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| Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Three speed automatic turntable replacement
I got an old, (what looks like a BSR) three speed automatic turntable
in for repair. It doesn't work on auto because the plastic trip pawl is worn. I can't get to the trip pawl without doing a semi major strip down. And this guy isn't going to go for that. I would like to replace the turntable with an equivalent inexpensive BSR type for him. I used to be able to buy these from my parts suppliers for about 20 bucks about 100 or so years ago but I haven't looked into this for a long time. Is it still possible to find something like this, a basic general replacement type idler driven mechanical turntable with a cheapo ceramic cartridge? Thanks, Lenny |
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#2
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Three speed automatic turntable replacement
Are you sure it's a BSR ? IIRC they used a piece of flat stamped metal on the bottom which was lightly sprung away, and then the "velocitrip" was right on the main drive gear right under the platter. If there was a piece of plastic at the end of it, that would not require a complete teardown.
What kind of unit is this in ? If you're looking for a dropin I assume this unit is what used to be called a "mahogany monster". The BSRa were only used in a couple of brands, Zenith had their own, Magnavoxes used a Colarro or something like that and then there were a few others. I think there were about five major types in all. Those cheapo dropin replacements were not satisfactory as far as I am concerned. All plastic and in a word - junk. The real question here is whether this is THE complaint or not. You say the customer won't pay, well then he has a fine manual turntable if the rest of it works alright. If he doesn't understand what it take which is likely to require you to cut and grind because you aee not going to get the part, I guess you will have to make him understand. Actually when confronted with this situation and a really unusable turntable someties I sold an upgrade. You could get like a Dual 1218 or something used, get the automatic spindle for it and everyhing. Even a magnetic cartridge and a preamp. But then no tightwad wants that, or people who want to maintaain the integrity of an antique. Of course a dropin is not for them either. And sawing up their turntable cutout ? It's like when they put those godawful 22" tires on a nice old Oldsmobile from the 1960s. I would like to shoot those people but alas it is illegal. Can't do it in public. If the guy is cheap, what is wrong with a manual turntable ? On the other hand if this is a "restoration" job, he should know not to be cheap. J |
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#3
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Three speed automatic turntable replacement
"klem kedidelhopper" wrote in message
... I got an old, (what looks like a BSR) three speed automatic turntable in for repair. It doesn't work on auto because the plastic trip pawl is worn. I can't get to the trip pawl without doing a semi major strip down. And this guy isn't going to go for that. I would like to replace the turntable with an equivalent inexpensive BSR type for him. I used to be able to buy these from my parts suppliers for about 20 bucks about 100 or so years ago but I haven't looked into this for a long time. Is it still possible to find something like this, a basic general replacement type idler driven mechanical turntable with a cheapo ceramic cartridge? Thanks, Lenny How many cases of them do you want? Google USB turntable. Geek.com had them on special this week for $29.95. |
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#4
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Three speed automatic turntable replacement
On Sun, 12 Aug 2012 11:23:23 -0700 (PDT), klem kedidelhopper
wrote: I got an old, (what looks like a BSR) three speed automatic turntable in for repair. It doesn't work on auto because the plastic trip pawl is worn. I can't get to the trip pawl without doing a semi major strip down. And this guy isn't going to go for that. It's also likely that the rubber parts are going bad on anything that old. I would like to replace the turntable with an equivalent inexpensive BSR type for him. I used to be able to buy these from my parts suppliers for about 20 bucks about 100 or so years ago but I haven't looked into this for a long time. Is it still possible to find something like this, a basic general replacement type idler driven mechanical turntable with a cheapo ceramic cartridge? Thanks, Lenny https://www.google.com/#q=usb+turntable&hl=en&tbm=shop http://www.shopping.com/usb-turntable/products?CLT=SCH&KW=usb+turntable I have one I picked up at Costco for about $75. The big problem is finding replacement needles. Check for availability before buying. Also, make sure that it will play 33.3, 45, and 78 rpm disks. The one I bought only does 33.3 and 45. However, such turntables are boring. Sell the customer one of these: https://www.google.com/search?q=ultimate+turntable&hl=en&tbm=isch Only $150,000. http://www.onedof.com or maybe this 400 lb monster: http://goodwinshighend.com/manufacturers/basis/work_of_art.htm But those use a stylus. Modern turntables use a laser: http://www.elpj.com Only $9,000 to $12,000. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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#5
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Three speed automatic turntable replacement
In article ,
Jeff Liebermann wrote: On Sun, 12 Aug 2012 11:23:23 -0700 (PDT), klem kedidelhopper wrote: I got an old, (what looks like a BSR) three speed automatic turntable in for repair. It doesn't work on auto because the plastic trip pawl is worn. I can't get to the trip pawl without doing a semi major strip down. And this guy isn't going to go for that. It's also likely that the rubber parts are going bad on anything that old. I would like to replace the turntable with an equivalent inexpensive BSR type for him. I used to be able to buy these from my parts suppliers for about 20 bucks about 100 or so years ago but I haven't looked into this for a long time. Is it still possible to find something like this, a basic general replacement type idler driven mechanical turntable with a cheapo ceramic cartridge? Thanks, Lenny https://www.google.com/#q=usb+turntable&hl=en&tbm=shop http://www.shopping.com/usb-turntable/products?CLT=SCH&KW=usb+turntable I have one I picked up at Costco for about $75. The big problem is finding replacement needles. Check for availability before buying. Also, make sure that it will play 33.3, 45, and 78 rpm disks. The one I bought only does 33.3 and 45. However, such turntables are boring. Sell the customer one of these: https://www.google.com/search?q=ultimate+turntable&hl=en&tbm=isch Only $150,000. http://www.onedof.com or maybe this 400 lb monster: http://goodwinshighend.com/manufacturers/basis/work_of_art.htm But those use a stylus. Modern turntables use a laser: http://www.elpj.com Only $9,000 to $12,000. The laser ones actually don't do that good a job. There are a *lot* of mechanical "errors" in a needle-in-groove system that are "automatically" taken care of by stylus reproducers, in a system that has been refined by "cut and try" over a period of years and has no real spec. Basically, the cutter "pre-distorts" the groove so that when the reproducer adds its own distortion, things sort of come out even -- sort of. If you use a laser to read the groove, then you have to do all those things some other way, and the list of them is long and isn't well defined. Isaac |
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#6
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Three speed automatic turntable replacement
On Sun, 12 Aug 2012 22:37:59 -0700, isw wrote:
In article , Jeff Liebermann wrote: On Sun, 12 Aug 2012 11:23:23 -0700 (PDT), klem kedidelhopper wrote: I got an old, (what looks like a BSR) three speed automatic turntable in for repair. It doesn't work on auto because the plastic trip pawl is worn. I can't get to the trip pawl without doing a semi major strip down. And this guy isn't going to go for that. It's also likely that the rubber parts are going bad on anything that old. I would like to replace the turntable with an equivalent inexpensive BSR type for him. I used to be able to buy these from my parts suppliers for about 20 bucks about 100 or so years ago but I haven't looked into this for a long time. Is it still possible to find something like this, a basic general replacement type idler driven mechanical turntable with a cheapo ceramic cartridge? Thanks, Lenny https://www.google.com/#q=usb+turntable&hl=en&tbm=shop http://www.shopping.com/usb-turntable/products?CLT=SCH&KW=usb+turntable I have one I picked up at Costco for about $75. The big problem is finding replacement needles. Check for availability before buying. Also, make sure that it will play 33.3, 45, and 78 rpm disks. The one I bought only does 33.3 and 45. However, such turntables are boring. Sell the customer one of these: https://www.google.com/search?q=ultimate+turntable&hl=en&tbm=isch Only $150,000. http://www.onedof.com or maybe this 400 lb monster: http://goodwinshighend.com/manufacturers/basis/work_of_art.htm But those use a stylus. Modern turntables use a laser: http://www.elpj.com Only $9,000 to $12,000. The laser ones actually don't do that good a job. There are a *lot* of mechanical "errors" in a needle-in-groove system that are "automatically" taken care of by stylus reproducers, in a system that has been refined by "cut and try" over a period of years and has no real spec. Basically, the cutter "pre-distorts" the groove so that when the reproducer adds its own distortion, things sort of come out even -- sort of. If you use a laser to read the groove, then you have to do all those things some other way, and the list of them is long and isn't well defined. Isaac One plays a vendor supplied calibration record on the turntable to calibrate it for those distortions and anomalies. For example, they record a clean low distortion sine wave at various frequencies using the standard record cutting lathe. When played back on a laser turntable, the processor look for distortion products (harmonics) and tweak a DSP to compensate. Resonances can be taken out via a freqency sweep. http://www.elpj.com/about/howitworks.php -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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#7
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Three speed automatic turntable replacement
The laser ones actually don't do that good a job. There are a *lot* of
mechanical "errors" in a needle-in-groove system that are "automatically" taken care of by stylus reproducers, in a system that has been refined by "cut and try" over a period of years and has no real spec. Basically, the cutter "pre-distorts" the groove so that when the reproducer adds its own distortion, things sort of come out even -- sort of. If you use a laser to read the groove, then you have to do all those things some other way, and the list of them is long and isn't well defined. Not really. Pre-distortion requires a specific technique, first (and last) used by RCA in the early 60s. |
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#8
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Three speed automatic turntable replacement
isw wrote:
In article , The laser ones actually don't do that good a job. There are a *lot* of mechanical "errors" in a needle-in-groove system that are "automatically" taken care of by stylus reproducers, in a system that has been refined by "cut and try" over a period of years and has no real spec. Basically, the cutter "pre-distorts" the groove so that when the reproducer adds its own distortion, things sort of come out even -- sort of. If you use a laser to read the groove, then you have to do all those things some other way, and the list of them is long and isn't well defined. Someone did a master's degree thesis about 10 years ago on writing a program that would read a photo scan on a desktop scanner of an LP and convert it to audio files. It worked within the limitations of resolution and size of the scanner, and computer processing ability available to him. 10 years later, it would be possible to do a much better job, but no one seems to interested in doing it. Oh well. The distortion is not a big deal. One just has to find a few master tapes (or films) and the corresponding records, digitize and compare them to come up with a "correction". We may even be lucky enough that someone could build a library of them, and be able to trace a recording to the specific lathe used to master it. Geoff. Geoff. -- Geoffrey S. Mendelson, N3OWJ/4X1GM/KBUH7245/KBUW5379 |
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#9
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Three speed automatic turntable replacement
The distortion is not a big deal. One just has to find a few
master tapes (or films) and the corresponding records, digitize and compare them to come up with a "correction". This was known and done 50 years ago -- qv, Dynagroove. |
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#10
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Three speed automatic turntable replacement
In article ,
"William Sommerwerck" wrote: The distortion is not a big deal. One just has to find a few master tapes (or films) and the corresponding records, digitize and compare them to come up with a "correction". This was known and done 50 years ago -- qv, Dynagroove. Which, as it turns out, died a quick and well-deserved death. There's a good reason why it was abandoned by RCA and never adopted by any other recording company. It sounded terrible. Isaac |
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#11
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Three speed automatic turntable replacement
Boy this is a useful group. Get a USB turntable. Sure, now where the **** do I plug it into this 1968 Magnavox mahogany monster ? LOL
Or a laser can read those grooves, just buy the interface and a PC to feed the tape input (if any) of the mahogany masterpiece. ****ing amazing how people actually live. I mean not starve to death. To cook dinner, right click the desktop and go down to food. In the categories there choose from meat, veggie, fish, poultry etc. Click on the category you want and then read (OH NO) the contents of the window that opens. Then choose side dishes. Make your selection and allow autocomplete to give the pizza guy your life history and access to all your money and wait for the bell to ring. Note if you live in a hi-rise apartment, death may occur from starvation. We apologize for any inconvenience. J |
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#12
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Three speed automatic turntable replacement
In article ,
"William Sommerwerck" wrote: The laser ones actually don't do that good a job. There are a *lot* of mechanical "errors" in a needle-in-groove system that are "automatically" taken care of by stylus reproducers, in a system that has been refined by "cut and try" over a period of years and has no real spec. Basically, the cutter "pre-distorts" the groove so that when the reproducer adds its own distortion, things sort of come out even -- sort of. If you use a laser to read the groove, then you have to do all those things some other way, and the list of them is long and isn't well defined. Not really. Pre-distortion requires a specific technique, first (and last) used by RCA in the early 60s. There were lots of sorts of pre-distortion used in the vinyl recording process: noise reduction EQ (the RIAA curve), radial EQ (poorer HF response on inner grooves), bass mixing to reduce groove cut-through, stylus shape pre-distortion because the cutter is flat and the playback stylus is a cone or an ellipse (and they need different treatment during recording) (this is NOT Dynagroove), treble boost to account for loss of HF due to the cutter being heated to reduce noise), corrections because the cutter traverses the disk radially and the playback stylus does not, several others. If you think it's easy, here's a nice thought experiment: If the waveform you want out of the phono preamp is a square wave (or near enough), what path must the groove cause the stylus to trace to produce that? (Hint: it's *not* a square wave). Once you figure out what the groove looks like for a square wave output, you'll realize that the groove *never* really "looks like" the waveform of the "sound", and that the conversion from one waveshape to the other is yet another compromise, though not so much as the recording process. It is, in fact, quite difficult to analyze the shape of the groove and determine "analytically" what the resulting sound waves should look like. A mechanical playback method takes care of all that "automatically" because the recording process is arranged so as to minimize the *system* distortion, *assuming the reproduction is going to be by means of a stylus in the groove*. Any other playback process must perform all those things explicitly in order to get good results -- i.e. it must simulate the behavior of a stylus in the groove -- and that's not so easy. Isaac |
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#13
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Three speed automatic turntable replacement
On Aug 13, 10:32*pm, wrote:
Boy this is a useful group. Get a USB turntable. Sure, now where the **** do I plug it into this 1968 Magnavox mahogany monster ? LOL Or a laser can read those grooves, just buy the interface and a PC to feed the tape input (if any) of the mahogany masterpiece. ****ing amazing how people actually live. I mean not starve to death. To cook dinner, right click the desktop and go down to food. In the categories there choose from meat, veggie, fish, poultry etc. Click on the category you want and then read (OH NO) the contents of the window that opens. Then choose side dishes. Make your selection and allow autocomplete to give the pizza guy your life history and access to all your money and wait for the bell to ring. Note if you live in a hi-rise apartment, death may occur from starvation. We apologize for any inconvenience. You don't think it's a bit quixotic to demand a drop-in replacement for a half-century old consumer apparatus? In the 1960s were you still trying to keep your 1918 Maxwell running? My mom used to be a Victor Comptometer operator. Do you think she could get that kind of work today? One suggestion: When my late grandfather decided there was no more use in maintaining his seven-year-old monochrome TV, just about that same time, he disposed of the guts and turned the fine woodworking case into a curio cabinet. |
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#14
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Three speed automatic turntable replacement
The distortion is not a big deal. One just has to find a few
master tapes (or films) and the corresponding records, digitize and compare them to come up with a "correction". This was known and done 50 years ago -- qv, Dynagroove. Which, as it turns out, died a quick and well-deserved death. There's a good reason why it was abandoned by RCA and never adopted by any other recording company. It sounded terrible. I knew I shouldn't have said anything about Dynagroove. The Dynagroove system was intended to make recordings "sound good" on cheap playback systems. It abandoned the concept of fidelity to the original sound, producing recordings that sounded worse the better the quality of the playback system. Almost everything about it was aesthetically invalid or technically dubious. ALMOST everything. The one thing Dynagroove "got right" was the pre-distortion of the groove, to compensate for the finite radius of the playback stylus. End of story, case closed. |
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#15
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Three speed automatic turntable replacement
There were lots of sorts of pre-distortion used in the vinyl recording
process: noise reduction EQ (the RIAA curve), radial EQ (poorer HF response on inner grooves), bass mixing to reduce groove cut-through, None of these are forms of pre-distortion, because the effects they compensate for are linear -- they are not distortion. (I'm going to insist on this, because "distortion" has a clear, specific meaning.) stylus shape pre-distortion because the cutter is flat and the playback stylus is a cone or an ellipse (and they need different treatment during recording) (this is NOT Dynagroove) It was a component of Dynagroove -- the only one that actually worked. treble boost to account for loss of HF due to the cutter being heated to reduce noise) Not a form of distortion. corrections because the cutter traverses the disk radially and the playback stylus does not This is a form of distortion, but it's not compensated for during recording, because there is no standardized playback-arm geometry. If the waveform you want out of the phono preamp is a square wave (or near enough), what path must the groove cause the stylus to trace to produce that? (Hint: it's *not* a square wave). Once you figure out what the groove looks like for a square wave output, you'll realize that the groove *never* really "looks like" the waveform of the "sound", and that the conversion from one waveshape to the other is yet another compromise, though not so much as the recording process. It is, in fact, quite difficult to analyze the shape of the groove and determine "analytically" what the resulting sound waves should look like. Actually, it's quite simple, because we know how cutting systems were designed. In the electrical era, cutter heads were velocity devices, with EQ applied to produce what the record label considered a practical approximation of constant-amplitude recording. A mechanical playback method takes care of all that "automatically" because the recording process is arranged so as to minimize the *system* distortion, *assuming the reproduction is going to be by means of a stylus in the groove*. No, it isn't. If distortion in one part of the system cancels out distortion in another part, it's either dumb luck, or because somebody "fiddled" with things. This was particularly true in the days of acoustic recording, when recordings were intended to be played back on the reproducing equipment made by the record manufacturer. Please read what Western Electric said about its system of electrical disk recording -- it was intended that each element of it be as perfect as technology then allowed, without errors in one part of the system being compensated for in another part. This allowed for continual improvement without having to periodically re-design everything. Any other playback process must perform all those things explicitly in order to get good results -- i.e. it must simulate the behavior of a stylus in the groove -- and that's not so easy. Sure it is. The math to do this existed long before any of us was born. In general, mechanical analog recording stinks, and mechanical analog playback is even worse. There's nothing inherently "correct" about it. It's amazing that phonograph records were as good as they (sometimes) were. |
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#17
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Three speed automatic turntable replacement
On Aug 13, 12:37*am, "Klaatu" wrote:
"klem kedidelhopper" wrote in message ... I got an old, (what looks like a BSR) three speed automatic turntable in for repair. It doesn't work on auto because the plastic trip pawl is worn. I can't get to the trip pawl without doing a semi major strip down. And this guy isn't going to go for that. I would like to replace the turntable with an equivalent inexpensive BSR type for him. I used to be able to buy these from my parts suppliers for about 20 bucks about 100 or so years ago but I haven't looked into this for a long time. Is it still possible to find something like this, a basic general replacement type idler driven mechanical turntable with a cheapo ceramic cartridge? Thanks, Lenny How many cases of them do you want? *Google USB turntable. *Geek.com had them on special this week for $29.95. USB turntables are plastic junk.... |
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#18
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Three speed automatic turntable replacement
"Use the MaggotBox for firewood and replace it something
more modern" (My dear old Dad used to call them that :....) But the customer is in LUV with it ! Of course not enough to spend "too" much money on it lol. Really though some people do like those, at one shop where I worked on a few of them they were clearing estimates for near $300. Still want that weenie roast ? Another alternative is to replace ALL the guts. It takes a bit of woodwork but you get a modest 25 WPC reciever from the 1970s, a regular turntable and just hook it up to the existing speakers. It depends on the "purism" of the customer. In fact my Uncle BUILT a mahogany monster a long time ago. Copied a MacIntosh Williamson push pull design and built a pair of monoblock amps, dug up a preamp and tuner and mounted them, put in an Elac Miracord turntable and built the speakers separate but in matching cabinets. You couldn't buy something like this and I think if I had it today it would be worth quite a bit - to the right person (read fanatic) of course. In fact his son, my cousin also built his own amp and speakers, but of course that was more modern having them thar newfangled transistors. Another thing that brought in some money a while back was putting new TVs in old cabinets. It was the cost of the new table model TV which we had to choose of course, plus about $250 labor. If a combo we would wire the TV sound to go through the amp and speakers, for a small fee of course. People paid it. " I thought it was a good idea, " It seems I heard those words before, now where was that ? OH YEAH, ME ! Plus about ½ the people I've ever known. Amazing how many ideas I had, and now tht I have spare parts to burn, PCB making supplies and a small machine shop, I draw a blank. Well almost. "You've been watching too much old Star Trek episodes. These days, we take dried soybean curd, add flavoring, modify the texture, heat, and serve." Careful with a can of worms that big. I correspond internationally and just joined Internations in fact. Get this, there are people who LEAVE AMERICA because they can't stand the food. I **** you not. By the way, I am having a very hard time getting any Star Trek online. It seems CBS is very stingy with them. "There are numerous supermarket delivery services" Yes but some of these high security buildings are ridiculous. Sign this, stand here for the photo, show ID. Next the TSA will be there doing cavity searches. Anyway this has been wonderful banter but I would lke to get on to this pre-distortion thing. I had a concept a while back having to do with tape recoding. As you all may know if a tape is underbiased, it loses some midrange and lows, and has odd order distortion in the phase which extends the peaks.. An overbiased tape loses highs and has odd order distortion in the phase which flattens the peaks. Now if one had a misbiased tape, and then copied it misbiasing the tape to be recoded on the opposite way, that might concievably cancel out no ? Of course it would be a PITA because then you have to determine the lavels. But IN THEORY it should work. "IN THEORY it should work" If you have never heard that one raise your hand. J |
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#19
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Three speed automatic turntable replacement
In article ,
"William Sommerwerck" wrote: There were lots of sorts of pre-distortion used in the vinyl recording process: noise reduction EQ (the RIAA curve), radial EQ (poorer HF response on inner grooves), bass mixing to reduce groove cut-through, None of these are forms of pre-distortion, because the effects they compensate for are linear -- they are not distortion. (I'm going to insist on this, because "distortion" has a clear, specific meaning.) I would argue that any difference between the input to a system and its output would be "distortion" by definition. One reason some early CDs sounded so bad is that they were made using the cutting masters intended for driving cutting lathes. Everything that was done to the master tapes to prepare them for making vinyls (and that is a hell of a lot) is distortion, in my definition. stylus shape pre-distortion because the cutter is flat and the playback stylus is a cone or an ellipse (and they need different treatment during recording) (this is NOT Dynagroove) It was a component of Dynagroove It was also used long before (and after) Dynagroove came out, by many labels. -- the only one that actually worked. Which would explain why is was abandoned so soon after its introduction .... treble boost to account for loss of HF due to the cutter being heated to reduce noise) Not a form of distortion. corrections because the cutter traverses the disk radially and the playback stylus does not This is a form of distortion, but it's not compensated for during recording, because there is no standardized playback-arm geometry. For information on this, and some of your other statements, I strongly recommend that you get, and read, an earlier edition of John Eargle's "Handbook Of Recording Engineering" -- earlier (2nd. ed. for instance), because later ones make no mention of vinyl techniques, but they are well covered in early ones. If the waveform you want out of the phono preamp is a square wave (or near enough), what path must the groove cause the stylus to trace to produce that? (Hint: it's *not* a square wave). Once you figure out what the groove looks like for a square wave output, you'll realize that the groove *never* really "looks like" the waveform of the "sound", and that the conversion from one waveshape to the other is yet another compromise, though not so much as the recording process. It is, in fact, quite difficult to analyze the shape of the groove and determine "analytically" what the resulting sound waves should look like. Actually, it's quite simple, because we know how cutting systems were designed. In the electrical era, cutter heads were velocity devices, with EQ applied to produce what the record label considered a practical approximation of constant-amplitude recording. OK. It's simple. So what *does* the groove look like? A mechanical playback method takes care of all that "automatically" because the recording process is arranged so as to minimize the *system* distortion, *assuming the reproduction is going to be by means of a stylus in the groove*. No, it isn't. If distortion in one part of the system cancels out distortion in another part, it's either dumb luck, or because somebody "fiddled" with things. This was particularly true in the days of acoustic recording, when recordings were intended to be played back on the reproducing equipment made by the record manufacturer. Please read what Western Electric said about its system of electrical disk recording -- it was intended that each element of it be as perfect as technology then allowed, without errors in one part of the system being compensated for in another part. This allowed for continual improvement without having to periodically re-design everything. I've read it. Eargle's book is a lot more recent, and embodies a whole lot of knowledge and *practice* that was simply unknown at the time the Western Electric stuff was written. Any other playback process must perform all those things explicitly in order to get good results -- i.e. it must simulate the behavior of a stylus in the groove -- and that's not so easy. Sure it is. The math to do this existed long before any of us was born. And that is why vinyl recordings sound soo good ... In general, mechanical analog recording stinks, and mechanical analog playback is even worse. There's nothing inherently "correct" about it. It's amazing that phonograph records were as good as they (sometimes) were. On that, we can absolutely agree. Isaac |
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#20
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Three speed automatic turntable replacement
"I would argue that any difference between the input to a system and its
output would be "distortion" by definition. " Well I would argue something else, in fact I will. You may have made a blanket statement unknowing of certain aspects of hifi, or you may be one of those purists that require the plastic for the faceplate to be grown in th...... nevermind. That statement would mean then that you object to RIAA equalization as well as NARTB. The reason RIAA equalization exists is because of the properties of vinyl. Black vinyl is the toughest, and was produced by adding carbon to the material, just like many plastics and similar things. Before that the laquer or whatever records (78s) that were CUT also had alot of grit in them. This made HISS. Since the high frequency waves ARE actually smaller, they decided to crank them up on the recording side and do the EXACT opposite on the playback side. It's like having to steer right when you have a flat tire on the left. Without what you erroneously call distorion everything you hear would sound hissy, to the point maybe of unlistenability. This also applies to tapes and therefore to the master tapes made to record music. Hiss upon hiss. Think AM was bad ? In an RIAA compliant phono preamp a calibrated EQ curve is applied. Actully if you see the "curve" it is actually a tilt. Two resistors and two capacitors per channel achieve this. It matches because they match the "time constants" of the opposite network applied to the signal when it was recorded. On tape the NARTB curve is THE standard, but for better results they do not approach it separately. Very long ago they did, you could get an outboard preamp and it would amplify your signal right from the tape heads, apply the requisite NARTB equalization and give you flat response at "line level", which is all pretty much what a tuner put(s) out. However in a tape deck there is so much equalization to do with the heads that the NARTB, as I said, is not considered sepatrately, and neither is it in playback. HOWEVER for compatibility between different decks, it must be adhered to, that is the only thing. You may not be aware but digital sound also has such schemes. Understand this (listen up y'all I ain't doing this twice)....... OK you got wonderful 16 bit sound, it is great right ? Well what happens when you are at a piece of the music that is at -66dB ? It ain't 16 bit no more, is it even 8 bit ? Just that very soft part of it, understand ? Well the people who designed the system DID figure this out and as such there was a pre-emph signal on CDs from day one. When it got below a certin level the preemph would kick in and the deemph on the playback side. This gave it more bits during the soft passages of the music. This lack of bits situation is also abated by something called dither. Dither is white noise added to the program material to prevent these digital artifacts from cropping up during the soft passages of you favorite jam. Is it that good ? Well CD quality has been quite surpassed by certain DVD audio formats. In fact the Sony PCM-1 or PCM-F1 could take a DVDR or any VCR and record better than a CD. Almost thirty years ago ! More later, this is long enough and I need to go eat. Cook and eat actualy. J |
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#21
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Three speed automatic turntable replacement
None of these are forms of pre-distortion, because the effects
they compensate for are linear -- they are not distortion. (I'm going to insist on this, because "distortion" has a clear, specific meaning.) I would argue that any difference between the input to a system and its output would be "distortion" by definition. That's not correct usage. Any linear transformation of a system's I/O characteristics is, by definition, //not// distortion. Distortion is a non-linear transformation. One reason some early CDs sounded so bad is that they were made using the cutting masters intended for driving cutting lathes. Everything that was done to the master tapes to prepare them for making vinyls (and that is a hell of a lot) is distortion, in my definition. As far as I know, all the changes were linear changes, and were not distortion, stylus shape pre-distortion because the cutter is flat and the playback stylus is a cone or an ellipse (and they need different treatment during recording) (this is NOT Dynagroove) It was a component of Dynagroove It was also used long before (and after) Dynagroove came out, by many labels. Name one. -- the only one that actually worked. Which would explain why is was abandoned so soon after its introduction. I don't know how long it took RCA to abandon Dynagroove. My understanding is that RCA continued to use pre-distortion for some years. It was the only part of Dynagroove that was a technically and aesthetically legitimate improvement, and I doubt RCA wanted to immediately abandon the hardware for it. corrections because the cutter traverses the disk radially and the playback stylus does not This is a form of distortion, but it's not compensated for during recording, because there is no standardized playback-arm geometry. For information on this, and some of your other statements, I strongly recommend that you get, and read, an earlier edition of John Eargle's "Handbook Of Recording Engineering" -- earlier (2nd. ed. for instance), because later ones make no mention of vinyl techniques, but they are well covered in early ones. If John Eargle's views differ from mine on these points, he is incorrect. If the waveform you want out of the phono preamp is a square wave (or near enough), what path must the groove cause the stylus to trace to produce that? (Hint: it's *not* a square wave). Once you figure out what the groove looks like for a square wave output, you'll realize that the groove *never* really "looks like" the waveform of the "sound", and that the conversion from one waveshape to the other is yet another compromise, though not so much as the recording process. It is, in fact, quite difficult to analyze the shape of the groove and determine "analytically" what the resulting sound waves should look like. Actually, it's quite simple, because we know how cutting systems were designed. In the electrical era, cutter heads were velocity devices, with EQ applied to produce what the record label considered a practical approximation of constant-amplitude recording. OK. It's simple. So what *does* the groove look like? Read the my preceding paragraph. A mechanical playback method takes care of all that "automatically" because the recording process is arranged so as to minimize the *system* distortion, *assuming the reproduction is going to be by means of a stylus in the groove*. No, it isn't. If distortion in one part of the system cancels out distortion in another part, it's either dumb luck, or because somebody "fiddled" with things. This was particularly true in the days of acoustic recording, when recordings were intended to be played back on the reproducing equipment made by the record manufacturer. Please read what Western Electric said about its system of electrical disk recording -- it was intended that each element of it be as perfect as technology then allowed, without errors in one part of the system being compensated for in another part. This allowed for continual improvement without having to periodically re-design everything. I've read it. Eargle's book is a lot more recent, and embodies a whole lot of knowledge and *practice* that was simply unknown at the time the Western Electric stuff was written. What does that have to do with the first paragraph of this section? Any other playback process must perform all those things explicitly in order to get good results -- i.e. it must simulate the behavior of a stylus in the groove -- and that's not so easy. Sure it is. The math to do this existed long before any of us was born. And that is why vinyl recordings sound sooo good ... I don't know whether you're being ironic, but on the assumption you're not... About a year ago I sat down with a pile of audiophile LPs and sonically browsed them. Many had really nice sound -- highly listenable -- but little of it sounded as much like //live// sound as the best SACDs (and the rare CD). LPs can be highly euphonic -- but when push-pull comes to shove, they simply aren't that //accurate//. As only a few had performances I wanted to hang on to, I sold almost all my audiophile disks to Silver Platters, and got $600 in store credit. In general, mechanical analog recording stinks, and mechanical analog playback is even worse. There's nothing inherently "correct" about it. It's amazing that phonograph records were as good as they (sometimes) were. On that, we can absolutely agree. |
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#22
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Three speed automatic turntable replacement
You may not be aware but digital sound also has such
schemes. Understand this (listen up y'all I ain't doing this twice)....... Yes, we don't have all day, Vince. OK you got wonderful 16 bit sound, it is great right? Well what happens when you are at a piece of the music that is at -66dB ? It ain't 16 bit no more, is it even 8 bit ? Just that very soft part of it, understand ? Well the people who designed the system DID figure this out and as such there was a pre-emph signal on CDs from day one. When it got below a certin level the preemph would kick in and the deemph on the playback side. This gave it more bits during the soft passages of the music. The pre-emphasis was optional, and was abandoned years ago. I believe some CD players have no way of compensating for it. CD quality has been quite surpassed by certain DVD audio formats. In fact the Sony PCM-1 or PCM-F1 could take a DVD-R or any VCR and record better than a CD. Almost thirty years ago! I don't think you know what you're talking about. The PCM-F1 (and its Nakamichi equivalent, the DMP-100) could record at 14-bit or 16-bit resolution. That was its limit. I own a DMP-100. 25 years ago I made parallel live recordings with the dbx 700, a processor using a system similar to Sony's Direct Stream Digital. To my ears, the dbx 700 was superior. |
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#23
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Three speed automatic turntable replacement
I beg to differ. Everything you have heard in the last twenty years is somehow compressed. Not the data but the music. the texchnique was developed for the 8mm Sony digital audio format which ran on the same tapes as the camcorder. It would record IIRC 12 tracks, like an old eight track. You could switch tracks but to get back to the beginning unless you rewind the tape.
That process split the fields on the diagonal sweep of the heads into 12 sectors. The 8mm system had integral flying erase heads, just as PAL had an integral COMB filter. You COULD change tracks with ease, if the tape position was near. But that is not the point. If you look at the specs for that system you find out a few things. First of all it's LIMITATIONS are that of an FM broadcast. Well two, in tandem to give you two channels. But you are only getting 15Khz. Now the PCM-1 had it's own format, and really all I knowe is that is worked.. But I have in my posession the full manual on the PCM-F1 which explains it's operation in more detail than anyone could ever want. It has the normal mode which is 44,100 siteen bit. Your CDs are not that. The 16 bit audio is cropped down by EFM which separates the positive and negative, then it is further compressed down to eight bit words. Additionally there is a Dolby like noise suppression scheme. That is not quite high fidelity, yathink ? The PCM-F1 doesn't use this, making it better than a CD out the box. But if tha isn't good enough, it has a 48Khz mode, which is what the big movie theaters etc. use. And there is no compression at all. Well they do use it but they have REAL sisxteen bit, CDs do not. Yes, it was better even back then. What's more in case you didn't know, the ubiquitous CD is capable of four channel discrete sound. (reference a book called "Principles Of Digital Audio" circa 1990 or so for that) You don't think I know what I am talking about ? I think you should have stopped before the "you know what you are talking about" part. J |
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#24
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Three speed automatic turntable replacement
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#25
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Three speed automatic turntable replacement
On Wed, 15 Aug 2012 06:25:17 -0700, "William Sommerwerck"
wrote: You may not be aware but digital sound also has such schemes. Understand this (listen up y'all I ain't doing this twice)....... Yes, we don't have all day, Vince. OK you got wonderful 16 bit sound, it is great right? Well what happens when you are at a piece of the music that is at -66dB ? It ain't 16 bit no more, is it even 8 bit ? Just that very soft part of it, understand ? Well the people who designed the system DID figure this out and as such there was a pre-emph signal on CDs from day one. When it got below a certin level the preemph would kick in and the deemph on the playback side. This gave it more bits during the soft passages of the music. The pre-emphasis was optional, and was abandoned years ago. I believe some CD players have no way of compensating for it. CD quality has been quite surpassed by certain DVD audio formats. In fact the Sony PCM-1 or PCM-F1 could take a DVD-R or any VCR and record better than a CD. Almost thirty years ago! I don't think you know what you're talking about. The PCM-F1 (and its Nakamichi equivalent, the DMP-100) could record at 14-bit or 16-bit resolution. That was its limit. I own a DMP-100. 25 years ago I made parallel live recordings with the dbx 700, a processor using a system similar to Sony's Direct Stream Digital. To my ears, the dbx 700 was superior. Fine. Dbx systems included dynamic compressors, like A-law and u-Law telephony systems. Provided better dynamic range and other nice properties at the cost of more processing, see also SACD. ?-) |
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#26
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Three speed automatic turntable replacement
In article ,
"William Sommerwerck" wrote: --snip -- For information on this, and some of your other statements, I strongly recommend that you get, and read, an earlier edition of John Eargle's "Handbook Of Recording Engineering" -- earlier (2nd. ed. for instance), because later ones make no mention of vinyl techniques, but they are well covered in early ones. If John Eargle's views differ from mine on these points, he is incorrect. He was chief engineer for several recording companies. What are your qualifications? If the waveform you want out of the phono preamp is a square wave (or near enough), what path must the groove cause the stylus to trace to produce that? (Hint: it's *not* a square wave). Once you figure out what the groove looks like for a square wave output, you'll realize that the groove *never* really "looks like" the waveform of the "sound", and that the conversion from one waveshape to the other is yet another compromise, though not so much as the recording process. It is, in fact, quite difficult to analyze the shape of the groove and determine "analytically" what the resulting sound waves should look like. Actually, it's quite simple, because we know how cutting systems were designed. In the electrical era, cutter heads were velocity devices, with EQ applied to produce what the record label considered a practical approximation of constant-amplitude recording. OK. It's simple. So what *does* the groove look like? Read the my preceding paragraph. Yeah ... I didn't think you knew. Isaac |
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#27
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Three speed automatic turntable replacement
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#28
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Three speed automatic turntable replacement
Everything you have heard in the last twenty years
is somehow compressed. Not the data but the music. the texchnique was developed for the 8mm Sony digital audio format which ran on the same tapes as the camcorder. It would record IIRC 12 tracks, like an old eight track. You could switch tracks but to get back to the beginning unless you rewind the tape. The only compression used was dynamic-range compression, which was (badly) needed for 8-bit (!!!) digital recording. As you said, you could make audio-only recordings. Pioneer produced a machine that could record 24 hours on a single two-hour video tape, using six passes. (Pioneer's presenter at the SCES remarked sarcasticly that some people could put their entire LP collection on a single tape!) If you look at the specs for that system you find ... its LIMITATIONS are that of an FM broadcast. Well two, in tandem to give you two channels. But you are only getting 15Khz. A good live broadcast on FM has far better sound that most CDs. 15kHz is hardly a meaningful limitation. The PCM-1 had it's own format, and really all I know is that it worked. But I have the full [technical] manual, which explains its operation in more detail than anyone could ever want. Agreed! (I have it, too.)] It has the normal mode, which is 44.1 kHz, 16-bit. Normal mode is 44.056 kHz, 14-bit. 16-bit recording gains two bits by weakening the error correction, making uncorrectable errors more likely. (I never had problems with 16 bit.) Your CDs are not that. The 16 bit audio is cropped down by EFM which separates the positive and negative, then it is further compressed down to eight bit words. Additionally there is a Dolby-like noise suppression scheme. That is not quite high fidelity, yathink? If you're talking about CDs, that's mostly wrong. The CD format is linear. There is no "Dolby-like noise suppression scheme" of ANY sort. EFM means "eight to fourteen modulation", which maps eight bits of each 16-bit data word into a 14-bit "space". This reduces read and pressing errors, and makes it easier to correct those that do occur. The PCM-F1 doesn't use this, making it better than a CD out of the box. The PCM-F1 is essentially identical to CD. Both are 16-bit, and their sample rates differ only by 0.1%. But if that isn't good enough, it has a 48Khz mode, which is what the big movie theaters etc. use. And there is no compression at all. Well, they do use it but they have REAL sixteen bit, CDs do not. You're confusing the PCM-F1, CD, and DAT. DAT has 48kHz sampling (plus 44.1 and 32). The others don't. NONE of these systems use lossy compression. And they're all "real" 16-bit. Most systems of theatrical digital sound use some form of lossy compression. But I believe non-lossy compression is beginning to appear. (Someone fill me in, please.) Yes, it was better even back then. What's more, in case you didn't know, the ubiquitous CD is capable of four channel discrete sound. (Reference a book called "Principles Of Digital Audio" circa 1990 or so for that). The original Red Book standards defined a four-channel disk that ran at double speed (halving the playback time). Unfortunately, the idiots at Philips neglected any provision requiring two-channel-only CD players to be compatible with four-channel disks. As long as we're on it... The Philips idiots also missed the opportunity to double the playback time for mono recordings. You don't think I know what I am talking about ? I think you should have stopped before the "you know what you are talking about" part. To quote Alexander Pope: "A little learning is a dangerous thing." |
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#29
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Three speed automatic turntable replacement
For information on this, and some of your other statements, I strongly
recommend that you get, and read, an earlier edition of John Eargle's "Handbook Of Recording Engineering" -- earlier (2nd. ed. for instance), because later ones make no mention of vinyl techniques, but they are well covered in early ones. If John Eargle's views differ from mine on these points, he is incorrect. He was chief engineer for several recording companies. What are your qualifications? I know what I'm talking about. Does Mr Eargle? I didn't say John Eargle was wrong. I said I was right, and that if his views (which I don't know in detail) were different, then he's wrong. I stand by that. If the waveform you want out of the phono preamp is a square wave (or near enough), what path must the groove cause the stylus to trace to produce that? (Hint: it's *not* a square wave.) Once you figure out what the groove looks like for a square wave output, you'll realize that the groove *never* really "looks like" the waveform of the "sound", and that the conversion from one waveshape to the other is yet another compromise, though not so much as the recording process. It is, in fact, quite difficult to analyze the shape of the groove and determine "analytically" what the resulting sound waves should look like. Actually, it's quite simple, because we know how cutting systems were designed. In the electrical era, cutter heads were velocity devices, with EQ applied to produce what the record label considered a practical approximation of constant-amplitude recording. OK. It's simple. So what *does* the groove look like? Read my preceding paragraph. Yeah ... I didn't think you knew. The paragraph reads: "In the electrical era, cutter heads were velocity devices, with EQ applied to produce what the record label considered a practical approximation of constant-amplitude recording." Do you know the difference between velocity and constant-amplitude recording? If a recording approximates constant-amplitude, then the groove waveform will approximate the original waveform. Right? RIGHT? |
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#30
Posted to sci.electronics.repair
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Three speed automatic turntable replacement
In article ,
"William Sommerwerck" wrote: For information on this, and some of your other statements, I strongly recommend that you get, and read, an earlier edition of John Eargle's "Handbook Of Recording Engineering" -- earlier (2nd. ed. for instance), because later ones make no mention of vinyl techniques, but they are well covered in early ones. If John Eargle's views differ from mine on these points, he is incorrect. He was chief engineer for several recording companies. What are your qualifications? I know what I'm talking about. Does Mr Eargle? Why don't you just google on his name and decide for yourself? I didn't say John Eargle was wrong. I said I was right, and that if his views (which I don't know in detail) were different, then he's wrong. I stand by that. If the waveform you want out of the phono preamp is a square wave (or near enough), what path must the groove cause the stylus to trace to produce that? (Hint: it's *not* a square wave.) Once you figure out what the groove looks like for a square wave output, you'll realize that the groove *never* really "looks like" the waveform of the "sound", and that the conversion from one waveshape to the other is yet another compromise, though not so much as the recording process. It is, in fact, quite difficult to analyze the shape of the groove and determine "analytically" what the resulting sound waves should look like. Actually, it's quite simple, because we know how cutting systems were designed. In the electrical era, cutter heads were velocity devices, with EQ applied to produce what the record label considered a practical approximation of constant-amplitude recording. OK. It's simple. So what *does* the groove look like? Read my preceding paragraph. Yeah ... I didn't think you knew. The paragraph reads: "In the electrical era, cutter heads were velocity devices, with EQ applied to produce what the record label considered a practical approximation of constant-amplitude recording." Do you know the difference between velocity and constant-amplitude recording? If a recording approximates constant-amplitude, then the groove waveform will approximate the original waveform. Right? RIGHT? Nope. Not even close. An electrical generator (a magnetic cartridge) provides a constant voltage in response to a constant velocity. To get a more-or-less square wave, the groove is a triangle wave. The slopes equate to the flat top and bottom, and the inflection points to the rising and falling edges. Isaac |
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#31
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Three speed automatic turntable replacement
The paragraph reads: "In the electrical era, cutter heads were velocity
devices, with EQ applied to produce what the record label considered a practical approximation of constant-amplitude recording." Do you know the difference between velocity and constant-amplitude recording? If a recording approximates constant-amplitude, then the groove waveform will approximate the original waveform. Right? RIGHT? Nope. Not even close. It's dead-on. An electrical generator (a magnetic cartridge)... There are non-magnetic electrical generators. You meant a /velocity/ device. provides a constant voltage in response to a constant velocity. Only if it's a velocity generator. To get a more-or-less square wave, the groove is a triangle wave. Yes -- out of an UNEQUALIZED magnetic pickup. Do I have to explain it all over again? Seems so. When you cut a phonograph record with an electromagnetic head, you get a constant-velocity recording. That is, groove modulation is huge for low frequencies, teensy for high frequencies. There two basic problems with this. The extreme low-frequency excursions require a very wide groove pitch (reducing playing time) and the high frequencies are "down in the dirt" (making the sound noisier than we might like). The solution adopted by the recording industry was to cut the bass and boost the treble to produce an approximation of constant-amplitude recording. I say an "approximation", because a huge amount of boost and cut would be needed to get constant amplitude from (say) 50Hz to 20kHz (about 50dB). In practice, the bass cut stops at about 500Hz and the treble boost begins at about 2kHz (which needs only about 30dB). The result is a recording that's much closer to constant amplitude. If one looks at a constant-amplitude recording under a microscope, it will resemble the original acoustic waveform -- not the temporally integrated waveform produced by an un-EQ'd magnetic cutter head.. When recording using RIAA (or other) EQ is played back with a constant-amplitude pickup, the output is essentially flat, exactly what we want in a cheap phonograph. When played with a magnetic (velocity) pickup, the constant-amplitude waveform is differentiated, requiring integrating equalization in the amplifier. Which is what phono preamps provide. I realize this can be confusing, but the preceding is correct. You need to think it through. |
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#32
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Three speed automatic turntable replacement
On Aug 16, 7:31*am, "William Sommerwerck"
wrote: Everything you have heard in the last twenty years is somehow compressed. Not the data but the music. the texchnique was developed for the 8mm Sony digital audio format which ran on the same tapes as the camcorder. It would record IIRC 12 tracks, like an old eight track. You could switch tracks but to get back to the beginning unless you rewind the tape. The only compression used was dynamic-range compression, which was (badly) needed for 8-bit (!!!) digital recording. As you said, you could make audio-only recordings. Pioneer produced a machine that could record 24 hours on a single two-hour video tape, using six passes. (Pioneer's presenter at the SCES remarked sarcasticly that some people could put their entire LP collection on a single tape!) If you look at the specs for that system you find ... its LIMITATIONS are that of an FM broadcast. Well two, in tandem to give you two channels. But you are only getting 15Khz. A good live broadcast on FM has far better sound that most CDs. 15kHz is hardly a meaningful limitation. The PCM-1 had it's own format, and really all I know is that it worked. But I have the full [technical] manual, which explains its operation in more detail than anyone could ever want. Agreed! (I have it, too.)] It has the normal mode, which is 44.1 kHz, 16-bit. Normal mode is 44.056 kHz, 14-bit. 16-bit recording gains two bits by weakening the error correction, making uncorrectable errors more likely. (I never had problems with 16 bit.) Your CDs are not that. The 16 bit audio is cropped down by EFM which separates the positive and negative, then it is further compressed down to eight bit words. Additionally there is a Dolby-like noise suppression scheme. That is not quite high fidelity, yathink? If you're talking about CDs, that's mostly wrong. The CD format is linear.. If you don't count quantizing error and aliasing effects. There is no "Dolby-like noise suppression scheme" of ANY sort. EFM means "eight to fourteen modulation", which maps eight bits of each 16-bit data word into a 14-bit "space". This reduces read and pressing errors, and makes it easier to correct those that do occur. |
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#33
Posted to sci.electronics.repair
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Three speed automatic turntable replacement
In article ,
"William Sommerwerck" wrote: The paragraph reads: "In the electrical era, cutter heads were velocity devices, with EQ applied to produce what the record label considered a practical approximation of constant-amplitude recording." Do you know the difference between velocity and constant-amplitude recording? If a recording approximates constant-amplitude, then the groove waveform will approximate the original waveform. Right? RIGHT? Nope. Not even close. It's dead-on. An electrical generator (a magnetic cartridge)... There are non-magnetic electrical generators. You meant a /velocity/ device. provides a constant voltage in response to a constant velocity. Only if it's a velocity generator. And kindly describe another kind of electromagnetic generator? To get a more-or-less square wave, the groove is a triangle wave. Yes -- out of an UNEQUALIZED magnetic pickup. Do I have to explain it all over again? Seems so. When you cut a phonograph record with an electromagnetic head, you get a constant-velocity recording. That is, groove modulation is huge for low frequencies, teensy for high frequencies. There two basic problems with this. The extreme low-frequency excursions require a very wide groove pitch (reducing playing time) and the high frequencies are "down in the dirt" (making the sound noisier than we might like). The solution adopted by the recording industry was to cut the bass and boost the treble to produce an approximation of constant-amplitude recording. I say an "approximation", because a huge amount of boost and cut would be needed to get constant amplitude from (say) 50Hz to 20kHz (about 50dB). In practice, the bass cut stops at about 500Hz and the treble boost begins at about 2kHz (which needs only about 30dB). The result is a recording that's much closer to constant amplitude. If one looks at a constant-amplitude recording under a microscope, it will resemble the original acoustic waveform -- not the temporally integrated waveform produced by an un-EQ'd magnetic cutter head.. When recording using RIAA (or other) EQ is played back with a constant-amplitude pickup, the output is essentially flat, exactly what we want in a cheap phonograph. When played with a magnetic (velocity) pickup, the constant-amplitude waveform is differentiated, requiring integrating equalization in the amplifier. Which is what phono preamps provide. I realize this can be confusing, but the preceding is correct. You need to think it through. In fact, I did not "think it through" until I happened to actually LOOK AT THE GROOVE of the "square wave" track of a test record. Then I thought "well, that's odd ..." and then I realized what must be going on. Isaac |
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#34
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Three speed automatic turntable replacement
In article
, spamtrap1888 wrote: On Aug 16, 7:31*am, "William Sommerwerck" wrote: Everything you have heard in the last twenty years is somehow compressed. Not the data but the music. the texchnique was developed for the 8mm Sony digital audio format which ran on the same tapes as the camcorder. It would record IIRC 12 tracks, like an old eight track. You could switch tracks but to get back to the beginning unless you rewind the tape. The only compression used was dynamic-range compression, which was (badly) needed for 8-bit (!!!) digital recording. As you said, you could make audio-only recordings. Pioneer produced a machine that could record 24 hours on a single two-hour video tape, using six passes. (Pioneer's presenter at the SCES remarked sarcasticly that some people could put their entire LP collection on a single tape!) If you look at the specs for that system you find ... its LIMITATIONS are that of an FM broadcast. Well two, in tandem to give you two channels. But you are only getting 15Khz. A good live broadcast on FM has far better sound that most CDs. 15kHz is hardly a meaningful limitation. The PCM-1 had it's own format, and really all I know is that it worked. But I have the full [technical] manual, which explains its operation in more detail than anyone could ever want. Agreed! (I have it, too.)] It has the normal mode, which is 44.1 kHz, 16-bit. Normal mode is 44.056 kHz, 14-bit. 16-bit recording gains two bits by weakening the error correction, making uncorrectable errors more likely. (I never had problems with 16 bit.) Your CDs are not that. The 16 bit audio is cropped down by EFM which separates the positive and negative, then it is further compressed down to eight bit words. Additionally there is a Dolby-like noise suppression scheme. That is not quite high fidelity, yathink? If you're talking about CDs, that's mostly wrong. The CD format is linear. If you don't count quantizing error and aliasing effects. Quantization is nicely taken care of by the dither, and aliasing by the oddly named "anti-aliasing low-pass filter" which is an integral (and mandatory) part of the process. Isaac |
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#35
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Three speed automatic turntable replacement
In fact, I did not "think it through" until I happened to actually
LOOK AT THE GROOVE of the "square wave" track of a test record. Then I thought "well, that's odd ..." and then I realized what must be going on. I still have my CBS Labs test LPs, and don't even need to look at the square-wave disk to know that the groove doesn't resemble a triangle waveform. IT CAN'T, because an LP cut with RIAA equalization comes much closer to being constant-amplitude than constant-velocity. ----------------- After writing that, I decided to pull out the STR 112 test disk. It turns out it //does// have triangle waveforms. Here's what the liner notes say... "Two groups of four 1000 Hz square-wave [sic] test bands are provided on the STR-112, Side A, at the outer and inner radii of the disc. ... The actual modulation excursion, as viewed under a microscope, is a triangle wave. Therefore, playback with an ideal velocity responsive [sic] pickup will yield a square wave." In other words... This is NOT a constant-amplitude recording, and it is to be used //without// RIAA equalization. "The square wave modulation allows rapid appraisal of stylus-tip mass, damping, and tracking." But the disk doesn't have "square wave modulation". If the conclusion isn't clear, I'll beat it into the ground with a sledge hammer. This disk DOES NOT test what it claims to test. You cannot test the "square wave" response of a pickup by applying a grossly different stimulus! What the disk actually tests is the response to a triangle wave. The fact that a (nominal) square wave pops out of a velocity-responding pickup is beside the point -- especially because an LP mastered with RIAA EQ //would// have a groove displacement that looked a lot like a square wave -- the pickup's response to which is what we're supposed to be testing. QED. Case closed. |
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#36
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Three speed automatic turntable replacement
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#37
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Three speed automatic turntable replacement
On Sat, 18 Aug 2012 04:15:30 -0700, "William Sommerwerck"
wrote: In fact, I did not "think it through" until I happened to actually LOOK AT THE GROOVE of the "square wave" track of a test record. Then I thought "well, that's odd ..." and then I realized what must be going on. I still have my CBS Labs test LPs, and don't even need to look at the square-wave disk to know that the groove doesn't resemble a triangle waveform. IT CAN'T, because an LP cut with RIAA equalization comes much closer to being constant-amplitude than constant-velocity. ----------------- After writing that, I decided to pull out the STR 112 test disk. It turns out it //does// have triangle waveforms. Here's what the liner notes say... "Two groups of four 1000 Hz square-wave [sic] test bands are provided on the STR-112, Side A, at the outer and inner radii of the disc. ... The actual modulation excursion, as viewed under a microscope, is a triangle wave. Therefore, playback with an ideal velocity responsive [sic] pickup will yield a square wave." In other words... This is NOT a constant-amplitude recording, and it is to be used //without// RIAA equalization. "The square wave modulation allows rapid appraisal of stylus-tip mass, damping, and tracking." But the disk doesn't have "square wave modulation". If the conclusion isn't clear, I'll beat it into the ground with a sledge hammer. This disk DOES NOT test what it claims to test. You cannot test the "square wave" response of a pickup by applying a grossly different stimulus! Wrong. Oh and BTW the velocity of the track IS (approximately) a square wave. Think that through. What the disk actually tests is the response to a triangle wave. The fact that a (nominal) square wave pops out of a velocity-responding pickup is beside the point -- especially because an LP mastered with RIAA EQ //would// have a groove displacement that looked a lot like a square wave -- the pickup's response to which is what we're supposed to be testing. QED. Case closed. And you really missed a lot. The output of the cartridge is a approximate square wave for that track, if you run that through RIAA playback equalization you get a very different signal. ?-) |
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#38
Posted to sci.electronics.repair
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Three speed automatic turntable replacement
In other words... This is NOT a constant-amplitude recording,
and it is to be used //without// RIAA equalization. "The square wave modulation allows rapid appraisal of stylus-tip mass, damping, and tracking." But the disk doesn't have "square wave modulation". If the conclusion isn't clear, I'll beat it into the ground with a sledge hammer. This disk DOES NOT test what it claims to test. You cannot test the "square wave" response of a pickup by applying a grossly different stimulus! Wrong. I just /knew/ someone was going to claim that. It's called "blindly believing a manufacturer's claim despite all evidence to the contrary". The LP doesn't "know" what sort of a pickup is playing it. The groove is engraved with a triangle wave, and the behavior of the pickup's mechanical system represents its response to a TRIANGLE WAVE driving function. What part of that don't you (or CBS) understand? The fact that a velocity pickup converts the triangle into a square wave is beside the point -- yea, even meaningless. If I played the disk with a amplitude-responding pickup (such as a Sonotone) its output would be a TRIANGLE WAVE. Would the test then be a SQIARE WAVE test? According to CBS's perverted use of language and logic, it would be. Oh and BTW the velocity of the track IS (approximately) a square wave. Think that through. Of course. You're repeating what I said. But the fact that a velocity pickup has an output that resembles a particular waveform DOES NOT mean you're testing how the pickup responds to a groove modulation of that sort. If you want to call the STR 112 a test of transient behavior, go right ahead, because it arguably is. But it DOES NOT test the pickup's response to square-wave modulation. What would you call its behavior for a amplitude-responding pickup? And you really missed a lot. The output of the cartridge is an approximate square wave for that track, if you run that through RIAA playback equalization you get a very different signal. No, I missed nothing. You are guilty of blindly believing what "experts", without thinking about it. You can easily find books that say that simply sampling a continuous waveform converts it into digital data. But that doesn't make it true. |
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#39
Posted to sci.electronics.repair
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Three speed automatic turntable replacement
On Wed, 22 Aug 2012 04:38:31 -0700, "William Sommerwerck"
wrote: In other words... This is NOT a constant-amplitude recording, and it is to be used //without// RIAA equalization. "The square wave modulation allows rapid appraisal of stylus-tip mass, damping, and tracking." But the disk doesn't have "square wave modulation". If the conclusion isn't clear, I'll beat it into the ground with a sledge hammer. This disk DOES NOT test what it claims to test. You cannot test the "square wave" response of a pickup by applying a grossly different stimulus! Wrong. I just /knew/ someone was going to claim that. It's called "blindly believing a manufacturer's claim despite all evidence to the contrary". The LP doesn't "know" what sort of a pickup is playing it. The groove is engraved with a triangle wave, and the behavior of the pickup's mechanical system represents its response to a TRIANGLE WAVE driving function. What part of that don't you (or CBS) understand? The fact that a velocity pickup converts the triangle into a square wave is beside the point -- yea, even meaningless. If I played the disk with a amplitude-responding pickup (such as a Sonotone) its output would be a TRIANGLE WAVE. Would the test then be a SQIARE WAVE test? According to CBS's perverted use of language and logic, it would be. First off you have to find/have/create an amplitude responding pickup. Do that first then re-enter the discussion. Second a triangle wave is the integral of a square wave, or the same relation between amplitude and velocity response. Oh and BTW the velocity of the track IS (approximately) a square wave. Think that through. Of course. You're repeating what I said. But the fact that a velocity pickup has an output that resembles a particular waveform DOES NOT mean you're testing how the pickup responds to a groove modulation of that sort. If you want to call the STR 112 a test of transient behavior, go right ahead, because it arguably is. But it DOES NOT test the pickup's response to square-wave modulation. What would you call its behavior for a amplitude-responding pickup? And you really missed a lot. The output of the cartridge is an approximate square wave for that track, if you run that through RIAA playback equalization you get a very different signal. No, I missed nothing. You are guilty of blindly believing what "experts", without thinking about it. You can easily find books that say that simply sampling a continuous waveform converts it into digital data. But that doesn't make it true. But they will claim that the z-transform make it so when challenged. Just as you argue about velocity versus amplitude responding pickups. Find me a phonograph pickup that is amplitude responding. Then we have something to discuss. Hint, stylus connected to a diaphragm and horn is not one. I constantly fight with other engineers that claim that just because it is on some manufacturers' data sheet it is right/true. e.g. that the name of the standard is RS-232 when the cover of the current 15+ year old (1997) version of standard says TIA-232. Likewise network connectors which are IEC 60603-7-x (See page 13 of TIA-568.2) or 8P8C modular instead of RJ-45 (which not even phone companies use any more). I will bet that you have seen such issues but rarely dug into it to the finish. ?-) |
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#40
Posted to sci.electronics.repair
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Three speed automatic turntable replacement
First off you have to find/have/create an amplitude-
responding pickup. Do that first then re-enter the discussion. They're commonly found in cheap turntables, especially of the USB ilk. Second, a triangle wave is the integral of a square wave, or the same relation between amplitude and velocity response. Yes, of course. That's simple calculus, which I took in high school almost 50 years ago. But they will claim that the z-transform make it so when challenged. Just as you argue about velocity- versus amplitude-responding pickups. Find me a phonograph pickup that is amplitude responding. Then we have something to discuss. First of all, the issue has nothing whatever to do with whether amplitude-responding pickups exist, ever have existed, or ever could exist. We are talking about a manufacturer claiming that a test record shows how a pickup responds to (mechanical) square-wave modulation, when the disk doesn't have such modulation. Piezoelectric transducers are basically amplitude-sensitive. Crystal and ceramic pickups were manufactured for decades, but gradually disappeared as magnetic pickups grew less expensive and tracked at lower forces. There have been "good" ceramic pickups (Sonotone and Weathers, for example), but they were rare. However, you can still find ceramic pickups in cheap turntables. http://www.knowzy.com/computers/audi...comparison.htm (The author's claim that anti-skating is an absolute necessity is debatable, to say the least.) If you want to get super-ultra picky about it, many ceramic pickups are mechanically equalized to compensate for the ~12dB shelf in response when playing RIAA LPs. This doesn't change the fact that the pickup is, fundamentally, an amplitude-responding device. I constantly fight with other engineers that claim that just because it is on some manufacturers' data sheet it is right/true. e.g. that the name of the standard is RS-232 when the cover of the current 15+ year old (1997) version of standard says TIA-232. Likewise network connectors which are IEC 60603-7-x (See page 13 of TIA-568.2) or 8P8C modular instead of RJ-45 (which not even phone companies use any more). I will bet that you have seen such issues but rarely dug into it to the finish. It appears that we are equally annoyed by the spread of misinformation. |
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