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"It might sound like some gimmick similar to a voodoo circuit from the spec wars of the 80s. I assure you it's not but you be the judge. What we hear after a speaker's electromechanical conversion of sound are simply pulses of pressurized air that propagate as zones of compression and rarefaction. They travel outward from the transducer one after another at a rate equal to the rate of the source vibration. When the output from individual woofers, midranges and tweeters combines to energize the surrounding air, there are a myriad of variables that distort the pulses' response.


"The human ear is very very sensitive to the leading edge - whether all frequency components line up accurately or not. But this you cannot measure because sine waves won't tell that story. Let's backtrack to illustrate it.
After the widely accoladed launch of Anthony Gallo's revolutionary Reference 3 speaker a few years ago, things had been relatively quiet at the house of the round sound. But the man's been busy behind the scenes. 2009 will see the first fruits of his latest labors. Those are OPT. That stands for optimized pulse technology. Anthony rang me from NYC to get technical:
CES 2009 prototype of new Ref 3.5


"Imagine Captain Kirk getting teleported back to Starship Enterprise only to collapse. After Bones examines him, they realize his heart hasn't reproduced properly. While 95% of Kirk did transition intact to look like him, the man is dead. That's how I personally felt about the best speakers regardless of price. It became the impetus for developing the OPT system. It's not any singular discovery however as a new crossover topology or the development of some exotic driver technology might be. No, OPT isn't sensational like that. We do feel it's infinitely more important though. I started by doing research on psychoacoustics. I purchased books and lectures to dig into the subject. Roughly three months later, I began finding possible answers to some of the questions that had plagued me since I built my first speaker at age 14.


"When we hear sound emanating through a wall sight unseen, how do we instinctively know whether it's real or a hifi? OPT was developed to blur that line. You see, the human brain is truly remarkable. Its ability to extrapolate and process a seemingly limitless amount of stimuli simultaneously is almost incomprehensible. To cut to the chase, our brains are more adept at processing chaotic non-symmetrical sounds. Those are mostly known as non-sinusoidal waves when they are in their electrical state. Once they get converted by the loudspeaker, they're considered pulses in the air as described earlier. Almost all naturally occurring sound is non-sinusoidal. Herein lies one of the problems. Loudspeaker testing software and measuring equipment are mostly designed to generate sinewave test signals which are very well controlled. Some tests are gated for impulse response and decay but most still generate sinewaves for test signals.


"I found that speakers optimized with such tests are at a substantial disadvantage immediately. And why would you optimize a device intended to faithfully reproduce music with sinewaves that don't occur in music in the first place? We need to investigate the transient edge of chaotic signals and rely on our human bio computer and ears for that. The attacks and dynamic contrasts in non-sinusoidal non-amplified live music get us so involved that they can completely alter our emotional state. It always happens to me when I attend the symphony or an unplugged jazz venue. There are other visual factors which contribute but I've experienced this phenomenon time and again even when my location precluded me from seeing the performers (seated behind a support column at Carnegie Hall for example). When a stereo system, specifically the loudspeakers, can't accurately recreate the rise time, amplitude contrast and decay time ratios from the start of the initial attack to its max amplitude rise and instead round off the waveform, we're listening to what is more representative of a sinewave function. And this alteration is not conducive to recreating the cerebral response or emotional factor originally experienced. In summary, rise time, group delay/decay, full-spectrum dynamic tracking, phase coherence and a strategic propagation pattern are all prerequisites to 'believe' the stereo illusion most fully.


"Quite by accident one day, I stumbled upon a way to dramatically enhance the transient response of our already fast CDT tweeter. CDT stands for Cylindrical Diaphragm Transducer (patent granted Oct. 27, 1998). This process became a nightmare when I look back on how much time and resources I had already spent on the original Ref 3 development and how often I felt that a loudspeaker was simply never developed for this level of performance. Back to the drawing board it was, being well aware that certain performance parameters of our Reference 3.1.seemed overwhelming. It led to the development of the Strada/Strada Center. It forced me to include other refinements which, on their own, might appear small. In conjunction however, they effect profound differences. What set all of this off were the raw material costs to build the Ref 3.1. They shot way up over the intervening years. I was faced with a quite serious retail price increase as a result. In actuality, Gallo had been absorbing these increases for a few years not for purely altruistic reasons of course. We simply could not raise the price on a product that was constantly back-ordered for dealers and customers alike. We hadn't predicted the enormous press reactions and their impact on production. Regardless of how we scaled up our capabilities, there would be the next Speaker Of The Year award and put us behind again. By the second year of the Ref 3, additional resources necessary to assure all quality control criteria were met despite a 270% increase in the number of critical items. This added complexity and forced us to acquire another QC technician. Costs almost doubled for inspections and associated resolutions alone. Since I was thus faced with a significant price increase for this speaker, I set out to improve on a design that had won numerous awards around the world; and improve it by a very significant margin. It wasn't as easy as some current Gallo owners might imagine. Let's cover the key points of the makeover.

"Certain fanatical users over the years had stripped off the protective grills from our CDT cylindrical diaphragm tweeters, assuming they'd sound better that way as most speakers do. Our CDT does not. But why? It turns out that the grill is a far more vital element to the proper functioning of this one-of-a kind tweeter than previously assumed. By going to a higher rebound foam behind the membrane to accelerate restorative times; to a completely form-stable stainless steel grill; and a 45% rather than 80% open perf pattern; the rise-time response of this transducer improved dramatically. It actually relies on the friction loading from the carefully arched and now accurately resistive grill to cancel out certain phase irregularities on the surface of its membrane. As a consequence, it turned out to be imperative that the grill not give or change form no matter how minimally during playback.


"Once this design element was in place, the Ref 3.1's deliberate but minor response dip between 2 and 3kHz at the mechanical crossover region became very audible. This is due to a mismatched dispersion pattern between the upper range of our hyperbolic carbon-fiber mids and the lower range of the tweeter. I thus revisited the geometry of the stainless steel spheres and added a bezel to tweak the dispersion pattern. (By the way, the bezel which is machined to achieve the perfect geometry also utilizes a proprietary decoupling material before contacting the sphere. This prevents vibrations from reentering the transducer. This is essential since we hard-mount the dynamic drivers on all our reference products utilizing a single point fastening system. It locks the transducer's motor structure as opposed to the conventional screws-through-the-basket-flange method which softens the attack too much for the implementation of our OPT technology. Only when the motor assembly is firmly locked and properly torqued can the OPT system perform as intended.)


"Presto, suddenly I had perfect linearity. As a result, transient fidelity in that critical range shot up. But now the old woofer proved too slow. Yes, it's all interrelated. I had to go to a ceramic-coated aluminum unit and change its series-filter inductor to an E-core and lower the winding gauge to 20AWG. Huge! Subjective bass speed went up but far more importantly, I was now able to 'line up' the transient behavior across the audible range. Hence the combination of these (mostly mechanical) addresses was dubbed optimized pulse technology. That's exactly what it does.
Experimental curved rods: "In production, there may be an extension on the Ref 3.5 frame so the outrigger rods integrate more gracefully. The rods will look like they are piercing through the speaker chassis instead of being bolted on as though an afterthought. Neither of the two bases shown will be used and the 10" ceramic/aluminum woofer will have a black-colored cone in final production."

"With this in place, one steps into a realm where even the smallest of mechanical adjustments become audible. Driver mount torque is super critical now. The only way to guarantee non-changing parameters is stainless steel. Aluminum and regular steel are too soft. Forget wood or MDF. They won't hold. I've also improved the speaker's lateral stability with stainless steel outriggers. Those created a significant bass improvement by annihilating the side-firing woofer's tendency to want to displace the speaker. But not only are the attachment points of those outriggers to the enclosure vital, I found that where the rear brace needed to be, it didn't couple to the floor sufficiently far back. Now I had to change the straight brace to a curved one. Simply moving the straight one farther back was inferior. And so forth.
"As you know, some people complained about somewhat low image height with the Ref 3 and 3.1. Would you believe that this got solved simply by implementing the above? I'm still investigating this whole OPT phenomenon in greater depths since the impact on the auditory experience is colossal. It creates that live impact and emotional involvement we're all striving for but which seem impossible to correlate to specific measurements. And by the way, at CES I had someone in our room who in the past had complained that he couldn't safely drive his 3.1s loud enough without 'arcing the tweeters'. I ran two Spectron Musician 4 monoblocks into protection at 1500 watts a side on a monstrous drum track while that gent was pinned to the wall with a huge grin this year. I think it's safe to say that dynamic compression will not be an issue with our forthcoming Reference 3.5, even for folks with insatiable SPL appetites."


Having honed his design and manufacturing chops to the necessary levels to pursue OPT refinements, Anthony of course couldn't reserve things for the Ref 3.1. It was time to revive the Due, the first small satellite model that had championed a CDT. With hacksaw and duct tape in hand (not), Anthony converted the Ref 3.5 stem into the new Reference Strada, a d'Appolito-type mini with integral wall/ceiling or table top mount available in upright mains and horizontal center-channel configurations.
"Because of the material price increases, the new Reference 3.5 will have to come in at about $5,995/pr. This vacates the previous price point of $3,000 which pained me to no end. Enter the Strada. At $1,000/ea., it's identical to the array of the 3.5. For bass, I developed the new TR-3 active subwoofer which, basically, takes one Ref 3.5 bass can and extends it in length. For just shy of $3,000, a customer can now assemble a 3-piece sub/sat system that will outperform my earlier Ref 3 and 3.1 models in certain areas while otherwise turning stereo into mono bass; and was designed to be either wall-mounted or, on a table top or credenza, sit within one meter from a wall behind the satellites. It's very decor-friendly and performs superbly." To illustrate some of the technical details covered, I asked for a few assembly photos. Anthony was kind enough to forward the following prototype images. They provide candid insights of what goes into a Strada - a heckuva lot more complex custom bits than your average miter-folded and glued MDF box would ever dream of.
Albert Porter's pictorial coverage of CES 2009 shows the Strada/TR-3 setup discussed, albeit with stereo subs and stands which may not go into production since Anthony foresees primarily on-wall/desk-top uses for the Strada.