John Curl's Blowtorch preamplifier part II

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- big issue: an abundance of clicks and pops, MUCH louder and sharper than I have ever heard! They were greatly reduced in number after the record was cleaned with compressed air so it appears to be specks of dust, maybe the dust caused reflections in the laser beams in some way.

This is what all the reviews at the time said. You basically need a record cleaner to clean your vinyl each time before you play. The laser cannot tell between dirt and vinyl unlike the diamond plough you normally use.
 
Digital filters are not necessarily equivalent to analog filters in the time domain.
Oh yes, so true.
One of my major problems, at the beginning of the digital mixing desks, was here. Impossible to sculpt the sound of an instrument the same way. Whatever you try, it is like if you are unable to modify the size and weight of an instrument in digital, even with huge corrections.
On an other side, each time you try to remove some unwanted frequencies from a track, in analog, you affect the nature of the instruments.
Well, I carried with me analog correctors that i could plug-in in the digital mixing desks : the best of the two worlds. Cleaning in digital, sculpting in analog.
 
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I agree, although for reasons of my own I prefer to do only the 75us tau in the first stage.
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I would normally be in full agreement, but Scott does have this habit of planting doubts. Of course if you are going digital you can think completely outside the box and do things completely differently. After all you are not limited to 2 channels of A/D...
 
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This is what all the reviews at the time said. You basically need a record cleaner to clean your vinyl each time before you play. The laser cannot tell between dirt and vinyl unlike the diamond plough you normally use.

The player apparently includes a pop suppression circuit that looks at amplitude and slew rate of signals and suppresses it when the values indicate it isn't music. But clearly not at all effective enough.

OTOH it makes it easy to hear the difference between CD and LP even quadruple-blind ;-)

Jan
 
.......Sound quality (the important thing): fully subjectively: never in my life heard such a clean, detailed, lifelike reproduction from a record. Caveats: you really had to listen 'through' the pops and clicks to enjoy the music
Jan
Laser vinyl PB looks ripe for capturing to hi-res digital and then apply declick/denoise processing....best of both worlds.

Dan.
 
Laser vinyl PB looks ripe for capturing to hi-res digital and then apply declick/denoise processing....best of both worlds.
I believe this type of technology would be fantastic to recover old vinyl original sound directly from the metal master or "mother" in metal.
They were not exposed to durst. The metal is shining and easier to be read by light, i think.
And the grooves not affected by the wear of diamonds reading them during decades.
A way to get better sound than using master tapes demagnetized by years ?
 
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Laser vinyl PB looks ripe for capturing to hi-res digital and then apply declick/denoise processing....best of both worlds.

Dan.

That's an interesting idea. Note that you can adjust the lasers so they read at the top of the groove, which has never been touched by a cartridge which ploughs lower in the groove.

No idea ho effective a digital de-clicking could be though - the basic problem is to decide when something is music and when it is not; the rest is straightforward engineering, whether digital or analog. There is bound to be some false decision making in the border area.

Jan
 
.......Thank you Richard
I quote from KEF’s paper:"Initial experiments, carried out using program material recorded using the equipment described earlier, suggested that lowering the cutoff frequency produced the subjective effect of less bass. This at first surprising result may be due to the fact that the ear is assessing the overall bass response more in terms of the frequency- dependent time delay at low frequencies, which imparts a "boomy" characteristic to the sound, rather than on spectral content."

I would like to have the underlined (by me) text confirmed as being really a "fact" before rushing out for a linear phase capable DSP package.

George
IME on a lot of different audio items infrasonic cut switches can indeed impart a 'boomy' quality to lower bass.
Speakers like 8" two ways can in some ways benefit....less out of band power/cone travel reduces bass perceived distortion, and the touch of subjective boominess can serve to augment the perceived bass.
On more capable larger/higher power loudspeakers the distortion reduction is not so significant, but the 'boominess' taint changes timbre of lower frequency sources.
For 'sinewave' like sound sources the effect is not so great, but for impulsive/asymmetrical low frequency content, the timbre change can be disagreeable.

Dan.
 
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Would not the original master tapes be of a higher effective resolution than the record produced from it though.

If you follow that line then the ultimate master would be a digital one, and then why go to vinyl in the first place ;-)

But I agree that a master tape would most probably be cleaner than any master disc.

Jan
 
That's an interesting idea.....No idea how effective a digital de-clicking could be though - the basic problem is to decide when something is music and when it is not;
Jan
I had a play with Samplitude (IIRC) declicking, denoising and declipping restoration/processing.
All processes had adjustments that required careful attention, but the result was quite satisfying.
I also played with LP recorder denoising/declicking.
I don't know what smart software is available nowadays, but it's worth Googling.

Dan.
 
If you follow that line then the ultimate master would be a digital one, and then why go to vinyl in the first place ;-)

But I agree that a master tape would most probably be cleaner than any master disc.

Jan
Yes, provided you can find the master....not likely/not economical for a huge proportion of music currently archived/collected on vinyl.
There are sound archives preserving vinyl content....what transcription equipment do they use ?.

Dan.
 
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I had a play with Samplitude (IIRC) declicking, denoising and declipping restoration/processing.
All processes had adjustments that required careful attention, but the result was quite satisfying.
I also played with LP recorder denoising/declicking.
I don't know what smart software is available nowadays, but it's worth Googling.

Dan.

Dan, if you can, try to get hold of a SAE 5000 device. It was made specifically to take out the clicks and pops on LPs, and it did an incredible job of it. It had an "Inverse" switch, and if you used it, you could hear what he was taking out the signal. VERY telling. I had it for years, and I have heard a few other attempts at that, none of which could touch the SAE.

If memory serves, it used to fill the gap of something taken out with the signal from the other channel, or an approximation based on preceeeding and following program. I sold it off when I moved on to the CD, in the mid-80ies.
 
If you follow that line then the ultimate master would be a digital one, and then why go to vinyl in the first place ;-)
Not least because often the 'master tape' was discarded following the first generation of digital transfers, based on the mistaken belief that the original digital transcription was totally accurate and adequate. So the scrape around for 'master tapes' often results in production copies, or even re-generated analog tapes from digital sources. The idea that all master tapes were archived in some library is far from the case.

So, often, early generation vinyl is as close to the true analog source as there is. Warts and all. Besides, more than half of the audio art lies in mastering, and decisions made by vinyl mastering engineers shape the finished sound to be what is 'definitive' in that sense.

The master tape would sound very different in post production terms from the vinyl product, or indeed the vinyl production mastering tape if the engineer used one.

The art of vinyl sound lies in its mastering, and very different decisions apply to digital domain post production.
 
What if it was recorded in digital, some of us listen to modern music as well and a lot has been digitally recorded anyway.
As previously discussed an LP is not a very high resolution media...
I refer to the master tape USED for cutting the master stamp disk by the way, it WOULD have the mixing done on it, though this may have been altered to fit onto the limited resolution media it was destined for, an LP...........
 
But I agree that a master tape would most probably be cleaner than any master disc.
I don't think so. Not after long years of slow demagnetization, layer copy (pre and post echo) physical deterioration of both the support and magnetic layer (lubrication etc.).
I still have some old masters from the 70, and they are in a real bad shape.
Losses of treble, dynamic, full of dropouts etc.
and then why go to vinyl in the first place
I said that, on my point of view, the only interest of this "laser for Vinyl" technology was restoration of old recordings from the past.
 
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