In some circles $240 is not considered much for access to all these folks and what they are doing right now, I dropped my membership as soon as they eliminated the group retirement insurance benefit.
If you haven't come across it before, pages 5 and following of this document may shed a little light.
http://www.temporalcoherence.nl/docs/TYDGEDRG.pdf
Piezo crystal cartridges could be mu metal shielded like the best magnetic cartridges are but it is not necessary. Without shielding, their S/N ratio is so high they can operate with very low residual hum without additional shielding. This is one more advantage they have over magnetic cartridges in mass produced phonographs, the turntables can be driven with motors that are cheaper because they require little or no shielding.
Piezo crystals respond to mechanical stress, not electrical and magnetic fields the way magnetic cartridges do. More rugged, easier to manufacture, no shielding required, much higher output, little or no equalization required, they'd seem the far better choice for a phonograph cartridge or microphone but for some reason, this design was rejected by the high end audio industry.
If the ouput impedence is high, all that's required is a much higher impedence input load to a preamp. Tube preamps can easily achieve 100 kohm to 1 megohm with no problem. Probably MOSFETS too. A shunt clipper if necessary would protect them from static electric discharge which could otherwise destroy them. Until the late 1940s/early 1950s, I think most cartridges were of this type. An impedence matching transformer is another option. Early magnetic cartridges I'm aware of were manufactured by GE, Shure, and Fairchild but there may have been others.
I agree that MCs can sound better. Often they do not and are zippy bastards nerving the listener , the superdupervdh or whatever stylus make them able listen to the dust in groove and the scratches at the surface.
MC are a mechanical non balanced mass/spring system due the kind of suspension of the cantilever.
We have a resonance depending of tip mass, vinylelasticity of the record and damping rubber of the mc and hardness of the suspension.
(MM are mass balanced by construction and when well made, they sound very good indeed and are affordable.)
Now, if we can control the MC Resonance we can fix one problem.
This can be done partially with parallel resistance at the MC Imput.
This can be done very good with aluminium cantilever breaking the resonance up and we have a pretty flat response up to 30 Khz and more.
Hard cantilevers (boron etc)do this not and resonate at apx. 25 - 30 khz, so it must be damped by the tonearm and suspension only.
But : to much damping kills the sound. Now the most MCs have a raising frequency response up to 6 dB and more a in this area, because you must choose between to evils.
Many audiophile think this brightness is air in the music or simply they can no more hear it.
The other thing, MMs have no pole shoes, MCs with pole shoes have a concentrated magnetic field there were the generator coil is.
Thus lesser strayfield loss = more precision.
As I have pointed out more than once, MC and MM cartridges work on exactly the same principle. One problem with MC cartridges is their high dynamic mass due to the coils themselves. Inertia of this mass is very high in relative terms. This means that the required tracking force to damp out the resonances is high and the velocity related damping force from the elastomer is also high making compliance relatively low. The arm/cartridge mechanical FR is strictly in conformance with Newton's second law of motion as applied to forced oscillation and can be seen as an ordinary second order differential equation in any college level text in physics or mechanics (Resnick and Halliday volume I JC, the one with the yellow cover you didn't lose.) The approximate solution to it is also always given and is well known. Solving the equations for different combinations of mass/spring/damper parameters shows the clear inferiority of the moving coil principle when compared to the moving magnet principle if for no other reason, it's much higher dynamic mass. This is what causes its poorly damped high frequency resonant peak. This peak and deliberate comparable peaks in inexpensive low end moving magnet cartridges such as those made by Pickering used in high end mass produced console and all in one package stereos of the 1960s and 1970s such as those produced by Fisher and KLH among others were useful in offsetting the inherent high frequency rolloffs of speakers of that era. Their peak of about 5 db at 15 khz was exactly what was needed. This allowed users to set their tone controls in their sacred flat positions and still hear an acceptable level of treble. It's interesting that in one review of the original Bose 901 in one of the three popular magazines of the day, the reviewer suggested that the HF cut equalizations would be best suited for use with Ortofon cartridges. Their peak was well known.
I still find it remarkable that audiophiles have a schizophrenic attitude towards electronic frequency equalization. I attribute this to their lack of knowledge. Their most cherished source, long playing vinyl phonograph records made from magnetic tape recordings require multiple levels of frequency equalization, typically a minimum of six for master tape/mixdown tape/record without Dolby A, fourteen with Dolby A yet they are adamant that any further equalization to correct for other inherent FR imbalances anywhere in a sound recording/reproduction chain is unacceptable. You can add to the old adage about how you don't want to see sausages or legislation being made, vinyl phonograph records being made if you are an audiophile. Without equalization, not only would phonograph records be impossible, so would analog tape recording, FM radio, and analog television. The only recording technology which does not require equalization is the digital compact disc made from a digital master tape, the bane of many audiophiles.
The energy imparted to the disc by the stylus will increase with the square of the tracking force and stylus velocity. It can be enormous at highly modulated high frequencies. At 2 to 2 1/2 grams the cartridge had better have a HF peak because in all likelihood, any HF components on the vinyl will likely be shaved off with just a few playings. I personally look for cartridges that will track well at 1 gram or less. Shure V15 type II improved, Type V MR, Empire 999VE and 4000 DIII all perform very well in this regard in the Empire 980 GA arm and in the arm of the 698 phonograph. This is in part because this arm is dynamically balanced, its center of mass coincides with the pivot point of the arm bearings. Vertical tracking force is applied with a long clock mainspring in both. I think antiskating is applied the same way in the 698 arm, but with a weight on a nylon thread similar to the SME in the 980GA arm. This is different from the way force is applied in most other arms. They rely on an imbalance between the mass on opposite sides of the pivot. This method increases tracking forced requirements.
Relative to what? Numbers and examples?
Numbers and examples?
Cite? Do you think you might be missing a term here? Like contact area? Vinyl compliance?
Cite?
Stick to audio discussion please. OT and personal removed.
I said E field not H field and that the high output swamped the hum anyway. There are different SNR issues with capacitive transducers to be sure but many other phono pickups are surface noise limited, no mention yet of MI which I prefer.
They are reciprocal and respond to applied electrical signal, piezo-buzzers. There were several mechanical/frequency response problems dealing with the fact that the stylus is actually bending a crystal and the fact that all preamps would need an equalization switch which made them less attractive financially. BTW I see your in the +/- 6dB RIAA is good enough camp. Micro-acoustics made the best foray into this market but they ended up making it plug into a normal MM phono input. Virtually all highest-end recording mikes in fact are capacitive.
I use 5G-Ohms myself. Considering piezo-crystals are used to generate some nice sparks I don’t think they are static sensitive. Transformer for capacitive transducer ??? , electrostatic speaker maybe never saw it the other way around. >1megohm down to a lower impedance implies a large voltage step down and a place for EMI to get in again.
Last edited:
I found this compact and crispy with some historical information i did not know :
Data Windows : What, why and when? | Prosig Noise & Vibration Measurement Blog
Data Windows : What, why and when? | Prosig Noise & Vibration Measurement Blog
Hi, everybody, as long as people are involved elsewhere, I might get a message through.
This discussion and various links have been invaluable to a better understanding (for me) of differences in phono cartridges. Even some stuff, that I have never even measured have been discussed here. This can only come from 'inside' experience rather than general postulations.
For the record, TIP MASS was the very first major issue that was addressed in the '60's. It so happens that moving coil cartridges have a LOW tip mass, and most moving magnet cartridges have a HIGH tip mass. This can be shown by the 'compensation' due to tip mass resonance that is necessary for reasonably flat frequency response with the ELECTRICAL FILTER inside the phono cartridge doing its job. To find out, what you do is first: determine the cartridge inductance.
second: find the cartridge manufacturer's recommended load capacitance.
third: plug the value into: 2piF=1/sqr.rt. LC
Lets try an example: L=1/2H, C=200pf The answer would be about 15KHz.
There is an empirical balance between the electrical rolloff and the tip mass resonance and the Q's of both the resonances that make for a flat MM cartridge.
The MC cartridge has no electrical filter to work against, and it often will not be as flat in response, especially when scanning losses are added. Shure wrote a long article in 'Audio' magazine a few decades ago, showing and proving this. (enough for now)
This discussion and various links have been invaluable to a better understanding (for me) of differences in phono cartridges. Even some stuff, that I have never even measured have been discussed here. This can only come from 'inside' experience rather than general postulations.
For the record, TIP MASS was the very first major issue that was addressed in the '60's. It so happens that moving coil cartridges have a LOW tip mass, and most moving magnet cartridges have a HIGH tip mass. This can be shown by the 'compensation' due to tip mass resonance that is necessary for reasonably flat frequency response with the ELECTRICAL FILTER inside the phono cartridge doing its job. To find out, what you do is first: determine the cartridge inductance.
second: find the cartridge manufacturer's recommended load capacitance.
third: plug the value into: 2piF=1/sqr.rt. LC
Lets try an example: L=1/2H, C=200pf The answer would be about 15KHz.
There is an empirical balance between the electrical rolloff and the tip mass resonance and the Q's of both the resonances that make for a flat MM cartridge.
The MC cartridge has no electrical filter to work against, and it often will not be as flat in response, especially when scanning losses are added. Shure wrote a long article in 'Audio' magazine a few decades ago, showing and proving this. (enough for now)
Focusing on a single element in a system to the exclusion of the system performance of an entirety is neither physics nor engineering. It does make for good advertising copy and hype though.
The cartridge/tonearm record perform as a system. It strictly obeys Newtons second law of motion for forced oscillation whose approximate response is well known. electrical damping of the motor structure to reduce or eliminate inherent resonances in the transduction of mechanical vibrations to electrical signals is entirely effective and a legitimate technique, every bit as legitimate as mechanical parameter manipulation through strictly mechanical means. This is because the electrial load of what amounts to an electrical generator imposes added mechanical load at the resonant frequencies.
Therefore it is the oveall effective dynamic mass, damping, and displacement (spring) coefficients that determine the tuning of the system. The parameters control FR as can be seen in any text explaining this equation. The proof that the moving magnet system is overall far superior is that it requires less vertical tracking force. Stylus velocity is controlled by groove modulation and the rotational speed of the disc, the same for both. As the stylus is thrust upwards by the groove, the vertical tracking force counteracts this thrust to keep it in contact with the groove. The higher the effective dynamic mass, the higher the moment of inerta that must be overcome or counterbalanced by the vertical tracking force applied. MC cartridges typically require 2 to 2 1/2 grams of vertical tracking force while the best MM cartridges require 1 or less. Many like 999VE, 1000ZE/X and 4000 DIII track at 3/4 without distortion on the Shure Audio Obstacle Course. V15 Type II improved and Type V MR when the added force of the cleaning brush is taken into account track at 3/4 too. Some cartridges like ADC XLM (or was it ZLM) have a system mass so low and compliance so high they will track at 1/2 gram or less.
The importance of vertical tracking force cannot be overemphysized in the role it plays in record wear. The stress on the vinyl is the Force divided by the contact area. Too low and the stylus loses contact with the groove at high modulation only to come crashing down to damge it on impact. Too high and it exceeds the vinyl's elastic limit. Plastic deformation occurs and the record never sounds the same because its shape does not recover.
Experts had various opinions about what point a vinyl phonograph record no longer sounded identical to an unplayed duplicate on its first play. Estimates ranged from 15 plays down to 1.
Manufacturer's claims of flat FR to 20 khz for the best MM cartridges were borne out over and over again by all three laboratories that tested them for the popular magazines of the 1960s and 1970s. These cartridges exhibited tone burst and square wave photos consistent with their FR, that is little ringing that was well damped or none at all. If a system requires an FR adjustment to bring its overall response to flat, choosing a cartridge with a high end peak is just as poor an engineering solution as choosing a cable that has been engineered to have a particular frequency contour in some systems because of its bizarre electrical parameters. FR is easily adjusted at the preamplifier signal level. However, poor mechanical design which requires high VTF to overcome high dynamic mass of MC cartridges and consequential record wear cannot be corrected except by replacement with a better engineered product.
I had a collectors record that continued to sound clean and lively despite repeated playings on a V-15 unitil I let it get played on a friends MC tt.
After that one play it never sounded the same back on my V-15....became dulled a bit and the dynamics got lost.
I have always been dubious of high tracking force cartridges.
Old piezo groove busters used to run at high vertical forces similar to MC.
A high force MC changes the groove on the first play which then stays sounding the same....I still reckon MM's can play with minimal damge to the groove.
Eric.
After that one play it never sounded the same back on my V-15....became dulled a bit and the dynamics got lost.
I have always been dubious of high tracking force cartridges.
Old piezo groove busters used to run at high vertical forces similar to MC.
A high force MC changes the groove on the first play which then stays sounding the same....I still reckon MM's can play with minimal damge to the groove.
Eric.
Last edited:
I HAVE actually done some tracking tests with real test records and selected music that brings out mistracking, for my 1978 IEEE paper. I tested perhaps a dozen cartridges, mostly MC, and measured the mistracking artifacts and even published a few examples.
IF I deliberately use to LITTLE tracking force, I get MUCH more mistracking. Is this good for the record? I think not. Of course, too MUCH tracking force will damage the record as well. I think that anything under 2 gr, with a modern stylus is probably OK. It just so happens that I was told that the cartridge designer adjusts the cartridge at precisely 1.68 gr, so I will first try that, as close as possible. Usually I prefer slightly more tracking force.
IF I deliberately use to LITTLE tracking force, I get MUCH more mistracking. Is this good for the record? I think not. Of course, too MUCH tracking force will damage the record as well. I think that anything under 2 gr, with a modern stylus is probably OK. It just so happens that I was told that the cartridge designer adjusts the cartridge at precisely 1.68 gr, so I will first try that, as close as possible. Usually I prefer slightly more tracking force.
- Status
- Not open for further replies.