Krell S-275

The S-275 is a slim line stereo power amplifier boasting our latest advancements in circuit design featuring an impressive 275 Watts per channel into 8 Ohms and 550 Watts per channel into 4 Ohms in stereo mode. Setting the rear panel switch to mono operation, the S-275 boasts a massive output of 550 Watts into 8 Ohms and 1,100 Watts into 4 Ohms. Technologies developed for the Krell Evolution amplifiers including Krell Differential Current Mode circuitry, wide bandwidth topology, and surface mount technology have been incorporated throughout the design. Combining flagship technologies in an elegant presentation, the S-275 is the ideal choice for high impact systems where space is at a premium.

Digital power supplies sterilize music and rob it of its musical essence. In classic Krell fashion, a highlight of the S-275 is a 1,650 VA linear power supply. Coupled to 135,000 microfarads of filter capacitance, this power supply insures that the output stage and the connected speakers have exactly the right amount of power under all circumstances.

Each S-275 output channel employs fourteen high current power devices to deliver the exact power required by the speakers under any demand. Alone, the S-275 drives 275 Watts into 8 Ohms and 550 Watts into 4 Ohms. For the ultimate performance, monaural configuration increases the output to 550 Watts at 8Ohms and 1,100 at 4 Ohms.

Featuring circuitry sourced from the Evolution amplifiers, the S-275 includes technology previously incorporated in the reference level components only. The topology is executed with Krell Differential Current Mode circuitry for the lowest noise signal path. Class A input, pre-driver, and driver stages provide the most accurate signal path for critical low level signals. Surface mount technology is utilized for maximum circuit density resulting in the widest dynamic range and bandwidth possible. The amplifier circuitry also features very low negative feedback for improved clarity and detail resolution.

Each S-275 is only 8.6" wide allowing two S-275 amplifiers to fit in the same space normally occupied by one full size component. The S-275 includes 12V trigger input/output connections and a selectable -6dB switch for gain level matching. High performance WBT speaker binding posts and input terminations complete the elegant rear panel.

Inputs

- 2 balanced via XLR connector

- 2 single-ended via RCA connector

Outputs

- 2 pr. via WBT binding posts

Control input

- 1 12 VDC trigger input via 2-conductor 3.5 mm connector

Control output

- 1 12 VDC trigger output (30 mA maximum current) via 2-conductor 3.5 mm connector

Input impedance

- 20 kOhm (balanced or single-ended)

Frequency response

- 20 Hz to 20 kHz +0, -0.08 dB, stereo

- <0.3 Hz to 170 kHz +0, -3 dB, stereo

- 20 Hz to 20 kHz +0, -0.12 dB, mono

- <0.3 Hz to 155 kHz +0, -3 dB, mono

Signal-to-noise ratio

- >107 dB, wideband, unweighted, referred to full power output

- >115 dB, "A"-weighted

Gain

- Stereo: Selectable, 25.8 or 19.8 dB

- Mono: Selectable, 31.8 or 25.8 dB

Input sensitivity

- Stereo: Selectable, 2.40 V or 4.80 V RMS

- Mono: Selectable, 1.70 V or 3.40 V RMS

Total harmonic distortion

- <0.030% at 1 kHz, at 275 W stereo or 550 W mono, 8 Ohm load

- <0.20% at 20 kHz, at 275 W stereo or 550 W mono, 8 Ohm load

Output power

- Stereo: 275 W RMS per channel at 8 Ohm

- Stereo: 550 W RMS per channel at 4 Ohm

- Mono: 550 W RMS at 8 Ohm

- Mono: 1100 W RMS at 4 Ohm

Output voltage

- Stereo: 47 V RMS or 133 V peak to peak

- Mono: 66 V RMS or 188 V peak to peak

Output current

- Stereo: 20 A peak

- Mono: 26 A peak

Slew rate

- Stereo: 80 V/μs

- Mono: 120 V/μs

Output impedance

- <0.060 Ohm at 20 Hz, stereo

- <0.067 Ohm, 20 Hz to 20 kHz, stereo

- <0.14 Ohm at 20 Hz, mono

- <0.15 Ohm, 20 Hz to 20 kHz, mono

Damping factor

- >130 at 20 Hz, referred to 8 Ohm, stereo

- >120, 20 Hz to 20 kHz, referred to 8 Ohm, stereo

- >60 at 20 Hz, referred to 8 Ohm, mono

- >55, 20 Hz to 20 kHz, referred to 8 Ohm, mono

Power consumption

- Standby: 40 W stereo or 35 W mono

- Idle: 85 W stereo or 65 W mono

- Maximum: 1900 W

Heat output

- Standby: 140 BTU/hr stereo or 120 BTU/hr mono

- Idle: 290 BTU/hr stereo or 220 BTU/hr mono

- Maximum: 2800 BTU/hr

Dimensions

- 8.60 in W x 5.80 in H x 24.00 in D

- 218 mm W x 147 mm H x 610 mm D

Weight

- Unit only: 49 lb [22.2 kg]

- As shipped: 58 lb [26.3 kg]