Print-through and lateral adjacency effects are not that small, although I can't quantify them. I do hear a very audible pre-echo on some highly-regarded RCA Red Seal LPs---the Stravinsky Song of the Nightingale a good example. And that was mastered pretty soon after the tape recording.
I found four years about the time needed to do some instrumentation with much in the way of innovation. The consensus at the time was that the project would never be finished, and if finished would never work. My supporters (all two of them) warned that it could be finished but take at least another year of debug. Actually it worked within two weeks of power up as a complete system, with the need for temperature stabilization I'd warned about, and the need for a puff of photons to compensate for charge pumping in the detector unexpected but easy to implement.
But this was not even attempting space qualification. The irony: a professor who came to hate my guts for taking so long (he wanted something to facilitate the award of grant money for another instrument, and good for him he didn't get it as the detector envisioned was plagued with issues) migrated to the Space Telescope Science Institute, where he languished for years waiting for the instruments to be finished. The Challenger disaster saved the day for the tardy instrument developers by postponing launch.
Is that from tape print through, or from the cutting/pressing, or a bit of both?
True story BTW, I was unemployed in 1973 at at the end of funds and went to a headhunter who set up some interviews, when it was time to switch interviewers at Raytheon I asked the HR person to instead show me the nearest exit so I would not be late for my interview at Analog.
I don't know how to separate them, I was told the exact timing could tell you but I never pursued it.
Yes the timing is a giveaway. Can be either, but mostly tape originated IME.
I suspect you are right, I have one from Bob Ludwig and I have a hard time thinking he would let disk cutting do that.
I burned out on software development because I'm a perfectionist by nature - I can't let something go out to be trialed by others unless I'm convinced that there are no bugs that can be reasonably discovered. Which means huge amounts of testing and repetitive analysing and digesting - the upside is that what I delivered always just worked, only misunderstandings on needed functionality and the discovery of new requirements by the users raised issues; the downside is that the brain can only take so much of this sort of pounding, year after year, as I discovered ...
So far that i have found... yes based on many different researchers' observations.
F.Toole's book 'Sound Reproduction .......' he says Craven & Gerson (1992) stated that the phase distortion caused by high-pass response is audible even if the cut-off freq is reduced to 5hz. They say it causes the bass to lack "tightness" and becomes "woolly"......"
IMO, all the HP filters have this affect IF the GD is not taken into consideration and reduced to below audibility.
THx-RNMarsh
Last edited:
If a system has "wooly" bass then the last thing that's going to fix that is fooling around with filters - unless you get rid of the bass entirely ....
??
We are not fixing woofers. We are cutting out LP system infra-junk with a Hpass, low GD filter in the preamp.
If you did not have woolly bass before the filter,you will have it if the GD is too large.
Looks like it is going to fall to the DSP to get it done.
THx-RNMarsh
Last edited:
And the schedule. Never enough time to get it right. Always enough time to do it over.
When I told the story about the four-year development of the spectrometer to a boss at Harman, he said Around here you would spend the first six months working on the project, and the next 3.5 years looking for another job.
The impoverished department was actually a huge benefit, as the system had to be constructed out of raw parts, even though purchased modules in many cases would have been quite adequate. So I learned a lot. My modest salary was budgeted, but to buy a module from Analog Devices was out of line, and as well, for any purchase over 50 dollars, one had to go through the university purchasing department. By the time the thing was done, there were two modules from Datel in the big box with a bunch of circuit boards: a sample-hold and an ADC. Everything else was designed and built with raw parts, helped by generous donations from a guy in Zoology who had a cushy relationship with the government excess property people and had amassed a veritable treasure trove, on the tenuous basis that he used them in his research on nocturnal animals. You can't make this stuff up.
I had a blast. I finally resigned when I didn't get my way with a new instrument, which was vetted by a crook who had influence over another professor, whom he had fooled into believing in his surpassing competence in instrumentation. As an example of the latter, he didn't know that femtoamps were smaller than picoamps. Really. And he went on to head the aforementioned Space Telescope Science Institute for a while. Sometimes crime pays---again, for a while.
Would tiny brush and anti static gadget (gun?) before Laser reads the vinyl solve the problem somewhat ?
Regards.
Two offshoot questions. I listen to Western Classical, pop and rock; generally what period the digital recording/mastering took over completely. Want to avoid buying vinyls after that period. Another question is since we have noise cancelling headphones, is it possible to have real time anti noise/resonance (Rumble, tonearm etc.) circuit before the preamplifier ? It would be wonderful.
Last edited:
My first thought before I posted was to use (similar to Bcarso) a single rolloff in the preamp and the DSP to correct everything else. The difference was to set it at 50 Hz. I think your measurement validates that concept?
Measuring composite group delay etc. from digital master to digital output may be a challenge. Looking only at the playback preamp is not adequate. There are anywhere from 2 to ?? high pass filters upstream. The microphone will usually have a limit. So will the console and definitely the cutting chain (cutter heads are way too expensive to risk). Any ideas on how to measure phase open loop? I may be able to get a suitable test record made. With adequate DSP its possible to do phase correction for the chain. Correcting phase shift in tape systems made a big improvement.
I met with the Finial guys when the turntable was being designed 30+ years ago. They contacted me for help with the drive system. Shortly afterwards the underlying investor scam blew up and it essentially vanished.
A friend had one for a while. At first he loved it but in about 6 month he sold it. He said the inner grove distortion was intolerable eventually.
I believe there are two versions, one with a "preamp" and one without. I'm not sure what processing could be done without a preamp stage. And if it has servos following the grove wall those servos would need to be as fast as the movement of the groove walls. That would be a tall order.
Film optical audio is a very different process. The recording process was mechanical for the most part (a few eye tube based systems were hatched but not used commonly. I worked on a project with Keith Johnson to extract the optical tracks using a different method. It used a CCD line scanner to capture the audio and some simple processing to prevent the various bad things that happened with the recording "shutters" from passing through. The first customer used it to restore the "I Love Lucy" sound tracks.
- Status
- Not open for further replies.