From: liz@poppyrecords.invalid.invalid   
      
   Geoff  wrote:   
      
   > On 16/09/2025 8:23 pm, Liz Tuddenham wrote:   
   > > Geoff  wrote:   
   > >   
   > >> On 16/09/2025 7:25 am, Liz Tuddenham wrote:   
   > >>> Scott Dorsey  wrote:   
   > >>>   
   > >>>> Liz Tuddenham  wrote:   
   [...]   
      
   > >>> The only system that seemed to do it really effectively and in real time   
   > >>> was Cedar: it claimed to synthesise a 'gap-filler' from the Fourier   
   > >>> transform of the sound before and after the click.  Even that wasn't   
   > >>> really intended to handle the continuous crackle of some of the worst   
   > >>> gritty solid stock material (particularly inter-wars U.K. HMVs).   
   > >>>   
   > >>> I wondered if some sort of resonator could 'ring' and fill the gap, but   
   > >>> it would need quite a lot of them to cover the whole audio band.   
   > >>> Octaves seemed the logical way to go but that involved either a large   
   > >>> number of ferrite pot cores or a lot of op-amps in state-variable   
   > >>> filters.  I tried the pot-core approach many years ago and gave up   
   > >>> because it was becoming too unweildy.   
   > >>>   
   > >>> This time I opted for state-variable filters and my design finished up   
   > >>> with 170 op-amps and several other I.C.s.  It was a bit of a gamble   
   > >>> whether it would be worth building it, as the principle was untested, as   
   > >>> far as I knew.  It has paid off, the results are stunning; as the   
   > >>> sensitivity is increased, the crackle just fades into the background and   
   > >>> the music comes through absolutely unaffected.   
   > >>>   
   > >>> There are still a few things that need attention, as I can hear residual   
   > >>> artefacts at a very low level - but I exhibited it to a group of   
   > >>> gramophone enthusiasts at the weekend and they were completely bowled   
   > >>> over by the sound quality.   
   > >>   
   > >> Isn't this all now trivial to do, better, in software ?   
   > >   
   > > In real time?  In a portable record player?   
   >   
   > OK, I missed the 'real time' bit.   
   >   
   > But wonder what the circumstances are for real-time. Demonstration of   
   > vinyl (or shellac !) playback for historical or sentimental purposes ?   
      
   Shellac* (what's this 'vinyl' of which you speak?)  Mainly to accompany   
   live presentations on singers, musicians and other performers of the   
   past - and for entertainment in the evenings after the presentations.   
      
   The original purpose, which has now become secondary, was to be able to   
   take the playing equipment to collections of recordings which were too   
   valuable to transport to a studio.   
      
   Something which I hadn't realised until recently, is that people are   
   finding it allows them to hear subtleties on the records in their   
   collection which they never heard before.  It might be useful to loan or   
   hire out as a standalone analysis tool because it gives the ability to   
   just  pop on a record and audition it quickly without a lot of faffing   
   about with digital computers.   
      
      
      
   *   In the UK, particularly during the1930s, the 'shellac' material used   
   by the biggest group of record companies was appalling.  If you have   
   never heard a British inter-wars HMV pressing you can have no idea of   
   just how terrible the sound was.  Ordinary de-clickers which are   
   designed to deal with occasional scratches on vinyl discs or good   
   quality American or Australian shellac pressings simply cannot cope with   
   it   
      
      
   --   
   ~ Liz Tuddenham ~   
   (Remove the ".invalid"s and add ".co.uk" to reply)   
   www.poppyrecords.co.uk   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)