Manufacturer: Jeff Rowland Design Group
eff Rowland Design presented the Continuum S2 integrated amplifier in the third quarter of 2013. It had two predecessors in the form of identical-looking Continuum 500 and Continuum 250, both using the ICE modules from Bang & Olufsen operating in the analog class D (manufactured between 2009 and 2013). The new version also features class-D power stage topology but employs completely different modules so we are in fact dealing with a completely different design. As before, the amplifier can be equipped with a phono stage. A new feature is an optional D/A converter. The relatively small unit is capable of delivering up to 400 Watts into 8 Ohms and 800 Watts into 4 Ohms. The Continuum is not the first Jeff Rowland amplifier to feature this output stage technology, although previous designs used the M3xx ICEpower modules. The preamplifier stage is based on the Capri S2, a new version of Jeff’s preamplifier.
“Over my career I have designed using a wide variety of technologies. I prefer to believe that my work displays a willingness to explore audio design regardless of class designation. While my basic design goals seem best suited to the solid-state domain, I am not overly concerned about which class of technological platform I work within. You might say I am a proponent of the classless society of audio design taking the best that each has to offer in an attempt to create the finest components possible.
I consider class-D to be highly competitive in the present, and to offer an evolutionary pathway of audio design that may produce even more astonishing results in the future. Again, it is not a matter of class distinction. The application of technology is what is important. It can produce brilliant or poor results depending on its implementation. Strict adherence to a class designation for an audio designer is like asking a painter to reduce the number of colors on his palette.
This is not another "something something" statement, which is used by every second company to explain their transition from class-AB (or A) to class-D. Most of them are hard to believe; it seems to be the easiest way to reduce manufacturing costs, adapt to the requirements of environmental protection and to achieve high output power. While many of those designs are acceptable and some are even pretty good, they have nothing in common with the high end. You need people like Shirokazu Yazaki, head of SPEC Corporation – referred to earlier – to understand the latent capabilities of class D and the problems that need to be addressed. With that in mind, Jeff Rowland’s explanations appear in a different light and are much more credible.
The new Continuum (S2) integrated looks very similar to its predecessor. It is a solid unit housed in an enclosure made of aluminum panels, with a very characteristic thick faceplate from 6061 billet aluminum (aircraft-quality material). Its wavy surface finish had also been used by Enlightened Audio Design, and more recently can be seen in components from Wow Audio Lab. I don’t know who manufactures enclosures for the people from Hong Kong, but earlier production for EAD and now for Jeff has been covered by Vertec Tool. This high precision CNC machining shop is located a few blocks away from Rowland’s factory in Colorado Springs. The film showing the work on enclosures for the Continuum S2, 825, 525 and the Corus can be see HERE.
Albums auditioned during this review
The American amplifier has a sleek, compact form factor and distinctive visual design. I really like this combination. Naturally, I have deep respect for huge amplifiers and I use one myself, knowing that it’s not possible to obtain certain things from a "small" unit. Jeff Rowland is certainly aware of that as his top power amplifiers, the Model 725, 825 and 925, are massive boxes. However, there is something special about well-designed audio that goes beyond their limits and makes them complete, finished products.
Its sound has been clearly shaped and has its strengths and limitations. It's not that I want to associate this amplifier with a certain kind of music and claim that it’s not suitable for anything else, for that would be a misunderstanding. However, certain design choices and the resulting sonic envelope clearly favors certain aspects over others. It's a warm and smooth sound that is so characteristic of products from this manufacturer to warrant calling it, with some reservations, “trademark Jeff Rowland’s”. At the same time, however, we get a beautiful and very deep soundstage. The warmer the audio components’ sound, the more they emphasize the foreground and pull up the background. This often has an amazing effect. For example, that’s how the JBL 4429 monitor creates its large sonic volume and saturated phantom images, showing their perceptible bodies to create a palpable sound. The Continuum S2 does something more. Albums like This Mortail Coil’s Blood, Kraftwerk’s Minimum-Maximum or the ultra-purist production from the Japanese duo Arimasa Yuki and Hisatsugu Suzuki (Duet) turn into a real music event to the extent that we accept them "on faith", without asking questions about their other sonic aspects. It’s a holistic, holographic presentation where each dimension is just as important, and in which they all together form something more than just a left-right and forward-backward perspective.
And yet, in the context of this presentation it’s difficult to talk about distinctive sources or high selectivity, or even clear focusing of attention on particular events. In this respect, the sound is reminiscent of that of digital sources from emm Labs, like the XDS1 V2 SACD player reviewed last month in “High Fidelity”. In spite of that, I was never missing any clear-cut edges and their definition in space, as long as I remained within the above circle of albums.
The Continuum S2’s presentation is coherent, as if everything in it was "geared up". No makeshift whatsoever. This gives the impression of a fast and precise sound with lots of oomph, even somewhat "raw" and austere. A long term product audition is more important for me than a short listen. In this respect, the Rowland amp proves excellent and perhaps even dangerous, because it’s addictive.
High power = punch, energy and even aggression. This is often true and that’s the sound of amplifiers used on stage. However, the American amplifier confirms what I heard with the best amplifier designs where high power = ample reserves and calm. It's like driving a 300 hp car (say, Audi A5) in the city. The point is not about taking it up to high speed, even though it’s part of the whole "package". What is more important is that there are no surprises when it comes to accelerating or braking suddenly, and the car won’t even notice that. We operate in a wide safety margin, rather than "touch-and-go".
‘Nuff said. If the above is up your alley this amp could last you forever.
A small amplifier size doesn’t necessarily mean light weight. I know it from everyday experience, when I move around my Leben CS300XS [Custom Version]. The Continuum S2 integrated from Jeff Rowland is another perfect example. It is really very heavy and the weight is concentrated in a small area. Taking it in hand, so to speak, confirms the impression that this is a solid piece of audio equipment.
Electronic circuits are assembled “upside down”, which is typical for Rowland. In this case, however, the enclosure is not machined from a single aluminum billet, with milled out chambers for separate PCBs but is assembled from metal panels instead. The PCBs are mounted to an aluminum chassis across the width of the enclosure. The most important is a large PCB housing a complete stereo amplifier. It is the M-PRO2 module manufactured by Pascal A/S. Delivering a staggering 800 Watts into 4 Ohms in stereo mode, this is actually the lowest-power amplifier module from this manufacturer! The top X-PRO3 is capable of 2500 Watts for the subwoofer and, simultaneously, two times 800 Watts into 4 Ohms. Interestingly, the amplifier modules can be bridged and the M-PRO2 can deliver up to 1400 Watts at 8 Ohm in BTL (bridge tied load) mono configuration. The Continuum doesn’t make use of that feature, though. The modules employ Pascal’s proprietary UMAC class-D technology with full bandwidth PWM modulator. Adjacent to the main amplifier PCB is a supplementary switch mode power supply board. The amplifier module has its own integrated switch mode power supply with Pascal’s UREC technology.
The remote control unit is not worth a mention. It is so ugly and in such stark contrast to the amplifier elegant and refined looks that if you accidentally step on and break it, it may actually bring a smile of satisfaction to your face. Of course, it’ll only last until you need to get up to adjust the volume level or channel balance, or to turn off the display. The latter two can only be done via the remote control. If it’s not one thing it’s another…
RMS Continuous Output Power: 400 W / 8 Ω | 800 W / 4 Ω (both channels driven)
Frequency Response: 5 Hz - 70 kHz (-3 dB / 8 Ω)
THD + Noise: 0.05% (20 Hz - 20 kHz)
Inputs: 2 x Balanced XLR | 2 x Unbalanced RCA | 1 x Unity Gain (Bypass) RCA
Outputs: 1 x Balanced XLR | 1 x Unbalanced RCA
DAC Board: optional
RIAA Phono Board: optional
Weight: 15.9 kg (35 lbs)
Dimensions (HxWxD): 135 mm x 394 mm x 380 mm (5.3 in x 15.5 in x 15.0 in)
Start of production: 3rd quarter 2013
- Turntable: AVID HIFI Acutus SP [Custom Version]
- Cartridges: Miyajima Laboratory KANSUI, review HERE | Miyajima Laboratory SHILABE, review HERE | Miyajima Laboratory ZERO (mono) | Denon DL-103SA, review HERE
- Phono stage: RCM Audio Sensor Prelude IC, review HERE
- Compact Disc Player: Ancient Audio AIR V-edition, review HERE
- Multiformat Player: Cambridge Audio Azur 752BD
- Line Preamplifier: Polaris III [Custom Version] + AC Regenerator, regular version review (in Polish) HERE
- Power amplifier: Soulution 710
- Integrated Amplifier: Leben CS300XS Custom Version, review HERE
- Stand mount Loudspeakers: Harbeth M40.1 Domestic, review HERE
- Stands for Harbeths: Acoustic Revive Custom Series Loudspeaker Stands
- Real-Sound Processor: SPEC RSP-101/GL
- Integrated Amplifier/Headphone amplifier: Leben CS300XS Custom Version, review HERE
- Headphones: HIFIMAN HE-6, review HERE | HIFIMAN HE-500, review HERE | HIFIMAN HE-300, review HERE | Sennheiser HD800 | AKG K701, review (in Polish) HERE | Ultrasone PROLine 2500, Beyerdynamic DT-990 Pro, version 600 - reviews (in Polish): HERE, HERE, HERE
- Headphone Stands: Klutz Design CanCans (x 3), review (in Polish) HERE
- Headphone Cables: Entreq Konstantin 2010/Sennheiser HD800/HIFIMAN HE-500, review HERE
- Interconnects: Acrolink Mexcel 7N-DA6300, review HERE | preamplifier-power amplifier: Acrolink 8N-A2080III Evo, review HERE
- Loudspeaker Cables: Tara Labs Omega Onyx, review (in Polish) HERE
- Interconnects: Acoustic Revive RCA-1.0PA | XLR-1.0PA II
- Loudspeaker Cables: Acoustic Revive SPC-PA
- Power Cables: Acrolink Mexcel 7N-PC9300, all system, review HERE
- Power Distributor: Acoustic Revive RTP-4eu Ultimate, review HERE
- Power Line: fuse – power cable Oyaide Tunami Nigo (6m) – wall sockets 3 x Furutech FT-SWS (R)
- Power Cables: Harmonix X-DC350M2R Improved-Version, review (in Polish) HERE | Oyaide GPX-R (x 4 ), review HERE
- Power Distributor: Oyaide MTS-4e, review HERE
- Portable Player: HIFIMAN HM-801
- USB Cables: Acoustic Revive USB-1.0SP (1 m) | Acoustic Revive USB-5.0PL (5 m), review HERE
- LAN Cables: Acoustic Revive LAN-1.0 PA (kable ) | RLI-1 (filtry), review HERE
- Router: Liksys WAG320N
- NAS: Synology DS410j/8 TB
- Stolik: SolidBase IV Custom, read HERE/all system
- Anti-vibration Platforms: Acoustic Revive RAF-48H, review HERE/digital sources | Pro Audio Bono [Custom Version]/headphone amplifier/integrated amplifier, review HERE | Acoustic Revive RST-38H/loudspeakers under review/stands for loudspeakers under review
- Anti-vibration Feets: Franc Audio Accessories Ceramic Disc/ CD Player/Ayon Polaris II Power Supply /products under review, review HERE | Finite Elemente CeraPuc/ products under review, review HERE | Audio Replas OPT-30HG-SC/PL HR Quartz, review HERE
- Anti-vibration accsories: Audio Replas CNS-7000SZ/power cable, review HERE
- Quartz Isolators: Acoustic Revive RIQ-5010/CP-4
- FM Radio: Tivoli Audio Model One