User's Manual

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User’s Guide ADI-2 DAC v2.2 © RME
31.4 DA Impulse Responses
Short delay Sharp Sharp
Short Delay Slow Slow
The screenshots above show the analog output signal of the DAC filters, stimulated by a digital
single sample impulse at 44.1 kHz sample rate. While Slow has the most perfect response, it
looses around 1.2 dB already at 15 kHz, see chapter 31.4. Both Short Delay are IIR filters, the
other two are FIR type. FIR is phase linear over the whole frequency range.
NOS (Non-Oversampling, SuperSlow)
The DAC includes another filter which is called Super Slow in its data sheet. The impulse re-
sponse looks perfect, but checking the output signal with an Oscilloscope reveals steps that are
more typical for so called Non-OverSampling (NOS) devices, so we renamed it NOS within the
DAC filter menu. Note that there is no audible distortion, the steps equal high frequency har-
monics that are mostly higher than 20 kHz. Please also note that Slow and NOS filters cause
much more aliasing into the audio band and out-of-band noise than Sharp filters.