From Newsgroup: rec.audio.pro
Geoff <
geoff@nospamgeoffwood.org> wrote:
On 17/09/2025 8:26 pm, Liz Tuddenham wrote:
Geoff <geoff@nospamgeoffwood.org> wrote:
On 16/09/2025 8:23 pm, Liz Tuddenham wrote:
Geoff <geoff@nospamgeoffwood.org> wrote:
On 16/09/2025 7:25 am, Liz Tuddenham wrote:
Scott Dorsey <kludge@panix.com> wrote:
Liz Tuddenham <liz@poppyrecords.invalid.invalid> 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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