This design can either be considered a 'joke' started by a hi end audio designer, or an example of rational engineering, much like the VW 'Beatle' was considered, back it its day. It will NOT be perfect, it will easily be beaten by more expensive and exotic designs. However, it would be cost effective to make, compact, AND meet virtually every engineering requirement asked of it. This is a textbook example of value engineering.
It would have met my requirements when I was high school or college student, relying on part-time jobs or parental support, at the time.
Like the VW, of the past, it should be simple, bulletproof, and hard to break. No stupid cost effective measures like the Renault Dauphine, no hidden unreliability like the Jag sports car. Better internal drive devices than the Austin Healey Sprite's engine (derived from the Austin A-20, I'm told). Quality added where it does the most good.
It would have met my requirements when I was high school or college student, relying on part-time jobs or parental support, at the time.
Like the VW, of the past, it should be simple, bulletproof, and hard to break. No stupid cost effective measures like the Renault Dauphine, no hidden unreliability like the Jag sports car. Better internal drive devices than the Austin Healey Sprite's engine (derived from the Austin A-20, I'm told). Quality added where it does the most good.
Then R14 is 600 Ohm. Isn´t that a bit noisy after modern standarts ? I could life with scaling by two.
The OPA1644 is better then the OPA4134. I know, because i have just modified a CD player, where i have exchanges one to the other. It has lower distortion and the bipolars in the OPA1644 are made with the new Si-Ge process making the topology of the input stage somewhat simpler. It also has a distortion canceling driver stage but so far the topology of that part has not being reveiled.
The OPA1644 is better then the OPA4134. I know, because i have just modified a CD player, where i have exchanges one to the other. It has lower distortion and the bipolars in the OPA1644 are made with the new Si-Ge process making the topology of the input stage somewhat simpler. It also has a distortion canceling driver stage but so far the topology of that part has not being reveiled.
When i was a student in the 70th and early 80th the "best" chip there was, was the NE5534. I buid a preamp back then with the Leach MC stage and the NE5534 that sounded decent. A chip like the OPA164..... range whould have being a dream back then.
You can do worse then this little stage i have thrown together here and it costs virtually nothing. Why young people here in Europe think that good quality music is too expensive and unnecesarry i can partly explain by the crazy prices that are asked for in High End Audio. There is no decent preamp on the market under 10.000,-€ is the impression you could get. Cheaper is second rate, the marketing guys tell you.
You can do worse then this little stage i have thrown together here and it costs virtually nothing. Why young people here in Europe think that good quality music is too expensive and unnecesarry i can partly explain by the crazy prices that are asked for in High End Audio. There is no decent preamp on the market under 10.000,-€ is the impression you could get. Cheaper is second rate, the marketing guys tell you.
Joachim, get you own thread, if you will not go along with the program. You made several mistakes, already. I will explain, later.
Joachim, why the 'crazy prices' of MC phono cartridges that you sell? This question is just as valid as why electronic audio equipment is also expensive.
I know that your best cartridges are difficult to build and only a select few can do it. Why not train more people in mainland China to do this? Do you see where this is leading? You and I both know that exotic materials, and precision construction make a superior MC phono cartridge. This, I do not argue. But please understand, when I started out, a MC phono cartridge might cost $75, transformer included, and moving magnet cartridges were available for under $25, that were fairly high quality. What is this $5000 for the cartridge that you personally use? Is this appropriate?
To help you get off the hook on this, because sometimes we have language translation problems between us, I would go a LONG WAY to acquire a $5000 Lyra Titan phono cartridge. Yes, I would. I KNOW that it is a GREAT SOUNDING cartridge and that it sounds somewhat better than the $2500 Lyra cartridge that I had hoped to have over several years, but I just can't afford the Titan. That is life, and I will live with it, but Stig(sp) wanted to buy a CTC Blowtorch from me, but decided not to, when he realized that OUR profit differentials were very low, and we could not afford to significantly discount it for him, even though he was in the 'family' so to speak.
Perhaps, many other manufacturers actually want to make a living from making their hi end products and cannot give them away at near cost, like we did with the Blowtorch.
I know that your best cartridges are difficult to build and only a select few can do it. Why not train more people in mainland China to do this? Do you see where this is leading? You and I both know that exotic materials, and precision construction make a superior MC phono cartridge. This, I do not argue. But please understand, when I started out, a MC phono cartridge might cost $75, transformer included, and moving magnet cartridges were available for under $25, that were fairly high quality. What is this $5000 for the cartridge that you personally use? Is this appropriate?
To help you get off the hook on this, because sometimes we have language translation problems between us, I would go a LONG WAY to acquire a $5000 Lyra Titan phono cartridge. Yes, I would. I KNOW that it is a GREAT SOUNDING cartridge and that it sounds somewhat better than the $2500 Lyra cartridge that I had hoped to have over several years, but I just can't afford the Titan. That is life, and I will live with it, but Stig(sp) wanted to buy a CTC Blowtorch from me, but decided not to, when he realized that OUR profit differentials were very low, and we could not afford to significantly discount it for him, even though he was in the 'family' so to speak.
Perhaps, many other manufacturers actually want to make a living from making their hi end products and cannot give them away at near cost, like we did with the Blowtorch.
First and foremost i am not selling Lyra cartridges. I did that in the 90th but it was handed over to Fast Audio. I am assosiated with Allen Perkins that sells Lyra in the states but i am only the designer of the speakers he sells.
I do not even have my own company any more and work currently as a freelancer, do some wrighting and DIY.
I could not afford a Titan i if it was not handed over to me from Stig and Mishima. What i could afford is a Delos and that is in many ways more advanced then the Titan. The sound i get with the Delos on a 2000,-€ Clearaudio table ( i do not own one myself but my good friend nearby has one ) is 100% satisfying to me. That is progress and still using a Titan in an SG1 with Triplanar arm is an experience hard to describe. It is alsolutely crazy and makes no common sense but it is FUN.
In terms of electronics i do think that a good sounding system can be setup with much less money then it was posible 20years ago and i build all my electronics myself so it is not that expensive for me but time consuming. Loudspeakers are again mechanical transducers and compromise costs money. See the above.
By the way, i can understand why a Blowtorch is expensive. I have no problem with cost as such but what does it buy you ? If it is a unique experience i consider it as art and that has no price so to speak. I whould rather prefer to own a Blowtorch then a Modigliani. Reproduced muisic talks to me more then any other artform.
I do not even have my own company any more and work currently as a freelancer, do some wrighting and DIY.
I could not afford a Titan i if it was not handed over to me from Stig and Mishima. What i could afford is a Delos and that is in many ways more advanced then the Titan. The sound i get with the Delos on a 2000,-€ Clearaudio table ( i do not own one myself but my good friend nearby has one ) is 100% satisfying to me. That is progress and still using a Titan in an SG1 with Triplanar arm is an experience hard to describe. It is alsolutely crazy and makes no common sense but it is FUN.
In terms of electronics i do think that a good sounding system can be setup with much less money then it was posible 20years ago and i build all my electronics myself so it is not that expensive for me but time consuming. Loudspeakers are again mechanical transducers and compromise costs money. See the above.
By the way, i can understand why a Blowtorch is expensive. I have no problem with cost as such but what does it buy you ? If it is a unique experience i consider it as art and that has no price so to speak. I whould rather prefer to own a Blowtorch then a Modigliani. Reproduced muisic talks to me more then any other artform.
Don't worry, Joachim. I got 'diverted' from my path that I was trying to put forth, that is why I thought that you had gone a little too far, when adding new circuits that do not follow what I was putting forth. Of course, your opinions are OK with me, so long as I am not interrupted from my 'lecture'. The op amp, the OPA1644 is interesting, but it still may not be the best choice for the design example that I was putting forth. As far as impedance scaling, I think that a final load of LESS than 600 ohms just asks for trouble. You wanted to use 200 ohms, this will get you in trouble with a standard output stage in the IC.
Sorry, John, i thought that this was a kind of "role game" that was popular here some time ago. I had really missed the point. When it comes to sound and technical improvements i had known better that you are VERY serious.
I'm fortunate that my hearing which I've protected from loud noise all of my life is still excellent as verified by periodic audiometric tests. I get periodic hearing tests as well as eye exams. While my hearing is no better than it was when I was young, it is not much worse. Howerver, my skills as a critical listener have improved enormously. I've trained myself over many years to be conscious of, sensitive to, and to memorize many details I overlooked when I was younger. This as someone learns to be a wine tasting expert or an art critic. It's not that I enjoy sound anymore than I once did or other people do, I'm just more analytical about why.
You can design a $40 thousand phono preamp stage or a $40 million phono preamp stage, it still won't turn donkey cart technology into a formula one race car let alone an airplane. The vinyl phonograph system has inherent limitations that are inadequate as an electromechanical storage and retrieval system for electrical analogs of much recorded serious music. The physical fragility of the records themselves and their vulnerability to permanent damage for a wide variety of reasons is only one of many of them.
In my view, a phonograph cartridge's number one design goal should be to play a phonograph record without damaging it. In the 1960s the question arose of how many plays it takes given state of the art equipment before a record sounded different from another copy that had never been played. Answers from experts ranged from fifteen down to one.
To avoid damage to a phongraph record, the contact pressure the stylus exerts must not exceed the vinyl's elastic limit. This is the point where deformation of the vinyl by the stylus' mass exceeds the point where deformation is permanent, where the deformation has gone from elastic to plastic. This is easly understood by looking at stress-strain curves for various materials. To achieve this goal, stress is reduced by producing systems with very low dynamic mass, high compliance, and well damped mechanical resonances. This is summarized in the term "tracking ability." Moving coil cartridges installed in statically balanced tonearms are the worst possible arrangement because they do not meet these criteria. This is due to the mass of the coil which is generally too high, the resonance of the cartridge often being underdamped, and the inertial mass of the dynamicallyb imbalanced tonearm which adds greately to what must be overcome by the force of the stylus.
Moving magenet and moving coil cartridges work on exactly the same principle. The only difference is that in a moving magnet cartridge the stylus vibrates the magnet and the coils are fixed, in a moving coil cartridge the stylus vibrates the coils and the magnets remain fixed. It is possible to make relatively powerful magnets that are perfectily machined and aligned extremely small and light. Not so with coils. The more turns of wire the heavier the coils get. But fewer turns means lower output while more turns means greater mass. What's more, adding cores to the coils to increase their mutual transconductance with the fixed magnets would increase their mass even more. The increased mass required for MC cartridges creates problems requiring stronger and therefore heavier cantelevers and greater stylus force. Higher mass, lower compliance, and greater mechanical resonances are the hallmarks of MC cartridges which are difficult to overcome. It is also much harder to assure unit to unit consistency in manufacture.
Minor electrical resonances of any cartridges are now cheap and easy to overcome. Electrical signal frequency equalization is an inherent aspect of the long playing phonograph record, a necessary component to overcome one of the system's inherent limitations, namely the limitations of modulation amplitude at low frequencies and surface noise at high frequencies. Since the criteria for a high fidelty sound recording reproducing system requires flat frequency response from the microphone input to the speaker output, and since there are no standards to assure uniform frequency response of recordings, equalization of each recording individually is a necessary element for accurate playback to critical listeners.
It would be difficult today to find turntables that not only meet every NAB standard for a transcription turntable but also have minus 90 db unweighted rumble or better and are built to last a lifetime. Fortunately there are few people around today who are sufficiently in the know to buy them used or the prices would be even higher than they are.
Good posts, Soundminded.
Take into account that MM principle has lower F-3dB roll off, and there is a strong 2nd-order LP effect of Lc,Rc (cartridge) and Ccable, usually something like 1k, 400mH, 200pF and 47k load resistor (usually not optimal value). The MC cartridge F-3dB is usually twice higher.
Take into account that MM principle has lower F-3dB roll off, and there is a strong 2nd-order LP effect of Lc,Rc (cartridge) and Ccable, usually something like 1k, 400mH, 200pF and 47k load resistor (usually not optimal value). The MC cartridge F-3dB is usually twice higher.
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The dynamically balanced Empire tonearms place the center of mass exactly at the arm's pivot point. This effectively reduces the arm/cartridge combination's dynamic mass to about zero. Tracking force is applied by a long clock type mainspring which does not alter the center of mass. Unbalance arms rely on the difference between the weight on the two sides of the pivot. Comparing a dynamically balanced tone arm with one that isn't, is almost unfair. The limiting factor of tracking ability in a dynamically balanced arm/cartridge becomes the cartridge, not the arm.
One reason why the individually balanced massive flywheel of Empire turntables (6 pounds for the 398, 8 pounds for the 698) has better than minus 90 db unweighted rumble is that the massive journal bearings which are individually matched and machined to a tolerance of +/- 1/100,000 inch. Tell me about the competition's products and what they charge for them.
TOTL Empire MM cartridges from the 1960s and 1970s typically have from 30 to 35 x 10-6 cm/dyne compliance and track well below 1 g. The 4000 D/III designed for the RCA CD4 system has FR extended to beyond 45 khz. It's polyhedral stylus which tracks well at 1/2 g increases contact area substantially reducing stress and record wear.
BTW, you won't need to design a phono preamp for me, I'm not asking for one. I'm perfectly satisfied with the ones I already have. I could buy a fairly nice brand new car for $40,000 even at today's prices.
The concept of slew rate is something that should be familiar and easily understood by anyone who is trained as an electrical engineer to analyze and design analog electronic circuits. It is embodied in the notion of gain-power bandwidth product. This is recognition that as power/voltage output increases, frequency response falls off. For historical reasons frequency response is usually measured at some arbitrarily low level, say 1 watt for a power amplifier, X millivolts for a phono stage, Y millivolt for a preamplifier. Usually the load is some fixed resisitive load like an 8 ohm resistor for a power amplifier. This was adequate in the 1930s when electronic circuits were so poor these measurements could show real differences between equipment. But by the late 1940s and 1950s, it was possible to design equpment which performed identically by these criteria on a test bench but performed differently in the real world.
Frequency response at maximum required output will tell you everything you need to know about slew rate. It is the maximum rate of change of voltage or power output with time. Whether presented as square wave response, FR curves, transient rise and fall time, or maximum slew rate they are all different ways of looking at the same thing. To be valid they must use the actual load the circuit will work into because increasing the load (decreasing its impedence) or making the impedence complex (not entirely resistive) or presenting the circuit with an active load (a loudspeaker woofer which generates significant reverse emf for example) will affect slew rate performance.
The maximum slew rate required of a high fidelity audio sound reproducing system is the maximum slew rate of the human ear or the music to be reproduced, whichever is less (the limiting factor.) In theory this can be no greater than 120 db / 1/40,000 second which is from the threshold of pain to the threshold of hearing in one half cycle at the highest frequency a human being can hear. In practice it is much less because music has a much more limited dynamic range and no real world musical signal slew that fast. A slew rate of say 75-80 db in 1/40,000 second which is the difference between a dead silent concert hall at about 25db background noise (AIA criteria) and 100-105 db, the loudest sound the audience will hear (pop music's criteria is far more modest by tens of db/microsecond) is exceeded by the Redbook CD system.
The sole exception is in the phono preamp stage of a circuit designed to decode an RCA CD-4 record because the rear channel audio signals are frequency shifted to above 20 khz.
The problem are non-audio signals. Audio systems are not only 20Hz-20kHz waves, but D/A residuals, induced RFI, LP scratch and mistracking etc. For this reason you need not only several V/us, but more than 50V/us even for the line stage. And RC input filter is not enough, as fast edges bypass usually poorly designed (from HF point of view) audio blocks.
P.S.: everyone is able to calculate necessary slew rate from highest audio sine frequency and wave amplitude. But it is not enough at all.
P.S.: everyone is able to calculate necessary slew rate from highest audio sine frequency and wave amplitude. But it is not enough at all.
Then don't. It wouldn 't matter which one(s) I said I have. To afficionados who appreciate $40,000 phono preamps, any one I name you'd turn your nose up at. The peformance limits of my phono preamps is not the reason I rarely listen to any of my approximately 3000 vinyls. I now regard them much as I viewed my parent's old 78 records when I was a kid. Any ones I really liked I duplicated with the same recordings on CDs. They also happen to be completely disorganized on a giant racking system in my basement. It would take time to even find a specific one if I knew what I was looking for.
Only makes me curious where you draw the line for a transport/DAC, in favor of a 4-wheel conveyor ?
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