SPEC Designer Audio - Positive Feedback

SPEC Corporation is a Japanese company founded by Mr. Shirokazu Yazaka, a former chief engineer at TEAC and Pioneer, to achieve one goal: to deliver tube sound using semiconductor technology. The RSA-V10 is its latest integrated amplifier in class D. This is its world premiere.

It seems that Class D amplifiers are no longer a case of a "rotten egg" that disgusts "real" audiophiles. There are a lot of good and very good devices of this type on the market, and the best of such amplifiers offer such good sound that it doesn't matter anymore what class it operates in, what amplifying elements it features and what logo appears on the amplifier's front. Unless... it is the SPEC logo.

This brand has a special place in my heart. That's the way it is and I can't help it. I know its director well, as well as his engineers—both the previous project leader and the current one—but, more importantly, I think I understand and share their philosophy of sound. And SPEC took on a difficult path, one for others to follow. To use class D power amplifiers in a high-end product, you had to be blunt and have a strong belief that what you do was right. Something else was also important—they had to know how to do it.

RSA-V10

SPEC amplifiers are expensive and not very big at the same time. This can be misleading during a quick inspection in the audio showroom, or during short visits to the website. Inside, however, one finds unique solutions developed in-house in cooperation with the best components manufacturers and supported by the experience of people who are true audio fanatics and had been building tube amplifiers all their lives. Yes, tube amplifiers are their reference point and I mean extreme designs featuring exotic and rare tubes, NOS oil capacitors and American speaker cables remembering the first sound movies.

Realizing that this is a job for the few, that ones needs to constantly look after such an amplifier, constantly change something in it, improve it, etc., that these are unique devices, and therefore very expensive, but wanting to share this sound with a larger group of music lovers, SPEC's amplifiers used new solutions in combination with techniques from the 1920s, 1930s, and 1940s. All devices of this company bear the "Designer Audio" description because they reflect the views on the sound of their designers, and the devices themselves are referred to as "Real-Sound Amplifier," which emphasizes the "truthfulness" of their sound.

RSA-V10 vs RSA-M99

People who designed and developed the RSA-V10 (from the left to the right)

Mr. Yasuhiro YAMAKAWA | Ms. Masami TAKEI | Mr. Tsutomu BANNO

I asked SPEC about the differences between the new amplifier and the slightly more expensive RSA-M99. It turns out that they are not too big at all:

The reason for developing the RSA-V10 is simple—SPEC was very pleased with the M99 performance, but some customers thought it was still a bit too expensive. So we decided to reduce costs and that's how V10 came to be. The changes include primarily a slight reduction in power supply and output power, as well as several changes as far as used components are concerned. So there are some differences between these two models, but they are not very dramatic.

The unit that we got for testing is really a pre-release one—the official premiere of the RSA-V10 is scheduled for June. The amplifier with serial number 000001 that we are testing is an almost finished product, and changes compared to the product that will be sold worldwide can only include the type of wood used to damp vibration. It features wooden elements made of Austrian spruce (boards) and Canadian maple (feet), but this can still change.

Features

RSA-V10 is an amplifier integrated with four line inputs—three RCAs and one XLR (balanced); the latter is added for the user's convenience, because the circuit is actually unbalanced. On the front panel there are two large, comfortable to use knobs—an input selector and volume control.

Both are illuminated with milky light (in the pictures it comes out as if it was amber, but in fact it is white). In earlier amplifiers of this company the backlight was blue. I must say that white is much more elegant and I like it very much. However, if this illumination bother any user, they can turn it off using the switch on the back panel.

Using the same switch one can transform the RSA-V10 from integrated into a power amplifier—the preamplifier section (attenuator) is then bypassed and signal is sent directly to the output stage. This function is intended for those who want to integrate the SPEC amplifier with a home cinema system—the RSA-V10 amplifier in such setup will work as a power amplifier for the front channels. And going back to the front of the device let me add that there are also two light-emitting diodes (LEDs)—white, which is a power LED, and red one, which indicates the activation of the protective circuit. Next to it there is a mechanical switch with a fantastic locking system.

One will not find a remote control in the box with the amplifier. This is because the company's engineers believe that the control circuit placed inside an amplifier interferes with its operation. Therefore, an external remote control is available, with radio signal transmission, which is connected to the amplifier with a mini-jack cable. The receiver is placed next to the amplifier - it's a small box made of aluminum and wood. The control system (remote control plus receiver) is sold separately.

Class D

SPEC amplifiers work in the analog class D. In the company materials you can find a graph that shows the progress that has occurred according to it: from tube amplifiers referred to as "generation 1" through classic semiconductor amplifiers, or "generation 2," up to new class D amplifiers, being the 3rd generation of amplifiers in general. It's interesting because the company engineers belong to the tube aficionados club and they own many fantastic tube amplifiers. So the point of this "generations scheme" was about something else, namely, about transferring the sound they know from their sleek, esoteric tube designs to more affordable ones.

To achieve this, the company has made several key decisions that set it apart from other manufacturers. First of all, the usage of linear power supply and is based on an R-core transformer. Secondly, the modulator was developed jointly with the American company International Rectifier. This is the IRS2052SM system, controlling a pair—per channel—of tiny, extremely linear, MOS-FET transistors, thanks to which it was possible to achieve an output of 50 W at 8 Ω and 100 W at 4 Ω. And finally, in the power supply and output stage they used selected capacitors, including rare Arizona Capacitors oil capacitors manufactured based on an old specification of Western Electric products.

What's more, the amplifier is treated as if it used tubes, i.e. the vibration damping is taken very seriously. It would seem that this is not the case, that in the case of class D amplifiers there is nothing to worry about. The truth is different—in all impulse circuits, power supplies and amplifiers, the high frequencies they work with make them extremely sensitive to vibrations.

SPEC dampens chassis of its amplifiers with wood saying that they follow in footsteps of a luthier building musical instruments. Such a "package" consists of three elements: a large board that is screwed to the bottom of the chassis, a wooden crossbar that is screwed to the front edge, and three feet—two at the front, attached to the crossbar and one at the back, attached to the board. During development process they listen to each model specifically to choose the best type of wood for these elements to be used in it.

So we have is a modern amplifier working in the analog class D, but with solutions sourced from tube designs. We are the first magazine in the world to test this model, actually before its official premiere, because it will not be released until June.

HOW WE TESTED IT

The RSA-V10 amplifier requires proper vibration damping. So it was placed on the Acoustic Revive RAF-48H pneumatic platform, which was placed on the top shelf of the Finite Elemente Pagode Edition rack. In addition, I placed the Nordost QPoint module on its top. The amplifier was powered by a Siltech Triple Crown cable.

I used two sources:

Analog - Miyajima Labs Destiny cartridge + SAT LM-09 tonearm (9") + TechDAS AIR FORCE III turntable → RCM Audio Sensor Prelude IC phonostage → Crystal Cable Absolute Dream interconnect,

Digital - Mytek Brooklyn Bridge → Acoustic Revive RCA-1.0 Absolute.

The signal was sent to the Harbeth M40.1 speakers using the NOS Western Electric WE16GA speaker cable, on which I installed ferrite elements, which are delivered together with the set by the manufacturer. During the test I used SPEC REAL-SOUND Processor RSP-AZ9EX modules connected to the loudspeakers.

SOUND

Recordings…

Frank Sinatra, Swingin' Session!!!, Capitol Records/Mobile Fidelity MFSL 1-407, "Special Limited Edition | No. 346," 180 g LP (1961/2012)

AC Records – Two For Two: "Godzinki" & For D," AC Records ACR 016, "AC Records Acoustic References For Audiophiles," 12"/45 rpm, Test Pressing LP (2020)

John Coltrane, Giant Steps, Atlantic/Rhino R1 512581, "Atlantic 45 RPM Master Series | No. 2335/2500," 2 x 180 g, 45 rpm (1960/2008)

Dire Straits, Brothers in Arms, Vertigo/Mobile Fidelity Sound Lab MFSL-2-441, "Special Limited Edition | No. 3000," 45 RPM, 2 x 180 g LP (1985/2014)

The Beatles, Sgt. Pepper's Lonely Hearts Club Band, Apple/Gold Note DT-01, "Limited Edition | No. 82," (1967/1998)

TIDAL

Beethoven, Triple Concerto, wyk. Anne-Sophie Mutter, Yo-Yo Ma, dyr. Daniel Barenboim, Deutsche Grammophon/Tidal MQA 24/48 (2020)

Dus Lipa Future Nostalgia, Tidal MQA Studio 24/48 (2020)

Kurt Elling, Secret Are The Best Stories, Edition Records/Tidal MQA Studio 24/96 (2020)

The Weekend, After Hours, Tidal MQA 24/44,1 (2020)

Tony Allen & Husge Masekela, Rejoice, World Circuit/Tidal MQA Studio 24/96 (2020)

This is not a conspiracy or even a "set-up", but the latest SPEC amplifier sounds in an incredibly similar way to my system, consisting of the Ayon Audio preamplifier and the Soulution power amplifier. Of course, we are talking about sound with lower resolution, lower dynamics and not as vivid as in the case of my reference setup. Yet, the differences are not staggering, because what was the most important factor for me was the balance of all these elements, their "order" in the sound in the tested amplifier that were very similar to what I know from my system. As if we, me and SPEC engineers, shared a common goal.

So what I heard was a bit warm, but it was a warmth coming from density, not from treble roll off, presentation. The RSA-V10 amplifier sounded dense and full. The drums of Tony Allen from the Rejoice album, which I mentioned in the review, sounded in a swinging way, but with a broken rhythm, which is so characteristic for this album. Hugh Masekela's flugelhorn was slightly darker than with my system, but only just a bit. It was also placed slightly closer to me. Importantly, the fullness of this recording and its dynamics were well shown.

Listening to commercial recordings, whether Dua Lipa from her new album Future Nostalgia, available on Tidal in MQA Studio files, or also the new, Weeknd album entitled After Hours, I noticed that the Japanese amplifier gently, but still smoothed the presentation. You can hear it in both, rhythmic and timbre aspects of the music. The changes are small, but important, because they show the "SPEC world" from its best side. Switching to the V10 from my system, I felt as if I had switched from the "master" tape to the LP.

Both recordings are highly compressed—the display of the Mytek Brooklyn Bridge file player showed that they almost constantly have the maximum level at the peak, and the average value is only lower by 1 or 2 dB. But this is mainstream music. But also perfectly produced and played—this is the first league of popular music (pop) of the 21st century. Also, I like both, the Dua Lipa, that my daughter presented to me once, playing a music video for one of her songs, as well as Weekend, whose album Starboy was brought to me by my son when he was still working for the RMF radio to "check it out."

Such highly compressed recordings sounded very nice with the tested amplifier, because the rhythm was preserved, there was also proper drive, but the brightening and hardening in the vocals' voices were tuned down, leaving good vividness and strong bass. And these three elements, I think, speak the most about the RCA-V10: timbre, vividness, bass.

Oh, how obvious it was the reissue of the Brothers in Arms by Dire Straits on the Mobile Fidelity version on two 45 rpm discs. It features a "tuned up" bass, but otherwise it is brilliantly dynamic and coherent. As you know, the album was recorded on the Sony DASH PCM-3324 digital tape recorder and ripped to a ½" stereo analog tape on a mastering tape recorder, in a different studio. This combination resulted in a unique sound—clean, accurate, but also dense and rich.

Sometimes, however, slight hardness can be felt in it—the A/D and D/A converters used in Sony tape recorders were not the pinnacle of technology. The SPEC amplifier slightly smoothed these hardnesses and extinguished the sharpness of the cymbals. As a result I got a brilliantly fluent, large sound. Because it is a big sound, powerful, rich, and big scale performance. The bass is not ultra-precise, it does not have any outstanding selectivity, in which it resembles the sound of KT150-based tube amplifiers.

Because, by the way, the sound is largely "tube-like"—with the tubeiness of the Kondo Overture II amplifier. So artistic and one in which nobody kills for precision or selectivity. Direct sounds are more important here than reflected ones and reverbs, which is why Sting's vocals, usually located quite far behind the speakers, was placed bit closer. But the guitars, spread out on the sides and fleshy, were presented exactly this way—dense and fleshy.

Staying with the 45 rpm reissues, I listened to John Coltrane's Giant Steps. Released by the Atlantic Records in 1960, the album was re-issued on its fiftieth anniversary by Rhino Records and pressed on two discs; lacquer was cut from the original "master" tape. One can already find yet another remaster in stores, this time celebrating its 60th anniversary. Anyway, SPEC played it brilliantly, because although it slightly cooled the dynamics, but really only slightly, and extinguished the "air" between the performers a little, it presented beautiful colors, great swing and performers' enjoyment, which one can clearly feel on this album. It was a great experience.

In today's terms, the amplifier offers a relatively small rated power of 50 watts per channel, especially in the context of a class D amplifier, it is not much. But if we take another look at the specification, we will see that its 50W @ 8 Ω, for 6Ω it turns into 75 W, and at 4 Ω it goes up to 100W. That means, that the power supply adapts perfectly to power consumption—you can see that the amplifier has "rigid" power supply.

And that gives you much more than just raw power. It offers effortlessness and smoothness, gives fluidity to the presentation. And that's how this amplifier sounds like. This was also obvious with the fantastic Frank Sinatra album entitled Swingin' Session!!! from 1961, again on the Mobile Fidelity reissue. It has a low tonal balance, which the Miyajima Labs Destiny cartridge emphasized in the lower midrange, and which the amplifier even further enhanced. But it didn't "spoil" anything, it didn't distort anything. It simply emphasized the good features of this sound, enhancing sometimes the tonality and sometimes transients at the bottom of the band.

SUMMARY

The SPEC RSA-V10 amplifier delivers a spectacular sound. Of course, for those who know what they want and are not fans of super-taut, precise bass and lightning fast treble. It presents fantastic vocals, because they are big, with beautiful timbre. Their bodies are not remarkably three-dimensional, but it's just not this type of an amplifier. It focuses rather on general, big picture than micro details and on the atmosphere and consistency of all elements of the sound.

It should be a dream come true for jazz and classic lovers, as long as they are aware of its limitations. Rock will also be treated royally, but it will lack punk revolt and madness. Not for everyone, but for those who will like it it will be like a Christmas present, like a card from a loved one from the other end of the world. This is a beautiful amplifier from the people with beautiful souls.

DESIGN

Front and back

RSA-V10 is an integrated solid-state amplifier working in class D. It features four line inputs, three of which are unbalanced (RCA) and one is balanced (XLR). There are no line outputs, only speaker one with gold-plated sockets.

The chassis is made of thick steel sheets and the front is made of aluminum. In the front there are two large knobs illuminated around the perimeter. On the back there is a switch that can remove the backlight, and in the third position it turns the integrated amplifier into a power amplifier. Use the left knob to select an input and the right one to adjust the volume. On the right side there is an on/off switch. This is a fantastic element with a latch that prevents the device from being accidentally turned off. Next to it there are two LEDs—a white one, indicating the operation of the amplifier, and a red one, indicating the activation of a protective circuit.

Wooden vibration damping elements are installed from below. They are produced for SPEC by one of the furniture companies from Japan—Oak Village. On the front crossbar, from below, we can find the burnt brand mark of this manufacturer.

Inside

SPEC amplifiers feature clearly separated modules inside. The basis of the device is a large, shielded R-core transformer with several secondary windings. High-quality Nichicon electrolytic capacitors, as well as their variation, developed jointly by Nichicon and SPEC, contribute to the suppression of power grid ripples. On their casing we can find Japanese Kanji characters—HIBIKI-ICHI, where "HIBIKI" means "vivacity" (naturalness, credibility, etc.) of the sound. And there are also Arizona Capacitors oil capacitors there.

The modulator was placed on a small PCB, and this one is plugged into a larger one. On the larger board there is an integrated circuit with a resistor ladder and coils—with a toroidal core—which are part of the output filter. The attenuator bears the name of its manufacturer - Tachyonix Corporation—and its symbol—3310IR01. This is an element manufactured by this Japanese company under the International Rectifier license, based on the 3310S06S model. The whole circuit is shielded.

I mentioned the coils in the output - this is the part of the circuit in which the impulse signal is converted into a sine wave. It turns out that this is one of the key elements of this type of amplifier. That is why SPEC has been experimenting with its second element for years, namely with capacitors. Instead of one, they select several of various design, checking the sound during listening sessions. These capacitors are mounted on a separate board and shielded.

The tested amplifier features three different capacitors in the output of each channel:

oil, by the American company Arizona Capacitors, modeled on the Western Electric model known from the 1960s,
mica, produced for SPEC, belonging to the MC-DA series. They are made of laminates, which is supposed to reduce inductance, and the material comes from India, it is the best mica cap of this type, "ruby mica". The electrodes are made of sputtered silver,
polypropylene.

The amplifier looks quite modest, but its design is extremely advanced. This is a great example of how one can combine modern and traditional elements in an artistic way.

Technical specifications (according to the manufacturer)