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Liker den bedre enn RPM appen fra samme utvikler.
Kom selvsagt tilbud på RPM + W/F til 60kr en time etter at jeg hadde kjøpt Wow/Flutter appen for 159kr. Ja ja
2. Turntable speed accuracy is measured using a test disc cut with a 3150Hz steady tone. DIN 45 465 is one such and has the great attribute of a locked outside groove which allows the disc to be carefully and accurately centred, thereby taking disc eccentricity out of the equation. With this done, it is possible to measure down to around 0.06% unweighted wow, sufficient to identify the performance of top quality turntables. The best direct-drives manage this level of performance. Most belt drives are worse with measured wow being about 0.12% pk = 0.24% pk-pk.Sek and Moore's study involved the presentation of two successive steady tones with slightly different frequencies. The subject was asked to judge whether the first or the second had the higher pitch. The order of the tones was varied randomly from trial to trial, and the minimum perceptible change of frequency was taken as that frequency separation between the tones at which the subject achieved a certain percentage of correct responses (75%). This measure is called the difference limen frequency (DLF)Sek and More found it to be 0.2% at 500Hz.
A second measure of threshold change-of-pitch perception invetigated by Sek and Moore was using tones which were frequency modulated (FM) at a low rate to determine the amount of modulation required for detection. This measure is called the frequency modulation detection limen (FMDL). Clearly the FMLD test is closer to the case of pitch perception due to the unsteady speed of a gramophone record. The study showed that FMLDs are always higher than DLFs at all frequencies.
So taking the low limit for DLF (0.2% pk-pk at 500Hz) maybe over-safe as the lower bound for the perceptibility of wow. This is confirmed in an old, but very good, paper by Hisao Sikai of NHK (Perceptibility of Wow and Flutter JAES, June 1970) who determined in extended experiments that the threshold for peception of wow on the most critical music programme reproduction (found to be solo piano music) is 0.14% RMS which is equivalent to ±0.2% peak or 0.4% peak-to-peak variation. So this figure is taken as the lower bound in the Stereo Sauce WOW! correction algorithm.
However, the DLF is worth knowing because it does give an indication of the acceptable quantisation of the correction process. Provided pitch discontinuities are restricted to 0.2% in either direction, the pitch change won't seem to "jump".
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