|Equi=Tech is probably the most high-profile maker of balanced power delivery products for the consumer and pro audio markets. Its principal was involved in having balanced power written into the National Electrical Code where first references to this approach appeared in the 1996 edition. But, as popular Science Fiction movies would remind this trail-blazing firm, they're no longer alone. Furman Sound and BPT now too offer transformer-coupled "technical power". BPT's $1,495 BP-2+ is the 60 lbs heavy, 2000VA Plitron toroid-powered, 15-amperes subject we have under review today (inclusive, btw, of the firm's Clarity C-7 seven-gauge, silver-plated, shielded copper power cord with Schurter plugs).
What's balanced power anyway? Instead of delivering 120V-to-ground as is the norm for any standard AC wall receptacle in the United States (except, of course, for the 240-V 'electric dryer' versions you might find in your utility room), balanced power inserts an in-line transformer which splits the incoming AC into inversely-phased +/-60V components. Noise artifacts and line harmonics riding atop the AC sine wave subtract through the resultant phase cancellation -- also called common mode rejection -- when these signal halves are recombined and summed. Naturally, the efficiency whereby phase-differential components are cancelled is contingent on the precision of the isolation transformer's bifilar windings. The closer its halves match, the more rigorously they cancel even minuscule noise elements. Part & parcel of superior balanced power units is thus transformer quality. Transformer size and weight are directly proportionate to intended load requirements, the raw power rating often synonymous with increasing levels of hum unless all that iron is optimized for low-noise performance.
|For measurable results of superior implementations, a technical article on Equi=Tech's website claims lowered system noise floor and concomitant exploded dynamic range by up to 16-20dB. Removal of ultra-sonic line harmonics is said to reduce digital component jitter by up to 70%. Just as laundry detergent commercials begin not with faint stains but the most audaciously intense spots of blood, berries and other high-impact accidents the marketeers can dream up, so before/after improvements of powerline conditioners are magnified to greatest audibility when the incoming power's purity is most severely corrupted,
For review purposes, this is a vital consideration indeed. Our own Chip Stern's enthusiasm for his Equi=Tech units is due not only to their innate excellence of execution but also the sorry 'inverse polarity' state of power delivery in Manhattan's upper EastSide. Conversely, the non-industrial and rural environs of this publication's HQ caused me to return another balanced power example many moons ago. I couldn't hear one iota of difference. How many pages was I gonna waste to tell you that x-amount of dollars remained utterly inaudible? I felt compromised by my physical location. I reckoned that another writer bedeviled with dirtier power would be more appropriate to render judgment on such a component. After all, its entire raison d'être is removal of dirt. No dirt, no results.
Knowing of my remote mountain hideaway, BPT's Chris Hoff remained confident. His 10-outlet unit would offer audible benefits even if the local population density and non-existence of heavy industry conspired against a nicely polluted noise environment, for the kind of drastic before/after demonstrations such a manufacturer would fancy. Incidentally, due to electrical complexity and long runs of wiring, balanced power has made major inroads in especially professional applications.
In his introductory e-mail, Chris 'splained: "... The unit sent is our BP-2 Ultra Balanced Power Isolator in black ( brushed stainless steel case available at no extra charge). This is our 15 amp model representative of the current line-up, with 5 other models -- ranging from our 2.5 amp BP-Jr.II ($499) up to our flagship 20 -amp BP-3.5 model ($1699) -- available. There are a few other companies building balanced power conditioners. This begs the question what sets BPT apart. First and foremost, our units are designed for high dollar value. This means no bells or whistles on the outside, but the best quality parts available on the inside.
In the beginning, the goal was simply to make a great unit at a fair price and we have certainly achieved this goal. Alas, I am a passionate audio tweaker obsessed with getting the absolute best performance-per-dollar. This led to endless trial-and-error experiments to find ways to further improve the performance of our units while still maintaining their high value. The results are our list of performance upgrade options, each raising the sound quality of our units in a cost-effective manner. Current options include 10 gauge 99.99% pure silver internal wiring, Auricaps, Hubbell hospital grade isolated ground duplex outlets, additional High Current Filter, ERS Stealth cloth and Bybee Quantum Purifiers.
Each option brings us a little closer to the music and together produce a unit of exceptional performance/value. The unit you received has all these options onboard (BP-2 is $995, all options add to $1499). By offering these performance upgrades as separate options, we can provide a standard unit to the less well-heeled audio enthusiast and provide a maximum performance unit for the truly obsessed. An audiophile can literally order a unit to fit his or her budget and personal preferences. Not many companies offer this kind of design flexibility for a power conditioner. We assemble each unit to order and do custom work as well..."
The photo above clearly shows the optional High Current filter, a balanced design for both hot and neutral legs said to reduce AC line noise between 10kHz and 30MHz by up to 70dB. It's rated for 20 amperes at 250V AC and handles short-term peaks of up to 60 amperes. Completely enclosed in a grounded case to reduce RF/EMI interference and damped to minimize physical resonances, it precedes the custom Plitron LoNo toroidal transformer whose +/- 60V secondaries are wound separately and -- for an extra fee Chris pays to Plitron -- hand-tested and adjusted to insure perfect matching. This low-noise transformer uses copper foil lamination between its primary and secondary windings to reduce capacitive coupling and add filtering power. It also offers in-rush current reduction by 40-50% compared to standard transformers. As I can attest, this prevents tripping your main circuit breaker upon power-up, even when all components plugged in are already set to 'on' to generate a nastily massive instantaneous burst of load current. This is not the recommended procedure at all but a test I felt compelled to make. You're supposed to turn on the conditioner via its circuit breaker first, then connect the gear and switch it on one at a time. The sequence of placement follows the usual logic. Wire up the most current-hungry high-power amplifiers closest to the power inlet, follow with the preamp, source components and video last. Avoid having digital and analogue components share a duplex if possible. BPT's LoNo transformer is claimed to remain unaffected by over-voltage or DC offset and, despite its monstrous size, operated without discernable hum in my system, instantly whisking off my greatest concern to Tombstone for Western-style execution at the OK Corral.
On back, a grey duplex with integral ground fault circuit interruption protection sits adjacent to the thermal on/off back-lit Schurter switch. In case of a ground fault incident, it cuts power to the four paralleled duplexes. The central image shows the thick silver distribution rails that connect the individual outlets, each of which benefits from a single capacitor across its hot and return terminals. These HF filters reduce component interaction, by isolating each duplex from 'retrograde' noise as generated by the individual kit and leaked back into the power distribution circuit like toilet sewage into a leech field. Four stages of separate EMI/RFI filtering treat both incoming unbalanced and outgoing balanced AC while generous applications of Paul Wakeen's ERS Stealth cloth shield the entire enclosure case including the cover. Inspecting the BP-2+ up close and personal, I couldn't help but feel convinced to the core that Hoff's value statement wasn't empty propaganda. He means it literally. Build quality is top notch, the grounding post a nice while uncommon feature and 10 outlets total should outfit every but the most complex of systems. All that for a paltry $1,495? Many makers competing in this price range give you 6 outlets and considerably less internal hardware. Color me impressed. Unless my old parts/build-cost cap's too bleached for a realistic reading, someone at BPT is not making the usual profits here...