February 2011
I recently found myself looking back to a time before digital media, before multichannel home theater, and yes, before even VHS tape. Things were simple -- movies were projected from film, and music was pressed into discs made of vinyl. In 1970, RCA Records changed everything by introducing a new way of listening to music called Quadraphonic, which, as its name implies, used four discrete channels instead of two. Quadraphonic was the beginning of the surround-sound formats that we have today.
In 1976, Dolby Laboratories put its own spin on things by introducing Dolby Stereo, designed for the analog sound systems of movie theaters. Though also a four-channel format, Dolby Stereo differed from Quadraphonic in consisting of front right, front left, and center channels, and a mono matrixed surround channel. Dolby Stereo was adapted in 1982 so that it could be experienced in the home using a Hi-Fi-capable VCR, albeit through only two channels. It wasn’t until 1987 that the original Dolby Stereo, renamed Dolby Pro Logic, was made available to the public for surround-sound use in the home. To fully exploit the potential of this early codec, you had to purchase either a five-channel Pro Logic receiver or a Pro Logic processor and pair it with a five-channel power amplifier -- at that time, a rare item.
Surround-sound codecs continued to evolve bit by bit (so to speak), as did multichannel home-theater receivers and amplifiers, until 1992, when Dolby once again shook the foundations of surround-sound codecs by introducing Dolby Digital 5.1. Using six discrete channels instead of four, DD 5.1 not only set the stage for future codecs such as Dolby Digital EX , EX Surround, and Dolby Digital Plus, but pushed the number of discrete channels offered by multichannel amplifiers to eight, as 7.1 became the norm. In 2006 the industry took yet another evolutionary step forward with the release of the world’s first truly lossless, high-resolution surround-sound codecs, Dolby True HD and DTS-HD Master Audio. Although capable of supporting up to 14 discrete channels of 24-bit/96kHz audio at up to 18Mbit/s, only eight of those channels are so far usable, because of the limitations of the HD DVD and Blu-ray formats. Now using eight discrete channels to feed a fully lossless 7.1-channel surround-sound codec, it wasn’t long before two more effects channels, for height information or additional side speakers, were added, giving us a vastly improved 9.1 format. It is this codec that has driven the development of Integra’s all-new DTA-70.1 nine-channel home-theater power amplifier.
Not long ago I was in the market for a new A/V processor that would not only be up to date with all the new codecs, handle two video displays via HDMI, upscale any video signal I could throw at it, and serve my multizone needs, but also be flexible and durable enough to become my new reference processor, capable of handling any piece of review equipment that might be sent my way. My choice was Integra’s 9.2-channel DHC-80.1 -- which, as it turned out, is the intended companion product to the DTA-70.1. So a review was scheduled.
Under the hood
When I took delivery of the DTA-70.1, which Integra claims can deliver 150W into 8 ohms to each of its nine channels, I was sure it had to be a digital amplifier -- how else could an amplifier capable of this kind of flexibility and this much power fit into a small case measuring only 17"W x 7.75"H x 17.4"D and weighing only 50.7 pounds? I was also impressed that not only is the DTA-70.1 the first nine-channel amp to hit the market, it also bears THX’s Ultra2 certification. And it costs only $1800. I was most curious to remove its cover and see exactly how all this was accomplished.
When I removed that cover, it became clear that some innovative engineering has gone into the DTA-70.1’s design. The chassis of this all-analog, discrete-component power amplifier is in two sections. Directly behind the thick front panel of solid aluminum is a massive toroidal power transformer. Dividing the front of the chassis from the rear is a row of substantial heatsinks that span the DTA-70.1’s entire width, and directly behind these are two 22,000µF capacitors. To either side of the capacitors are the nine separate output stages. According to Integra, these are "identical symmetric circuit layouts that are configured in a push-pull topology utilizing high-performance three-stage inverted Darlington circuitry and powerful custom-designed output transistors."
On the circuit boards, 70µm-thick copper traces make possible high current and low impedance, and grounding problems are all but eradicated by heavy copper bus plates. In addition, Integra’s Wide Range Amplifier Technology (WRAT) is used to achieve low negative feedback, and High Instantaneous-Current Capability (HICC) with closed ground-loop circuits employed to reduce noise, improve dynamics, and deliver an unmitigated frequency response. The DTA-70.1’s claimed frequency response is 5Hz-100kHz, ±3dB, with a signal/noise ratio of 110dB, IHF A-weighted. In fact, Integra claims that the DTA-70.1 has an FTC dynamic-power specification of 180Wpc into 8 ohms, which it more than doubles into 3 ohms, to a whopping 400Wpc.
The rear panel is well laid out, with ample space between inputs and outputs to permit the use of thick cables. At the top left are toggle switches for selecting between 4- and 6-ohm loads and between automatic and manual power-down, as well as a 12V trigger input for remote turn-on/off. Below these, and taking up most of the rear panel, are gold-plated XLR sockets (even though the DTA-70.1 is not a true balanced design) and RCA jacks of machined brass for each channel, with a toggle switch for selecting between them. Below the RCA inputs are the color-coded speaker binding posts; these have transparent cases, and are gold-plated and compatible with banana plugs.
A one-box wonder
Before sitting down to listen to the Integra DTA-70.1, I had to decide how I would hook it up in order to take advantage of all nine of its channels. Although designed to be used in a 9.1-channel system, the DTA-70.1 gives you plenty of options if you lack a space that big, or if your processor isn’t equipped with a 9.1 codec. I have space for only a 5.1-channel system in my living room, so I could use the remaining four channels to biamp the two main speakers and add an extra pair for a 7.1 setup, or run stereo out to second and third zones, etc. In the end, I kept things simple and went with the multizone option, but depending on your particular situation, the possibilities are many.
That done, I rifled through my Blu-ray collection and began with Oliver Stone’s JFK, as that would let me focus on low-level details. In chapter 4, the spatial presentation of the solo snare drum was articulated against an almost inky-black background, which let the nuances and echoes of the snare decay with a dramatic sense of presence. Voices throughout the film were presented with well-defined pitch, and dynamic swings never sounded compressed or showed any sign of strain.
In chapter 6 of Edward Zwick’s The Last Samurai, as Tom Cruise’s character describes what it’s like to be scalped, the scenes switch back and forth between a quiet conversation, the intense sounds of gunshots, people screaming, and archers firing at a target. The DTA-70.1 handled these dynamic swings wonderfully, in one moment conveying the emotion of a single voice against a silent background, and in the next imaging powerful gunshots with intensity and accuracy. In chapter 11, the sounds of children playing in the fields, birds chirping, wind blowing over blades of grass, were all clearly articulated at various points in my room against the slow, deep rumble of a drum. All of this proved that the DTA-70.1 was brilliant at highlighting microdetails against any kind of aural background.
Kicking things up a notch, I cued up chapter 5 of Joe Johnston’s Wolfman. Again the Integra handled microdetails and dynamic swings with aplomb, but what really caught my attention were the speed and impact of the sounds made by the wolf as it rushed to attack its victims, the thunderous growl of the grizzly bear as he gets wind of the wolf, and the width of the soundstage in complex and intense scenes. The DTA-70.1 had an uncanny ability to envelop me in the worlds of films, revealing a sense of realism that made watching them all the more engrossing.
So far, no matter what I threw at the Integra, even when driving all of its nine channels by running stereo sound in Zones 1 and 2, I couldn’t get it to break a sweat. When I put my hand on top of the amp, only the area directly above the heatsinks was warm, and even then, only barely so. Impressive -- though it should be noted that the least efficient speaker I’d connected to the DTA-70.1 was rated at 88dB, and I was turning the volume up to only 70 in my processor's volume-control range. So next up was a bit of a torture test: In went Michael Bay’s Transformers: Revenge of the Fallen, and up went the volume to 85 -- louder than I would ever listen to a film for enjoyment, or my neighbors would permit.
In chapter 8, as Megatron interrogates Sam, the 85 volume setting produced voices that weren’t quite as smooth and natural as before, and that now sounded slightly edgy and nasal, with a hint of sibilance. When the Autobots come to Sam’s rescue by crashing through the roof, the soundstage, which before had been so open and vast, now seemed slightly more focused, losing just a hint of the airy realism that it had at lower volumes. That’s not to say that it sounded congested; on the contrary, the DTA-70.1 still delivered a very believable soundstage, with excellent delineation of detail and solid weight behind impacts. But it just didn’t sound as rich and natural as it had at lower volumes. And now, when I placed a hand on the amp’s top panel, it felt well on its way to getting very hot indeed.
Competition?
Finding something with which to compare the Integra DTA-70.1 proved a bit of a challenge: Currently, it’s the only nine-channel amplifier made. With ten channels delivering the same power output as the DTA-70.1, you could consider Denon’s POA-A1HDCI, but the Denon is almost four times the Integra’s price. Marantz’s eight-channel MM 8003 amplifier costs $2399 and puts out 140Wpc, but again the match is inexact: The Marantz costs $600 more, but is slightly less powerful and has one fewer channel.
So I used two amplifiers to do the job the Integra does with one compact, flexible package. When I stacked my Rotel RMB-1095 ($1995, discontinued) atop my RMB-1075 ($1199, discontinued), the result was just under 17" high and weighed a total of 128 pounds. The space-saving Integra is just under 8" tall and weighs just over a third the Rotels’ combined mass.
In side-by-side comparisons of the Integra’s and my Rotels’ 5.1-channel sounds using the same chapters from Transformers: Revenge of the Fallen, the Integra’s wide soundstage, highly dynamic nature, and nonaggressive sound bested the Rotel RMB-1075 every time. This was surprising, considering that the Rotel boasts almost four times the Integra’s capacitance and gives up only 25Wpc in power.
Comparing the Integra DTA-70.1 to the Rotel RMB-1095 was a different story. The larger Rotel produced a similar yet somewhat more relaxed sound at lower volumes. When I pushed both amps a bit harder, bass from the RMB-1095 was smoother and tighter in the scenes from Wolfman, the soundstaging was deeper and wider in scenes I watched from The Last Samurai, and voices were consistently more full through the Rotel, showing no signs of strain, congestion, or sibilance, especially at higher volumes. The RMB-1095 proved more in control in the scenes from Transformers, painting a more organized sound picture than the Integra, though not by a large margin. This was no surprise -- the Rotel RMB-1095 puts outs 200Wpc into 8 ohms or 400Wpc into 4 ohms, has two 1.2kVA transformers and eight 15,000µF capacitors, and costs about 10% more than the DTA-70.1. The fact that the Integra could competently compete in the same class is something in itself.
I have a few nits to pick. The relays in the DTA-70.1 made a loud clicking noise when the amp was turned on. My Integra DHC-80.1 A/V processor does the same thing, though not as loudly. Also, the cobalt-blue LED in the middle of the DTA-70.1’s faceplate, indicating that it’s powered up, was bright enough in my darkened room to cast a light-blue haze over everything. This proved distracting while watching movies; a dimmable option would be greatly appreciated.
The bottom line
I was thoroughly impressed by the consistently high levels of quality and performance offered by Integra’s DTA-70.1 home-theater amplifier, not to mention the obvious synergy between it and its counterpart, the Integra DHC-80.1. Even when driving all nine channels simultaneously, the DTA-70.1 took in stride everything I threw at it, producing vast soundstages, pinpoint imaging, and a clearly dynamic personality. The flexibility offered by this amplifier is second to none save Denon’s POA-A1HDCI, but that amp costs four times as much -- the DTA-70.1 is an incredible value for $1800. With the ability to power anything from a 5.1-channel system in a smaller room such as mine, as well as two additional zones, to a 9.1-channel theater in a large room, the DTA-70.1 sets the bar high. I’ll be sad to see it go. Well done, Integra!
. . . Aron Garrecht
arong@soundstagenetwork.com
Associated Equipment
- A/V processor -- Integra DHC-80.1
- Amplifiers -- Rotel RMB-1095, Rotel RMB-1075, Bel Canto REF150
- Sources -- Rotel RCD-1055 CD player, Oppo BDP-83 Blu-ray player
- Power conditioner -- Rotel RLC-1040
- Speaker cables -- River Cable Flexygy 8
- Interconnects -- Analysis Plus Copper Oval-In
Integra DTA-70.1 Multichannel Power Amplifier
Price: $1800 USD.
Warranty: Three years parts and labor.
Integra
18 Park Way
Upper Saddle River, NJ 07458
Phone: (800) 225-1946
Website: www.integrahometheater.com
