Above: Reference, Input 1 kHz Test Tone (192 kHz 24 Bit Audio File)
Conditions: input level -0.1 dB vs. digital full scale, AIFF uncompressed file with 1 kHz 24 bit test tone (note: the FFT Cosine window used causes broadening of the peak, the reason why the peak doesn't reach full scale on the display. This is normal behavior for a windowed FFT.)
Above: After applying Pure Vinyl Precision 64 Bit RIAA and Pure Vinyl's zero-phase-shift "rumble" (high pass) filter
Compare with the first spectrum; this shows that Pure Vinyl's 64 bit RIAA (and rumble) filter contribute no distortion. (Pure Vinyl's rumble filter cutoff frequency is adjustable from 14 to 70 Hz.)
This remarkable result is a consequence of good filter design plus Pure Vinyl's use of a 64 bit signal path (error accumulation with 64 bit double precision floating-point math is many orders of magnitude below the noise level of the signal).
Above: After applying Pure Vinyl Precision 64 Bit RIAA and zero-phase-shift rumble filter, then sample rate converted to 44.1 kHz / 24 bit using Pure Vinyl
Compare with previous 192 kHz sample rate waveforms; this shows that Pure Vinyl's 64 bit resampling algorithm contributes no distortion.
Click here for more tests of sample rate converters.
Above: After applying Pure Vinyl Precision 64 Bit RIAA and zero-phase-shift rumble filter, then sample rate converted to 44.1 kHz / 16 bit using Pure Vinyl (and uniform dithering option)
Clean output, all the way down to the noise floor.
If unaccustomed to using an FFT analyzer, the displayed "noise floor" indicated in the FFT will be smaller by 1/square root(number of FFT bins), compared to the expected -96 dB for 16 bit precision. For a 1024 bin FFT, this will be approximately 30 dB; the -96 dB "floor" accordingly becomes shifted to -126 dB, as in the graph above.