T+A DAC 200/A 200 DAC/Preamp & Power Amp Consonant Coefficients

Consonant Coefficients

T+A's own synchronous upsampling algorithms are further refined in the DAC 200 with FIR Long, FIR Short, Bezier/ IIR, Bezier and two NOS (non-oversampling) modes. FIR Long and Short are traditional linear-phase types while the other pair are minimum-phase filters based on Bezier polynomials. 'FIR Long' [black, inset Graph with 1kHz-20kHz scale] betrays obvious pre/post ringing but has low phase distortion and excellent rejection of aliasing images (>100dB with 48kHz media). 'FIR Short' [red] has much reduced pre/post-ringing but also has a very limited 7.5dB rejection of out-of-band images and a steep treble roll-off of –3.6dB/20kHz. The mixed 'Bezier/IIR' interpolation filter [blue] behaves like a slow/minimum phase filter with no better suppression of stopband images than FIR Short, slightly increased phase distortion and a +0.8dB/13kHz treble peak. The NOS filters [green] offer almost perfect time domain behaviour – no ringing – but a rolled-off treble of –3.5dB/20kHz with CD and 48kHz media.

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Specifically, with 48kHz, 96kHz and 192kHz LPCM inputs, the DAC 200's frequency response(s) up to 20kHz, 45kHz and 90kHz, respectively, are –0.1dB, –1.0dB and –3.8dB (FIR Long); –3.6dB, –2.5dB and –3.8dB (FIR Short); –2.2dB, –30dB and –7.5dB (Bezier/IIR); –4.4dB, –5.1dB and –7.5dB (Bezier); –3.5dB, –3.5dB and –5.7dB (NOS 1); and –3.2dB, –3.5dB and –5.7dB (NOS 2). PM

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T+A elektroakustik GmbH & Co. KG
Germany
Supplied by: The Audio Business Ltd, Wilts, UK
01225 704669
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