Definitive thread: Does a step-down transformer for US amp matter?

[Joost Assink]

Well, I got a used Carr Mercury off this board (and it's a US version) and imported it into Europe. I got a step-down transformer at the local parts store and played. It worked fine, but since I got my burkey Flatliner 6, I realized the importance of power supplies to tone.

I did a lot of searching on the board here and it's unclear to me still whether the step-down transformation will hurt my sound. From what I know now, almost all transformers change the voltage, but not the frequency, so I am feeding 110V 50hz into the amp, instead of 60hz.

Also, speaker watts aren't the same as the power consumption, or so I've learned.

What is the best solution here? What step-down convertor should be over-dimensioned enough to handle power consumptions for transients etc.

[donnyjaguar]

The best solution is a 220V power transformer. The coupling efficiency of a 60Hz transformer run at 50Hz is going to be less. The result will be less current available to the amplifier. Also, the filter capacitors in theory will need to be larger to cope with the slower AC frequency. Whether this makes a difference will depend largely upon the design of the amplifier's power supply. If you look at any given amplifier that's available in USA voltage but has a version with dual-voltage you'll notice the transformer is larger in the latter. This is to offset the aforementioned issue.

[SatelliteAmps]

Dual voltage power transformers are also larger because they need to use more wire to get the higher voltage (adding a 220v tap for instance). Putting a 120v tap on a 220v transformer doesn't need to add a lot of extra wire.

Also, buying a 220v power transformer doesn't mean it is made for 50hz or 60hz. In the US, all multiple tap power transformers are made to run on 60hz. There are no multiple voltage and multiple cycle transformers that I know of.

Using a step down transformer is going to be fine for that amp. Tonally, there won't be a huge difference.

[VacuumVoodoo]

Dual voltage power transformers are also larger because they need to use more wire to get the higher voltage (adding a 220v tap for instance). Putting a 120v tap on a 220v transformer doesn't need to add a lot of extra wire.

Also, buying a 220v power transformer doesn't mean it is made for 50hz or 60hz. In the US, all multiple tap power transformers are made to run on 60hz. There are no multiple voltage and multiple cycle transformers that I know of.

Using a step down transformer is going to be fine for that amp. Tonally, there won't be a huge difference.

Transformers designed and manufactured in accordance with EU norm 61558 (this one applies to the PTs we use) are specified for mains frequency range 40 to 65Hz.

[SatelliteAmps]

There's your European answer.

[VacuumVoodoo]

There's your European answer.

Adam, equivalent US norm is UL61558......it's all in the IEC drive for global harmonization of norms and standards.
Just as mains voltage is allowed +/-10% departure from standard 120V in US or the 230V in EU (forget 220V nominal, it's gone, EU will be going 240V in a few years) so is the frequency allowed some fluctuation. You have a power grid to which several power plants supply their output so they must be frequency and phase synchronized - that synchronization is not instantaneous so the frequency fluctuates a few Hz up and down over time. This is main reason for requirement of 40-65Hz specification on transformers.

So, yes, transformers designed specifically for US market for operation on strictly US mains frequency of 60Hz give or take a few Hz may exhibit reduced efficiency and increased temperature rise when run on 50Hz and fed through a step down transformer in EU. On the other hand a transformer designed for 50Hz and run in US through a step up transformer will be just happily tugging along.

[jay42]

I got a step-down transformer at the local parts store and played.What is the power rating for this transformer. It might be expressed in units of "VA." It's also possible it would read something like "220V/10A."

[Joost Assink]

Thank you everyone for the great and very complete replies.
The step down transformer says output 110V/100 watts.

What is the power rating for this transformer. It might be expressed in units of "VA." It's also possible it would read something like "220V/10A."


On another subject, I called the guys at Carr and they were very helpful as always. Their customer service is top notch. They offered to send me the 220v transformer they put in their European models (as far as I know that's the only change to the amps).

I don't think that's optimized for 50 hz then, so it'll be easier and better to get a better step-down transformer (one that can supply at least 300VA), because replacing the internal transformer would require surgery. Now the amp has no rattles or anything, so I would not like messing with that (or well, having an expert do that, if I can find one over here).

Or am I getting this wrong? What would you do?


.

[jay42]

That step-up transformer must not be very big. The Mercury has a 1A fuse. Your step-up is rated for roughly 0.9A, which while not optimum, shouldn't cause any problems. The Carr could probably get away with a smaller fuse, but 1A is very sensible. Is the step-up fused?

I'd prefer a 2x or 3x margin on the step-up, so 300VA is a better size. It would run cooler and eliminate any concerns of it affecting the tone of the amp. Unless you've already noticed a ghosting problem with low notes, I wouldn't worry about the 50Hz vs. 60Hz issue.

If a step up isn't greatly inconvenient, then stick with it. I would change out the PT, but I'd be doing it myself so it's just the cost of the part and a weekend afternoon.

[Joost Assink]

That step-up transformer must not be very big. The Mercury has a 1A fuse. Your step-up is rated for roughly 0.9A, which while not optimum, shouldn't cause any problems. The Carr could probably get away with a smaller fuse, but 1A is very sensible. Is the step-up fused?

I'd prefer a 2x or 3x margin on the step-up, so 300VA is a better size. It would run cooler and eliminate any concerns of it affecting the tone of the amp. Unless you've already noticed a ghosting problem with low notes, I wouldn't worry about the 50Hz vs. 60Hz issue.

If a step up isn't greatly inconvenient, then stick with it. I would change out the PT, but I'd be doing it myself so it's just the cost of the part and a weekend afternoon.

Thanks, would you get change out the PT for convenience, or do you think it'll change the tone?

[jay42]

Thanks, would you get change out the PT for convenience, or do you think it'll change the tone?I would change it out only for convenience sake. I seriously doubt it would change the tone. Carr has a very good reputation, which makes it unlikely that they haven't put the proper effort into qualifying their export transformers.