KECES S300+ – power amplifier with power and control

KECES S300+ is a power amplifier for those who already have a good preamplifier and want power and control. It delivers 2 x 130 watts into 8 ohms and 2 x 225 watts into 4 ohms, while also offering current reserves of up to 45 amperes peak per channel.

With a damping factor of 4000 and stability at impedances below 2 ohms, the KECES S300+ is designed to maintain control when the speakers place high demands on the amplifier. If you choose High Bias, the first 5 watts are delivered in pure Class A before the amplifier gradually transitions to Class AB. This combines finesse at normal listening levels with power reserves for dynamic passages.

Highlights

• Stereo power amplifier
• 2 x 130 watts continuous into 8 ohms
• 2 x 225 watts continuous into 4 ohms
• Up to 45 A peak current per channel
• Damping factor of 4000 at 20 Hz
• High Bias Class A/AB operation
• First 5 watts per channel in Class A with High Bias
• Stable at speaker impedances below 2 ohms
• Dual-mono design
• JFET input stage and MOSFET driver stage
• 1.2 kVA toroidal transformer
• 65,600 µF Rubycon filter capacitance
• XLR and RCA inputs
• WBT-0703Cu speaker terminals
• Stereo, bi-amp, and bridged operation
• 410 watts into 8 ohms in bridged mode
• 12 V trigger

A power amplifier for demanding speakers

One of the key characteristics of the KECES S300+ is its ability to deliver current and control the speaker drivers. KECES specifies a peak capacity of 45 amperes per channel and a damping factor of 4000 at 20 Hz.

This is especially relevant with speakers whose impedance varies across the frequency range and where the amplifier needs a firm grip on the bass drivers. The S300+ is designed to remain stable at impedance dips below 2 ohms and is therefore not intended only for easy-to-drive speakers.

HiFi Pig highlights, among other things, the amplifier’s control, articulation, and effortless delivery as some of its strong points.

Class A for the first watts

KECES S300+ lets you choose between High and Low Bias. With High Bias, the first 5 watts per channel are delivered in pure Class A. When more power is needed, the amplifier gradually transitions to Class AB.

This creates an interesting combination, because normal music listening often requires relatively modest power, while dynamic passages and higher volume levels can place significantly greater demands. Here, the S300+ has up to 225 watts per channel into 4 ohms available.

HiFi Pig describes the High Bias setting as smooth, effortless, and natural, while also highlighting the S300+’s ability to retain its character in the transition to Class AB.

Dual-mono design with large power supply

KECES S300+ is built according to the dual-mono principle with separate power supplies for the left and right channel input, driver, and output stages. The large 1.2 kVA toroidal transformer has independent secondary windings for each channel, while 65,600 µF Rubycon capacitors provide the energy reserve for the output stages.

The signal path is directly coupled without capacitors or coils, and the design combines JFET input stages with MOSFET driver stages. Compared with the previous S300, KECES has increased the damping factor from 1500 to 4000, upgraded internal materials, and fitted WBT-0703Cu speaker terminals.

The S300+ can be used as a regular stereo power amplifier, for bi-amping, or in bridged mode, where it delivers 410 watts into 8 ohms. You can therefore also add another S300+ later and use the two power amplifiers as monoblocks.

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