Technics R1 Reference System

A Triumphant Return

Equipment report
Solid-state power amplifiers,
Music servers and computer audio
Technics SB-R1,
Technics SE-R1,
Technics SU-R1
Technics R1 Reference System

The front panel offers controls for input selection (balanced, unbalanced, and digital), gain (for the analog inputs), speaker choice (the amp supports two separate sets of outputs or bi-wiring a single set), and dimming of the meter’s backlight (which I wish offered more low-light options). There’s also a curious, deceptively innocuous-looking button labeled LAPC. More on that later. In back there are two sets of the burliest binding posts I’ve ever encountered. I flat-out love them. Their size affords tremendous grip. No need for tools to tighten down these babies!

Inside, the SE-R1 is no less impressive. The power supply is fully discrete and utilizes a proprietary choke-rectified circuit said to reduce coloration. The transformer is massive, which contributes to the unit’s overall heft. Also adding bulk, no doubt, is the amp’s 7mm-thick aluminum chassis, a 3mm-thick aluminum inner chassis, and die-cast aluminum columns that connect the two while also evacuating vibrations.  

 The final member of the R1 triumvirate is the SB-R1 speaker. A large, traditional-looking, floorstanding three-way tower, the SB-R1 is designed to act as a point source. Such designs have theoretically ideal dispersion properties, and my experience with speakers like the KEF Blade bear out the approach’s benefits. Like the Blade, the SB-R1 utilizes a coaxial (sometimes called “coincident”) midrange/tweeter, which is a point source by nature. But unlike similar drivers from KEF and TAD, the Technics’ unit is flat. Delving deeper into that intriguing driver, the midrange element is a sandwich of carbon cloth with a honeycombed aluminum core. Meanwhile, the tweeter has a carbon graphite dome and is said to be good to 100kHz. That’s ribbon territory. The whole dual-driver assembly is framed in vibration-dispersing die-cast aluminum.

Technics extends the point-source frequency range by flanking the coax with a pair of long-throw 6.5" woofers. To supplement bass, an additional pair of these woofers occupies each tower’s lower half. Internal dividers kill standing waves within the cabinet, which is curved to the same end.

By now it should be apparent that each of these components, if not necessarily innovative, is dead serious and uncompromising in both design and execution. Yet there are, indeed, advances, though they’re only evident when viewing the R1 system as an integrated whole. That’s the context in which the intersection between components comes into play, and that’s where Technics found the largest sonic losses in today’s audio systems, and therefore where it focused most attention.     

The first intersection is the connection between the SU-R1 player and the SE-R1 amplifier. Like all streamers and DACs, the SU-R1 spends most of its time in the digital domain. And, like all such products, it can discharge music through either single-ended or balanced analog outputs. In that case, though, the DAC function takes place early in the signal path, employing traditional DAC technology, before an analog version of the signal travels downstream to be amplified.

Technics had two problems with this industry-standard approach. First, traditional DACs involve a complex series of steps, each of which has the capacity to—and frequently does—degrade the end result. Second, since analog signals are noise-prone, it makes sense to keep digital sources in the digital domain as long as possible. Nonetheless, the norm is to convert to analog early on. Far better, Technics felt, to move the D-to-A function to the amplifier. Better still to have the amp somehow accomplish the conversion by a simpler, more “native” means than traditional DACs. 

Digital Amplifiers
As with Class D amplifiers, digital amplifiers use a switching output stage; however, they accept digital rather than analog input signals. These “digital” amplifiers take in the pulse-code modulation (PCM) signal from a music server or other source and convert those audio data to a pulse-width modulated signal. This PWM signal then drives the output transistors, just as in a Class D amplifier. The difference between a Class D amplifier and a digital amplifier is that the digital amplifier accepts digital data rather than an analog signal.

This difference might not seem that great at first glance, but consider the signal path of a conventional digital-playback chain driving a Class D—or any other traditional—power amplifier. Your digital source feeds audio data to a DAC that converts the digital data to an analog signal; the DAC’s current output is converted to a voltage by a current-to-voltage converter; the signal is low-pass filtered, then amplified in the DAC’s analog-output stage. This analog output signal travels down interconnects to a preamplifier with its several stages of amplification, volume control, and output buffer. The preamp’s output then travels down another pair of interconnects to the power amplifier, which typically employs an input stage, a driver stage, and the Class D output stage. In addition to the D/A conversion, that’s typically six or seven active amplification stages before the signal gets to the power amplifier’s output stage.

To reiterate the contrast with a true digital amplifier, PCM data are converted by DSP into the PWM signal that drives the output transistors. That’s it. There are no analog gain stages between the PCM data and your loudspeakers. The signal stays in the digital domain until the switching output stage, which, by its nature, acts as a digital-to-analog converter in concert with the amplifier’s output filter. The volume is adjusted in DSP. Digital amplifiers are usually not just power amplifiers, but also include a range of inputs, source selection, and volume control, effectively giving them the functional capabilities of an integrated amplifier.  Robert Harley

Putting this plan into action meant, first of all, giving the SU-R1 a digital output and the SE-R1 a digital input. That enabled moving D-to-A conversion to the amp. The natural course would have been to enlist SPDIF as the conveyance between the SU-R1 and the SE-R1, but Technics rejected that approach. For one thing, standard SPDIF lumps both channels onto the same cable, raising the potential for inter-channel effects. Technics could have used two SPDIF links, one for each channel, but that wouldn’t address a separate problem having to do with volume control.

Normally, when a traditional DAC is connected directly to a power amplifier, volume control (assuming the DAC supports it) takes place at the DAC—usually in the digital domain. But the optimal place to control volume is right before the D-to-A conversion, which in the Technics scheme occurs inside the power amp. So why not put a volume knob on the amp? Because in systems where there’s no linestage or integrated amp, users expect to control volume at the source—in this case the SU-R1. The solution was to allow users to set volume on the SU-R1—via either its front panel knob, the remote, or the Technics Music App—but for actual volume adjustment to take place in the amp.

But that, in turn, meant that the SU-R1 had to send the SE-R1 not only music data but also metadata about the desired volume. SPDIF can’t do that. So Technics developed a proprietary interface called the Digital Link. A pair of Ethernet cables—one per channel to minimize inter-channel artifacts—carries both musical and level information from the SU-R1 to the SE-R1. (Note that the Ethernet protocol itself plays no part in this scheme; Technics chose the interface for its bandwidth.) This approach allows the user to interact with the system in a familiar way yet places volume control circuitry at its optimal location.

It’s worth pointing out that that big knob labeled “Volume” on the SU-R1’s front panel is deceiving. As noted, the SU-R1 doesn’t really control volume; it merely transmits volume commands to the SE-R1. As a result, if you connect the SU-R1 in the traditional (analog) way to a traditional power amp, you’re going to get maximum volume. I learned this the hard way. To quote Forrest Gump, that’s all I have to say about that.

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