I’ve known about the theory and benefits of using balanced AC power sources for many years; it’s actually an old idea. At the beginning of the twentieth century Thomas Edison and Nikola Tesla invented two incompatible and competing power transmission systems, one direct current (DC) the other Alternating Current (AC). As we all know eventually Tesla and his AC distribution system prevailed. But even back then the advantages of a balanced source of AC power were known but dropped in favor of simplicity and economy. Based on earlier work engineers at Bell Labs in the early sixties devised a transformer with a single point grounding system. That is the basis for the BP-30 an “Isolated Symmetrical Power Supply” made by Alpha Core. But technically it does not generate power on it’s own so to call it a supply is, in my opinion, a bit of a misnomer. It might be more accurate to refer to it as an Isolated Symmetrical Power Transformer. While almost every audio component has a power supply, they actually convert power from the wall outlet into some internally usable form. The power is of course sourced from the generators of the electric utility. Why split hairs, the better to understand what this device actually does and its inherent limitations.

Raison D`etre

The BP-30 is a low-profile rectangle of heavy black anodized aluminum with a lighted rocker switch and 8 three pronged outlets on the top surface. The serial number of the review sample is #100. Inside the BP-30 is a large doughnut shaped toroidal transformer consisting of one primary winding and two secondary windings wired in series. The electrical power sourced from the wall outlet passes through the primary winding generating a magnetic field that causes electricity to flow through the two secondary windings. In an ordinary Isolation transformer the number of turns of wire on the primary is the same as the number of turns of wire on the secondary. This one to one ratio means that if you pass a 120 volts AC through the primary winding you will “Induce” nearly all of that voltage into the secondary winding. Why bother to do all that stuff if you in fact lose some power in the process? The key operating theory is “Isolation”; Noise (RFI) will not affect devices connected to the output side of the transformer from the power source. That includes much of the extraneous interference picked up by the lines running between you and the power company. The Alpha Core device takes all of this one step further. It is an Isolation transformer with symmetrical/balanced dual output secondary windings. Ordinarily voltage sourced at the wall outlet alternates between positive and negative potential and at some point in time the voltage is at zero as it changes direction. The 3-wire standard we all use in our homes is Hot, Neutral, and Ground. The Alpha Core transformer does not use a neutral wire. As voltage swings lower on the hot wire it is increasing on what was formally the neutral wire. That is the purpose of two equal but opposite secondary windings. In this isolation transformer the two balance each other and the effective voltage is a constant 120volts. Additionally the middle or starting point between the two secondary windings is connected together to form a common ground point/tap. This common point is the ground (green wire) connected to the 8 outlets and the green grounding post on the metal case. This center tap yields the additional benefit of “Common Mode” noise rejection (CMR). In a nutshell, electrical interference that enters from the power source is split into equal but opposite positive and negative voltages. These extraneous voltage signals cancel each other at the equipment side of the transformer. Alpha Core specifies at least 60db CMR for the BP-30

Cut to the chase

What will this gizmo do for you, or more to the point what will you hear? Well that depends on a couple of things, the two biggest factors are how dirty is your power source, and how well designed is the power supply inside the component you plug into the BP-30. This is where isolation and that CMR thing should produce good things for your ears to hear. At this point common sense will tell you it is very hard to predict ahead of time what benefits $895.00 will buy. Inexpensive or poorly designed components will probably benefit the most but that is only a generalization.

During this evaluation I used three power amplifiers: the Audio research Classic 60, Hafler 500, and the new Music Hall Mambo integrated amp. Unequivocally all of these components benefited to some extent by using the BP-30. In my bi-amped reference system I started with the main Quad ESL 63 speakers plugged into the BP-30 and I got a slight improvement in high-frequency detail. Then one by one I added my AR CL60 main amp powering the Quads and Roy Halls Mambo amp driving the Gradient woofers, that’s a total of four components. What a wonderful transformation! (That was a pun) At each step in this process the bass sounded deeper with better control, and treble frequencies had more refined detail, now freed from grainy hard edges. But as with all things there is a down side. After initial favorable results I tried to power all of my bi-amped main system from the BP-30. The result was a dull more recessed and veiled sound. I believe this was a result of placing too much of a load on the transformer. Mind you I did not blow the 15-amp line fuse or trip the thermal cut off, it seems that the sound degrades before you reach its max ratings. The other possible explanation is something in my interlinked system actually sounded worse. If I were going to power all of my system with this device I believe I would need to use two BP-30 transformers.

Summary

What is the thing that you hear? It is silence; it is a darker background that allows detail and delicacy to paint its sonic presence. All of this is a result of lowering the noise floor. You could not, would not expect such an increase in resolution until you hear it for yourself. As I listened I felt a sense of calm and relaxation ease my tensions, feelings that I did not know I had. Only then would you know what sonic stresses you had unwittingly been living with. All of this is coming to you from a guy living on the sixth floor of a large apartment building in New York City. Aside from a possibility that you might overload this device I can’t imagine any thing out there that would not benefit to some extent by cleaner power, the BP-30 doesn’t seem to have a down side. A couple of years ago I reviewed the second version of the Exact Power line conditioner and a year later the PS Audio P300. Without getting into details the Alpha Core beats the Exact by a small margin and equals the PS Audio performance in my system. Both of these sell for three or four hundred dollars more than the BP-30.You have thirty days to try it in all parts of your system and then decide before Alpha Core comes to get their money. Get out the Windex or throw open all your windows and breathe in the clean sound. I think you’re in for a treat.