bkrop Posted August 1, 2003 Share Posted August 1, 2003 There was a discrete LP format with 4 channels, 2 on either side of the groove. The matrix format is what you describe with the signal being processed to obtain the rear channels. Quote Link to comment Share on other sites More sharing options...
Mallette Posted August 1, 2003 Share Posted August 1, 2003 Wasn't arguing that point. What I said was that the two rear channels were not just processed, but raised in frequency such that 22khz was 44khz on the disc. Since this is a process by definition, I would not call it "discrete." There were four separate channels, but the rear had to be analog "downsampled" for playback. QS and SQ both used matrixing to attempt to increase separation front to rear. They worked well at best, but the public confusion, poor artistic use, and often poor performance insured it was not the time yet. DyanQuad circuits will provide some degree of decode of old QS and SQ recordings. Dave Quote Link to comment Share on other sites More sharing options...
bkrop Posted August 1, 2003 Share Posted August 1, 2003 Sorry, I was using 30+ year memories, but http://personal.riverusers.com/~manderso/quaddisc/quadclas.htm Quote Link to comment Share on other sites More sharing options...
Mallette Posted August 1, 2003 Share Posted August 1, 2003 Fascinating. I wonder what the other "discrete/matrix" format was. I was only aware of the one. Almost had to be similar, as you've got to have some way to piggyback discrete tracks in the two channel mechanical space on an LP to do it, and about all that was available was frequency shift. Wish they'd defined further. I'd forgotten about SQ encoded cassettes. I am not entirely certain that a few discrete 4 channel cassette decks weren't built and set off the initial home studio movement... Seems logical. Anyone else recall? Dave Quote Link to comment Share on other sites More sharing options...
toddc Posted August 1, 2003 Share Posted August 1, 2003 Thanks for posting this article link Grif, it's definitely a good article! Frankly, I'm surprised at the number of people who are responding negatively on this thread who either haven't read the article or who are arguing with issues that were simply not discussed in the article. Read the article folks. It's amazing to me how many recordings these days have the recording level pushed. There was an article recently on how FM radio stations also push the transmittion level as much as possible in order to be the loudest station. Their tradoff is against quality. But listeners want loud. We all remember back in the seventies and eighties when making tape recordings of our favorite songs that we'd push the sound level to make them louder. The distortion and muffled sound was the risk. While it's great that someone has identified the parallel problem experienced in CD recordings (parallel in that it is the result of pushing the recording level too aggressively for greater volume levels) it is unlikely that studios will see the light. Most consumers play back on the cheapest quality equipment and the only difference they hear is loud or not loud enough. Sounds like longer term a newer technology like SACD which has built-in safeguards is required. Quote Link to comment Share on other sites More sharing options...
Mallette Posted August 1, 2003 Share Posted August 1, 2003 I did read the article and fully agree that such practices, especially early on, were responsible for really bad sound. I just disagree that implementing best practices for CD recordings will make them sound any better on demanding acoustic material. Sorry if I didn't make that clear. Analog engineers pushed the level to maximize S/N. When I was mixing audio for optical film, even -3 db would really increase the noise on the answer print. Clipping, especially with tube circuits, wasn't devastating and brick wall like with digital. When digital came along, it was a tough habit to break. Given my digital recorder has 120 S/N, I typically run peaks no greater than -6db. That makes it nice, because I often don't even bother to monitor after the event begins, since clipping isn't going to happen and there really isn't much else to watch for, in most cases. Go in, have a beer, enjoy the show. If anybody can show just cause why I should run higher, I'd like to hear about it. Regardless of how it might appear, my mind is open and ready to learn. Top notch normalizing software can take you as high as you want without clipping or adversely affecting the quality, and that combined with S/N levels far beyond need means there is simply no need to push location or studio recording. Dave Dave Quote Link to comment Share on other sites More sharing options...
Marvel Posted August 1, 2003 Share Posted August 1, 2003 "I'd forgotten about SQ encoded cassettes. I am not entirely certain that a few discrete 4 channel cassette decks weren't built and set off the initial home studio movement... Seems logical." Dave, Do you mean that decks were made for home use but were quickly picked up as a low cost studio medium? Seems logical to me as well. I just went straight to a 4 track reel to reel. I don't have any surround tapes though, as I mostly used it for production work with overdubs. A friend of mine has a video disc player that uses a stylus, and not a laser for signal pickup. If you think a four channel disc will show signs of wear quickly this is far worse. I can't remember just how it works. I think it was marketed by RCA. Marvel Quote Link to comment Share on other sites More sharing options...
Mallette Posted August 1, 2003 Share Posted August 1, 2003 Those RCA videodiscs were based on capacitance. The stylus would read various size pits as variable capacitance, and you are right, it was even worse than the 4 channel "discrete" audio discs. RCA had a lot of bad ideas about that time, including 33/4ips cartride system that was about 4X7 in size. And, yes, I was suggesting that that the attempt at 4 channel discrete cassette decks spawned the home recording "business." I recall that I had one in professional use by the late seventies. Dave Quote Link to comment Share on other sites More sharing options...
Audio Flynn Posted August 1, 2003 Share Posted August 1, 2003 Calculus kind of comes into play. Calculus fully defines wht a curve is doing; an integral for the ...Area Under a Curve. VERY ACCURATE! Sound is a wave form or curve. ------------------ Computers can calculate the approximation of an integral for the...Area Under a Curve. If you graph a curve on the X Y axis the approximation of the Area Under the Curve is sort of the sum of the area of many very thin tall rectangles to easily calculate the area. Somewhat inaccurate! This is an oversimplification of the CD software technology. It is an example that correlates pretty well to the errors found in mathematical approximations. There are parralells. I defer to Mallet on his work in the field as benchmarkably thorough; outside of the confusing industry and magazine politics. Quote Link to comment Share on other sites More sharing options...
Mallette Posted August 1, 2003 Share Posted August 1, 2003 Thanks, Flynn. Personally, I believe the algorithms for CD are very accurate, but that is not the limiting factor. It's the assumption that freqs above the threshold of hearing do not have an impact on those within said threshold that I have found evidence to disbelieve. Discriminating people are not flocking back to LP for the signal to noise... At a live concert, you have to put up with a lot more noise than you get from an LP in good condition, but nobody complains unless your cell phone goes off. Dave Quote Link to comment Share on other sites More sharing options...
Griffinator Posted August 1, 2003 Author Share Posted August 1, 2003 ---------------- On 8/1/2003 9:08:13 PM Mallett wrote: Thanks, Flynn. Personally, I believe the algorithms for CD are very accurate, but that is not the limiting factor. It's the assumption that freqs above the threshold of hearing do not have an impact on those within said threshold that I have found evidence to disbelieve. Discriminating people are not flocking back to LP for the signal to noise... At a live concert, you have to put up with a lot more noise than you get from an LP in good condition, but nobody complains unless your cell phone goes off. Dave ---------------- I completely understand all your misgivings about sampling frequency and how it relates to the sonic accuracy of digital audio reproduction. We tend to think digital audio is the same as digital video in that respect - that more pixels (samples) = better quality. It's simply not a reality. Nyquist's theorem proved conclusively that, for an waveform of (n) Hz, you need no more than 2(n) samples per second to accurately reproduce that waveform. Shannon proved the theorem in 1948, long before CD ever existed. It is mathematical reality. Sampling frequencies higher than 44Ks/S are not necessary to reproduce audio. As far as the "above the threshold of hearing" argument is concerned, I'd really like to see your sources. The only test I'm aware of that suggested that audible differences were detectable between sources with supersonic information and without was a fatally flawed test which did not represent realistic sonic incidence - the source was doctored with nothing but odd-order harmonics at the same amplitude as the source - this does not happen with natural instruments (or even natural sounds!) Quote Link to comment Share on other sites More sharing options...
Audio Flynn Posted August 1, 2003 Share Posted August 1, 2003 Cause to think more in depth... when the words TRUNCATED Or Approximate come into play. CD discussions are still young 20 years after the introduction. We still talk about LPs do we not? SUPER sonic influences i cannot comment on. JITTER Meridian, MarkLevinson and Theta SEEM to have multiple power supplies for each process within a CD player. Keep jitter isolated? Somone on the forum i forgot has a Theta and has described this. ----------------- CD is implemented most times on the cheap in most cases. ----------------- Let the EMI and Jitter fly. WHOOPIE The consumer will never know. HEHE ------------------- I like my MSB LINK II outside of the wild EMI in the transport. I should bypass the LEDs to get their influence out of the way. xxxxxxxxxxxxxxxxxxxxx obnoxious and subjective opinion audio...out Quote Link to comment Share on other sites More sharing options...
Mallette Posted August 1, 2003 Share Posted August 1, 2003 >Nyquist's theorem proved conclusively that, for an waveform of (n) Hz, you need no more than 2(n) samples per second to accurately reproduce that waveform. Shannon proved the theorem in 1948, long before CD ever existed. It is mathematical reality. Nothing I've said in any way debates this. As to: >As far as the "above the threshold of hearing" argument is concerned, I'd really like to see your sources. I really can't figure a way to get you into my brain, which is the main source of this idea. I do intend to write up the massive material I've experienced, shared, and heard in the past 10 years to support the the fact that, while 22khz might be the edge of human hearing, it is not without impact on the human perception of sound. If you can't hear it, it will make no more difference than attempting to explain color to the blind...and I do not mean that as a flame or bear bait. If I am full of it, then the 16th of August when independent ears come to hear the 24/192 surround and compare it to separately recorded 24/88.2 (from the same mics) downsampled to 16/44.1 without dithering will result in your complete vindication. You are welcome to attend. Dave Quote Link to comment Share on other sites More sharing options...
Vetts and Horns Posted August 1, 2003 Share Posted August 1, 2003 http://www.stereophile.com/fullarchives.cgi?203 Make sense to me. Quote Link to comment Share on other sites More sharing options...
Mallette Posted August 1, 2003 Share Posted August 1, 2003 Thanks. I've scanned it, and will read in detail tomorrow. Initial impressions remind me of Dr. Diamonds late 70's impressions of replacing his crappy portable analog record player with a brand new CD for music therapy in old folks homes. They became agitated, didn't really listen, etc. He was roundly repudiated with the same theories discussed in this thread. No reason to assume he had a bone to pick, and since the poor guy was a music therapist, early adopter, and didn't even have a dog in the race, and if you say "perfect sound forever" often enough and sell enough solent green to the people, they will buy it. They have and do. But less and less. Dave Quote Link to comment Share on other sites More sharing options...
Griffinator Posted August 2, 2003 Author Share Posted August 2, 2003 ---------------- On 8/1/2003 10:33:18 PM Mallett wrote: If I am full of it, then the 16th of August when independent ears come to hear the 24/192 surround and compare it to separately recorded 24/88.2 (from the same mics) downsampled to 16/44.1 without dithering will result in your complete vindication. You are welcome to attend. Dave ---------------- Sorry, but that will not prove anything - especially since you intend to truncate those 8 bits. 1) By truncating to 16 bits you guarantee an audible difference. 24/44.1 would be the more accurate way to compare. Even if you do 24/44.1, you still have to deal with... 2) SRC - you're starting with an 88.2 from those mics and then SRC'ing them to 44.1. Sure, that's an easy math to manage, but it's still an SRC, and errors happen when you convert sample rates. It's reality. You've already degraded your signal twice before you even get a chance to do the comparison. Outside of that, there are other things you need to consider as well: - What AD converter are you planning to use on the capture? - Are you intending to burn these to DVD and CD, respectively? If so, what do you intend to play them back on? Will you be using an external DAC with your playback device? - Will you be verifying the HF content of the recording? If your intent is to prove that supersonic frequencies impact our perception of the audible spectrum, you'd better make certain via spectrum analysis that the frequencies do exist in your recording - and you'd better make certain those frequencies came from the recorded source, not your artificial additions to the recorded data (not an accusation - just reinforcing the fallacy of several such attempts) Let me offer you an alternative method for your testing. 1) Record source at 24/192 (or whatever you'd like to record it at) 2) Run a lowpass filter on one copy of it - set it to filter everything above 22.05Khz. 3) Let your listeners audition them - mix them up, so roughly half the group hears the original source first, the other half hears the altered source first. Then let me know what your results are. Hell, I may come down to check it out myself. The first key to a successful test procedure is to ensure that the only variance is the one you allow. Quote Link to comment Share on other sites More sharing options...
jdm56 Posted August 2, 2003 Share Posted August 2, 2003 Y'all are talking way over my head, but there is one little point I'd like to throw in here: Isn't it interesting that so many bad-sounding CD's sound bad in the same way? To me at least, the bad ones all tend to sound thin, hard and brittle, with no air, depth or life to them. And usually the bass is thin or just flat. So maybe that could be at least partly be due to digital clipping?...Sounds plausible to me. As to CD's (in general?) sounding good with acoustic music and not so good with electric, while not disputing anyones perception, I can't say that that is mine. I've just got too many CD's of acoustic music that absolutely carry me away, if you know what I mean. Nanci Griffith's "Other Voices, Other Rooms" comes immediately to mind. "Flocking back to vinyl" ? Not this turkey! Quote Link to comment Share on other sites More sharing options...
Audio Flynn Posted August 2, 2003 Share Posted August 2, 2003 Mallet Any personal comments on JVC K2 process or whatever it is called I have some good soundign Cds from this Quote Link to comment Share on other sites More sharing options...
Mallette Posted August 2, 2003 Share Posted August 2, 2003 Griff: You still don't quite understand that I don't have a dog in this race. I have no real interest in proving anything about CD's one way or the other. My interest is in high accuracy recording, especially sharing this 24/192 X 4 recording. I've recorded CD level for years, and my CD's sound better (to me and a few others at least) than all but a handful of those on the market. However, they don't sound remotely as good as LP's, or my 24/96 and up work. I presume you prefer to record for CD at 16/44.1 to start with. When I was first recording CD's, I used the Sony RM-500 with super bit mapping and achieved very nice results. It was my theory that it was pointless to record info you were just going to dither down inaccurately anyway. As to the comparison, we will be comparing the raw 24/88.2 material as well, apples to apples. And, of course, you would not only be welcome the 16th but anytime you can make it. I can only learn when proven wrong, which requires exposing my concepts to skeptics, not choir members. I am sure you will not care for this, but I find the "what equipment are you using?" "...is it calibrated?" etc. debate in such things as absurd. Only the fine caps and cables (no slight intended...I've made my respect for these folks known before) crowd would do this. Even your average audiophile neither considers nor indulges in such things. I am frankly more interested in how things compare on various systems of various configuration. However, we will be making some effort to keep things equal here in order to satisfy all tastes. Flynn: I am not familiar with the process you mentioned. As I mentioned before, I've largely abandoned the CD format for acoustic music and don't really pay much attention to it anymore. Dave Quote Link to comment Share on other sites More sharing options...
sunnysal Posted August 2, 2003 Share Posted August 2, 2003 Harry Nyquist described the minimum rate needed to model a waveform. he did this to save BW on telegraph lines. this does not mean that higher sample rates are not better in some respects, certain applications. Many of us here at the b-board tend to talk over our heads, it is our right and part of the learning process, more power to us! this is a specific technical issue. The sample rate is one factor in perfecting musical sound sampling, storage and reconstruction. do not forget we are never seeing the ideal strived for, just what is practical or cheapest. regards, tony this article is quite interesting: http://www.iar-80.com/page25.html by J. Peter Moncrieff Quote Link to comment Share on other sites More sharing options...
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