Lyngdorf Audio SDAI 2175 - Manual (Page 5)

5
Introduction
Lyngdorf SDAI 2175 is a compact, high performance semi digital integrated switch-mode amplifi er utilizing
some of the circuit topologies originally developed for the Lyngdorf Millennium amplifi er. Due to the
switch-mode topology, with an effi ciency of up to 85%, the SDAI 2175 will provide its output power
with minimal heat dissipation. A massive power supply with a 650VA toroid transformer and more than
40000uF capacitors ensures that the SDAI 2175 can deliver the current to drive even the most demand-
ing loudspeakers.
The SDAI 2175 has 2 gold-plated XLR connectors accepting balanced input signals and 6 stereo inputs
with 2 gold-plated RCA connectors for unbalanced signals. The SDAI 2175 has a stereo tape out of the
selected line level input signal and pre out of the selected input signal after the volume control as either
balanced signal from the gold-plated XLR connectors or unbalanced from the gold-plated RCA connec-
tors.
The volume control is implemented as a high precision digital controlled analog attenuation in 0.1 dB
steps over a 100 dB range. Input selection is performed via precision relays with double gold plated
construction of the contact set. These kind of relays are normally only used in expensive measurement
equipment for high linearity and low losses.
All controls can be operated from the front panel via the logical user interface or by use of the remote
control. Or as an option the setup and operation can be performed via a PC interface.
The input signal is fed to the volume control circuit via an AC coupled true instrumentation type input
amplifi er. Except for this AC coupling, the SDAI 2175 is fully DC coupled with no bypass capacitors or DC
servos to degrade the performance. The protection circuitry in the SDAI 2175 shuts down the unit in case
of over-temperature, DC voltage on the outputs and too high output current. The amplifi er will resume
normal operation when the fault condition is no longer present.
A trigger output on a 3.5mm jack connector allows the SDAI 2175 to control one or more SDA2175’s
power condition.