- Written by Michael Galvin
- Published on 19 June 2008
Peter Lyngdorf is a high-end audio industry veteran. He is especially well known for his innovations in room correction with Tact Audio in the 1990s. Peter left TacT over 3 years ago to found Lyngdorf Audio. If you were familiar with Tact, browse through Lyngdorf's current product offerings and that will come as no surprise. From the split they share certain technologies including the Semi-Digital Amplification on which the SDAI2175 is based (They do not share room correction technology; Lyngdorf's RoomPerfect is proprietary).
"SDAI" stands for Semi-Digital Integrated Amplifier. Lyngdorf uses this term to define a switching amplifier driven by an analog input - the SDAI features a digitally controlled analog volume control, which differentiates it from a true switching integrated amplifier such as the Lyngdorf TDAI-2200. In addition the SDAI-2175 uses a fixed switching frequency of 400 kHz and has a fully balanced signal path.
Lyngdorf's website features a very accessible, in-depth explanation of the amplifier and the technology underlying it. Summarizing the design goal, Lyngdorf explains that the combination of both analog and digital technology results in a low distortion, neutral-sounding amplifier. Moving up to the fully digital TDAI is one of those "more of the same" upgrades as well as offering the option to include Lyngdorf's "Room Perfect" room correction processor in the same chassis.
- Design: Integrated Stereo Amplifier (Preamplifier and Power Amplifiers)
- Power: 200 Watts RMS x 2 into 8 Ohms, 375 Watts into 4 Ohms
- S/N: 113 dB
- Dimensions: 4" H x 17.8" W x 14" D
- Weight: 29 Pounds
- MSRP: $2,800 USA
Seemingly carved from a block of solid aluminum (either silver or black), the SDAI is not a flashy piece of hardware. Where some might see austerity, however, I see purpose and substance. The panels are fastened with Torx screws, and the sides of the unit are flanked by thin strips of black heat sinks. Perhaps surprising for a digital design, the amplifier did get warm on occasion. This never caused me problems or even concerns, but maybe someone out there cares, I don't know.
Overall, the thing is sleek - there are no knobs and the single row of buttons are nearly flush-mounted. The power button on the front is recessed. In a less-intuitive design, these choices may have resulted in some ergonomic weirdness, but here, the buttons are spaced perfectly and the click of the relay provides audible feedback when switching inputs, so those issues are non-existent for me. The SDAI also features an excellent full-function remote, obviating the need to even touch the amplifier. All the labels on both the SDAI itself and the remote are easy to read. The display allows for adjustable brightness of its very neutral yellow LED lighting.
The SDAI includes six pairs of single-ended line inputs, one pair of XLR balanced inputs, both a balanced and unbalanced set of pre-outs, and an unbalanced tape out. Internally, all unbalanced inputs are converted to fully balanced. The SDAI also features a wealth of customizable settings including input sensitivity, relative volume, default volume, maximum volume, and input naming.