However, as noted in the quote from Positive Feedback in post #16, the stainless steel used is claimed to be non-magnetic.
TechDAS AF1 Stainless Steel upper platter.
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However, as noted in the quote from Positive Feedback in post #16, the stainless steel used is claimed to be non-magnetic.
Do the different platters sound different because they alter magnetic fields in different ways? I thought it had something to do with vibration control and energy dissipation. Does anyone here know why the platters sound different?
300 series stainless steel can be slightly magnetic depending on whether it is hot rolled or cast. Cast is slightly magnetic. Here is a link to an article about it, http://suprememetalcomponents.com/c...ews/Articles/Is+Stainless+Steel+Magnetic.html
The residual magnetic properties of 316L (which the AF1 sub-platter and SS upper platter is made of) is too low to easily verify with a magnet. The only way would be to hang a magnet on a thread and see if the platter deflects the thread off vertical. IMHO if the magnetism of the platter is of the same magnitude as the Earth's magnetic field, it shouldn't affect the cartridge.
316L is supposed to be non-magnetic, but when cold rolled, and cold worked, it can become slightly magnetic. Because the platter has to be precision machined, some magnetism is unavoidable. That may be sufficient to affect the coils of your cartridge - which may account for some of the sonic differences between the three different platter materials. Although I wouldn't know if is measurable using conventional measuring equipment.
It will also become more magnetic if subjected to extreme cold.
316L is supposed to be non-magnetic, but when cold rolled, and cold worked, it can become slightly magnetic. Because the platter has to be precision machined, some magnetism is unavoidable. That may be sufficient to affect the coils of your cartridge - which may account for some of the sonic differences between the three different platter materials. Although I wouldn't know if is measurable using conventional measuring equipment.
It will also become more magnetic if subjected to extreme cold.
Thanks for additional info. The stronger the magnet the easier it is to detect, correct? The magnets in MC cartridges are usually very strong.
The other issue is how stainless steel will reshape the cartridge coils' magnetic field by shear virtue of its permeability, which for carbon steel is ~100 (compare with ~1 for air, aluminum and probably acrylic materials), and do not know about this particular material. Because of this, I personally avoid iron-based platters like the plague.
Ok, I'm a novice.....
The issue about material affecting magnetic field is not about whether the material is magnetic, but it is about whether the material is electrically conductive.
It is known that nonferrous metals such as aluminum (duralumin is a kind of aluminium) can still affect magnetic fields because they are electrically conductive, and fluctuating magnetic field in proximity will induce eddy currents in nonferrous metal materials, generating an opposing magnetic field that could affect the original field, thereby leading to an effect on sound in audio applications. That why some more enlightened manufacturers have chosen to totally eschew metal (even aluminum) in the construction of chassis for their audio products.
Ferrous metals of course have the same effect insofar as they're electrically conductive.
However, any material made of steel will affect magnetic fields noticeably less than one of brass or copper, which are more electrically conductive. More conductive = less resistance = larger induced eddy currents = larger opposing magnetic field.
Any expert in this field, please feel free to chime in with your experience.
Thanks.
The issue about material affecting magnetic field is not about whether the material is magnetic, but it is about whether the material is electrically conductive.
It is known that nonferrous metals such as aluminum (duralumin is a kind of aluminium) can still affect magnetic fields because they are electrically conductive, and fluctuating magnetic field in proximity will induce eddy currents in nonferrous metal materials, generating an opposing magnetic field that could affect the original field, thereby leading to an effect on sound in audio applications. That why some more enlightened manufacturers have chosen to totally eschew metal (even aluminum) in the construction of chassis for their audio products.
Ferrous metals of course have the same effect insofar as they're electrically conductive.
However, any material made of steel will affect magnetic fields noticeably less than one of brass or copper, which are more electrically conductive. More conductive = less resistance = larger induced eddy currents = larger opposing magnetic field.
Any expert in this field, please feel free to chime in with your experience.
Thanks.
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I have been using the SS upper platter for two weeks now. I removed the poron mat last night and I like the sound better. It seems that with the poron, the midrange is a bit more damped giving the treble a bit more tipped up sound. I feel w/o the mat, the sound is more coherent. At this point, I think I like the added ambience, deeper/more focused bass and quicker dynamics of the SS over the Duralumin. YMMV.
This is using which arm/cartridge/cable combination? I can understand the additional brilliance to the sound but what I don't get is the comment about coherence. You shouldn't have had that problem to begin with.
david
I felt the midrange was a bit more subdued compared to the treble. System voicing will have an impact on preferences. In my system, the midrange is integrating better with the treble range than it did with the poron mat. I am not suggesting removing yours. My mat was not put on by TechDAS. It was put on by Bob with a few tacks of contact cement. There were bubbles in various places under my mat and it looked like crap, so I pulled it off and used mineral spirits to remove the contact cement from the platter and the bottom of the mat. The mineral spirits does not affect/dissolve the bottom of the Matt material that is of different material from the poron. Overall the sound is more balanced without the mat in my system. I am using a phantom supreme 12" and a Koetsu Coralstone, Nordost Odin tonearm cable. I gather you have some disdain for Nordost. Odin is the best cabling I have ever heard and I am 100% satisfied with it. My entire system is Odin.
I am expecting my Elite arm to ship next week. At least it had better. I have been promised for weeks now.
I know that you've been waiting on that arm for a very long time, good luck.
david
PS. Its not about my personal feelings on Nordost, I'm trying to understand what you have in common with dmnc02 since he also mentioned the discontinuity. Aside from the cable you might have the same demo platter from Bob that he had or it could be other things causing this discontinuity which I find puzzling.
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I am keeping my fingers crossed too. I ordered mine (and paid for it) in February 2013.
I should also add that in my case the ss platter is leaner and more open than the duralumin in the mids so the more subdued sound that you're reporting is opposite of what I'm hearing. I would ask for a proper replacement platter from Bob or for a thin leather mat like what they used to have for Micro Seiki tables to use with ss platter. You should have satisfactory sound both with and without the mat or the poron material.
david
david
I remember that he had the prototype at CES way back then, I thought that Christian was waiting for a new batch to finish didn't realize that Bob never got any done.
david
My platter is new from TechDAS unless someone isn't telling the truth... that said...the SS platter bought when the TT first came out is no different than one that can be bought today. The poron mat does not need to be glued on in order to use it. The vacuum holds it secure with the record. I will try both with and without as time goes by. Like I said, last night was the first time using it w/o the mat. I need more listening time to be more definitive on my preference. There is no one shoe size fits all approach. All of our systems and rooms are going to sound quite different relatively speaking.
Arms= SME 3012-R & 3010-R
Cartridges= A variety I tried on this table, Ortofon SPU, both mono and stereo. Ortofon A90, Lumiere and Neuman DST, stereo and mono versions.
Phono cables= Older SME pre hybrid version
AF1 is sitting on a Kinetic Systems 9100 series workstation with VibraDamped steel top, but I'm not using any air with it.
Electronics= Lamm LP1, LL1 and ML3
Speakers= Siemens Bionor with JBL B460 subs
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