I tried to listen but a little someone had other ideas so will have another go in the office today. Sadly no promenading for me this year.
Cool. Enough grunt left to do an active crossover as well? Was thinking on the cycle in to work that, as I have a 1KHz crossover point in my speakers that gives me a win from maximising resolution (if I felt that important)
You'll be arguing that a Decca is the one true cartridge next ! Understand that messing around with the shape matters, but starting with 6 times the Young's modulus would seem to be good.
What I haven't looked at for decades is coating/hardening technologies that could push the stiffness right up. Certain areas in materials science have come an awfully long way in the last 20 years.
Or maybe fat ally was the best all along and the rest is marketing.
Maybe not quite that far. If you're going to ignore accuracy, at least craft the writing well.
Re: cantilevers, I understand the desire to use short and fat if you want to optimize stiffness all things being equal, but do you not lose something on the other end with linearity and effective mass, since the magnet or iron end is at the wrong end of the lever? I suppose that's why the high performance manufacturers often chose thin, hollow boron, so that the stiffness could be attained without a geometric disadvantage. I also suspect (but don't know for sure) that the tubes were fabricated to achieve some anisotropy in their mechanical properties; SEM photos indicate that there is a "grain" direction along the tube for the Technics cartridges, so there may be greater than textbook stiffness.
As someone mentioned before, the reductio ad absurdum of the short and fat is the Decca line. They do have a very lively and fun sound (I spent a few years using them), but are not exactly the most accurate of transducers.
Actually it's the other way round, messing around with the material matters, but the shape dominates. Even a materials factor of 6 can be blown away in whole or part by relatively small adjustments to profile and shape, so dependant is stiffness on radius and length.
Yes - new materials might readily offer fresh opportunities one might think. Coatings - yes as to both stiffness and damping opportunities, much of the action is at the outer surface layerbillshurv said:
"And what is well and what is badly—need we ask..(..) ?"billshurv said:
There could be genuine advantage in say Boron tube, but it's not a gimme, and not necessarily so.
re mechanical resonance, see this (Fig. 4, play with C3 and R)
http://shure.custhelp.com/ci/fattach/get/29245/
If there was real commercial interest/need, we would have seen cantilevers implemented acc to this SONY aged patent. Carbon fibers are adequate but boron fibers are available too
Cantilever for use with pickup cartridge
Thanks Lucky. Here is a good article
http://www.diyaudio.com/forums/atta...equivalent_mass_fact_fiction_audio_mar_78.pdf
That's nice Scott. And you can increase the 2x4MiniDSP input sensitivity by changing two resistors,
see page 20:http://www.analog.com/media/en/technical-documentation/data-sheets/ADAU1701.pdf
I am away from home now.When I'll be back, I will be able to say which are these two resistors on the 2x4MiniDSP PCB board.
George
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As someone mentioned before, the reductio ad absurdum of the short and fat is the Decca line. They do have a very lively and fun sound (I spent a few years using them), but are not exactly the most accurate of transducers.
You are a braver man than I am then! But clearly some people must love them as they still make them (albeit probably only a few a year)
Yes. Short cantilevers have different disadvantages to long ones, so that's a tradeoff. Your man is right, damping holds the key, especially for MC where mass of the armature is coupled to spring of the cantilever (in lumped terms) and so forms a resonant system.Thank you, very interesting reading.
When i spoke with my Cartridgemaker, he explained me very well, that he try to make the best compromise between mass, stiffness and damping properties of his cantilevers, which are hollow alu tubes.
Very short cantilevers tend to limit the trackabilty and giving higher amount of distorsions( or brighter sound with more air
There's still a resonance in MM/MI due to the fact that the cantilever can flex, and so has self resonant modes of vibration which are also relevant. This is the resonance which is often used in conjunction with the LCR resonance to extend the hf range.
Cantilevers aren't very stiff, because there's always a mass budget. If it were rigid, and moved as a body, then trackability largely depends upon that mass, as in the paper George linked. However, that paper makes the bad assumption that cantilevers are rigid - they aren't, they flex. Think Tacoma bridge.
Transverse self resonance of a cantilever has several modes, which are sketched out in the image below. Some of them are only supported during mistracking otherwise the stylus does not have a free end. During mistracking, the mode labelled F1 is possible, and happens typically in the 6kHz-12kHz region, one reason mistracking often sounds as sibiliance, BTW.
Otherwise, the mode labelled f1# is typically the lowest supported resonance, perhaps typically c 12kHz - 24kHz IME, and this is the resonant system used in combination with LCR resonance to obtain an overall flat response. This still happens in MC carts, but interacts with armature mass.
If we moved the stylus laterally with a mathematical impulse, in slow motion there would be a transverse pulse which travelled up the cantilever. It would take a finite time to reach the armature, and some of the energy would be reflected back as a wave along the cantilever toward the stylus. It can be described and modelled as a mechanical transmission line. For sinusoidal displacement, resonant mode f1 (below) happens at a frequency where the propagation time represents a phase shift of 90 deg. F1# 180 deg. etc
One can calculate and predict propagation velocity and self resonant frequencies for any given cantilever, depending on geometry and material, and it works out pretty much spot on observations IME.
The mistake the paper George linked as to 'effective tip mass' is to assume the cantilever is rigid. Because it isn't rigid, the whole concept of effective tip mass is flawed, and this is why it makes so little sense as a figure of merit.
Attachments
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Cartridge (5mV) directly into line level A to D with no amplification, losing maybe 10 Bits DNR most of the time.
Yes I defeated that for now. I had the stuff sitting on my bench but I can't get to putting a flat SSM2219 pre-amp together till at least the weekend, so I just put the cart right into the miniDSP and the output right into the amp. This was pretty feeble so I gabbed that Chinese JC-2 clone that I bought to play with and put it in the chain.
I want to work up some suggested gain structures as follow up to the article on computing the IIR coefficients.
I haven't studied anything about how carbon nano tubes can be assembled and formed into advanced shapes but perhaps this would be an area that those properties could be used to advantage in the production of a cantilever for a phono cartridge? I can imagine many structures that could be achieved with both stiffness and low mass where you could control the flexural properties, compressive properties and other factors through selective construction. As someone pointed out the bridge mentioned comes to mind.
At the same time I don't know that this is worth the bother at this point in time for vinyl reproduction, it seems the limitations of the vinyl media itself would still be the dominant factor in the equation.
ps. This reminds me of the time Buckmister Fuller came to my architecture school and spoke of advanced construction methods and alternative shapes for homes. Problem always has been you can't easily place pictures on curved walls nor many other things we use in our homes. But his ideas always come to mind.
At the same time I don't know that this is worth the bother at this point in time for vinyl reproduction, it seems the limitations of the vinyl media itself would still be the dominant factor in the equation.
ps. This reminds me of the time Buckmister Fuller came to my architecture school and spoke of advanced construction methods and alternative shapes for homes. Problem always has been you can't easily place pictures on curved walls nor many other things we use in our homes. But his ideas always come to mind.
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Probably true. For me, since I'm doing some optical stuff now, those fiber guide stylii with optical pickup are interesting. There are folks making 30bit optical encoders, and we have a 9 digit optical x/y stage so there is lots of technology to bring to this problem.
Scott,
You are definitely the man to do this and have all the nicest toys to play with. I would think that with reading the surface optically the important point is how well you can track the groove with all its eccentricities in manufacturing? Where is the target to track the groove, the very bottom of the track, where is a consistent surface to track from, is there truly a linear radial section anywhere in the groove?
You are definitely the man to do this and have all the nicest toys to play with. I would think that with reading the surface optically the important point is how well you can track the groove with all its eccentricities in manufacturing? Where is the target to track the groove, the very bottom of the track, where is a consistent surface to track from, is there truly a linear radial section anywhere in the groove?
No I meant the link posted earlier this week where a fiber rides in the groove with a very gentle tracking force. The examples BTW did not seem re-equalized for constant amplitude.
The actual structures that are freed from their surroundings would be too fragile, I'd do a MEMS pressure sensor attached to a stylus assembly.
P330
Thanks for the correction on the concept Scott. I didn't catch that post earlier. I imagine there would have to be some kind of secondary tracking going on, a fiber optic by itself would seem to be a very iffy proposition due to its lack of stiffness to track a groove by itself. I may be totally missing the point but you don't have to go into details about that here.
Last night I saw a documentary on the comparison between film and video in making movies. Yes, there still is a debate, because many examples of film still look BETTER than hi def video. Of course, not all film is better, and some movies, like animation, really get better with digital, but 'the real world' still can be better captured with film, in many cases. Now, nobody says that film is NOT an obsolete technology from the previous century, just like vinyl records, but you just have to look at the difference and then you know, when it comes to film. For vinyl, you have to listen to the difference, to know, BUT you don't take mid fi playback equipment to make an obvious comparison, anymore than using 8-16 mm film stock to show how 'good' film can be. This is what concerns me here. Have top quality, as defined by hi end reviewers, or just realize that you have not heard the 'best' that vinyl can offer.
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