50/60 cycles - difference in tone?

[Quatro]

I was chatting with a guy in Europe about swapping the PT on a US amp for an "export" transformer so it would operate there. He said his tech told him the amp would sound a bit different because of the 50 cycle mains there.

Is this accurate? If so, how and why?

thanks

[tubeswell]

... his tech told him the amp would sound a bit different because of the 50 cycle mains there.

The only situation I could imagine where this might (possibly) apply is if you could hear some ripple hum. (But that would be because of something going wrong or mismatched output tubes or lack of decent filtering - especially in an SE amp)

But 50Hz mains iron-core PTs do need to be about 20% bigger than 60Hz mains equivalents, because of the greater inductance at 50Hz. This is why US-made PTs for 'euro-voltage' countries burn up quickly if they use the same core and bobbin size and wire etc.

[Quatro]

This is why US-made PTs for 'euro-voltage' countries burn up quickly if they use the same core and bobbin size and wire etc.

Wow. Do you know of brands that are known to self destruct? How is it possible a transformer company underbuilds it's export transformers?

[tubeswell]

This is why US-made PTs for 'euro-voltage' countries burn up quickly if they use the same core and bobbin size and wire etc.

Wow. Do you know of brands that are known to self destruct? How is it possible a transformer company underbuilds it's export transformers?

Because some power transformers are made for amp/amp parts suppliers by cheap asian-rim knock-off producers who don't understand about inductance at 50Hz.

[HotBluePlates]

I was chatting with a guy in Europe about swapping the PT on a US amp for an "export" transformer so it would operate there. He said his tech told him the amp would sound a bit different because of the 50 cycle mains there. ...

To use a U.S. model amp in Europe, it is advisable to have an "export transformer" designed for operation on the 50Hz main.

In general, the core of the transformer will be larger to provide the greater inductance needed for the lower frequency of operation. Looked at another way, a U.S. transformer intended for 60Hz operation, and used on a 50Hz main, will have somewhat less efficiency than a 50Hz model in the same situation. This will probably manifest as a bit more loss in the form of heat in the transformer.

I doubt there will be any significant tonal difference. For what it's worth, I used to own a blackface Princeton Reverb that had an export transformer intended for 50Hz, but I obviously used it on 60Hz U.S. line current. It sounded like a Princeton Reverb. I was always told the transformer was probably running cooler than the 60Hz version.

Again thinking in a different direction, if you want an output transformer to have full output power down to 20Hz instead of guitar-amp 80Hz, you'll need a bigger core to have sufficient inductance at the lowest frequency of interest. The smaller core simply won't pass all input power to the output at 20Hz because the core saturates too soon to allow that to happen.

A roughly similar condition exists for Europe power transformers vs. U.S. power transformers.

[HotBluePlates]

bottom line, the tone will likely change.  Review the article, posted in this thread.

That is their bottom line in the article, but strictly speaking from a scientific/experimental point of view, it is a secondary conclusion provided with no supporting evidence. In other words, the article presents the conclusion reached through experiment and then asserts an untested follow-on hypothesis based on the main conclusion.

And, that untested hypothesis is that the changed ripple frequency will have a tonal effect. They don't assert anything about using a 60Hz transformer with a 50Hz main current, or vice versa. The article is about ripple impacting tone; they say it happens, but also don't say how or why.

I don't like the article from a scientific rigor standpoint either, because they never show the new power supply circuit, so you can't know if there was a flaw contributing to their results.

If my memory serves me correctly, some of Fender's export transformers came with selector switches to be able to choose voltages ...

I can only speak to vintage Fender amps; these simply have various primary tappings to match local voltage conditions, and are hardwired to the power cord entry. Regardless of the tapping chosen (even 110/120v), you get the benefit of the larger core for 50Hz operation.

Did you try the export on a 50 Hz circuit and compare to that on a 60 Hz circuit. 

No. I live in the U.S. and I'm not going to build a generator to give me a 50Hz mains frequency. Even if I did, I couldn't be sure any significant result wasn't due to a poor attempt at replicating a power company.

It my opinion, that most rigs are not limited by the amplifier but by the speaker themselves. ...

The alternative transformer market provides some specs on replacement transformers. ...

So what does a bass player do if they want to play a bass with a B-0 string (about 30 Hz) ...

These comments do not help, because they diverge from the question regarding a power transformer. Yes, if you change speakers or output transformers, the sound will change. But that isn't the question.

Back to your earlier question:

, I used to own a blackface Princeton Reverb that had an export transformer intended for 50Hz, but I obviously used it on 60Hz U.S. line current. It sounded like a Princeton Reverb. I was always told the transformer was probably running cooler than the 60Hz version.

Did you try the export on a 50 Hz circuit and compare to that on a 60 Hz circuit. 

I can say from direct experience that playing multiple examples of a single vintage Fender amp model, with both domestic (U.S., 60Hz) and export (50Hz) power transformers, same model original speakers, I could not hear a difference between the versions that exceeded the normal variation of tone between any two individual amps of the same manufacturer, model and period.

This experience was derived over a period of several years in which I bought and sold numerous vintage amps, had a personal collection of ~20 amps, was a fixture at several vintage guitar shops in/around Nashville, and attended numerous vintage guitar shows as both a buyer and dealer (full disclosure: had buy/sell authority while helping a friend starting out as a vintage guitar dealer).

So we're citing references to support an assertion...

Look at Radiotron Designer's Handbook, Volume 4, Chapter 5.5(iii), Equation 2 (found on page 235). A digital copy of RDH4 is available here.

Equation 2 is given as a fundamental transformer equation, and gives the number of primary turns needed when primary voltage, frequency of operation, maximum flux density and cross-secitonal area of the transformer core are known.

Primary voltage is in the numerator; both cross-sectional area and frequency are in the denominator. Because the primary voltage is set by the power company and is assumed fixed, if frequency goes down (from 60Hz to 50Hz) then cross-sectional area must go up.

Translation: a 50Hz PT has a larger core than a 60Hz PT, all else equal.

I already said this another way 3 posts ago.