"As would be expected, the fingerprints of the master are all over these devices. The King rose from superb to state-of-the-art sound under the influence of the VAC “Royal Power Supply”. That’s pretty much how it goes with VAC gear – whatever it is connected to sounds about as good as it’s going to get!" - Doug Schroeder, DaGoGo, March 2010

The VAC Royal Power Supply was initially developed for the KingSound electrostatic loudspeakers, and has found application with other brands that use external 'wall wart' style power supplies.

The power supply can have a major impact on the sound of electrostatic speakers. In our auditions, typical wall warts give a sound that is too distant, too lean, lacking in intimacy and dynamics.

In a sense, the polarizing supply for an electrostatic loudspeaker is somewhat akin to the magnet used in a dynamic driver. As you know, there is a profound difference in sound character between the various materials (AlNiCo, ferrite/ceramic, field coil, etc.). The magnet for a dynamic speaker and the polarizing supply for an electrostatic speaker are in essence like the foundation of a house, or, if you prefer a different but slightly less apt analogy, like the springboard for a diver. For best results they have to be right, and they have to do their job in a stable, unvarying manner under all conditions.

Since the real world is never quite perfect, any deviations from perfection must be simple rather than complex, as more complex errors result in higher order distortions which are unmusical and easily detected by the ear. In the case of electrostatic loudspeakers, there are actually two factors. One is the quality (i.e., stiffness and cleanness) of the polarizing voltage; the other is the amount of the polarizing voltage. Varying the voltage will change the subjective sound quality; it is perhaps loosely like varying the magnetic flux level in a dynamic driver.

The goal of the VAC Royal PSU is to provide a very clean, unvarying, and dynamically stable supply of the optimum voltage; to do this, we have designed a stabilized, wide bandwidth, high current linear supply.

Starting with the power transformer, we have selected one with extremely high magnetic headroom with respect to the actual current demanded. This unit also has minimal capacitive coupling with the power line, i.e., it has high line isolation so that current variations, such as may be imposed on the power line by a high power amplifier, will not perturb the quality of AC being used.

For conversion to DC a full wave bridge rectifier is used in conjunction with steps that provide a gentle, smooth transitions rather than raspy conduction transients; this provides the advantages of vacuum tube rectification without the usual vices. Initial filtration is provided by a sizable energy storage reservoir utilizing high current impulse capacitors. This is followed by low feedback Class A voltage stabilization. The final energy storage bank again employs high current impulse film capacitors, which have a naturally wide band/low impedance characteristic and fast response that compliments the stabilization system. Throughout the unit we employ the same interconnect wire used in our finest power amplifier and preamplifier designs.

The VAC power supply for the Kings can provide 3 amperes of fast, quiet, and stabilized DC power, and is located close to the speaker itself.

All of these steps (high magnetic headroom, large energy supply storage, Class A low feedback stabilization, high speed capacitors, high quality wire, etc.) result in a supply that provides the correct voltage and is rock solid and unperturbed by line variations or by the audio signal being impressed on the speaker. We find the difference to be quite striking when compared to the OEM supply that comes with the Kings, and helps them convert that promise of great sound into a vibrant and compelling reality.

Please check out Doug Schroeder's review at dagogo.com of the King loudspeaker for his impressions of our power supply (excerpted below).

"I’m not an engineer or designer, so I can’t whip up my own recipe for an upgraded power supply. However, I know someone who can! His name is…Kevin Hayes! He is certainly not without options and means; as an owner of the King, he has taken it upon himself to develop a specialty, “VAC-worthy”, power supply! I knew there were excellent reasons for seeking Kevin’s input into this review! His input has gone beyond words, for he built me a set of his custom power supplies. As prototypes, they’re not pretty but they are petite. Machined aluminum boxes about 6”x4”x2”, they each have the necessary 15 Amp IEC socket on one end and about a 1 foot long lead for the speaker’s receptacle on the other. No bells and whistles, just a “get it done” effort. I know that if Kevin determines to market this power supply it will be done up right aesthetically.

"I picked Kevin’s brain about the advantages of his power supply. For electrostatic speakers, the power supply needs to influence the quality and amount of polarizing voltage. Variances in the polarizing voltage affect the subjective sound quality. Therefore, the goal of the VAC power supply for the King is to provide clean, unwavering and dynamically stable supply of the optimum voltage. To that end it has been designed as a stabilized, wide bandwidth, high current linear device. It employs high magnetic headroom, large energy supply storage, Class A low feedback stabilization, high speed capacitors, and high quality wire, the same used inside VAC’s best products. Suffice to say it’s built well. And it sounds, well, what-else-would-you-expect. It’s stupendous, like the Renaissance Signature Preamp MkII I’m using!

"Kevin, in his understated manner, said, “We find the difference to be quite striking when compared to the OEM supply that comes with the kings…” I concur. He’s on target when he suggests the VAC power supplies helps the King convert the promise of great sound into a reality.

"How important are these VAC power supplies? Consider that I would not want to run these speakers without them; in fact, from the first moment they were employed, they have not been separated from the King. If the King speakers are in use, the VAC power supplies are in use. They are so elemental to the best performance of the King that – allow me to play potentate for a moment - I would command owners to purchase them if I could do so. If you are spending $8K for the speakers, cough up the extra and do it right. You will not regret the investment in proper power supplies, especially ones as superbly executed as Kevin’s. I told him to get the product up and running, because when people buy the King they’re going to want to hear what else it can do. People buy stands for speakers. This is a much better and holistic improvement to the already prestigious performance of the King.

"My favorite quality that the VAC power supplies add is an elemental, deeper sense to the bass. With ESL’s being challenged in terms of bottom-end, this is a very welcome improvement! I have no clue at this time what the pricing on the power supplies would be; Kevin was unsure initially if he should produce them. I certainly feel he should, as they provide a most agreeable solution to the insipid wall warts. When the owners of the King hear what the power supply does, they will appreciate their speakers all the more; this is a win-win for audiophiles, and for both companies! Oh… remember the shorter wall wart that limited movement of the speakers? With the VAC power supply one can opt for a 2m or 3m 15A power cord to get the proper distance."

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