SALON AV: S.A.LAB Black Knight 2023 Integrated Amplifier

Март 08, 2023
Article on the reviewer's resource

We recently put to test a completely new product of Alexey Syomin's laboratory, literally red hot off the skillet. And, in the truest sense, the amplifier on MOSFETs works in class "A", so it runs hot a good deal. Both the circuitry and the design are traditional for the brand, proprietary and uncompromising.

As always, we will show you the internal structure of the amplifier and evaluate its musical abilities.


To be honest, we barely have time to review the projects of Russia's Sound Analysis Laboratory (S.A.Lab) as they appear with such speed in its catalog. And these are not some experimental models, but finished serial products, debugged, tested and designed externally according to the highest standard in the corporate style of the Laboratory.

I have always been struck by the variety of Alexey's approaches to the design of amplifiers, in which both electronic lamps and transistors of various types, including SITs sieves and germanium, were used as active elements. Alexey is completely free to choose the means to achieve his ideal, which is why his technique is of particular interest.

The new product that we are preparing to listen to is based on the popular audiophile MOSFETs, but the design is, as always, quintessentially the author's.

Own view of the classics

The motive behind the creation of Black Knight was the desire to make a transistor analog of the tube Thunderbird in a way that the sound style of both models was similar. The S.A.Lab catalog already has a pair that is similar in essence, but simpler — the pentode integrated amplifier Blackbird and its classmate White Knight on SITs (transistors with static induction).
Alexey admits that he has been racking his brains for a long time about which circuitry to choose and, after going through a lot of experimental options, found out that the best, from the point of view of sound identity, is a circuit with a single end driver on a MOSFETs and a push-pull output stage also on MOSFETs operating in class A. For this purpose, a complementary pair of Toshiba 2SK1530/2SJ162 was chosen — an audiophile classic, on which the top models of Japanese amplifiers of the 80s and 90s were built. The distortion spectrum of these MOSFETS is beautiful: at a drain current above 250 mA, the harmonic amplitude begins to decrease, and at 380 mA (in the used batch of transistors), an almost achievable minimum is reached. In each shoulder of the Black Knight output stage, three transistors work in parallel, and the total quiescent current, taking into account the driver, turned out to be 2.56 A. This gives 41 W in Class A at 8 Ohms, and in class AB the amplifier gives 350 W at 4 Ohms.

«A complementary pair was chosen for this purpose Toshiba 2SK1530/2SJ162 — audiophile classics, on
which the top models of Japanese amplifiers of the 80s and 90s were built.»

The amplifier is designed to work with five linear sources, and two of them can be connected with balanced lines. You can select the desired input either from the front panel or by using the remote control. Switching of sources and volume control is carried out using bistable relays with high-quality contacts. The input number and volume level in decibels are displayed on the indicator in the center of the round screen. Through a separate DIRECT input, the signal is fed to the terminal amplifier bypassing the volume control — this mode can be useful when integrating the device into a home theater system.
Black Knight has three linear outputs, one of which is balanced on XLR.

There is also an operating time counter on the back panel, although the amplifier will not require changing tubes or any other prevention over time.

The exterior finish of the amplifier is traditional for elite S.A. Lab models: the front panel is made of artificial stone, the steel body is painted with auto enamel of various colors. On request, an individual color option can be ordered, selected from the RAL table.

Under the hood

It's now time to get acquainted with the internal layout of the amplifier. I should note that with the lid removed, it makes a very strong impression — a two-story chassis, huge heat sinks anodized in gold, neat installation... However, you can see for yourself.
All outputs and inputs in the amplifier are from transformer, even those on RCA connectors. This is a fundamental decision of S.A.Lab.
The internal backlight signals the status of the amplifier: green in operating mode and red when overheating and protection is triggered.
A single-channel amplifier's output stage. The total quiescent current is more than 2.5 A at a supply voltage of ± 50 V. The power dissipated by the heat sinks is dependent on their size. In the Standby mode, they actually heat up to 80 °C — we measured this with a non-contact thermometer.
Each channel of the amplifier has three MOSFETs 2SK1530/2SJ162 with a power of 150 watts each.
On the lower floor, power supplies are mounted, independent for the right and left channels. Each of them has a 600-watt toroidal transformer (real dual mono) and filter capacitors with a total capacity of 200,000 μF.
General layout of the Black Knight. The fan cools off the radiator of stabilizers in the power supply. The weight of the amplifier is about 58 kg.

All-round puzzles

I must admit that, before listening, I had only general ideas about the design of the amplifier and did not know anything about circuitry or output power. The intrigue was further aggravated by the fact that it was absolutely impossible to determine by ear whether the tube or transistor device was playing — it was very easy to be deceived.

«The dynamics and accuracy of the sound were "transistor-like", and the emotionality and ability to captivate with music were like from an expensive tube amplifier.»

Both at exhibitions and in his office, Alexey demonstrates his amplifiers, using studio tape recorders as sources — so that you can assess the real dynamic potential. And this time we listened to copies of master tapes 38/12, which were played on Otari MTR-12, through Sonus Victor Mezzaluna speakers. So, dynamics and accuracy of the sound were "transistor-like", and the emotionality and ability to captivate with music were like from an expensive tube amplifier. In fact, this is a very rare combination, and now I will explain why. In order for the tube amplifier to better control the acoustics, i.e. in order to achieve the same accuracy, you have to introduce global feedback (FB) into it, which kills the naturalness of the sound. And, on the other hand, in order for a transistor amplifier to sound like a good tube amplifier, the FB is excluded from it (turns out, without the so-called lossless amplifier), but at the same time worsens load damping. This fuels endless debate about which amplifier is better and whether feedback is needed in it.
In Black Knight, there is no general feedback from the lyrics at all, and the desired sound character is achieved in two ways. Firstly, 2SK1530/2SJ162 have all the advantages inherent in transistors, but the characteristics of volt-ampere. Secondly, a single-ended driver adds a melodious second harmonic to the amplifier, dominating the spectrum of single-ended tube. Together, we have real transistor power with the intimate beauty of Ongaku, which instantly leads sophisticated listeners into a stupor. Yes, we hear music, beautiful, but without coloration and disturbances in the timbre nature of the instruments, and at the same time with completely tremendous dynamics and perfectly controlled bass.

«The voice is transmitted in such a way that the playback can be substituted for a live performer, and no one will notice the difference.»

At the same time, the level of distortion of the amplifier is extremely low, as evidenced by the exceptional naturalness of the timbres of acoustic instruments, as well as the sound of large and small cymbals (hi-hats). The voice is transmitted in such a way that playback can replace a live performer, and no one will notice the difference. And in general, Black Knight is great for demonstrations, during which listeners are asked to guess when real musicians are playing, and when a recording is played — in this regard, the new "Knight" is a real hoaxer, capable of confusing even a very experienced audiophile.

S.A.Lab (Russia)
Circuitry: push-pull, class AB
Analog inputs: 4 x RCA, 2 x XLR
Analog outputs: 2 x RCA, XLR, 8 acoustic binding posts
Frequency response: 20 Hz - 200 kHz (±0 dB)
Output power: 175/350 W (8/4 ohms)
THD: 0.01% (100 W, 1 kHz, 4 ohms)
Intermodulation: 0.008% (100 W, 1 kHz, 4 ohms)
Signal-to-noise ratio: -112 dB
Rated sensitivity: 1.4 V
Finish: artificial stone, auto enamel 12 colors
Power consumption in Standby mode: <12.5 W
Dimensions (L x H x D): 480 x 280 x 500 mm
Weight: 58 kg
Price: 1,200,000 rubles.


• Source: Otari MTR-12 Studio tape Recorder
• Sonus Victor Mezzaluna speakers
• Cables: S.A.Lab