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Analog Optical Recording

Discussion in 'The Cutting Edge' started by OldADC, Feb 5, 2018.

  1. OldADC

    OldADC Member

    Messages:
    97
    Location:
    Nashua, NH
    Thanks, Nathan. I believe we are touching on the digital vs. analog argument at its very heart. There are seriously passionate people on each side of the divide and I don't wish to engage in the rehashing of an argument that is now 35 yrs old. Just count me in the analog camp for the highest possible reproduction and the digital camp for dang near every other consideration (ease, storage, formats, etc. and on and on). However, the "perfect" analog system is likely to sound anything but digital. It is my opinion, and opinion only so lets not argue, that regardless of sampling rates, a necessary loss in digital sampling is the complex phase function linking all frequencies of the recording. This opinion stems from long familiarity with Fourier Transforms and the unbreakable bond between Fourier pairs. In ultrafast optics, a very short pulse in the femtosecond regime requires a broad spectrum from the source. Let any element in the system narrow the spectrum (ex. an optical coating that is not spectrally broad enough and truncates part of the spectrum) and the pulse will be longer in time. Back in the audio world, the same kind of relationship holds between frequencies and phase coherence. Sampling causes loss of inter-frequency phase coherence and therefore a loss in 3-D imaging and stability of image. That is my fundamental belief in analog. But you have to have a VERY good system to hear that difference in stage presentation and imaging. Utterly pointless conversation for ear buds! LOL

    Yeah, I really like the diamagnetically induced magnetic levitation for the cantilever. Just sounds cool. Might even work.
     

     

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  2. rave0035

    rave0035 Disassemble first, ask questions later.

    Messages:
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    I'm a mid-30's guy enjoying the vinyl resurgence, and I'd like to weigh in as a consumer.

    I know lots of folks at very different points on the vinyl resurgence spectrum (from hifi junky to folks who buy records to hang on their walls), and I can say that for most people I know the comeback of the format has almost nothing to do with the audio quality of the recordings, and nearly everything to do with the nostalgia of physical media... it's the covers, the liner notes, the act of collecting and digging through crates, and having to actually listen to albums again. Super high fidelity is not paramount for many consumers of the $40 LPs you referenced... many are buying them to play on Crosley decks they bought at Urban Outfitters for $50.

    Long story short, and with all due respect: I don't think there are many consumers out there saying "I really like the idea of vinyl records, but want something with higher quality and more accuracy".

    Mike
     
  3. Pio1980

    Pio1980 AK Member Subscriber

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    This idea is tantalizing, analogue recording and playback minus the physical drawbacks, including media deterioration.
     
  4. FileFixer

    FileFixer Well-Known Member

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    @OldADC Do you have any blog, forum or any other place where we can to see and where we can to participate in discussion about that technology?
     
  5. OldADC

    OldADC Member

    Messages:
    97
    Location:
    Nashua, NH
    Thanks, Mike. Good to hear another perspective and a valuable one at that. My involvement in audio has always been at the tweaky high end even if we did build low, mid, and high end cartridges when I was at ADC. So hearing from those who aren't necessarily audiophiles but represent different and diverse engagement with the hobby and the technology is imminently useful. One question back for you. Most nostalgia crazes have a distinct finite lifetime. Converse "All-Stars" (Chucks) can back with a roar. Are they still hanging in there? Old copper fixtures for baths and kitchens came back and have now faded as kitchen designers moved on to a next new great thing. Do you think the vinyl comeback, if it is indeed a nostalgia driven phenom is of limited lifetime?
     
  6. OldADC

    OldADC Member

    Messages:
    97
    Location:
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    No sir, I do not. Perhaps that is something I should remedy. Do you have any particular place on line that you think would be best for exposure and readership?
     

     

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  7. OldADC

    OldADC Member

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    Its the tantalizing part as you state it that makes me bring it up, do the research, poll you guys, think through all the business side as well as the technology.....yeah, it's really rather tantalizing....
     
  8. Pio1980

    Pio1980 AK Member Subscriber

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    BTW, don't recall if I had your name, but it's good to see you back. Been wondering how you were doing since our conversation in the Asterion thread re "free pivot" cantilever design.
     
  9. lini

    lini just me...

    Messages:
    5,902
    Location:
    Munich, Bavaria
    While you didn't ask me, I'll add my opinion nevertheless: I fear so, yes. One reason being that the vast majority of records out there are pre-1990. So to me the main era of microgroove vinyl records practically covers the music of my grandparents' and parents' generations as well as my own youth. But thinking ahead one or two generations from now, would I really deem these to still be very interested in music, which will then already be at least 50 years old, on a not exactly space-saving medium, requiring a comparatively bulky piece of equipment for playback?

    And on the equipment side there's a similar problem: The current vinyl revival to a certain degree still profits from the huge amount of turntables (and replacement parts for these), carts/needles and accessories from the heydays of vinyl playback, some of that stuff even still being available new old stock. Thinking one or two generations ahead, I don't think this still will apply...

    Or one could also simply put it like this: As long as the current vinyl revival remains smaller scale, the next one would seem likely to become an even smaller scale revival of a revival.

    Greetings from Munich!

    Manfred / lini
     
    ripblade, FileFixer and slow_jazz like this.
  10. slow_jazz

    slow_jazz AK Subscriber Subscriber

    Messages:
    13,859
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    SE Michigan, Downriver....
    As for vinyl I'm still using my Pioneer PL-550 from the 70's.

    It would take something great for me to switch.

    I wish you luck in whatever direction you go.

    Intrigued by some of your ideas.
     
  11. OldADC

    OldADC Member

    Messages:
    97
    Location:
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    Manfred, of course I asked you as well. Yours has always been thoughtful and valuable input and I find this missive quite insightful. "Small scale revival of a revival" should probably be etched somewhere and hung over my workbench in the lab. Thank you, sir.
     

     

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  12. j_loop

    j_loop AK Subscriber Subscriber

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    I have not read the articles yet, but I was wondering what implications a suspension like this would have in regards to compliance? Would it be customizable or fixed due to the suspension type? As with your new analogue system I am intrigued.
     
  13. OldADC

    OldADC Member

    Messages:
    97
    Location:
    Nashua, NH
    That is actually a great question!! From my original posts, you might remember I designed a variable compliance cartridge back in the early 80s and published a paper on that design with Audio Engineering Society (Montreaux Conference, 1982). So I am aware of how tuning the compliance can effect the compatibility of a cartridge with a tonearm.

    My suspicion is that the compliance will not be tunable. I think the balance of magnetic forces to accomplish the suspension will set the compliance value and equally set a narrow range of gaps and tolerances that will allow the suspension to be stable. Should those field gradients be a bit more forgiving than they appear to be at present (Finite Element magnetic field modeling), then a slight variation in suspension gap would yield a commensurate change in compliance.....larger gap, lower stiffness, might just fall down! We'll see.
     
  14. rave0035

    rave0035 Disassemble first, ask questions later.

    Messages:
    623
    Location:
    Twin Cities, MN
    It's a great question. By the way - I LOVE this discussion regardless of its commercial viability. Thanks for bringing it to the forum.

    Here's what I think: I believe that at some point in the next 5-7 years, vinyl production is going to outpace demand as bandwagoners drop out of the hobby, and we're going to see the reissue trend slow down dramatically.

    That said, I think that vinyl records are the physical media that will continue to live on as the digital revolution grows. One reason that I don't think another physical media can unseat records is that part of the allure for many enthusiasts includes collecting records that have been made over the past 50+ years... and any new media won't have the allure of digging through back catalogs and the 'score'.

    My opinion only... but I think one that is representative of an audio snob who has his finger on the pulse of the vinyl resurgence.

    Mike
     
  15. OldADC

    OldADC Member

    Messages:
    97
    Location:
    Nashua, NH
    Thanks, Mike. And I think you have quite correctly identified one segment of the vinyl population....and an important one at that. It's that first pressing edition of Miles or a rare Deutsche Gramophone of the Whatever Royal Orchestra's ABA reprise....exceptional and only 3 known to be playable, at least west of the Nile....

    I get it, and you've nailed them straight on. No new media will serve their real purpose.
     
  16. soundmig

    soundmig AK Subscriber Subscriber

    Messages:
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    Location:
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    Looking at what R2R tape "masters" are selling for ($400+) if you can develop a laser analog that out performs 15ips, 2 Track R2R and mass produce them at a retail of $40 a pop, wow ... that might fly. It may be a niche market, but it wouldn't be "tiny" - I don't think. If all you need is to fund your time for a year (say $200K) and $50k for equipment to do a proof of concept, there has to be someone out there that would spring for that (for a decent cut of future action). Maybe you could do a kickstarter or other public solicitation of funds to get the proof of concept phase underway?

    Even though the primary attraction to digital is storage space size, the lack of surface noise (both LP and analog tape) is what pushed us all that way back in the 80's. Eliminating the surface noise and the varying quality issues of AD and DA conversion would seem to be a win-win situation from the "audio" point of view. If it has to go on a physical medium (and I see that it does) you still have the size of the storage space as an issue with the mass consumer. But ... there would seem to be a decent sized population of musicians and audiophiles that appreciate the "analog sound" enough to make something like this attractive. Your idea also satisfies the "physical media" attraction that is helping LP sales revive.

    Even though the best use for this system might be something like Direct to Disk recording - For it to work, there will have to be buy-in from the music industry "powers that be", such that access to popular title masters can be realized. The music we all love will need to be acquirable for listening on this new optical analog audio system. Otherwise I think it would be difficult to get this thing off the ground commercially. You may want to talk to Chad at Acoustic Sounds as he seems to be a solid business man whose into audio and has demonstrated the ability to gain access to the wanted master tapes.

    Overall its a tall order project fraught with "market issues" that seem to be already satisfied by digital audio. BUT ... if done right I think it would have a chance for penetration into a niche market - like the one that is driving LP sales resurgences. Very interesting proposition. If I had a spare $250 grand or so laying around I would PM you!!!
     

     

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  17. Pio1980

    Pio1980 AK Member Subscriber

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    Last edited: Feb 9, 2018
  18. OldADC

    OldADC Member

    Messages:
    97
    Location:
    Nashua, NH
    At ADC, the design philosophy carried forward from Peter Pritchard was low effective mass, high compliance, low VTF. The basics of the design were exactly the same ranging across the whole product line from the $5 cartridge in a blister pack sold through Radio Shack up through the Astrion at $400 (in '82, inflation adj for today $1062). The injection molded plastic bodies and stylus holders were of different colors, the output pins identical. The magnetic circuits internally were physically the same parts but the windings of the coils were of different wire sizes and # of turns. So the bodies were substantially the same. If memory serves, there really were only two body configurations. The coil assembly used on the low end of the product line up to and including the QLM36, and the bodies used on all the high line product starting with the XLM. There may have been a slight change around the XLM II Improved, but it wasn't a big deal. Thus, if the stylus holder fits on the can of the body, ADC styli are interchangeable across bodies close to universally.

    Why bring this up? I've seen lots of questions on here where people have an ADC stylus and want to know if it will fit on another model's body. The biggest question is actually based on the mu-metal can of the body. If you look toward the bottom rear of the can on both sides, there is or is not an L-shaped bump on the can body. That bump was added to the ADC basic body design in 1979 by John Kuehn after some extensive testing and validation. The later bodies with the L bump and the styli that fit them, fit much tighter and much more stably. So now the matrix of compatibility is based on bump/no bump and high line/ low line.

    And now for the real reasons. The high line was really differentiated by cantilever and diamond selection. Within the bump/high end quadrant lies the most modern and interesting of the ADC product line. XLMII, XLMII Imp, XLMIII, ZLM, Astrion. And within that crowd you find tapered aluminum tube cantilevers on all but the Astrion which was the first sapphire rod cantilever ever used (after extensive testing of Boron rod, Beryllium rod, and the sapphire rod in engr tests and double blind listening tests). Diamond selection at the time included ellipticals, modified ellipticals, the Shibata cut, and some experimentals where the diamond vendors were trying a few things out, particularly different ratios between the bearing and scanning radii.

    Which cantilever materials and which diamonds do you like and why? I'd love to hear your opinions on these subjects.
     
  19. HTHMAN

    HTHMAN Super Member

    Messages:
    3,518
    Location:
    St Louis, Missouri, USA
    As much as I like physical media, it does not seem to be the future. With BestBuy dropping CDs, the writing is on the wall. While it may indeed be a better format and provide better sound, that no longer seems to matter with the majority of the population. The market will just be too small to be viable.
     
  20. OldADC

    OldADC Member

    Messages:
    97
    Location:
    Nashua, NH
    I did see where BestBuy and other retailers were no longer going to stock CDs. I guess ever dog has its day but doesn't this also mean that there are essentially no physical media formats that are being full range commercially supported? Thus music has become digital only...and you are quite correct that it is only a small percentage of consumers who actually care about fidelity as a major criteria. Serious swimming upstream for any physical media, new or well established, it would seem.
     

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