KRELL KSA-50S

Commentary

KSA-S Series small output stereo power amplifier.

The basic design is the same as the upper model of KSA-S series, but it does not come with a remote control.

It uses newly developed サスティーンド Pre-to-Bias Technology to solve the power and thermal issues of pure Class A operation.
In the KSA-50S, bias levels are set in three stages to ensure pure class A operation according to the input signal from idling to maximum output. This circuit enables high power and pure class A operation at the same time, improving thermal efficiency and saving power.

A newly developed high-speed (1,800 V / μ sec) アンティシペーター circuit is used for the bias level setting circuit in order to cope with instantaneous input changes caused by music signals with a margin. This circuit enables the bias setting at a speed approximately 200 times that of the music signal to cope with the instantaneous rise of sound. By maintaining this level for a certain period of time, the instability caused by constant bias fluctuations is eliminated.

The power supply section employs a 800 VA strong toroidal transformer and a 72,000 μ F large capacitor.

The circuit configuration is fully balanced up to the output-stage, and all stages are directly connected to the amplifier with a complete complimentary service circuit. In addition, the high-current output-stage and the power supply are directly connected to the busbars made of copper-beryllium alloy alloys with gold-plated surface to minimize impedance fluctuation to 0.

The KSA-S Series uses a high-current, low-impedance TO-3 can-type transistor, which has not been produced in the Japanese market due to cost issues. This transistor has been manufactured in cooperation with Motorola to meet Kroell's specifications.
In addition, the resistor uses a metal film resistor of very strict military standard with deviation value within 1%.

There are two types of speaker terminals for bi-wiring.

The input terminal is equipped with 2 systems of pin type and XLR balance type.

Equipped with a circuit breaker.

Model Rating

Type	Stereo power amplifier
Continuous Output (20 Hz ~ 20 kHz)	400W + 400W (1 ohm) 200W + 200W (2 Ω) 100W + 100W (4 Ω) 50W + 50W (8 Ω)
Total harmonic distortion factor	0.018% or Less (1 kHz) 0.18% or Less (20 kHz)
S/N ratio (A)	100 dB or more
Input Sensitivity / Impedance	1.34V/47k Ω
External dimensions	Width 483x Height 222x Depth 377 mm
Weight	28.5kg