Sugg. Retail: $39.95 (US)
Manufacturer: Sonic Impact Technologies
An AIG Online Exclusive
If you’re the kind of audiophile who keeps on top of all things related to reproduced music via the internet, then there’s a pretty good chance you’ve already heard about the Sonic Impact Class T Amp, which has recently become a hot topic of various forums, zines, newsgroups and other online text repositories dealing with audio gear.
The T Amp is a rare case of a product outside the established audiophile universe being “discovered” and enthusiastically outed as a sleeper sonic sensation. Remember the Radio Shack portable CD player that became a minor sensation about ten years ago? It was called the Optimus CD-3400, cost US $179.99, and, according to some, blew the doors off many a high-end, audiophile approved CD player of the era. In turn, tweakers, both professional and otherwise, emerged to proffer upon the newly converted all manner of special cables, battery power supplies and other baubles with which they could elevate the cost of the purchase into “audiophile” territory, and, presumably, make the thing sound even better.
The T Amp could very well become the CD-3400 of 2005. Like the little Optimus CD player, Sonic Impact’s little box is aimed squarely at the mainstream electronics buyer. It’s a tiny, flimsy portable amplifier hardly bigger than a couple of Ipods that’s meant to drive multimedia speakers just about anywhere you might want to. Due in part to the underground response it’s been back ordered just about everywhere, but you can pick it up at places like Target, Parts Express, and Ecost from prices ranging from between twenty and forty US dollars, or roughly the cost of a parking ticket. And yes, the tweakers have started to emerge, and various mods will dress up a little T Amp in full audiophile approved finery (ie. CNC machined aluminum chassis, proper binding posts, RCA connectors, and, of course, battery power supplies to name but a few). More on mods below.
It’s all in the Chip
The main reason the T Amp is so cheap is that it’s based on the latest generation of chip-based switching amplifiers from a manufacturer called Tripath. It uses a chip called the TA2024, which Tripath describes as a “15W/ch continuous average two-channel Class-T Digital Audio Power Amplifier IC.” Class-T amplifiers, they claim, “offer both the audio fidelity of Class-AB and the power efficiency of Class-D amplifiers.” Efficiency is key, since the T Amp is meant to run off 8 AA batteries and is said to do so for something like 8-10 hours. While it features a connection for a 12V DC power supply, it does not ship with one (another way to keep the cost down). Other Tripath chips, albeit ones often capable of much greater power output, can also be found in more “serious” audio products like Bel Canto’s Evo amplifiers, the Teac A-L700P (a three channel HT amp which has been causing a fair share of its own buzz of late), some Carver professional amps and a variety of car audio gear including some Blaupunkt models.
While it’s basically an integrated amp, since it only has one input the T Amp is a very spartan and simple product. On the box’s rear are small, spring clip type speaker connectors, a 1/8″ mini input, and the aforementioned power supply input. On the front you’ll find one red LED indicating power status and a rotary power/volume control. As far as controls and connections go, that’s it.
Output is rated at 15W into 4 ohms and 10W into 8, but these numbers, if you look at Tripath’s specs a little more carefully, are more than a little optimistic since total harmonic distortion (THD) at these power levels is rated at a whopping 10%! A little more distortion than you were looking for sir? I suspected as much. You’ll just have to restrain yourself and keep it under 6W, at which point, into 8 ohms, you’ll get a more usable THD figure of 0.1% (11W into 4 ohms). Tripath claims a dynamic rage of 98 dB for their chip.
With a whopping six watts on tap into 8 ohms it should come as no surprise that speaker matching plays a very important role with this little amplifier. I made arrangements to borrow the amp for a brief spell from a friend well before he received his from a back-ordered vendor. It was simply the fastest way to get my hands on one since no one had them in stock at the time and ordering one myself would just put me in the queue behind him anyway. During the wait I made arrangements for a suitable pair of speakers to drive with the Sonic Impact.
Klipsch was a natural choice since the company has long been known for their super sensitive horn speakers. A scan of the specs for the RB series showed a whopping 97 dB sensitivity for the Reference RB-75; an ideal candidate. A large bookshelf model the RB-75 features a 1.75″ titanium dome compression tweeter mounted behind an 8″ square Tractrix(tm) horn and an 8″ Cerametallic(tm) woofer/midrange driver in a bass reflex cabinet ported at the front. Wondering what the heck Cerametallic is? Seems to be a fancy term for aluminum. Klipsch describes the drivers thusly: “Their anodized-aluminum cones exhibit a very high stiffness-to-mass ratio and superb damping characteristics that translate to outstanding responsiveness and near-total absence of resonance and breakup. The result is quick, clean, articulate low-frequency reproduction”.
Considerably lager than it looks in photos, an RB-75 stands 20″ high and weighs 32 lbs. This helps it achieve bass response down to about 42 Hz, considerably more than most bookshelf speakers can muster. Not surprisingly for such a sensitive speaker, the Klispch presents an amplifier with a very benign 8 ohm load. They don’t come too much easier to drive than this baby, and so I stood ready to wring as much as possible from those 6 little watts; assuming the amp ever arrived.
Here at Last
After a good six weeks or so in back order purgatory the little box finally did arrive and I was good and ready to find out what all the fuss was about. I started out using the T Amp at work, driving it with my laptop via the Echo Audio Indigo soundcard I reviewed recently. I used a little 1/8″ mini to mini cable to get from the Echo to the Sonic Impact and some un-terminated copper speaker cable from a small company in the UK called Microphonic Audio to feed the speakers. With those tiny little spring loaded clips you can forget about your fancy banana plugs or spades with this amp. Big, stiff audiophile cables are more than enough to lift this little flyweight amp off the table!
After connecting everything I turned it on, twisting the volume just enough to power the thing up. I was greeted by loud and nasty white noise from the right channel. Not a great start, I thought, and I began to wonder if the little T Amp was DOA. I hastily shut it down and re-checked all my connections. All the wiring appeared in order so I turned it on again and was greeted by the same result in the right channel. In the left channel, however, I could hear music. An improvement, but the signal was fleeting, cutting out every few seconds.
I tinkered around some more, encouraged that some signal had come through the thing at all, and finally mustered the patience to sit through about forty five seconds of the white noise barrage from the right channel. When I was about ready to give up on the thing the noise finally stopped, and music appeared in it its place. Based on the fact that it did this every time I turned it on, it seems that the little T Amp needs a minute or so to warm up.
I began by listening to the new Beck CD, Guero, which I spun as a CD from the laptop’s drive rather than as ripped MP3s or AIFFs. Right off the bat the sound certainly didn’t bear much resemblance to what I might have expected from a twenty dollar plastic multimedia amplifier which, moments earlier, had assaulted me repeatedly with white noise. Surprisingly open, fast, with great microdynamics and abundant detail was my first impression. The harshness, brittleness and generally grungy nastiness I might have expected from such a product were nowhere to be found.
Further listening revealed this setup to be a very good sounding desktop system. It didn’t take long to realize that the Sonic Impact and the RB-75s were more lively, transparent and exciting than the powered Swans T-200A multimedia speakers I reviewed last issue and have been using on my desktop ever since. The system imaged well, soundstaged very wide, coughed up gobs of detail, and constantly drew my attention away from work with its speed and microdynamics. I was missing the silky smoothness and bottom end solidity and impact of the pricey Genelec HT 208s, but this combination was doing a lot of things right. This was all under battery power, by the way, since I had yet to acquire a 12V power supply. For an amp that cost slightly more than my lunch, impressive is putting it mildly.
A Harder Test
At the end of the day I popped the little Sonic Impact amp into my computer bag, took it home, and, just for kicks, hooked it up to my Energy Veritas 1.8s. With an anechoic sensitivity of 87 dB, the Veritas are not particularly well suited to flea powered amplifiers, so I wasn’t expecting much. I was surprised to find that the T Amp would drive the speakers to quite usable volume levels with reasonable bass, but the liveliness and microdynamics I heard with the Klipsches, both hallmarks of high sensitivity horn speakers, were largely gone. The big soundstage and solid imaging I had heard on the desktop remained but the sound was not nearly as smooth, transients and sibilants in particular taking on an unwanted edge perhaps best described as “crispy”. Listening to Leslie Feist’s latest record (the excellent Let it Die) the sound was lively with bass that seemed well controlled, if substantially attenuated in level and depth. Feist’s voice also took on something of a nasal character, sounding thin and threadbare compared to my Musical Fidelity A3CR amplifier. Switching back to the MF amp confirmed this, providing more tonally accurate, fuller, smoother sound with proper bottom end power and extension.
A week or so later I had both acquired a 12V, 1000 milliamp power supply for thirty bucks at Radio Shack and dragged the RB-75s home to make some comparisons with my reference system. With the Sonic Impact driving the RB-75s in my living room the quick and lively sound I heard on my desktop was still in evidence, but the T Amp sounded quite bright and zippy in the top end until it had warmed up for 15 minutes or so. What was more annoying, however, was that the noise in the right channel had become far more persistent and frustrating, only truly disappearing for a few minutes at a time.
When I was finally able to properly listen to the thing without white noise in the right channel it was clear the T Amp was much more successful driving the Klipsches than the Veritas, producing decent bass response and impact when called for and good detail and resolution on my CD of the Goldberg Variations arranged for Strings (Sitkovetsky on Nonesuch #79341). I pulled out another CD I recently picked up form an obscure Austin Texas dub band called Sub Oslo (The Rites of Dub) and was impressed to hear how well the T Amp and Klipsches reproduced the big drums, ultra-wide soundstage and deep bass on this record. This particular CD sounds a little overly mellow and rolled off on my reference system and the crispness of the T Amp and Klipsch combination complemented it very well. Again the soundstaging was a standout feature: Cinemascope wide, well outside the speakers and floating on lots and lots of air.
Transparency, however, was not a standout feature. Going back to the Feist record again, Leslie sounded pretty chesty and nasal, suggesting that something was amiss in the midrange. Ditto for the strings on the Goldbergs which sounded cloudier than they should. I wondered if running off battery power only might alleviate some of the boxy colorations I was hearing but flipping back and forth between battery and the power supply made no significant difference. When talking of “boxy” colorations it’s often the result of a poorly designed speaker cabinet resonating along with the music and clouding the sound, and cloudy was what I was hearing from the Sonic Impact. As such it’s easy to blame the speakers for such sins, but since these colorations evaporated and the speakers disappeared far better when driven by my Musical Fidelity A3CR, the blame, it seems, lies with the T Amp. In fact, when driven by the Musical Fidelity amp the Klipsches were just as dynamic, quick and tactile, if not more so, quite a bit smoother in the top end with much better controlled transients, much more tonally neutral and transparent (If you prioritize quick, tactile, highly microdynamic sound, these are speakers you should investigate for yourself, especially if you’re fond of low power amps). With the possible exception of a little extra “air” and soundstage width with the T Amp, my reference amp was quite a lot more musical. Also, the “boxy” character I had heard with the Sonic Impact, was gone. Mind you, the Musical Fidelity amp cost around $2300 ($1500 US) when I bought it a few years ago, or roughly 40 to 75 times more than a T Amp. I was planning on going back to the Sonic Impact for more comparisons, but by this point it was belching so much sonic filth from the right channel with such dogged persistence that I just gave up on it altogether.
Giants Slaughtered? Myths Exploded?
So what to make of all this? Obviously I didn’t find the T Amp to be the giant killer many people feel it is. Although what it does for the price is remarkable, what I heard from my sample didn’t make me want to abandon my much more expensive, traditional class A/B solid state amplifier for a second. You notice here that I qualify that statement with the words “from my sample”. This T Amp’s unpredictable right channel performance, combined with the fact that a friend of a friend’s order of three T Amps included two DOA units, makes me suspect that Sonic Impact’s quality control is erratic at best and that perhaps the sample I listened to might not be fully representative of what folks on the internet are so excited about. Then again, how could you ever know for sure? At the end of the day it’s still a twenty dollar amp, a price point at which, it seems, rolling the dice on quality and consistency is inevitable. You pays your money and you takes your chances, as they say.
A few enterprising souls have been selling modified T Amps which address the problems of the poor connectors, the flimsy box and limited battery life. A company called Red Wine Audio for instance, sells a Tripath TA2024 based amp in a little black box with a lead acid battery power supply, decent connectors and a host of other tweaks for US $499. If you’d rather do the work yourself there is no shortage of information or testimonials at places like www.diyaudio.com. With the most remarkable thing about this amp being the shockingly low price, throwing money at it will increasingly negate the point of the whole thing as you approach price points at which you might buy or build better sounding amps. If you’re really keen on a good class T switching amp companies like Channel Islands Audio or Bel Canto will be only too happy to help you, and, of course there’s the very reasonably priced (US $99 at the Needle Doctor) Teac A-L700P three channel amp based on the same technology. If you’re putting together a desktop system on a budget or have a pair of high sensitivity speakers you want to use in a minimalist system somewhere, than the T Amp, assuming you get a reliable sample, could be a great solution. In a more general sense it also bodes well for the state of amplifier technology that so much can be accomplished, sonically speaking, for so little. If it were more reliable I might consider one for my desktop audio system, but I think I might just investigate the little Teac instead.