Thank you Dimitri, for showing that I'm not completely senile. Yet.
B&O is such strange company. Massive amounts of original R&D, yet relatively mediocre performance.
I don't know what they are doing today, but about six or eight years ago, their annual turnover was over $400 million world-wide. That is probably equal to the sum total of half of all high end companies in the world combined. We are all just fleas compared to them.
Boron is de rigueur for high-end cartridges because of it's superior stiffness/density ratio. Apparently it doesn't damp vibration well and different companies have tried a variety of coatings to improve that. AT has used gold and titanium. I believe the titanium was an attempt to add damping without adding too much mass compared to the standard gold plating. Maybe the diamond coating damps without sacrificing stiffness or adding too much mass.
John
John
Boron - Wikipedia, the free encyclopedia :
Metal borides are used for coating tools through chemical vapor deposition or physical vapor deposition. Implantation of boron ions into metals and alloys, through ion implantation or ion beam deposition, results in a spectacular increase in surface resistance and microhardness. Laser alloying has also been successfully used for the same purpose. These borides are an alternative to diamond coated tools, and their (treated) surfaces have similar properties to those of the bulk boride.
Boron fibers and sub-millimeter sized crystalline boron springs are produced by laser-assisted chemical vapor deposition. Translation of the focused laser beam allows to produce even complex helical structures. Such structures show good mechanical properties (elastic modulus 450 GPa, fracture strain 3.7 %, fracture stress 17 GPa) and can be applied as reinforcement of ceramics or in micromechanical systems
Magnetic Ordering: Diamagnetic
Speed of Sound (thin rod): (20 °C) 16,200 m/s
Metal borides are used for coating tools through chemical vapor deposition or physical vapor deposition. Implantation of boron ions into metals and alloys, through ion implantation or ion beam deposition, results in a spectacular increase in surface resistance and microhardness. Laser alloying has also been successfully used for the same purpose. These borides are an alternative to diamond coated tools, and their (treated) surfaces have similar properties to those of the bulk boride.
Boron fibers and sub-millimeter sized crystalline boron springs are produced by laser-assisted chemical vapor deposition. Translation of the focused laser beam allows to produce even complex helical structures. Such structures show good mechanical properties (elastic modulus 450 GPa, fracture strain 3.7 %, fracture stress 17 GPa) and can be applied as reinforcement of ceramics or in micromechanical systems
Magnetic Ordering: Diamagnetic
Speed of Sound (thin rod): (20 °C) 16,200 m/s
There are lots of metals that have high specific damping capacities. You can tailor the coating to control damping in any manner you like. A material's ability to damp vibrations is in no way related to its stiffness.
John
I stand corrected.
I should have said: A stiff material like titanium can never add any vibrational damping to a mechanical system , apart from lowering it’s natural frequency due to mass increase.
Stiffness, which for vibrations is analogous to spring constant (k) is indeed an independent variable from damping ( c ).
The formula Damping Ratio=c/[2sq.rt(mk)] Damping ratio - Wikipedia, the free encyclopedia says that a material's ability to damp vibrations is related to its stiffness.
Increasing the stiffness of a vibratory system, requires increasing the damping of it too for to retain the same damping ratio.
I am not against this, but one has to be cautious with the added mass consequencies.
You can tailor the coating to control damping in some way(s).
Regards
George
I should have said: A stiff material like titanium can never add any vibrational damping to a mechanical system , apart from lowering it’s natural frequency due to mass increase.
Stiffness, which for vibrations is analogous to spring constant (k) is indeed an independent variable from damping ( c ).
The formula Damping Ratio=c/[2sq.rt(mk)] Damping ratio - Wikipedia, the free encyclopedia says that a material's ability to damp vibrations is related to its stiffness.
Increasing the stiffness of a vibratory system, requires increasing the damping of it too for to retain the same damping ratio.
I am not against this, but one has to be cautious with the added mass consequencies.
You can tailor the coating to control damping in some way(s).
Regards
George
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Percy Audio has new stock and the means to measure low resistances. This pair measures 0.0240 and 0.0249 ohms. As someone mentioned, Cal Weldon (who closed the thread) must have purchased the slipstream devices. SE posted the difference in size (shown below).
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
The leads and body (these large QPs) are not attracted to a rare earth magnet. (Same magnet reveals old Holco resistors non-magnet and newer devices lightly magnetic, inexpensive resistors very magnetic.)
.
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I stand corrected.
I should have said: A stiff material like titanium can never add any vibrational damping to a mechanical system , apart from lowering it’s natural frequency due to mass increase.
Stiffness, which for vibrations is analogous to spring constant (k) is indeed an independent variable from damping ( c ).
The formula Damping Ratio=c/[2sq.rt(mk)] Damping ratio - Wikipedia, the free encyclopedia says that a material's ability to damp vibrations is related to its stiffness.
Increasing the stiffness of a vibratory system, requires increasing the damping of it too for to retain the same damping ratio.
I am not against this, but one has to be cautious with the added mass consequencies.
You can tailor the coating to control damping in some way(s).
Regards
George
You should read up on the intrinsic damping factors of different metals and the variety of damping mechanisms there are. The simplified explanation of the spring-mass example you give is unrelated to the internal damping mechanisms of different metals. For example, in what order would you place the following metals in terms of its specific damping capacity, from highest to lowest? Aluminum alloy, stainless steel, cast iron, titanium, bronze, brass, mild steel, magnesium, and manganese-copper alloy.
John
Thank you for that positive contribution edward.
I'll pass on the masterclass thanks, I'm quite up to speed WRT DR & noise.
Maybe take it up with John, he appears to have reservations WRT low level
capabilities of digital.
I think what this shows, in general, that incremental improvements in phono cartridge design are fairly sophisticated. I measured more basic MC cartridges, 36 years ago, such as Supex, Dennon, and Ortofon to have self resonances at about 50KHz (tip resonance) and 160KHz (cantilever resonance?) and published a sample of some of these measurements in my IEEE paper in 1978. However, the need to 'improve' is always present in audio designers, and unlike many American car manufacturers, the status quo, just isn't enough. This, of course, increases the cost of production, as well as adding an R/D overhead cost, and the end price increases exponentially, due to limited production, marketing, and finally dealer support. These costs are usually linked to the initial maker's cost, and if they are 10 times more, then the final cost will be 4 times more (typically) at the advertised price. Perhaps some manufacturers take even greater percentages, due to the LIMITED production possible of a certain cartridge model.
However, like fine wine, it is worth it to some individuals, who have learned to appreciate it, and have the incomes to pay for it.
This is most of the reason that MC phono cartridges can go between $100 or so, and $5,000, yet look superficially the same.
However, like fine wine, it is worth it to some individuals, who have learned to appreciate it, and have the incomes to pay for it.
This is most of the reason that MC phono cartridges can go between $100 or so, and $5,000, yet look superficially the same.
Terry,
I did not intend to pick on you, but it is my hot button when spec's are nonsense, however I thought you would bring up our hearing mechanisms of critical bandwidth and masking. At 3,000hz the bandwidth is about 350hz, so in the midrange using a 150 ohm source the ear could pick out a signal of 29 nanovolts in the midst of 220nv of noise. Some believe even lower due to other discrimination factors.
So it actually may be possible to mimic this and produce A/D's that can do better than 24 bits!
Of course when you allow the ear some signal processing capability the idea that it can discriminate a signal voltage of -151 re 1 V @ 3khz would possibly support the idea that even for a CD player with a 2 V output 157 db or 26.1 bits would be required.
ES
HX Closure
HX and Pro machines. At the twlight of analog magnetic recording, er, I mean at its maturity, most of the major manufacturers of both studio and replication recorders integrated HX. Even stodgy Studer released an HX retrofit bias card and harness kit for the then-discontinued A80 series.
HX at 30ips vs 1-7/8ips. Due to the differing record HF pre-emphasis of 35uS (or none) for 30ips and 120uS for 1-7/8ips, the ratio of signal to bias was much greater and more heavily modulated at 1-7/8ips. This meant HX performed more bias servoing and gave a greater improvement than at 30ips.
Tape THD vs. Bias & Level.
Horn Toot. Although my work with Dolby on HX concentrated on high-speed cassette replication recorders, I was able to parlay that experience into work on an A820 1/2" at 30ips with HX. I modified the machine with a custom edge-slotted head stack with 90° face angles and permalloy pole pieces, and low-inductance reproduce head windings requiring the use of custom input transformers. The low-frequency head-bumps were reduced by this head to less than 1dB, and were easily equalized out. The stock eq board was removed and a custom equalizer substituted with head-bump correction and a lower-noise preamplifier section. We were able to achieve flat response + or - 0.75dB from <20HZ to >30KHz, with the region between 100Hz and 20KHz + or - 0.2dB. Using HX with Ampex 499 tape we acheived a non-NR S/N of around 80dB re: 320nWb/M, with 15dB of 400Hz headroom, and nearly 10dB of 20k headroom. This gave a non-weighted dynamic range at 400Hz of nearly 95dB, and 90dB at 20kHz. Being an analog medium, there was no sharp LSB cut-off requiring added dither to get resolution below the stated dynamic range, so signals more than 110dB below reference could easily be perceived (single full-band S/N or dynamic range numbers are so damn misleading with analog). Subjectively, we did not need a NR unit. Full disclosure: this machine was a lab queen which suffered rapid head wear due to extreme pole tip profile, which is why Studer would never have made one like it. But when it was running, it was sweet.
Listening tests were done in AMI's LEDE room with UREI and Genelec monitors, and when the HX was turned on and the bias changed to the appropriate HX preset, you could feel your ears relax, a characteristic I attributed to lack of FM sideband grunge, and by having the L-R imaging lock into place, instead of being modulated by HF content.
Relevance to Thread. Rightly or wrongly I have always tried to relate aural phenomena to how our ears must have evolved, and perhaps a human, being stalked by a tiger rustling in the leaves would need to be able to get a clear idea of the position of said tiger...it certainly would be important to me if I was with my girlfriend and heard my wife's car! Think of the stress of misinterpreting the arrival time! Seriously, I think this is relevant to this thread, because when I hear John talk about potential FM in large-signal amplifier excursions and his perception of the sound accompanying it, it reminds me of this experience.
Sorry to rant, but a large portion of my brain and time was dedicated to analog magnetic recording for over a decade (to the exclusion of other experiences, there only being 24 hours per day) which makes me feel so damn obsolete these days.
We now leave the paleolithic exhibit at the Audio Museum, and return to 2011, where all these analog recording problems have been obsoleted and the performance eclipsed by digital.
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
1st on the Internet
HX and Pro machines. At the twlight of analog magnetic recording, er, I mean at its maturity, most of the major manufacturers of both studio and replication recorders integrated HX. Even stodgy Studer released an HX retrofit bias card and harness kit for the then-discontinued A80 series.
HX at 30ips vs 1-7/8ips. Due to the differing record HF pre-emphasis of 35uS (or none) for 30ips and 120uS for 1-7/8ips, the ratio of signal to bias was much greater and more heavily modulated at 1-7/8ips. This meant HX performed more bias servoing and gave a greater improvement than at 30ips.
Tape THD vs. Bias & Level.
Although the optimum overbias for minimum distortion at a level far below saturation gave excellent low THD less than 0.1%, I have never seen it go to zero. John, I'm sure the machines I used were electronically inferior to your more highly-tweaked ones, but I know what you mean when you said that the distortion products would disappear into the noise floor. Changing bias while watching a HP TDA at 20dB below reference level, at some small overbias it certainly did just that! I always attributed the phenomena to the relatively high noise floor of the medium, not to a total lack of distortion in the system.
Horn Toot. Although my work with Dolby on HX concentrated on high-speed cassette replication recorders, I was able to parlay that experience into work on an A820 1/2" at 30ips with HX. I modified the machine with a custom edge-slotted head stack with 90° face angles and permalloy pole pieces, and low-inductance reproduce head windings requiring the use of custom input transformers. The low-frequency head-bumps were reduced by this head to less than 1dB, and were easily equalized out. The stock eq board was removed and a custom equalizer substituted with head-bump correction and a lower-noise preamplifier section. We were able to achieve flat response + or - 0.75dB from <20HZ to >30KHz, with the region between 100Hz and 20KHz + or - 0.2dB. Using HX with Ampex 499 tape we acheived a non-NR S/N of around 80dB re: 320nWb/M, with 15dB of 400Hz headroom, and nearly 10dB of 20k headroom. This gave a non-weighted dynamic range at 400Hz of nearly 95dB, and 90dB at 20kHz. Being an analog medium, there was no sharp LSB cut-off requiring added dither to get resolution below the stated dynamic range, so signals more than 110dB below reference could easily be perceived (single full-band S/N or dynamic range numbers are so damn misleading with analog). Subjectively, we did not need a NR unit. Full disclosure: this machine was a lab queen which suffered rapid head wear due to extreme pole tip profile, which is why Studer would never have made one like it. But when it was running, it was sweet.
Listening tests were done in AMI's LEDE room with UREI and Genelec monitors, and when the HX was turned on and the bias changed to the appropriate HX preset, you could feel your ears relax, a characteristic I attributed to lack of FM sideband grunge, and by having the L-R imaging lock into place, instead of being modulated by HF content.
Relevance to Thread. Rightly or wrongly I have always tried to relate aural phenomena to how our ears must have evolved, and perhaps a human, being stalked by a tiger rustling in the leaves would need to be able to get a clear idea of the position of said tiger...it certainly would be important to me if I was with my girlfriend and heard my wife's car! Think of the stress of misinterpreting the arrival time! Seriously, I think this is relevant to this thread, because when I hear John talk about potential FM in large-signal amplifier excursions and his perception of the sound accompanying it, it reminds me of this experience.
Sorry to rant, but a large portion of my brain and time was dedicated to analog magnetic recording for over a decade (to the exclusion of other experiences, there only being 24 hours per day) which makes me feel so damn obsolete these days.
We now leave the paleolithic exhibit at the Audio Museum, and return to 2011, where all these analog recording problems have been obsoleted and the performance eclipsed by digital.
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
1st on the Internet
Again, some of the hard gold platings with arsenic etc have a quite high hardness (not up to the boron levels though), but I suspect they were going the other way with a soft plating to damp and smear the resonant nodes on the pipe, with a lower q and a less well defined node point they may get their improvement that way.
Wrinkle
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