Recently we received this inquiry from a customer in the UK. He was trying to solve a serious problem powering his tube preamplifier, and wondered if we could help. Read on!

Hello, I live in the the UK and have recently purchased a pre-owned high end tube based pre-amplifier from the USA. I have tried a step down transformer to convert 240V AC to 120V AC but the pre-amp still does not function properly. This leads me to believe I also need a converter to change 50Hz to 60Hz.

The pre-amp is rated at 60w so I am looking at your Thor product. However, the pre-amp quotes 120V – 60W – 60Hz at the back, Thor outputs 115V AC. In your opinion would this be OK?

Also, do you think I have potentially damaged the Pre-amp by using 50Hz supply?

I am also curious about your product’s ability to clean up the mains supply. If that is the case I wonder if I should buy Hercules so I can connect my other hi-fi units such as the audio streamer and DAC. Would there be a benefit in audio quality?

Finally, may I ask where your products are manufactured in please? Thank you in advance for your assistance.

Here is our reply:

“Hello and thank you for your inquiry! Your analysis and observations are quite thorough and spot on.  You have come upon multiple reasons that explain exactly why our products are important!

First, while some (audio) devices are designed to tolerate 50Hz and 60Hz, many are not.  Your tube amplifier no doubt has an input power transformer that is not tolerating 50Hz, and is beginning to malfunction.  As frequency is lowered below the rating, the core of the transformer may be on the verge of saturation, and this could cause problems.

Usually when a transformer is on the verge of saturation, the first symptom is that it does not function exactly as it should, and becomes noisy.  Consequently, the output voltage supplying the amplifier circuitry might begin to droop, causing issues with performance.  If the transformer is subsequently pushed into heavily saturation (by further lowering the frequency), it will eventually overheat and fuses within the device may fail.  Your rectifier circuitry (after the transformer) may not be sized for 50Hz either, causing excessive AC ripple on the rails. (This could also translate to 50Hz hum making its way to the speakers.)

It is difficult to say from here if you have damaged your preamp, but my guess is, not likely.  If you now provide the proper voltage and frequency, it should return to proper operation.

Using a transformer (only) to power your system (which does NOT convert frequency) raises some interesting concerns.  Most of the commonly-available transformers for this purpose are low-quality Chinese-made E-I core designs, under-rated for the application, and rarely if ever have any certifications of safety.  This is because weight is a concern.  To make the units lighter and lower cost, they compromise iron and copper in the design.  Eventually they overheat and then become noisy, depending on the load.  Properly rated E-I core transformers with safety certifications are much larger and heavier, and are usually potted.  We never recommend the non-safety rated Chinese transformers for any applications.

Both Thor and Hercules are designed to provide the proper voltage and frequency in applications exactly like yours.  We regulate our output voltage to 115V AC because it is the mid-point of the specification for the voltage range in countries with this standard.  Keep in mind that the standard is 105V-125V AC, and mains power can be anywhere in that range and still be considered within specification.  If your device is rated at 120V AC, this is simply a convenient way to indicate that it requires a voltage within the range of 105-125V AC.  It will operate exactly as it should if supplied with 115V AC.  In fact, it should operate fine if operated at 105V AC or 125V AC, as well.

Thor and Hercules clean up the power, indeed!  The local mains voltage is first converted to regulated DC, and then reconstructed into pure sine wave AC at the correct frequency.  Subsequently, it is isolated with a very high quality toroidal transformer so there is no remnant of the original mains!  So yes, absolutely, there is no better way to clean up the mains.

Our products were designed and are manufactured right here in Broomfield, Colorado.  We have manufacturing partners here who do all of the electronics assembly.  Here at our center, products are integrated and tested, packaged and shipped.  It is all done right here, locally.  Quality is very closely controlled.  You will receive a detailed certification of inspection and test with every unit.  They are quite well done!”

Bottom line, Hercules or Thor are great solutions if you wish to power part or all of your audio system.  And, given the above-mentioned factors, there is no doubt that Hercules or Thor will greatly improve the audio quality!