Well, I would presume that this test pulse would have a hard time being passed properly through virtually any phono stage, but if your phono stage does it, then congratulations.
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I'm sorry that this long and detailed chit-chat is necessary. Please remember that I am also looking back at info that I measured 32 years ago, and I too, have to 'come up to speed' so to speak, in order to formulate an easy and convincing response. However, the measurements are real, have never been seriously disputed by any engineer, and were done by first class and calibrated test equipment, either by me, personally, or by tech's at the VTT Government Research Facility in Finland, in 1976. [Graph 1]
dV/dT in some amplifiers will change with even modest loads! So does your phono preamp drive an oscilloscope with a 10megohm compensated input or something else?
PMA
no problem and I can understand that. May I ask you what "test record" you are using, or is it just a square wave signal from the generator.
I'm glad that we can communicate now together and be sure I I don't bear grudges, and I respect your work.
to John:
thanks for the excurse and descriptions
Joao,
no test record, no vinyl scratch or mistracking reproduced by any even fastest and most differentiating cartridge would produce a signal with less than 200 nanoseconds rising edge, as I have shown in this post:
http://www.diyaudio.com/forums/anal...rch-preamplifier-part-ii-711.html#post2385003
This signal is produced by square wave generator and CR differentiating network. I do have measuring records, but I do not use them as fast impulse generator.
Best regards,
no test record, no vinyl scratch or mistracking reproduced by any even fastest and most differentiating cartridge would produce a signal with less than 200 nanoseconds rising edge, as I have shown in this post:
http://www.diyaudio.com/forums/anal...rch-preamplifier-part-ii-711.html#post2385003
This signal is produced by square wave generator and CR differentiating network. I do have measuring records, but I do not use them as fast impulse generator.
Best regards,
Well, perhaps it is best to cancel the 'test' and move on to another subject. The fastest test pulse that I use is a differentiated 1KHz square wave, with a 1 nS risetime differentiated by an inverse RIAA network. Or TIM (200K, 350MHz). Fast enough for you PMA? ;-) I have actually used this test signal to note secondary problems in phono circuits, such as 'tail pole capacitance', or the effect of the residual capacitance of the current source in a differential pair of devices. For further info, see Solomon, 'National Semi Applications'. 'The Monolithic Operational Amplifier: A Tutorial Study' This is a MUST READ for any aspiring amplifier designers. Please Google it, it is there for the taking.
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Yes. A nice paper documenting the problems that have been solved in todays opamps 😉
jan didden
Again, a paper that reflects SOA in 1974 used to argue in 2010. It is like to compare Douglas DC-3 (1935) with Boeing 707 (1957).
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For everyone else, almost no typical audio equipment uses IC's made much better than the IC's analyzed in the '1974 paper' Yes, slew rates have increased from .5 to 2V/us or so, but the VAST MAJORITY of what you buy as commercial audio equipment uses the cheapest (and slowest) IC's that they can get away with. Why? Because they are CHEAPER, that's why! When you must add a number of 'features' to make an audio product competitive in the marketplace, you add a number of IC's. Cost and complexity increases, and no 'practical' audio designer uses the best IC's in their midrange or cost effective audio equipment. It is just too expensive, just look at the AD797, or the LT1028. Even I have difficulty justifying them. Why are they so expensive? I don't know.
Good grief! I didn't realize they were that old, although I must say the Dakota I traveled in around 1985 didn't appear to have enjoyed any maintenance for the previous 40 years - 1/2 an hour to get the engines started, copious black oil rippling back over one of the cowlings once that was accomplished, a chilly breeze blowing in through an ill-fitting door etc etc.
It got us where we were going though, but that was certainly a memorable trip, made all the more "interesting" by some of the other passengers (including a dead Springbok in a body-bag that someone was taking home for the pot).
[/OT] Sorry about that 😱
Back to your regularly scheduled bickering...
Yes, the years have passed, and the youngsters grow up with contempt of what their elders lived with. My last experience with a DC-3 was a trip across Puerto Rico from one end of the island to the other in 1965. EVEN THEN it appeared small, noisy, and antiquated. Still, it was the right plane for the job, then, and maybe even now, with some updates.
What concerns me, today, is the CHOICE of IC's with the equipment that I must buy in order to source my audio system with CD's, DVD's or SACD's.
The digital sections look fine to me, but then, like many here, I am no real expert in differences there. However in the audio sections, that is where I find some of the CHEAPEST, SLOWEST, and generally NASTIEST IC's, direct descendants of the 741, almost transistor for transistor, except for a slight speed increase.
EVERY TIME I listen to SACD or DVD, I have to listen through these IC's, and YES I hear them. Why oh why did Sony put these IC's in this product? For cost reasons, of course, every penny counts, and besides the AES and most everybody here thinks that it is impossible to hear them. They are 'good enough'. Really? Not in my opinion.
What PMA is saying here, to the best of my understanding, is that the BEST, LATEST, IC's just out within the year, are pretty darn good, even competitive with discrete jfet technology. Well, good. Let's hope so, but they are not in MY Sony and I suspect that anything that I could afford today will not have these new IC's built into them. This is because so many do not believe that there are any serious listening differences anyway, so why bother with better IC's?
What concerns me, today, is the CHOICE of IC's with the equipment that I must buy in order to source my audio system with CD's, DVD's or SACD's.
The digital sections look fine to me, but then, like many here, I am no real expert in differences there. However in the audio sections, that is where I find some of the CHEAPEST, SLOWEST, and generally NASTIEST IC's, direct descendants of the 741, almost transistor for transistor, except for a slight speed increase.
EVERY TIME I listen to SACD or DVD, I have to listen through these IC's, and YES I hear them. Why oh why did Sony put these IC's in this product? For cost reasons, of course, every penny counts, and besides the AES and most everybody here thinks that it is impossible to hear them. They are 'good enough'. Really? Not in my opinion.
What PMA is saying here, to the best of my understanding, is that the BEST, LATEST, IC's just out within the year, are pretty darn good, even competitive with discrete jfet technology. Well, good. Let's hope so, but they are not in MY Sony and I suspect that anything that I could afford today will not have these new IC's built into them. This is because so many do not believe that there are any serious listening differences anyway, so why bother with better IC's?
Most of the 60's I was having regular flights in DC3's, some of them were recognised as being russian lease-lend from ww2 (the engine cowling was the giveaway) and they were still in service at least to the late 70's I was hearing from friends still in the area.
Well we all know that corners can be cut in any product you buy, just ask Jobst Brandt, he has a few scathing words to say about porsche, having been a designer there. Porsches and VW beetles (Jobst Brandt; Mark Drela; P. L. Albrecht)
Wrinkle
Well we all know that corners can be cut in any product you buy, just ask Jobst Brandt, he has a few scathing words to say about porsche, having been a designer there. Porsches and VW beetles (Jobst Brandt; Mark Drela; P. L. Albrecht)
Wrinkle
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Agree with John about American cars they are the no compromise option if you have problems fitting in to cars and don’t have to go around bends.
Unfortunately like IC they have poor slew rate 300HP out of a 5-litter engine and 12 MPH.
Fortunately no one mentioned the Concord otherwise we will never go back to the Phono stage.
O sugar just did didn’t I.
Hem cancels that and backs to phono.
Again I have to agree with John IC are easier to use and mass implement.
They also do the job they are designed for; same famous designer even uses them as DC Servos.
For me IC give me the opportunity to build something that sound better than what I had before and the satisfaction to say I did this myself
But what a foul I must be they don’t do square waves at first it was same 5Khz then cancel that 1KHz then cancel that completely for same reasons or not and Slew rate came up.
Ludwig is gona jump out of the groove and slap me one.
So what Slew rate we should aim for?
Or even better why not an expert to go trough the steps of design of a phono stage.
Say 60dB gain cartridge loading between 10 and 120 Ohms Passive RIAA with the famous hi frequency roll of one with IC one discrete one with Lumpa Lumpas if you like.
As long it is made with available components the 2SJ109 may be good but is not commonly available so is no option for me CAR resistors at £7 each yes maybe but why not stick with RC55Y or Holco I can get from RS components so are beter for me
I have a decent Meter a crappy oshiloscope same Computer stuff that I don’t know how to use
Very little knowledge about electronics and can do same maths with my Casio and most off al I would really like to learn.
Al
Unfortunately like IC they have poor slew rate 300HP out of a 5-litter engine and 12 MPH.
Fortunately no one mentioned the Concord otherwise we will never go back to the Phono stage.
O sugar just did didn’t I.
Hem cancels that and backs to phono.
Again I have to agree with John IC are easier to use and mass implement.
They also do the job they are designed for; same famous designer even uses them as DC Servos.
For me IC give me the opportunity to build something that sound better than what I had before and the satisfaction to say I did this myself
But what a foul I must be they don’t do square waves at first it was same 5Khz then cancel that 1KHz then cancel that completely for same reasons or not and Slew rate came up.
Ludwig is gona jump out of the groove and slap me one.
So what Slew rate we should aim for?
Or even better why not an expert to go trough the steps of design of a phono stage.
Say 60dB gain cartridge loading between 10 and 120 Ohms Passive RIAA with the famous hi frequency roll of one with IC one discrete one with Lumpa Lumpas if you like.
As long it is made with available components the 2SJ109 may be good but is not commonly available so is no option for me CAR resistors at £7 each yes maybe but why not stick with RC55Y or Holco I can get from RS components so are beter for me
I have a decent Meter a crappy oshiloscope same Computer stuff that I don’t know how to use
Very little knowledge about electronics and can do same maths with my Casio and most off al I would really like to learn.
Al
Please BKS, I have been designing phono stages for many decades. I do not teach elementary electronics, or (high school). There are others here, who do it better, and are happy to do it. My discussion on this thread is about more subtle issues of phono electronics design and performance, rather than the level I started at 45 years ago.
So, if I get you right, you don't have much in test equipment, money, or deep understanding of the issues of making phono stages, at least this it what I think you are saying. I'm sorry to say that this is the wrong thread for getting a successful phono stage that you can put together. Yes, you are a perfect fit for IC's. I recommend that you follow PMA wherever he leads you. He is actively designing IC based phono circuits successfully, and I too, will follow his lead, myself, if I find it useful.
For simple, interesting, phono stages, made of discrete semiconductors that are easy to find, then I recommend Joachim's circuits that regularly appear in a nearby thread.
I worry and debate over the subtle stuff, like what IC's are doing under severe transient conditions, or whether FM distortion exists to any extent in audio stages.
To get back to why PMA and I are having any debate here, it is because PMA apparently is not satisfied with any phono playback in his experience, and I think that he might be overlooking something, since I have had success with phono playback, to the point that it is my reference over all other practical audio sources. He would disagree, but then, that makes a debate possible.
So, if I get you right, you don't have much in test equipment, money, or deep understanding of the issues of making phono stages, at least this it what I think you are saying. I'm sorry to say that this is the wrong thread for getting a successful phono stage that you can put together. Yes, you are a perfect fit for IC's. I recommend that you follow PMA wherever he leads you. He is actively designing IC based phono circuits successfully, and I too, will follow his lead, myself, if I find it useful.
For simple, interesting, phono stages, made of discrete semiconductors that are easy to find, then I recommend Joachim's circuits that regularly appear in a nearby thread.
I worry and debate over the subtle stuff, like what IC's are doing under severe transient conditions, or whether FM distortion exists to any extent in audio stages.
To get back to why PMA and I are having any debate here, it is because PMA apparently is not satisfied with any phono playback in his experience, and I think that he might be overlooking something, since I have had success with phono playback, to the point that it is my reference over all other practical audio sources. He would disagree, but then, that makes a debate possible.
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Wrinkle, I read all 29 pages of the former Porsche designer's debate. I must say, my feelings are 'hurt' because I thought torsion bars were super, that air cooling had real advantages, and that Dr. F. Porsche was a genius that made VW, Audi, and Porsche the great companies that they are. (Actually, I still do, but I did learn something from that exchange).
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