KRELL KSA-250
¥ 1,250,000 (released in 1989)
Commentary
A stereo power amplifier designed to take advantage of a variety of program sources.
The KSA-250 and KSA-150 are identical in basic circuit configuration and used elements. Only the size and power value of the amplifier are different.
In addition, the KSA-250 uses gold plated solid copper bars for all internal wiring in order to cope with high output, and no wiring is used.
The KSA-250 is always focused on class A operation. It is based on the orthodox class A operation design that allows sufficient idling current as in the past combined with the latest variable bias technology to eliminate the cooling fan.
The circuit configuration is balanced transmission and balanced drive. The balanced transmission is achieved by providing balanced input as well as unbalanced input for the input, and the drive circuit is fully balanced drive in which the + side and - side of the signal are independent.
Two pairs of output terminals are provided for each channel, allowing for bidirectional connection.
Kroell's outstanding heat-resistant structure and thermal control technology ensure that the elements and parts used are always kept at the optimum temperature. As a result, we have achieved high performance and long device life.
We have also developed and adopted a dedicated self-adjusting bias circuit and DC offset to ensure stable operation of the amplifier.
A series of opto-coupled circuits constantly monitor the operation of the amplifier and protect the amplifier and speakers from DC power failure, short circuit, oscillation, and AC power failure.
The protective circuit is also designed to prevent damage caused by defective parts, wiring, equipment malfunction, and main body failure.
The output power of KSA-250 is described as 250W/8 Ω, but actually it is possible to take out the power of 320W/8 Ω.
The speakers are also designed to drive safely in low-impedance conditions.
The specifications of the KSA-250 could be changed to a monaural amplifier. With this change, the KSA-250 can be used as the MDA-500.
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Model Rating
| Type | Stereo power amplifier |
| Output | 500W + 500W (4 Ω) 250W + 250W (8 Ω) |
| Input sensitivity | 2.45V |
| Input impedance | 47k Ω |
| Frequency characteristic | 5 hz ~ 85 khz -3dB (Power Band Wide) |
| Total harmonic distortion factor | 0.1% or less |
| Signal-to-noise ratio | 96 dB or more |
| Damping factor | 150 |
| Power consumption | 900W maximum power consumption |
| External dimensions | Width 482x Height 215x Depth 620 mm |
| Weight | 58kg |