- 2014-03-01 11:53 pm
Yes, I’ve seen this done but I suspect the basis is fundamentally flawed. If the ‘silent groove’ is really silent, then there should be no stimulus and no output at all. If the ‘silent groove’ is stimulating LF resonance, then I suspect that the groove is really not silent. The stimulus is likely coming from one or more such things as: micro variations in formulation of the lacquer master or the vinyl pressing (causing amplitude variations), or some groove drag variation akin to scrape flutter on a tape deck. Note that if there are groove drag variation effects, then the dynamically varying drag force pulling on the cantilever would resolve into vertical and horizontal forces that excite both modes of resonance.Previously it has been shown that the LF resonance can be measured using a silent groove. Can the HF frequency response also be measured the same way? Would be great if it could as would remove all the questions over test record sweep accuracy...
Reminder: Along with the amplitude effects of LF resonance, the stylus scrubbing along the groove introduces FM distortion. In the vertical mode, the FM for a given resonance amplitude is primarily dependent on the VTA of the cartridge cantilever. In the horizontal mode, the FM for a given resonance amplitude is primarily dependent on the offset angle of the cartridge/arm combination.on the silent groove issue https://www.diyaudio.com/community/...-compliance-compatability.367565/post-6533937 . Does seem to show that linear trackers really are the way forwards if you can live with their other foibles.
George,The FFT of vinyl silence
Hi George,Hi Hans
Thank you for the as usually informative post.
Now a few more thinks for clarification.
I posted here only to show that there is life in silent grooves from all sources (vinyl composition, cutting equipment, playback system), the most prominent at lower frequencies.
The second attachment in my last post, is from silent groove on two different test disks, that’s why you see such different FFTs (it happens that both are located on Side 2 and are both Track 6).
The way Audacity presents it’s FFTs is not that good, I agree. Whether it’s FFT data is wrong, I can’t say. If you have evidence please inform us.
There is a way for better presentation of FFT from Audacity. There is the function of exporting the FFT data in .txt format (freq/level pairs), then to a spreadsheet. I did it and plots are attached below. (I noticed you showed your results in linear freq scale, so I added that too). Unfortunately there were sampled to 24kHz only (old recordings)
The RIAA preamp is your excellent Aurak trimmed for the M97xE
Cartridge: SHURE M97 Modified (“Glued”)
Arm: SME 3009 Improved
Interconnect Cable: PC Mouse, knitted (interlaced)
Mat: Velvet, on top original TD160 mat
Turntable: THORENS TD 160 FULLY MODIFIED
PreAmplifier: Aurak on batteries
Sound Card: M-Audio AUDIOPHILE (USB)