POSITIVE FEEDBACK ONLINE - ISSUE 32
as reviewed by Danny Kaey
It must have been around the mid to late eighties when I first heard of the concept of "room correction". Back in the day, Yamaha was flexing their engineering muscle in an effort to capitalize on the emerging boom in digital technology, i.e. the Compact Disc. I suppose digital was indeed the buzzword back then, what with "Perfect Sound Forever" marketing campaigns, etc. Of course, at the time, I was also nothing more then a rambling teenager struck in awe at the sight of a Yamaha preamp that featured fancy digital displays and thousand-and-one button remote controls. I remember walking into this high-end audio shop in Vienna that had the entire line-up of Yamaha's cost no object components playing in a system and just drooling over the "sound". Today, just the mere thought of all this early digital processing sends shivers down my spine; having embraced tube based gear, tape and vinyl in the last ten or so years.
Nevertheless, digital has marched on to sound quite well actually. Many modern day processors are capable of performing a gazillion calculations per nano second and it therefore stands to reason that clever men with even more clever ideas can achieve quite amazing things. TacT Audio is just such a "thing", or more precisely a company that prides itself in "all things digital", and can truly be considered a pioneer in this field. The man behind the company is Radomir Bozovic, a digital guru with a PhD. From room correction preamplifiers to true digital power amplifiers, TacT Audio can definitely be considered amongst the forerunners of such development.
I suppose if ever I wanted to demonstrate the effects of room correction, a trade show would prove as good a starting point as there is. Reading show reports, one realizes that hotel rooms are notoriously difficult to setup—fancy then that I would always run into TacT Audio at such shows. The results are always rather spectacular: with processing, sound is always far cleaner, tighter, and laser focused—unlike the same system with the bypass function enabled. Subwoofers in particular, always sounded rather good in such setups, with tight, dynamic bass pressurizing the room even if sometimes the placement of the loudspeaker/sub combo wasn't intuitively the best. However, I usually noted a rather "processed" quality to the sound, which while making everything sparkle in crispness, somehow made it also sound rather too clean and precise—almost sterile in perception. Thus, while room correction is supposed to be the Holy Grail in sound reproduction, its correct implementation appears to be the Achilles heel of this age-old concept.
The story unfolds… Part I
Fast forward to a few months back, when TacT Audio's Radomir Bozovic dropped by my house to setup the newly available 2.2 mini room processing preamplifier. Borrowing much of the technology found in the larger brother, the RCS XP 2.2, the 2.2 mini omits such features as analog inputs and less overall "processing" power. Then again, it also costs much less, retailing for around $3k. According to "Boz", the 2.2 mini was designed for those who wish to get a taste of powerful room correction in an all digital system, i.e. Transporter, Squeezebox, Sonos, etc. Like its siblings, the 2.2 mini features a computer-less interface: meaning the user does not necessarily have to have a computer to setup and correct the individual room. The supplied microphone plugs directly into the mini's back, and along with the supplied remote, one can then setup the system—in theory anyway. While this is certainly the case at perhaps a rudimentary level, I found that accessing the most powerful processing features of the 2.2 mini is of course best done through your computer's visual display and the proprietary TacT Audio software. Regarding that software, it is very powerful indeed, allowing you to completely alter the characteristic's of your audio system to your heart's content—for better or worse, naturally. Since all inputs to the 2.2 mini are in digital form, all manipulation is done in the digital domain, and with 24/192 accuracy. My heartfelt advice to the new owner would be to spend a good afternoon or two becoming familiarized with the online manuals and all aspects of the mini's tremendous functionality. Otherwise, you will be hopelessly overloaded. A word of caution: if by this day and age you are not able to download say photos from your digital camera to your favorite photo album, it's probably best to get the advice and setup help from an expert, even if the mini is designed to work without a computer per se.
During the review period my audio system was fundamentally hankered around the sly Zu Definition Pro Lautsprecher. In contrast to the "consumer" version of the Defs, the Pro version offers far greater flexibility in set-up. Whereas the consumer version includes a sufficiently powerful built in amplifier to drive the massively powerful quad 10-inchers in each backside cabinet, the Pro version allows you to use an outboard EQ/crossover with separate amplifiers to fine tune the Defs to their environment (more on the Defs and their new brethren the Def 2s in a few months). Since the mini is capable of controlling, equalizing, and time aligning a 2.2 setup—that is, a pair of front speakers and a pair of subwoofers—the Defs proved to be the perfect test subject for this review. A mix of amplifiers ranging from the svelte Yamamoto A-08S, a Brinkmann Vollverstaerker, a pair of Melody 50-watt monos, a fantastic Hypex powered Nomad Niagara, and last but not least, a most fabulous pair of original Quad IIs were used in this evaluation.
Onward and upward… Part II
The 2.2 mini is quite likely the most clever all encompassing preamp I have ever used in my system thus far—save for the fact that it has no provisions for any kind of analog inputs. Your favorite FM/AM tuner, tape decks, and of course vinyl rig are all pretty much left out in the cold. However, connect a Squeezebox or similar device and you will soon realize the benefits of an all-digital control center, particularly as the built in D/A converters and output stage in the 2.2 mini are of superior quality to the inexpensive mass market solutions found in most sources. A digital set of outputs provides further upgrade solutions.
There is no question about it: the 2.2 mini is a processing powerhouse. Besides the most obvious element, room correction, it also features what TacT has dubbed "DRC" or dynamic room correction. DRC takes room correction one-step further by providing on the fly, a Fletcher-Munson based correction for each 0.1dB of volume increments. Mr. Fletcher and Mr. Munson discovered some time ago (1933!) that our hearing is both frequency and level dependant. Think "loudness" button your favorite 60s and 70s receiver. What Fletcher and Munson discovered was that our ear's sensitivity is not constant, i.e. turn the volume down and bass/treble perception falls off dramatically. To compensate for this, the 2.2 mini can be configured around nine presets—for each 0.1dB increase in volume the 2.2 mini will automatically recalculate the frequency spectrum. Further, one can add their own personal characteristics to each of the presets, thus truly providing full control of the output signal in the digital domain. Simply put, according to TacT Audio, "the future of audio is here".
Part III… the meat and potatoes...
We all know that perhaps the single biggest influence in realizing the ultimate sound is the interaction of your loudspeakers with your room. A brochure showing a "flat" loudspeaker in an anechoic chamber means absolutely squat in the real world. After all, you don't live in an anechoic chamber—nope, we like it cozy: a sofa here, a bookcase there; often times the audio system is in fact part of the room's décor. Each of these elements to varying degrees can and do affect sound quality. Traditionally, most of us would use some form of absorption products from companies such as RealTraps to counter these effects. After some tweaking with an assortment of these products, my room sounds noticeably better then it did prior: far superior bass response, imaging, and high frequency extension compared to the same room without. Clearly, passive room correction has its benefits, although no amount of tweaking and setup can overcome the laws of physics that every room is subject to based on its dimensions and shape. Those physical boundaries are most notably associated with the term Room Node. Sound travels in waves; when waves get bounced off walls and cross each other we have what is called a node—a point of zero pressure, or in laymen's terms, the wave (frequency = sound) just got canceled out. Weird eh? For more detailed information and the physics involved, take a look at these fine pages from Dr. Dan Russell at the Kettering Universities applied physics department pages: http://www.kettering.edu/~drussell/Demos/RoomModes/driving.html
A standing wave—zero pressure—is essentially just that: dead. No amount of boosting EQ or amplification to overcome the suck out can ever correct for it. Quite to the contrary, you are running in serious danger of overloading your amp by trying to overcome this physical boundary through brute force. Let's look at the following example to illustrate the point. Say you are running a decent 70-watt amp; let's further assume that you have a 10dB suck out at 50 Hz (standard fair); lastly, let us assume you are running dynamic program material, which hits close to the 70-watt power limit of your amp. Thus, a 10dB increase on your EQ at say 50 Hz requires a tenfold increase in power output. So your little 70-watt amp needs to be able to produce a whopping 700-wats of output power—all other things being equal. Hardly something your amp will be capable of for any length of time before it goes poof.
The problem I am hinting at of course is the fact that, as demonstrated, a room node simply cannot be equalized out, no matter how much processing power or EQ you apply. Yet, TacT's 2.2 mini is supposed to achieve all that and then some—all in the confines of the digital domain and the added bonus of the dreaded WAF (Wife Acceptance Factor). So let's take a look at what one can realize with the mini all setup and ready to go by some critical listening. According to the TacT software, my Zu speakers were now fully equalized and time aligned throughout the frequency spectrum. Flat line so to speak. The burning $1,000,000 question I was dying to get the answer to was, "How does this flat lined system sound?"
Part IV… the $1,000,000 question…
In short, the system sounded pretty much the way I had heard it so many times before: ultra-clean, razor sharp, focused, and extended. It is as though you somehow managed to take a chisel and apply your handiwork on a new slab of marble with digital accuracy down to the last bit. Every note, instrument, and performer appeared bolted in front of you—each key on Martha Argerich's piano in her rendition of Ravel's concerto in G [DG ASIN B000001GQQ] appeared before you as an expertly chiseled statute. The attack, sustain, and decay of every note was rendered with ultimate precision. Think nanometer instead of millimeter. Equally as impressive was Boozoo Bajou's debut album, Satta! [Stereo Deluxe ASIN B00005KA1S]. The third track on the album, "Night of Manuas", features a pulsating electronic rhythm, which pretty much carries the entire tune. Through the 2.2 mini, this pulsating bass line has a weight and punch that I would describe as very coherent, almost pillar like. What I mean is that all the other tracks and electronic instruments follow that bass line with 100% accuracy, something that is a clear sign of proper time alignment throughout your system. Relief like exposure was also evident in the imaging department where on Duke Ellington's Ellington at Newport 1956 [Sony ASIN B00000IMYA] the venue was portrayed with hyper clarity. I could literally see all the musicians on stage before me; depth, width, and height of the performance were most evident, as was occasional clapping of hands, clinging of glass and cutlery, etc. Often times I felt like yelling to the guy two tables up to shush.
Another great example of the processing prowess of the mini'd setup was the DRC method of the 2.2 to continuously, variably, and on the fly, adjust the sound level based on the Fletcher-Munson curve—or any other user set parameters. Now that is something trez chique! Typically, at lower volumes, you lose all definition and sense of volume. Not so with DRC enabled. Here, the system continuously sounds the part, alas at far lower levels then is typical for my critical listening. Pretty neat stuff. Way ahead of any "loudness" button your 70s receiver may sport.
Part V... Food for thought…
All this supercut performance is of course compared to my regular reference setup, which consists of the aforementioned amplifiers and a high quality tube preamp. Not that my un-equalized, non-time aligned (as per the 2.2's definition anyway) system sounds otherwise less then stellar—if I dare say so myself. Still, no matter how spectacular the 2.2 mini'd setup sounded, I somehow never felt as though I was at home. Home is where I listen to music, not a perfectly extruded, machined from solid billet aluminum facsimile. As much as the 2.2 mini adds this certain Gestalt to the musical spectrum, I can't help but feel it sounds perhaps a bit too artificial, too analytical, too equalized …too perfect? This impression becomes immediately apparent when I make the switch back to my tube preamp. Almost to the snap of your fingers, music returns, albeit with all its imperfections and other anomalies. After all, music is alive—not some lab tested anechoic chamber formula. Therein lays the conundrum: fact is that you need some form of room correction. My RealTraps panels do the job admirably well and without the dreaded "suck" factor—as in sucking life out of music.
The fact that you are limited to only digital sources, the 2.2 mini doesn't really fit into my system, which consists of two turntables, two reel-to-reel machines, one cassette deck, and an FM tuner. On the other hand, techies—those who prefer razor sharp musical accuracy over musicality and only have digital sources—will no doubt find the TacT Audio 2.2 mini a pleasant surprise. It is full of whizz-bang technology that only years ago would have cost considerably more then the $3000 asking price. You will certainly appreciate the versatility and friendly relatively easy to use proprietary TacT Audio software. Stay tuned for more action from TacT Audio's true digital amplifiers. Danny Kaey