Description

The SDA 2175 is a high-performance power amplifier designed without compromise. It can act as a controllable amplifier in Lyngdorf systems or as a power amplifier for conventional pre-amplifiers. 

The SDA 2175 is not your regular class D power amplifier. The output stage uses Pulse Width Modulation with a patented switch speed optimization technology. This ensures a low and linear natural distortion, and an unmatchable performance is achieved by using less feedback compared to typical Class D amplifiers.
And the fully balanced signal path all the way through the amplifier to the PWM conversion stage guarantees a remarkable performance with a signal-to-noise ratio superior to any other Class D amplifier in the market!

Careful and sensitive design touches can be seen throughout the amplifier: it starts at the mains input with a low-noise Holmgren toroidal transformer with power supply feed-forward compensation, suppressing the variations in the output rather than relying on feedback-based error correction normally used. This feed-forward technique originates from the design of the Millennium – the Lyngdorf state-of-the-art true digital amplifier.

In the critical output stage only the highest quality components have been used, e.g. polypropylene capacitors and linear ferrite material in the output filter. Combined with other techniques this results in low and frequency-independent distortion. Consequently wideband musical instruments can be re-played without any added harmonics – any source will be recreated to sound the way it was recorded.

Semi Digital Amplifier

“Semi Digital” is in Lyngdorf terms a “digital” switching amplifier driven by an analog input. In principle, the output stage of most switching amplifiers has the same working principle. PWM = Pulse Width Modulation is simply a matter of variable open/close time of the transistors.

Fully balanced signal path

The amplifier is fully balanced from input to output if driven with a balanced source, and if not driven with a balanced source, the signal is immediately transformed to a balanced signal.

The fully balanced design gives clear advantages regarding hum and noise suppression – also from other sources. And the balanced design is not only used in the signal path – even the feedback loop internally in the output stage is designed to be fully balanced.

The signal path is furthermore DC coupled to the widest extent – except from DC blocking capacitors in the input the construction is DC coupled through the rest of the construction leaving no discussion about capacitor quality.

In the analog signal chain only the highest quality components are used as Ultra low distortion Burr-Brown op-amps in the input stage and Polypropylene capacitors in the output reconstruction filter.