With proper front ends both can be observed with 16/44.1. The 32 bits in this case is floating point it just makes computation easier. For most things 64bit float doubles are overkill, but for repeated flipping back and forth between time and frequency domain you can accumulate errors.
Scott,
You know perfectly well what I am poking fun at. 16 bits with double precision math is nice. Not quite the same thing as 32 bits all the way through.
But there really are folks here who would buy a 32 bit A/D or D/A if the saw the advert!
Is there a 24 bit accurate A/D made yet? (It is possible but very tricky)
ES
In this rather 'tedious' dialogue of test equipment design and availability, I have not really gotten to the 'point' as of yet.
Of course, advanced test equipment is made and can be VERY expensive. For example, the HP3563 that I have on my bench, cost new: approximately $25,000, approximately 20 years ago. It can do MORE than a typical home computer set-up, but not much more. Only large corporations can afford the State-of-the-Art in measurement power, that really works for research and development of advanced products. That is why we smaller manufacturers use less expensive and used equipment, cast off by the military, to do our measurements. Of course, today, a $30,000 Sound Precision can do a pretty good job, but think everyone. What would you want? A superior analyzer or a new car? This choice must be made by most of us. However, even with the best test equipment, can EVERYTHING be measured with one set-up? I have found it not to be so, and I will give examples, in subsequent inputs.
Of course, advanced test equipment is made and can be VERY expensive. For example, the HP3563 that I have on my bench, cost new: approximately $25,000, approximately 20 years ago. It can do MORE than a typical home computer set-up, but not much more. Only large corporations can afford the State-of-the-Art in measurement power, that really works for research and development of advanced products. That is why we smaller manufacturers use less expensive and used equipment, cast off by the military, to do our measurements. Of course, today, a $30,000 Sound Precision can do a pretty good job, but think everyone. What would you want? A superior analyzer or a new car? This choice must be made by most of us. However, even with the best test equipment, can EVERYTHING be measured with one set-up? I have found it not to be so, and I will give examples, in subsequent inputs.
Now, let us go back 40 years at the questions of that time:
Then, SMPTE IM was 'king' and we all used it. Crown made an IMA that could measure as low as 0.001% or -100dB, and that was pretty good. Also, it had a distortion output that could be evaluated with a wave or a spectrum analyzer, and even an oscilloscope would give us a fair approximation of the NATURE of the IM distortion. YET, my fellow designers found that it wasn't enough. We could measure some things, and they measured well, BUT they did NOT sound that good! What was going on? Well, the late Richard Heyser, an outspoken man with his friends and colleagues, flatly stated that it was 'negative feedback' that was causing the problem. He also pointed out that the TEST EQUIPMENT was designed with op amps, etc., that we would NOT use for audio, as they would not sound that good, so maybe, just maybe, the test is IGNORING something important, in almost any case.
At first, it was a mystery. What could an SMPTE IM tester miss? Distortion magnitude? No. Distortion order? No. Then WHAT? First we found that it could NOT measure TIM, even gross and obvious magnitudes of it, and obvious slew rate limiting. Yet, the test signal was 60 and 7000 Hz (in the USA), yet a measurement at the SAME level of the 7000 Hz sine wave, with a harmonic distortion test would give much more distortion through a uA741 IC op amp. Try it yourself, if you don't believe me. Wow! It was if the 7000 Hz tone did not even appear in the measurement, and that is so, on further analysis of the test method. YET, even Crown was amazed when we gave our TIM test paper in 1976, and showed the problem. In other words, the very test that we used primarily for maximum linearity was missing a great deal of the problem of the use of IC op amps in audio design. (more later)
Then, SMPTE IM was 'king' and we all used it. Crown made an IMA that could measure as low as 0.001% or -100dB, and that was pretty good. Also, it had a distortion output that could be evaluated with a wave or a spectrum analyzer, and even an oscilloscope would give us a fair approximation of the NATURE of the IM distortion. YET, my fellow designers found that it wasn't enough. We could measure some things, and they measured well, BUT they did NOT sound that good! What was going on? Well, the late Richard Heyser, an outspoken man with his friends and colleagues, flatly stated that it was 'negative feedback' that was causing the problem. He also pointed out that the TEST EQUIPMENT was designed with op amps, etc., that we would NOT use for audio, as they would not sound that good, so maybe, just maybe, the test is IGNORING something important, in almost any case.
At first, it was a mystery. What could an SMPTE IM tester miss? Distortion magnitude? No. Distortion order? No. Then WHAT? First we found that it could NOT measure TIM, even gross and obvious magnitudes of it, and obvious slew rate limiting. Yet, the test signal was 60 and 7000 Hz (in the USA), yet a measurement at the SAME level of the 7000 Hz sine wave, with a harmonic distortion test would give much more distortion through a uA741 IC op amp. Try it yourself, if you don't believe me. Wow! It was if the 7000 Hz tone did not even appear in the measurement, and that is so, on further analysis of the test method. YET, even Crown was amazed when we gave our TIM test paper in 1976, and showed the problem. In other words, the very test that we used primarily for maximum linearity was missing a great deal of the problem of the use of IC op amps in audio design. (more later)
I wish you could provide documentation for that claim. Otherwise this is yet another tired rehash of anecdotal stories. You state mainly evidence for the lack of sophistication of the average audio engineer in 1967.
I could contact Bascom King, formerly a designer for Marantz in 1970, who is now designs with Constellation Audio, along with Damian Martin and me. He co-designed the Constellation Audio preamp and he designed the latest Constellation power amps. Bascom King was with me when we visited Richard Heyser at his house, 40 years ago, to ask Richard what we were doing or measuring wrong. Would this help if we could get a statement out of him?
I must admit that I was surprised at Richard Heyser's assertions at the time. After all, I had just designed a mixing board with Radiation Inc's RA911's. You know, the company where you got the topology to make your AD797 in the '90's. I REALLY believed in op amp concepts at the time, and had used them for years, mostly for servos, but I was not against using them for audio in any way, if the slew rate was fast enough. Even 5V/us looked good enough at the time. It was the Grateful Dead who decided against them, subjectively, and went back to tubes, until I made something they could live with. I'm glad that they gave me a second chance, and of course this led to the Levinson JC-2, etc.
I am not here to assign blame to anyone for overlooking TIM, PIM, or phono cartridge mistracking, just 3 problems that I have found important over the decades, yet they were overlooked for many years, partially due to test equipment presumptions that we were measuring everything that we needed to measure.
I must admit that I was surprised at Richard Heyser's assertions at the time. After all, I had just designed a mixing board with Radiation Inc's RA911's. You know, the company where you got the topology to make your AD797 in the '90's. I REALLY believed in op amp concepts at the time, and had used them for years, mostly for servos, but I was not against using them for audio in any way, if the slew rate was fast enough. Even 5V/us looked good enough at the time. It was the Grateful Dead who decided against them, subjectively, and went back to tubes, until I made something they could live with. I'm glad that they gave me a second chance, and of course this led to the Levinson JC-2, etc.
I am not here to assign blame to anyone for overlooking TIM, PIM, or phono cartridge mistracking, just 3 problems that I have found important over the decades, yet they were overlooked for many years, partially due to test equipment presumptions that we were measuring everything that we needed to measure.
Now if I am allowed, I would like to go forward about another problem that home computer users would still probably not catch, without a lot of extra effort. This is phono cartridge mistracking. Here, you need some sort of fast storage scope that can capture transient mistracking events. This either takes a special analog oscilloscope, or perhaps a good digital scope, perhaps with an FFT processor to get the spectrum of the transient pulse.
Back in the late '70's, I used a Tektronix 7633 storage scope and a 7L5 plug in, that could give me the spectrum to 1 Mega-Hz or more. This cost JBL about $11,000 at the time, and they loaned it to me to do this work, for about 1 year. I certainly could not have afforded it at the time.
What this showed to me was that phono cartridge mistracking could put out a high level pulse with a rise-time of a few microseconds, even when mistracking a 1KHz sine wave. Wow! Could have missed that, but the following phono preamp would certainly have noticed it, if it was not fast enough. This is one of the secrets of good phono playback. That is: Make sure that the electronics can handle everything and anything that might be generated by the phono cartridge. If you cannot, then ticks and pops will more severely effect the overall sound of the playback and even become more obvious. Sound familiar, anyone? ;-)
Back in the late '70's, I used a Tektronix 7633 storage scope and a 7L5 plug in, that could give me the spectrum to 1 Mega-Hz or more. This cost JBL about $11,000 at the time, and they loaned it to me to do this work, for about 1 year. I certainly could not have afforded it at the time.
What this showed to me was that phono cartridge mistracking could put out a high level pulse with a rise-time of a few microseconds, even when mistracking a 1KHz sine wave. Wow! Could have missed that, but the following phono preamp would certainly have noticed it, if it was not fast enough. This is one of the secrets of good phono playback. That is: Make sure that the electronics can handle everything and anything that might be generated by the phono cartridge. If you cannot, then ticks and pops will more severely effect the overall sound of the playback and even become more obvious. Sound familiar, anyone? ;-)
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Hi Scott
Maybe true but I, for one, find the old "war stories" not only interesting, but educational as well. In the tube forums, there's no shortage of folks wishing they knew half of what the old-timers already forgot decades ago.
As new technology and techniques come along, it's all too easy to lose the "ancient" wisdom and knowledge. Anyone remember how the pyramids were built?
Next time i get trapped inside, i'll count on downloading Mr Curl's blueprint from the lobi temporales database.
I do realize that I have stated the same thing, repeatedly, on this and other websites. Yes, I am suspicious of very high global negative feedback, and LOW open loop bandwidth.
NOT because I am some old fossil who never designed or used anything but tube designs, or who did not acquire and try linear IC's since the very beginning of their very existence, or someone who never tried computer aided design. I have, instead, designed solid state since the middle '60's, attended class with the same professor, Don Pederson, who helped develop Spice when it was still run on a mainframe in 1971, etc., etc. I was there when we first tried an A-B test of an A-D then D-A converter in 1968 with the Ampex Research and Audio departments attending, realizing that there was a lot more to do, IF it were to be successful, and we used a 50KHz clock! 44KHz would have been considered a joke, at the time. Sure this was 40+ years ago, that's when we were rushing forward in electronics design. That is when Richard Heyser first presented his break-though papers on time delay and phase shift, and even invented a new way of testing loudspeakers. Alas, Richard Heyser died early in 1987, Don Pederson passed away a few years ago, etc, but that does NOT take away from THEIR work from 40 or so years ago. It just passes on to the next generation, if it is possible to interest them into it. For example, SPICE is considered almost mandatory with many designers, today. Had it remained in its early form, the machines that would be needed to process it would cost $1 million dollars or so, as they did in the past, but solid state digital processing has improved by leaps and bounds. Nobody can deny that. Yet, that does NOT mean that we can't get along without it in most audio design. There are other tools and methods, available, and there are pitfalls with ANY design approach. This is what I am warning against. Don't think that your computer simulation will tell you EVERYTHING you need to know about a circuit design, sometimes it will hide something that will effect your design when it becomes a reality. Also, home computer FFT based programs can be useful, and relatively practical, but they 'might' miss some real world problems, if you are not careful. The same with THD testing. This warning is the point of my contributing here, for better or worse.
NOT because I am some old fossil who never designed or used anything but tube designs, or who did not acquire and try linear IC's since the very beginning of their very existence, or someone who never tried computer aided design. I have, instead, designed solid state since the middle '60's, attended class with the same professor, Don Pederson, who helped develop Spice when it was still run on a mainframe in 1971, etc., etc. I was there when we first tried an A-B test of an A-D then D-A converter in 1968 with the Ampex Research and Audio departments attending, realizing that there was a lot more to do, IF it were to be successful, and we used a 50KHz clock! 44KHz would have been considered a joke, at the time. Sure this was 40+ years ago, that's when we were rushing forward in electronics design. That is when Richard Heyser first presented his break-though papers on time delay and phase shift, and even invented a new way of testing loudspeakers. Alas, Richard Heyser died early in 1987, Don Pederson passed away a few years ago, etc, but that does NOT take away from THEIR work from 40 or so years ago. It just passes on to the next generation, if it is possible to interest them into it. For example, SPICE is considered almost mandatory with many designers, today. Had it remained in its early form, the machines that would be needed to process it would cost $1 million dollars or so, as they did in the past, but solid state digital processing has improved by leaps and bounds. Nobody can deny that. Yet, that does NOT mean that we can't get along without it in most audio design. There are other tools and methods, available, and there are pitfalls with ANY design approach. This is what I am warning against. Don't think that your computer simulation will tell you EVERYTHING you need to know about a circuit design, sometimes it will hide something that will effect your design when it becomes a reality. Also, home computer FFT based programs can be useful, and relatively practical, but they 'might' miss some real world problems, if you are not careful. The same with THD testing. This warning is the point of my contributing here, for better or worse.
If this represents the general accuracy of your statements, you need more Omega 3's. Never heard of this, neither has Google. I know it existed op-amps with tubes existed in 1952, the term "slew rate" came from WWII (aiming guns), yadda-yadda. So the RA911 had sub-ppm errors and ONE gain stage, please put up the evidence.
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Don t know if this RA911 is a precursor of the AD797 ,
but the Luxman C 02 preamp sure is , although with discrete
components..
The C02 date back from 1983 or so , and the AD797 is a carbon
copy of its discrete phono preamp OP amp...
Indeed, LuXMAN say explicitly that this preamp use single stage amplification.
Luxman C-02 on thevintageknob.org
The schematic can be found at HifiEngine site..
This is a simple JFET folded cascode discrete op-amp, so what? Certainly lucky to have a 2000 or so AOL, no DC performance to speak of. Harris had them sans FET's in the 70's.
In order to not make work for the mods, I leave you guys to tip toe through audio history.
First there were electrons. Some old wine sipping Greek guy in a robe rubbed a yellowish thingy and he saw it got a charge. After 2300 yrs someguy Scott with same appreciation to wines squeezes them in a tiny plaque fast and silent. Meantime some other guys in kimono robes enjoyed routing them alike but not in a so little space which has a life and rules of its own. The main differences are in the type of robes IMHO.
Dom, zvardeya, kinim, arov, dever, shkin, barad, arbeh, khosekh, makat b'khorot.
So, back on topic, has anyone commercially implemented balanced phono inputs? Requires non-standard tonearm-to-preamp cabling, but advantageous for small signals.
The difference is, that whatever the audio 'old timers' knew or forgot, you can read up on for about $100 tops from Amazon. More accurately too.
jan didden
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