From: liz@poppyrecords.invalid.invalid   
      
   Geoff  wrote:   
      
   > On 17/09/2025 8:26 pm, Liz Tuddenham wrote:   
   > > 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   
   > >   
   > >   
   >   
   > But surely the Kellogs factor is a main attraction ;- )   
      
   It certainly is to a proportion of collectors - and the   
   clothes-peg-on-the-nose sound of many singers.   
      
   I remember the horrified reaction of a group of collectors when I first   
   played a recording of one of their favourite singers with the correct   
   frequency response - "but that doesn't sound at all like him!".  They   
   then demonstrated what he *should* sound like by playing the record on a   
   clockwork portable gramophone.   
      
      
   It isn't just confined to old record collectors: I was asked to dub a   
   piece of music to be played at a theatrical show, the recording they   
   supplied appeared to have been clumsily over-compressed with a slow   
   time-constant AGC and no dynamic range whatsoever.  I spent several   
   hours correcting it until it began to sound more like an orchestra   
   again.  When I played it to the producer she threw a fit, it was   
   supposed to sound like the compressed version.   
      
   It had come from a well-known film sound track, recorded by a   
   world-famous studio, so I checked back to the source and found it had   
   been clumsily over-compressed when they issued it.   
      
   --   
   ~ Liz Tuddenham ~   
   (Remove the ".invalid"s and add ".co.uk" to reply)   
   www.poppyrecords.co.uk   
      
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    * Origin: you cannot sedate... all the things you hate (1:229/2)