AOM Logo February 2001

On a Clear Day, You Can See Denver
Jeff Rowland Design Group "Concentra" integrated amplifier

Anthony Kershaw

The Jeff Rowland Design Group has, for some time now, been among the elite high-end manufacturers of transistor preamplifiers and power amplifiers. As such, it would seem that Jeff Rowland's talent has no end when designing and manufacturing behemoth amps that produce ultra clean and quiet power and preamps that are justly famous for their transparency.

Jeff Rowland's Concentra integrated amplifier

With the Concentra Integrated Amplifier, Jeff Rowland continues his quest for excellence in both interior and exterior design. Introduced in 1996, this one box version of his Synergy Preamp and Model 2 Amplifier has created quite a stir in high-end circles - for the most part, a circle in which many eschew the idea of audio brilliance in a one-box pre/power design.

Rowland's line is distributed here in Canada by Audiopathic. They were happy to offer the loan of a Concentra for a limited time - enough time, it turns out, to hear it enter my system seamlessly and for me to mourn its departure some five weeks later.

I transported the Concentra from the Audiopathic office, and as it had been burned in for some time, I started enjoying it almost immediately. After a quick setup, I read the manual and some information on Rowland's webpage, then serious listening began. Technically, the thing is a marvel of sophistication. Esthetically, it is simply magnificent. At fifty pounds and dimensions of 7.5 in (W) x 14.35 in (D) x 5.75 in (H), it was surprisingly easy to move around - well balanced, with smooth edges. It appeared so solid, that even a drop or two would seem impervious to its health. The fabulous faceplate of thick, stylized aluminum (this style graces many of the Rowland pieces), juts proudly in front, hinting quite clearly at what excellence there is to come. A set of seven small buttons with lights embellish the fascia, the lights indicating which input has been selected. These lead to a large LED display for volume dB with its accompanying pot. The volume control is a thing of tactile beauty, yet because of the wonderfully solid remote, it rarely got touched (the volume control resolution is 0.5 dB +/- 0.05 dB over the entire range - very precise levels were achieved easily).

With power into eight ohms of one hundred watts (my Gallos, at four ohms, allowed the Concentra to produce 150 watts), only the most inefficient speakers owned by the most primal headbangers need not apply (a Concentra II is close to manufacture with 150 watts into eight ohms). Mr. Rowland explains the technical specifications as part of a paper on his excellent web site : "The Concentra integrated amplifier consists of a separate 14 dB gain preamplifier section and a 26 dB power amplifier section. The power supply provides +30 volts DC to the power amp sections, which operate in a fully balanced bridge configuration. A 350 VA toroidal power transformer, encapsulated within a machined aluminum tube, is oriented such that stray fields do not interfere with the preamp circuitry located directly on the rear panel. Two 130 000 uF, low ESR capacitors and separate rectifiers allow floating power supplies of each polarity, eliminating capacitor charging current contamination of ground circuitry. Positive and negative precision regulation circuitry supplies analog, digital, relay and display voltages." Inner beauty, indeed!

The rear, while not quite as beautiful as the front, did offer everything that a serious audiophile will need in connectivity. Inputs include balanced line - three per channel/XLR, unbalanced line - three per channel/RCA, record - one per channel/RCA, and an unbalanced phono (optional, and yes, it takes both MM and MC cartridges) - one per channel/RCA. For outputs, you get one balanced pre out - one per channel/XLR, an unbalanced pre out - one per channel/RCA and one record - one per channel/RCA. The heavy-duty binding posts were of the highest quality.

Associated Components

Digital: Sony SCD-1 SACD player, Arcam Alpha 6, Cary CD-303 CD player.
Preamplifier: Audio Research SP9 Mk. II
Power Amplifiers: Assemblage SET-300B single ended triode power amplifier, Rowland Concentra integrated amplifier, Audio Research D300 power amplifier
Loudspeakers: Gallo Acoustics Nucleus Solo
Cables: Interconnects: Audioquest Emerald, Kimber PBJ, Wireworld Polaris III Loudspeaker: van den Hul M.C. The Sky-Line Hybrid, Monster Cable XP.
Accessories: Black Diamond Racing Cones (Nos. 3 and 4), Target wall shelf and stand, Seismic sink, BBC boards.

I assume that combining the two Rowland boxes into one is for convenience and cost (approx. $4500.00 under the two separate enclosures!) rather than a specific design direction. There is certainly a market for this type of convenience. If the idea of fewer cables, with more space and dollars grabs you, the Concentra will advance you to the head of the integrated line. If not, cable the two equivalent Rowland boxes accordingly and enjoy the same sound from superb separates.

The sound? As many audiophiles have heard, Rowland preamps are known for their ultra transparency, and in this regard, the Concentra preamp section upholds Rowland's brilliant tradition. The range from many sources was inspiring in its absolute beauty and lack of grain. The sound continually showered this listener (and many others) with the most gentle rain of delicate highs, always sounding clear and true. This truth manifested itself best on high flutes, strings and bells. The sound seemed to ring forever. After a particularly tricky chromatic flute section of The Happy Forest by Bax (Naxos 8.553608), the flutes and piccolo settle with the high strings on a sustained note. The sound from this note still resonates, with the note's purity (and soundstage with instrument separation) almost tactile. The Stephen Kovacevich 1 Beethoven volume on Phillips' masterful Great Pianists of the 20th Century series also sounded superb (456 877-2). Piano tone was as as good (via the Cary 303 - in fact, the combination of these two very impressive pieces seemed an excellent match as did the Concentra with Sony's SCD-1 SACD player) as I have witnessed from my vinyl setups (I have all the LP issues, and they are typical of Phillips' clean and scrubbed vinyl). Air and accurate timbre were but two highlights. The expansiveness of Beethoven's thundering octave passages was taken in stride by the Concentra and turned out so the unique sound of piano attack and decay was left intact. These important details are so often smeared by weak equipment. I heard Kovacevich when he was a young fellow (he was then known as Stephen Bishop), and the sound of his filigree playing through the Concentra reminded me of what a fantastic artist he is. The Concentra, on this and many other CDs (the phono option was not installed on this Concentra), brought its audience very close to the heart of the music and the ambiance of the event.

Concentra integrated amplifier

The highs and midrange were wonderful, but the lows were just as clear and refined. Tuba and string basses both retained their individual timbre in the lowest registers, a telltale sign of the best electronics. Many examples of high end amplifiers retain the whack and "oomph" but lose the tonality, producing a synthesizer-like sound from the instruments. The RCA CD of Reiner's Pictures at an Exhibition (09026-61958-2) can be problematic in the bass tonality, surprising when the sound from such a wonderful group of players is so unique. The low brass sound can coalesce on lesser equipment so that the trombones and tuba sound as one - a perfect ensemble, one would think. Yet, through the Concentra, the flawless Chicago ensemble remains, but Arnold Jacob' s tuba and Jay Friedman's trombone section retain their individual sounds. Yes, layering in all tessituras, so important to discriminating audiophiles was highlighted to superb effect on many recordings. This clarity was maintained and enhanced by the superb power section of the Concentra. My Gallos never congested, even at ear-splitting levels. In fact, the body gave up before the volume pot.

The price of the Concentra will be prohibitive for all but the most passionate audiophile. Although one gets both a preamp and an amp for the cost, it still is a major investment. Yet, I would urge all lovers of high fidelity to audition the piece, even just for the thrill. Connected to fine ancillary equipment, the Concentra's musical bang for the buck is exceptional. In fact, exceptionality is what Jeff Rowland is all about. His instict is sharp and he continues to advance the art. The air must be very clear in Colorado. Congratulations, Mr. Rowland, on another outstanding product. Highly recommended.

Concentra Integrated Amplifier
Manufactured by Jeff Rowland Design Group
PO Box 7231, Colorado Springs, CO 80933-7231, USA
phone:719-473-1181, fax: 719-633-4158
web:, e-mail:
Price: US$6500.00
Source of review sample: Audiopathic. (Canadian Distributor)

Manufacturer's Response

Dear Mr. Kershaw:

Thank you for the positive review and the opportunity to respond with a manufacturer's comment. We are appreciative of any review that provides insight into the fit, finish, and feel of our products as much as their sound, as we try to make them to be as appealing to touch and sight as they are to the ears. Jeff Rowland Design Group is one of the few high-end manufacturers to exist for 20 years, much less continue to adhere to the values and philosophies that brought about the inception of the company in the first place. This has been achieved by following Jeff's ideas about advancing technology and product value in relation to the investment made by the customer. Our aim is and has always been to provide the absolute best audio component that we can for a given cost and we feel that the Concentra has no peer in the integrated amplifier category with the exception of one product: the Concentra II. The new generation of integrated amplifier uses the same preamp section as the Concentra, however the power supply has been completely redesigned to provide 150 watts of output power into 8 ohms, 250 into 4 ohms. Output current capability has been increased, and the unit features better noise and distortion performance. Information on the new Concentra II or the upgrading of older units can be found at:, and can also be found by contacting Audiopathic in Canada (, your local dealer, or ourselves at the factory. Again, thank you for providing a glimpse into the capabilities of the Concentra and also for the kind words relating to it. We are always happy to receive positive feedback from the listening community.

Best regards,

Rich Maez, Technical Services Director
Jeff Rowland Design Group.
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