What power conditioners can convert 230v to 120v?

Jea48, not so in my experience
05-15-09: Detlof

Quote from Link:
7. Noise
Transformers make noise. This is not only the electrical noise that is created by the nasty current waveform through the windings, diodes and into the filter capacitors, but actual audible noise. One source is winding vibration, due to the wire moving because of the magnetic field and the current flowing through the conductors. This is to be avoided at all costs, since constant vibration will eventually wear away the insulation, the windings will short circuit, and the transformer is ruined. Fortunately, this is rather unusual, but it can (and does) happen on occasion.

Most of the noise is from the laminations or other core material, which contract when subjected to an intense magnetic field. This is called magnetostriction, and happens to a greater or lesser degree with all magnetic materials. A stethoscope will verify the source of the noise, and there is little or nothing that will stop it. A resilient mounting will stop most of the noise from being acoustically amplified by the chassis, and generally the noise will be worse at no load. In some cases, a transformer may have been designed for 60Hz, but is used at 50Hz. In this case, the flux density will probably exceed the maximum allowable for the core, and the transformer will get much hotter than it should, and will almost certainly be a lot noisier as well. Toroidal transformers will generally be much quieter than EI laminated (i.e. conventional) types.

Most(all?) transformers designed specifically for 60Hz will eventually fail with 50Hz mains, due to overheating. The reverse is not true, and 50Hz transformers can be operated quite safely on 60Hz.
http://sound.westhost.com/xfmr.htm#7-noise

I've read two similar but different things about using 60Hz transformers on 50Hz. One wrote that the transformer should be derated by 17% to 20% (50/60). The other wrote the input voltage must be 17% lower than the maximum rating.

The latter being from: http://www.solaheviduty.com/support/faq.html

The Sola portable (120V) I do have is quite noisey, but probably not indicative of the type or brand. With hard wired ones, there have been effective installation options.

Sola is one of the few I've seen offering 50Hz models (group IV) in both general purpose and regulated.

Jea48,
Just as well you persisted. I must apologize. I was quite wrong, because I mainly used transformers the other, safer way around, namely using 50Hz transformers on 60hz. Only in one instance I used a transformer the other way around for about a year or so and did not run into any trouble though. Not that this would prove your warning wrong. But as Ngjockey and you point out, the situation is more comple than I naively thought.

Hi all,

I'm in the same situation: I need some sort of power conditioner/surge protection that will also step down 240 to 120. The Richard Gray stuff looks nice, but is far more expensive than what I want to pay. Anyone know of cheaper (and simple) alternatives?

I was in the same boat as you guys, living with 230v power and Krell separates at 120v. Yes, the Krell separates have switches for 230v, BUT they also contain the 60Hz lock, meaning they will only work on 60Hz. Krell presumably does this to minimize gray market sales of their equipment overseas.

Anyway, my solution was to buy a used PS Audio P-500 power regenerator. With help from PS Audio I was able to convert the unit to accept 230V and output 120V regenerated balanced power. Basically, the conversion consisted of rewiring the input power transformer and replacing the passive filter components to 230V ones.

Gherrera