own earth (I've seen them in Unidy) but depending on where you live it might be a problem finding soil to hammer it in to!

I have a Kashimura TI-20 step up/down transformer and would recommend it. I use it in step UP mode to step up the voltage from 100v to 230/40v for my UK gear. It is pretty heavy duty and has worked perfectly and silently for years. I also think it naturally isolates from mains noise etc, and is recommended for audio use by a few sources.

I think you would need the TI-149 for 115v gear:

http://www.kashimura.com/goods/kaigai/TI15.html
????.com - ???? KASHIMURA TI-149 [?????????? 110-130V/1500W]??????

Cheers
Thank you - I'm trying one of these out.
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