OT centre tap

[jestaudio]

After recently cooking a cheap OT, is there any way of determining how much DC volts you can chuck at a OT if the specs are not available
Cheers Gary

[Kagliostro]

Sorry, as far as I can know

NO

Kagliostro

[VacuumVoodoo]

IEC61558-2-4 norm (that's what tube amp xfmrs need to comply with) requires 4kV DC or 2.5kV 50Hz rms for 1 minute AND 3x max operating DC voltage indefinitely between windings and windings to core. If the norm isn't quoted anywhere on the transformer, invoice, or any other documentation or confirmed in writing by manufacturer in direct communication I won't buy it. Buy only CE marked and norm compliant PTs and OTs. Ooooppss.....this excludes several US manufacturers irrespective of price...

[tubeswell]

After recently cooking a cheap OT, is there any way of determining how much DC volts you can chuck at a OT if the specs are not available
Cheers Gary

Good question Gary. As Alek says, insulation is a critical aspect. So is heat. Too much heat will cause insulation to break down. A bigger tranny will be better at dissipating heat. Heat is a byproduct of power. Power in electrical terms is volts-amps. So maybe look for a VA rating? Or look at a comparably-sized transformer with a known primary DCV rating?

[Prairie Dawg]

IEC61558-2-4 norm (that's what tube amp xfmrs need to comply with) requires 4kV DC or 2.5kV 50Hz rms for 1 minute AND 3x max operating DC voltage indefinitely between windings and windings to core. If the norm isn't quoted anywhere on the transformer, invoice, or any other documentation or confirmed in writing by manufacturer in direct communication I won't buy it. Buy only CE marked and norm compliant PTs and OTs. Ooooppss.....this excludes several US manufacturers irrespective of price...

Oooooops. Name the names or hold your peace Alex. Lay out the facts and stop being cute.

[diagrammatiks]

IEC61558-2-4 norm (that's what tube amp xfmrs need to comply with) requires 4kV DC or 2.5kV 50Hz rms for 1 minute AND 3x max operating DC voltage indefinitely between windings and windings to core. If the norm isn't quoted anywhere on the transformer, invoice, or any other documentation or confirmed in writing by manufacturer in direct communication I won't buy it. Buy only CE marked and norm compliant PTs and OTs. Ooooppss.....this excludes several US manufacturers irrespective of price...

Oooooops. Name the names or hold your peace Alex. Lay out the facts and stop being cute.

It's really all of them. But, VV's showing a european standards bias here. They've got standards on everything.

History of bad things happening in basement workshops over there.

[VacuumVoodoo]

OK, I'm not being cute. I placed RFQ and submitted detailed technical specs for both PT & OT to MM and Hammond. Firstly, they tried to convince me that I don't need CE marked transformers, then they claimed having no possibility to test higher than 2kV. Seems they never heard of test instrument rental. On top of that MM didn't want to wind to specs but requested a sample of my existing transformers to "wind an exact tone copy". When I explained that the existing transformers were wound to specs by a small father & son outfit in Brazil all communication stopped. I understand Hammond CE marks their PTs for EU market. I don't know about current MM position re CE. Above events took place 3 years ago.

It's really all of them. But, VV's showing a european standards bias here. They've got standards on everything.
History of bad things happening in basement workshops over there.

Not really. We learned how to prevent frivolous law suits.
Bear in mind UL61558 norm is based on IEC61558 ( "I" in IEC stands for International and USA is one of signatories) with minor changes reflecting lower mains voltage in North America. Canadian norms are just as stringent as EU. So you can't really claim any bias other than on your tubes.

[VacuumVoodoo]

double post

[diagrammatiks]

OK, I'm not being cute. I placed RFQ and submitted detailed technical specs for both PT & OT to MM and Hammond. Firstly, they tried to convince me that I don't need CE marked transformers, then they claimed having no possibility to test higher than 2kV. Seems they never heard of test instrument rental. On top of that MM didn't want to wind to specs but requested a sample of my existing transformers to "wind an exact tone copy". When I explained that the existing transformers were wound to specs by a small father & son outfit in Brazil all communication stopped. I understand Hammond CE marks their PTs for EU market. I don't know about current MM position re CE. Above events took place 3 years ago.

It's really all of them. But, VV's showing a european standards bias here. They've got standards on everything.
History of bad things happening in basement workshops over there.

Not really. We learned how to prevent frivolous law suits.
Bear in mind UL61558 norm is based on IEC61558 ( "I" in IEC stands for International and USA is one of signatories) with minor changes reflecting lower mains voltage in North America. Canadian norms are just as stringent as EU. So you can't really claim any bias other than on your tubes.

stay out of mah solder Europe

Never saw the appeal of mm. Well years ago when I was young and doe eyed.

[Prairie Dawg]

VV:

You've just indicted a Canadian manufacturer of transformers and even though some folks on both sides of the border (very few) think that maybe the war of 1812 shoulda went the other way, they're still very much the independent country and the border's for real. No driving through and waving, you've got to show a passport or stay home.


In short Hammond ain't a US company. As far as MM is concerned if I was MM and you came to me with some story about a sweatshop in the Amazon I probably wouldn't take your calls either unless you were talking tonnage with cash up front.

[diagrammatiks]

VV:

You've just indicted a Canadian manufacturer of transformers and even though some folks on both sides of the border (very few) think that maybe the war of 1812 shoulda went the other way, they're still very much the independent country and the border's for real. No driving through and waving, you've got to show a passport or stay home.


In short Hammond ain't a US company. As far as MM is concerned if I was MM and you came to me with some story about a sweatshop in the Amazon I probably wouldn't take your calls either unless you were talking tonnage with cash up front.

not to mention its pretty much common knowledge the mm only knows how to clone transformers that are already built.

If you were MM and I came to you with some story you'd try to sell me a 500 dollar transformer for a valve junior.

Also, not sure hammond was actually being attacked in that paragraph. It could go either way.

[VacuumVoodoo]

VV:As far as MM is concerned if I was MM and you came to me with some story about a sweatshop in the Amazon I probably wouldn't take your calls either unless you were talking tonnage with cash up front.

Your condescending comment is reminiscent of MMs and totally uncalled for. I came to MM with detailed technical specs. It's none of MMs business who and where made my transformers. They either can wind to technical specs or they can't. The guys in Brazil could. It so happens that I design my PTs and OTs and need to have them made by someone who understands specs. Apparently this was beyond MMs competence, at least in this particular case. The Brazilian winder is not a "sweatshop in the Amazon" but a well reputed small company with excellent customer service. Easy enough to find. It's all water under the bridge as I no longer use transformers on EI cores. It's toroids now, my specs & my design and a European manufacturer who "knows specs" and tests at 4kV.

[Prairie Dawg]

VV: As Werner Wolf used to say, "Let's go to the tape."

You started out with a blanket statement that several US companies don't comply with a particular IEC specification-although, not providing any information about that specification and how some people don't comply with it is equivalent to the lawyer asking the witness "Have you stopped beating your wife yet?"

I challenged you on that and you came back with complaints about Hammond-a Canadian company, and something about Mercury Magnetics and how they blew you off.

Now....I've got no love for MM because I think they're overpriced.

But you still have not adduced one bit of proof to demonstrate that either MM or Hammond or any other US based transformer company doesn't comply with a particular IEC specification, or if it even has to at all.

Perhaps your attitude came through loud and clear on the other end of the telephone in Chatsworth.

Just for curiosity's sake, how many custom winds were you prepared to order paid for up front?

[VacuumVoodoo]

VV: As Werner Wolf used to say, "Let's go to the tape."

You started out with a blanket statement that several US companies don't comply with a particular IEC specification-although, not providing any information about that specification and how some people don't comply with it is equivalent to the lawyer asking the witness "Have you stopped beating your wife yet?"

I haven't began to yet. You fail logic 101.

I challenged you on that and you came back with complaints about Hammond-a Canadian company, and something about Mercury Magnetics and how they blew you off.
Now....I've got no love for MM because I think they're overpriced.

Not "something". I gave specific details. Love's got nothing to do with it. There was no blowing on either side.

But you still have not adduced one bit of proof to demonstrate that either MM or Hammond or any other US based transformer company doesn't comply with a particular IEC specification, or if it even has to at all.

If they export to EU they have to comply and CE mark the product and provide a written declaration of compliance. If you had sold/exported to EU to a distributor or OEM you would have known it.

Perhaps your attitude came through loud and clear on the other end of the telephone in Chatsworth.

Chatsworth, Munich or Moscow - no language barriers or attitude problems there.

Just for curiosity's sake, how many custom winds were you prepared to order paid for up front?

This is irrelevant to subject matter. I can afford the extra cost of only one or two prototypes for evaluation. Usually it's not necessary if manufacturer is able to read technical specification and whose technological process makes his product compliant with requirements of applicable norm. How hard is this understand?
This discussion leads nowhere. I'm out.

[Prairie Dawg]

You said:

Ooooppss.....this excludes several US manufacturers irrespective of price...

I said, more or less, show me the money.

You slammed Hammond and Mercury Magnetics.

I said Hammond wasn't a US company.

To date you haven't provided any information at all to support what you're saying except that you said it. That's circular reasoning and it is one of the Skeptic's Guide to the Universe top 20 logical fallacies.

Makes me think you never got to Intro to Logic yourself.

You simply can't slam people and then change the topic when called out. It makes you look less than intellectually honest.

So yeah-I'm outta here too. I do hope that you'll come up with something more than hot air to support the premise you sideswiped people with here.