USA valve amps suffering from transformer saturation?

[Neil McCauley]

Recently I have been measuring the input voltage in the listening room of customers. This has varied between 216v (the customer got the electricity supplier to correct this) to 258v. Moreover this has varied during the course of the installation. THD has been typically 2.5% (strangely consistent across every installation of mine in SE England) and occasionally as high as 3.8%.

Years back, one of the reasons that so many of the US valve power amps I had for blowing up was that the suppliers had fitted 220v transformers. I might be wrong about this but my guess was that they were unaware of a European-wide agreement to settle on 230v.

Anyway, recently I have noticed that some valve amps (which I don’t sell) have been performing sonically unpredictably and not necessarily as well as the owner or indeed myself would have hoped. I’ve been looking for patterns to this.

The sample set is very small and thus any ‘pattern’ is open to inaccuracy. However what seems to be emerging is this.

1. All and any US made valve amps seem more susceptible to UK mains variations than UK ones.

2. Conrad Johnson seems more susceptible to this than ARC

3. This problem is more acute in rural areas than city ones.

4. I have never, not even once, encountered this problem with US solid state gear. The occasional poor sound of US sourced SS gear was usually down to inappropriate speaker matching, or the all too frequent application of MOM (marketing-over-mediocrity) techniques.

I'm not technical. However people who are have indicated to me that it is possible and indeed probable that the power supply transformers on some US equipment (220v rating, 230v rating? might be being saturated by 240v and certainly by 258v – the maximum I have encountered so far on site.

Any observations, comments or thoughts on this? These would be most welcome. Thanks. H

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[purite audio]

We have our transformers wound for 240v.

[Neil McCauley]

We have our transformers wound for 240v.

Thank you - but I'm not clear how this expands our collective knowledge regarding potential transformer saturation? Have I missed something?

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[lurcher]

The other thing to remember is that all other things being equal, you would normally choose a larger core for 50hz instead of 60hz operation. I suspect thats a issue in what you say about imported kit. Add that to the 255v mains supply and you can see why some have problems.

Oh, and don't forget the varying amount of DC that can be found in the supply.

[Neil McCauley]

The other thing to remember is that all other things being equal, you would normally choose a larger core for 50hz instead of 60hz operation. I suspect thats a issue in what you say about imported kit. Add that to the 255v mains supply and you can see why some have problems.

Oh, and don't forget the varying amount of DC that can be found in the supply.

Thank you for this. Little by little and with the kind help of the folks on the site, my woeful ignorance in this area is being confounded, rather than compounded. Rather a good feeling I have to say.

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[purite audio]

Perhaps Manley could wind 240v transformers for you?

[Neil McCauley]

Perhaps Manley could wind 240v transformers for you?

It seems that Manley who do serious business in Europe but have yet to make a serious (i.e more than a cult / underground reputation) in the UK do in fact already do this. This might account for the fact that so far I have achieved a consistent quality of sound. Mind you, everything here is run through a PS Audio Power Plant Premier. The impact of this is such that I have to draw potential customer's to this fact and without it, the magic and wonder of music via the Stingray might well not be replicated in their home.

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[purite audio]

Quite.

[anthonyTD]

The other thing to remember is that all other things being equal, you would normally choose a larger core for 50hz instead of 60hz operation. I suspect thats a issue in what you say about imported kit. Add that to the 255v mains supply and you can see why some have problems.

Oh, and don't forget the varying amount of DC that can be found in the supply.

i agree,
the 50 to 60hz aspect of transformer design can be an issue, ie, if a transformer is designed for 60hz [USA] when it comes to our shores and is run on our frequency it will be less eficient, ie, you will get less voltage out of the secondary, the other way around is also true, ie, a transformer designed to run on 50hz, when operated in usa on 60 hz will be more eficient hence a higher secondary voltage.
anthony...

[Togil]

3. This problem is more acute in rural areas than city ones.

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Certainly. We once tried to do a statistical analysis of voltage variations here in Oxford and the project had to be abandoned as the voltage was always 230 V with very little variation.