KRELL KSA-100mkII

Commentary

Stereo power amplifier with pure A-class operation.

The internal configuration is a twin monaural system with completely independent L/R. The power switch and AC cord are used in common. The left and right channels are completely independent except for the power switch and AC cord, and two monaural amplifiers are contained in one chassis.

The circuit employs a pure complimentary service circuit that takes into consideration not only the simple amount of harmonic distortion but also the appearance of the distortion mode which is affected by the sense of hearing. The NFB is suppressed to 15 dB due to the importance of dynamic characteristics.
Heat generation, which is a problem in pure A-class operation, is solved by configuring the power block with a heat sink and an extremely quiet cooling fan. This allows the temperature of the power block to be strictly controlled from 75 to 80 degrees Celsius, reducing thermal distortion.

The power supply consists of two 1.1 kW class toroidal transformers and a total of 160,000 μ F capacitors. It is equivalent to a 400W class amplifier for general B-class operation.
This configuration is robust against load fluctuations during actual operation of the speaker, and can stably deliver 800W + 800W power as calculated even when the impedance drops to 1 Ω.

Model Rating

Type	Stereo power amplifier
Rated output	100W + 100W (8 Ω, both channels operating, 20 Hz to 20 kHz)
Input Sensitivity / Impedance	1V/22k Ω
Total harmonic distortion factor	0.05% or Less (20 Hz to 20 kHz, 1W to Rated Output)
Frequency characteristic (1W ~ Rated Output)	0.5 Hz to 100 kHz -3dB 20 Hz to 20 kHz -0.5 dB
Signal-to-noise ratio (IHF-A)	110dB
Rated load impedance	1 Ω or more
Damping factor	120(1kHz)
Slew rate	80 v / μ sec
Pwer	100 VAC, 50Hz/60Hz
Power consumption	610W (maximum idling)
External dimensions	Width 483x Height 226x Depth 612 mm
Weight	Approximately 35 kg