(Reprinted from the Almanac 2000 Audio Ideas Guide)
Though the name Concentra may suggest a new Japanese compact car, one look at its lustrous, thick front panel tells you that, whatever it is, this ain’t no econobox. An inch thick, this machined aluminum fascia appears to have contours and depth, as if it were an acrylic surface, with visible gentle vertical curves that aren’t there when you run your hand along its smooth surface: The curvature is an illusion created by the manner in which the aluminum has been machined and polished. This process must take many hours of meticulous work. And it’s simply gorgeous!
Side, top, and rear panels are also machined from aluminum blocks, but painted a glossy black. The side panels serve as heat sinks for the output devices. I used my precision WBT Dyna Key torque driver to remove the top, and immediately realized that distributor Angie Lisi was right: Rowland should leave it open or use an acrylic top, because the amplifier interior is so pretty. At front is the large black encased power transformer, flanked by two very large capacitors, all three secured by a shiny aluminum locking harness. At the rear of this assembly are the power and driver electronics, while input and phono sections are on the rear panel’s interior. Both circuit boards are bright red and look to be the best you can get. The orange output devices are on their own red boards along the sides, and are unlike any power transistors I have ever seen. This neat, well organized interior brings to mind the phrase, “military spec”.
Returning to the front panel, once you get used to the dazzling finish, it can be seen to have 7 input select buttons for the 3 balanced and 3 unbalanced ins, and the Tape Monitor, these all in a horizontal row at lower left. At right is another similar button for Mute, with the Volume knob beside it, and a large red LED dB display. Input scrolling, Mute, Volume up/down, and Balance left/right buttons are offered on the grey metal-cased remote control.
The amplifier is rated at 100 watts per channel, 150 at 4 ohms, with rms and peak current capabilities of 16 and 28 amps, respectively. Its low impedance power is obviously limited by the single transformer. Little is said in the Rowland literature about circuit or output topology, so the provenance of those odd orange output devices will remain Jeff’s secret.
What the designer does say in the colour ring-bound brochure is this: “The Concentra is a spectacular performance blend of the ultra-transparent Synergy preamp and the elegantly powerful Model 2 amplifier. The result is a component that is so utterly without peer that it redefines the entire category of integrated amp design.” We shall see.
After firing it up, one of the first things I noticed about the Concentra was that it ran quite warm, though even at high levels, I could keep my hands on the side panels without discomfort. This suggests that the output is biased into Class A for at least the lower part of the power range.
I listened to the Concentra with both Soliloquy 5.0 and our reference Energy Veritas v1.8 speakers through Kimber 8TC bi-wire cables with WBT locking banana connectors. The CD source was the Panasonic DVD-L10 player, which also allowed audition of several 24/96 audio DVDs. It was connected by what can be called an overkill approach, a 1/2 metre Kimber Select KS 1030 interconnect with a gold-plated mini-to-RCA adapter at the source end. I also listened to the phono section from our Heybrook/SAEC/Ortofon MC-3000II setup using the superb Cardas Golden Cross phono cable, comparing the Rowland’s internal phono stage with the outboard AcousTech one.
With CD and DVD Audio sources, the Rowland amplifier sounded utterly neutral, though not analytic, with a powerful bass that even on the bookshelf Soliloquy speakers seemed to go below 30 Hz with authority. This transparency was combined with a transient speed that made music not liquid nor round, (or whatever else tube freaks like in addition to the heat and glow), but alive and vital, challenging and visceral, like real, live music. Yes, I could make it clip at high levels, especially with the Veritas speakers, but it did so quite gracefully; the red LED numbers are a good warning (though their dB calibration is approximate and related to speaker sensitivity), and when they got into the mid-90s, I could hear just the bit of an edge on peaks telling me to turn it down. With most other amps at this level you’d quickly back it off, but the Concentra’s distortion is so low that realistic levels are possible in an average room with speakers that can handle the power.
If there is any character to this amp, it is a quality of richness, that generosity of bass and mid-bass that I’ve heard from Class A designs in the past. By comparison our Bryston 3B ST sounds a little leaner and more analytical, and, dare I say, just a little more harmonically accurate in the lower octaves. But here we are delving into the realm of musicality, and what is perceived as such: the Concentra will probably be heard as more musical, and certainly is a thrilling reproducer of anything that plays through it.
The phono stage is very quiet, almost enough so for our 30- microvolt Ortofon MC3000 II to bloom. Though the small amount of hum and hiss was audible, it was below the surface noise of most pressings. The definition and clarity of LPs through this amplifier was outstanding, once I adjusted the loading DIP switches inside the amplifier for best perceived frequency balance, and set those for gain to their highest setting. After listening to a variety of the best pressings in my collection I was just about ready to buy the Concentra, it sounded so clean, open and natural. And when I added up the original purchase prices of my existing head amp, phono preamp, preamp, and amplifier I was getting pretty close to five figures, anyway. But I obviously couldn’t get that for them now.
One of the worst problems in phono reproduction is transient reproduction. Because of the extreme RIAA equalization, few phono stages reproduce these without some spitting distortion, and can also tend to emphasize surface noise. There was none of that here, the Rowland phono stage bringing out the resolution of the groove in a fashion that made analog clearly the better medium. The Concentra overall also showed the superiority of of 24/96 discs over CDs, which also indicates its very high level of resolution.
The phono section is based on the Cadence outboard phono stage, so I can perhaps steal a few specifications from that section of the Rowland brochure. RIAA accuracy is said to be within .03 dB 20-20,000 Hz, while highest gain is said to be 70 dB. Output noise is specified at 60 microvolts, which confirms that noise is just a bit too high for the Ortofon, with its 30 microvolt low level output, but perfect for any other not-so-low-output MC. Aside from this concern in my own case, LP reproduction is as good as I have ever heard from any phono-based system.
Would I break down and buy the Rowland Concentra? Well, I sure am tempted, especially when I look at those balanced inputs that I could plug my 96 kHz DAT recorder and other pro gear into; hey, even my Fanfare FT-1 tuner has balanced outs. Hmmmm. However, it would mean longer speaker cables, and problems swapping review components in and out, such as amps and preamps, not to mention speaker cables. That said, however, I could certainly enjoy listening to music forever through this superb piece of audio engineering from the Jeff Rowland Design Group.