That's the one. Martin was a very serrious hi fi fanatic in the past. Now it's just music. He was the DNM amplifier importer to Austrailia. Very good amps.
Frank. I will read your answer fully later. Some work has just come in !!
Hi Frank,
Thanks for your reply and a big thank you for all your help and inspiration on the forum over the years.
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After much machining and studying magnetic fields I started to realise that it was the ratio you mention that is the key to the bearing.I have not tried altering the size/ratio of the magnets but spent most of my time altering the flux by shaping the pole pieces and hit on a design which seemed to give reasonable figures.It would be interesting in future to try different magnet ratios to try and improve on the figures I obtained but as you have mention before getting flat magnets is a challenge in it’s self.
I had a lot of problems with irregular magnets at the start which caused difficulty in setting up the bearing ,I would suggest to anybody embarking on this project to check the flatness of the magnets been used, as I found out even the better quality ones which are supposed to be made to a tolerance are not flat. I went through 2 batches to find 2 that were completely flat these are easily checked on the lathe with a DTI any that are not completely flat discard as they cause endless problems.
Mike
Thanks for your reply and a big thank you for all your help and inspiration on the forum over the years.
[SIZE=+0][/SIZE]
After much machining and studying magnetic fields I started to realise that it was the ratio you mention that is the key to the bearing.I have not tried altering the size/ratio of the magnets but spent most of my time altering the flux by shaping the pole pieces and hit on a design which seemed to give reasonable figures.It would be interesting in future to try different magnet ratios to try and improve on the figures I obtained but as you have mention before getting flat magnets is a challenge in it’s self.
I had a lot of problems with irregular magnets at the start which caused difficulty in setting up the bearing ,I would suggest to anybody embarking on this project to check the flatness of the magnets been used, as I found out even the better quality ones which are supposed to be made to a tolerance are not flat. I went through 2 batches to find 2 that were completely flat these are easily checked on the lathe with a DTI any that are not completely flat discard as they cause endless problems.
Mike
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my build is slow, as i'm trying to build table plinth and arms. Also trying to design according to the theory that it's a good idea to be able to dissasemble and mod/replace all parts..this makes things challenging but I agree, so am proceeding accordingly.....getting closer to wiring it up though......
top is reclaimed redwood with cherry edge surround. the base is 6 plywood layers,I placed river rocks i gathered at local stream-about 2" worth, placed at bottom.... wrapped with black pleather. Real happy with the choice there. The total weight is about 70 lbs!
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sorry for the intrusion...
gentlemen (and any ladies if any following this thread),
it's been a long time since I've made comment in this thread, so firstly I must apologize for "jumping in" and perhaps asking a question that has already been answered or is WAY off topic.
Regarding VTA: were this to be of huge concern, I have to believe that arm and cartridge manufacturers would have made an attempt to find a consensus (but I suppose that would be asking to much) of what the standard should be (via the RIAA, DIN, standards, etc.). Would also have to believe that (perhaps) a standard would have been made for the application of anti-skate in an appropriate manner.
Unfortunately all of this would be asking too much. So what is the best that can be done? well for VTA. we can use a very thin shim to effect +/-5° adjustment at the headshell. Unfortunately this requires us to know what the cartridge manufacturer has used in their design, and the VTA of the cutting head. Way too much for a typical user, particularly if one has a single tonearm and cartridge (without a removable headshell). For those with more than one tonearm (or complete turntable and tonearm), a cartridge could be shimmed for the to allow for the +/-5° in one headshell, whilst the other could be left installed in the "regular" fashion.
What effects on tracking force could be observed? This is pure conjecture, but all else being equal, the VTF should increase when the correct VTA is as close as correct as possible. The requirement to actually measure this force would certainly be beyond the precision capabilities of the typical tracking force gauge, and so back to subjective hearing tests for most of us...
again , perhaps way off track...
plexi0: beautiful turntable and (of course) arm
gentlemen (and any ladies if any following this thread),
it's been a long time since I've made comment in this thread, so firstly I must apologize for "jumping in" and perhaps asking a question that has already been answered or is WAY off topic.
Regarding VTA: were this to be of huge concern, I have to believe that arm and cartridge manufacturers would have made an attempt to find a consensus (but I suppose that would be asking to much) of what the standard should be (via the RIAA, DIN, standards, etc.). Would also have to believe that (perhaps) a standard would have been made for the application of anti-skate in an appropriate manner.
Unfortunately all of this would be asking too much. So what is the best that can be done? well for VTA. we can use a very thin shim to effect +/-5° adjustment at the headshell. Unfortunately this requires us to know what the cartridge manufacturer has used in their design, and the VTA of the cutting head. Way too much for a typical user, particularly if one has a single tonearm and cartridge (without a removable headshell). For those with more than one tonearm (or complete turntable and tonearm), a cartridge could be shimmed for the to allow for the +/-5° in one headshell, whilst the other could be left installed in the "regular" fashion.
What effects on tracking force could be observed? This is pure conjecture, but all else being equal, the VTF should increase when the correct VTA is as close as correct as possible. The requirement to actually measure this force would certainly be beyond the precision capabilities of the typical tracking force gauge, and so back to subjective hearing tests for most of us...
again , perhaps way off track...
plexi0: beautiful turntable and (of course) arm
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Hi Nanook,
"...asking a question that has already been answered or is WAY off topic. "
So what was your question?
"This is pure conjecture, but all else being equal, the VTF should increase when the correct VTA is as close as correct as possible."
How so?
Cartridge VTA wasn't likely a HUGE concern at the time any such standard was set originally, particularly due to the fact that line contact stylii didn't exist. The smallest contact radius of a spherical stylus available at the time(early 60ies) was 13µ. And since the SRA is of no importance when a sphericals stylus is in use(VTA still is!), it wasn't until extremely small contact radii stylii like VdH 1 came into being that SRA, - and therefore VTA as a factor inseparable from SRA needs to be taken into account.
VTA of the cutting head is determined by the internal design and can't be set/altered at will by the user/cutting engineer. At least not on any Neumann, Westrex or Ortofon cutting head that I had the chance to inspect.
Here's another, in depth article that answers about any question regarding the historic background of setting a "norm" for VTA or SRA:
VTA
And I noticed the feet as well... hehe
Cheerio,
Frank
"...asking a question that has already been answered or is WAY off topic. "
So what was your question?
"This is pure conjecture, but all else being equal, the VTF should increase when the correct VTA is as close as correct as possible."
How so?
Cartridge VTA wasn't likely a HUGE concern at the time any such standard was set originally, particularly due to the fact that line contact stylii didn't exist. The smallest contact radius of a spherical stylus available at the time(early 60ies) was 13µ. And since the SRA is of no importance when a sphericals stylus is in use(VTA still is!), it wasn't until extremely small contact radii stylii like VdH 1 came into being that SRA, - and therefore VTA as a factor inseparable from SRA needs to be taken into account.
VTA of the cutting head is determined by the internal design and can't be set/altered at will by the user/cutting engineer. At least not on any Neumann, Westrex or Ortofon cutting head that I had the chance to inspect.
Here's another, in depth article that answers about any question regarding the historic background of setting a "norm" for VTA or SRA:
VTA
And I noticed the feet as well... hehe
Cheerio,
Frank
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where's the question, and how can mass indicate ?
Here it is:
The question goes back to the basic principles of Physics.. the equation for calculating the Force (of gravity). The only real changes are the precision that we now can accept the gravitational constant ( currently down to errors in the 21 PPM... of G:= 6.67545(18)x10-11 m3 kg-1 s-2), and the variance of R between the centre of gravity of the earth and the object that is being attracted to it (and the earth to the object). The later can vary substantially based on the specific location of the measurements being taken. How so? When the stylus tip is in the best vertical position R is reduced (by a minute amount) and thus G increases, and thus the F(g) or weight mass of the object being measured will increase, everything else being equal). So in essentially all cases observation could be made if the capability existed. Another might be to use a standard record (that has been manufactured to the higher possible degree of precision) and use laser measuring to measure the distance from a standard set location (for that particular setup at that particular time). perhaps using laser frequency comb techniques.
So although technically possible, perhaps not practical, and thus back to subjective tests (which I believe can answer most all questions we "audio files" present).
The +/- 5° question is much easier to adjust, but subjective listening is required (or perhaps the use of very fine signal processing) to allow us to see the difference...and to support our subjective observations. It may seem that I am provoking all into a subjective vs. objective argument (figuratively speaking), but it is farther from the truth. I believe (personally) that the best processing power we have is the grey stuff between our ears.
I only offer this up as a "devil's advocate" , trying to be as critical as possible so that even the biggest skeptic can be defended against. Many here know my commitment to analog (obviously not as great or experienced as Frank's). That was my whole point in injecting myself into this thread again.
Here it is:
The question goes back to the basic principles of Physics.. the equation for calculating the Force (of gravity). The only real changes are the precision that we now can accept the gravitational constant ( currently down to errors in the 21 PPM... of G:= 6.67545(18)x10-11 m3 kg-1 s-2), and the variance of R between the centre of gravity of the earth and the object that is being attracted to it (and the earth to the object). The later can vary substantially based on the specific location of the measurements being taken. How so? When the stylus tip is in the best vertical position R is reduced (by a minute amount) and thus G increases, and thus the F(g) or weight mass of the object being measured will increase, everything else being equal). So in essentially all cases observation could be made if the capability existed. Another might be to use a standard record (that has been manufactured to the higher possible degree of precision) and use laser measuring to measure the distance from a standard set location (for that particular setup at that particular time). perhaps using laser frequency comb techniques.
So although technically possible, perhaps not practical, and thus back to subjective tests (which I believe can answer most all questions we "audio files" present).
The +/- 5° question is much easier to adjust, but subjective listening is required (or perhaps the use of very fine signal processing) to allow us to see the difference...and to support our subjective observations. It may seem that I am provoking all into a subjective vs. objective argument (figuratively speaking), but it is farther from the truth. I believe (personally) that the best processing power we have is the grey stuff between our ears.
I only offer this up as a "devil's advocate" , trying to be as critical as possible so that even the biggest skeptic can be defended against. Many here know my commitment to analog (obviously not as great or experienced as Frank's). That was my whole point in injecting myself into this thread again.
And a separate concern ...
... most seem willing to take a "pat" answer to many issues concerning the vinyl playback chain (or recording chain for that matter). The devil IS in the details, my fellow analog friends...
"Start looking deeper at most things and the beauty of the answer will become apparent"(a quote from one of my Physics professors at university, and a truth I believe in...)
... most seem willing to take a "pat" answer to many issues concerning the vinyl playback chain (or recording chain for that matter). The devil IS in the details, my fellow analog friends...
"Start looking deeper at most things and the beauty of the answer will become apparent"(a quote from one of my Physics professors at university, and a truth I believe in...)
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got her a n runnin' ! Can't believe I built a turntable! Very early to isolate any real sound impressions but initial listen seemed to have an ease to the sound and a big natural bass are the two aspects that stand out.
The tonearm is unique in use as this is my only unipivot type arm that moves laterally. Seems pretty stable and no skips yet.
pretty neat! I've build a couple things in my day but this one may take the cake. Hope to learn more about the arm and dial it in even better.....
got her up an runnin' ! Can't believe I built a turntable! Very early to isolate any real sound impressions but initial listen seemed to have an ease to the sound and a big natural bass are the two aspects that stand out.
The tonearm is unique in use as this is my only unipivot type arm that moves laterally(rolls). Seems pretty stable all things considered however, and no mistracks in the 6 albums played as yet.
pretty neat! I've build a couple things in my day but this one may take the cake. Hope to learn more about the arm and dial it in even better.....
Will rout the wires probably down into the black aluminum block and out the back rca plate. need to add a ground wire and dial in the magnets a touch. Also need to add more mass via two auxilliary counter weights (one on each side/bottom to current aluminum weight. I believe that will give me some control over the 'cant'. The correct name escapes me at the moment.....
The tonearm is unique in use as this is my only unipivot type arm that moves laterally(rolls). Seems pretty stable all things considered however, and no mistracks in the 6 albums played as yet.
pretty neat! I've build a couple things in my day but this one may take the cake. Hope to learn more about the arm and dial it in even better.....
Will rout the wires probably down into the black aluminum block and out the back rca plate. need to add a ground wire and dial in the magnets a touch. Also need to add more mass via two auxilliary counter weights (one on each side/bottom to current aluminum weight. I believe that will give me some control over the 'cant'. The correct name escapes me at the moment.....
I've had more time to get to know this arm on this table and have noticed a very interesting phenomenon. I hear virtually no inner groove distortion on any record. I've got several that have bothered over the years no matter what arm or cart. Yes it's varied but it's always been there on at least half my record collection. I've gone through about 100 records so far and have barely heard a hint of IGD. I've owned about 10 tables and maybe 7 arms. I've used about 20 carts. This fis a first combo that yielded such nice sibilant free sound. I don't know but I can't imagine this is because the table, and the cart i've used
for years (shurev15IIImr) and while it was not overly sibilant in the past there is virtually none now and at this point I am attributing this to the arm.
also note, that i've used the same template to position the cart as i used on my last two turntables so I don't think the cart position is why there is now no igd.. I don't know but at this point, i'd still say its the arm. I wonder what quality to it is responsible? the magnet bearing must be involved i'd imagine......
for years (shurev15IIImr) and while it was not overly sibilant in the past there is virtually none now and at this point I am attributing this to the arm.
also note, that i've used the same template to position the cart as i used on my last two turntables so I don't think the cart position is why there is now no igd.. I don't know but at this point, i'd still say its the arm. I wonder what quality to it is responsible? the magnet bearing must be involved i'd imagine......
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looks like program now costs $25
Guest Last year The Download link Website Disabled is broken.
Guest Last year The Download link Website Disabled is broken.
- 0
Nordine Bjerke Last year Dear User! Thank you for your report! Unfortunately, Vizimag has been discontinued by the developer and is not available any more on the developer's website.
BUMMER! I liked ViziMag a lot... :-(
FEMM would be another option.
Finite Element Method Magnetics: Finite Element Method Magnetics
Good night,
Frank
FEMM would be another option.
Finite Element Method Magnetics: Finite Element Method Magnetics
Good night,
Frank
There are many possible reasons for a a variation of tracking force and Azimuth over the record radius:
Thread is not centered in regard to the vertical rotational axis
Magnet/s isn't/aren't centered relative to each other and/or in respect to perpendicularity
Magnets feature an uneven profile: cut at an angle other than 90° (VERY common these days...)
Wiring too stiff/poorly routed
Best,
Frank
Thread is not centered in regard to the vertical rotational axis
Magnet/s isn't/aren't centered relative to each other and/or in respect to perpendicularity
Magnets feature an uneven profile: cut at an angle other than 90° (VERY common these days...)
Wiring too stiff/poorly routed
Best,
Frank
my arm exhibits all these faults. I know the magnets are not totally level with each other and it's hard to tell when the string is perfectly above the center of bottom magnet....the more I try to fine tune things, the worse it gets. This is not easy. those magnets are a PITA to work with. I may even need to scrap the arm and start over...without a metal lathe this arm is not easy to get right. I'm doing it all by eye and with a drill press! But i will not give up, since I've already heard what it can do even when it's poorly executed so I can imagine what it can do when I dial it in correct. This is a job better suited to a jeweler, dentist, or watchmaker, not a carpenter