Unison Research S6 Black Edition

The S6 Black Edition is built for demanding listeners: a 40 W pure Class A tube integrated with three paralleled KT77 Gold Lion output tubes per channel, and three digital inputs included as standard. Unison Research says the power is 15% higher than the standard S6.

Six KT77 tubes, in Class A, with the bias set by hand.

The Design

To improve the S6, Unison Research gathered its strengths and pushed further toward higher sound quality. The circuits were revised in the signal path and in power management, going beyond what the S6 New had already achieved. The biasing of the output power tubes was completely redesigned to eliminate the cathode capacitor and resistor. The input selection circuit uses the same technology as Unison Research's most prized products, with extreme attention to ground paths and channel separation, and where possible the audio signal travels inside quality coaxial cables.

The output stage places three KT77 Gold Lion tubes in parallel for each channel, biased in pure Class A in the ultralinear region at 20%, and each power tube has its own individual bias adjustment. Two ECC83 Gold Lion tubes handle the signal stage, and a relay selects the inputs. The power is 40 W into 6 ohms, with a bandwidth of 15 Hz to 30 kHz (-1 dB).

Inputs and Connections

There are four RCA line inputs plus USB, S/PDIF, and Toslink digital inputs, which every Black Edition amplifier includes as standard. A stereo RCA subwoofer output completes the connections.

Where It Fits

Choose the S6 Black Edition when you want the most from Unison Research's tube integrated range, with plenty of drive for most loudspeakers and the convenience of built-in digital inputs. We're happy to help you decide between the S6 Black Edition, the Triode 25 Black Edition, and the Simply 845.

Press Recognition

Reviews of the S6 Black Edition are on the way. Unison Research, founded in 1987 in Treviso by a group of audiophiles led by Giovanni Maria Sacchetti, is recognized as Italy's leading maker of tube amplifiers.

Questions about speaker matching, or how the S6 Black Edition compares with the other Black Edition models? Give us a call.

Specifications

• Type: Tube integrated amplifier
• Output power: 40 W into 6 ohms
• Signal tubes: 2 x ECC83 Gold Lion
• Output stage: 3 x KT77 Gold Lion in parallel per channel
• Bias: Pure Class A, ultralinear at 20% (power tubes); adjustable individually for each power tube
• Input selector: Relay
• Bandwidth (-1 dB): 15 Hz to 30 kHz
• Inputs: 4 RCA line; 1 USB; 1 S/PDIF; 1 Toslink
• Outputs: 1 stereo RCA subwoofer
• Dimensions: 35 x 49 x 22 cm
• Weight: 25 kg
• Maker: Unison Research, handcrafted in Italy