KECES S300+ – power amplifier for demanding speakers

KECES S300+ is a power amplifier for those who have a good preamplifier and want power and control even for demanding speakers. 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 amps peak per channel.

With a damping factor of 4000 and stability at impedances below 2 ohms, KECES S300+ is designed to maintain control when the speakers place heavy 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 with 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 KECES S300+ is its ability to deliver current and control the speaker drivers. KECES states a peak capacity of 45 amps per channel and a damping factor of 4000 at 20 Hz.

This is particularly 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 during impedance dips below 2 ohms and is therefore not intended only for easy-to-drive speakers.

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

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 maintain its character in the transition to Class AB.

Dual-mono design with a 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 a JFET input stage with a MOSFET driver stage. Compared to the previous S300, KECES has increased the damping factor from 1500 to 4000, upgraded internal materials, and fitted WBT-0703Cu speaker terminals.

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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