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主旨寄件者更新日期
回覆 (1958): Null point calculation
 
 
幾天前和Daiwok傾用他的內窺鏡技術來攪,這是否有的水平  
ivanto
12-10-18
14:24:31
回覆 (1957): Null point calculation
當年人手一碌 SME,個個都係用張咭仔,枝針跌落窿就掂晒。  
_____  
 
We call this sublime simplicity, right?  
 
Nowadays, there is a tendency to complicate things especially simple things) to justify the insane or inflated price asked for.  
 
Business 101 told that this is called value-added.
icefox
12-10-18
14:11:30
回覆 (1956): Null point calculation
 
 
當年人手一碌 SME,個個都係用張咭仔,枝針跌落窿就掂晒。  
 
把聲不知幾靚,生活不知幾美滿。  
 
limage
12-10-18
14:06:08
回覆 (1955): Null point calculation
 
> 在我有限的見解這等同細路哥玩坭沙 <  
_______________________________________________________  
 
咁我係初哥嚟吖嗎! :-)  
 
有更精確辦法? 好有興趣知! 洗唔洗出動專業測量儀器?  
 
如果有辦法測量針桿喺運作時的偏側,就可證明limage話真線臂令針桿偏側係唔係真同有幾嚴重!  
 
thekong
12-10-18
13:42:26
回覆 (1954): Null point calculation
 
在我有限的見解這等同細路哥玩坭沙  
-----  
玩HIFI就是細路哥玩坭沙呀!
drwkng
12-10-18
13:30:40
回覆 (1953): Null point calculation
 
just need to draw a short line................  
 
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在我有限的見解這等同細路哥玩坭沙  
ivanto
12-10-18
12:47:12
回覆 (1952): Null point calculation
 
>最終目的是利用這2点null point來决定唱針尖及針杆是否更正確地安裝,<  
_________________________________________________________________  
 
Hi Ivan,  
 
So, you just need to draw a short line (or 2 lines if you want to place the stylus in between) perpendicular to the tracing arc at the null point, correct?  
 
While it is good for aligning the cantilever, I think you will have a very hard time checking the stylus alignment this way!  
 
Actually, I think your good friend, Mr Yip, of Mint is already producing this kind of protractor, no?  
 
thekong
12-10-18
11:27:23
回覆 (1951): Null point calculation
Cool...... even ivanto starts to write.......^^
icefox
12-10-18
10:57:05
回覆 (1950): Null point calculation
 
各位大哥,大哥大大,蛋散,粉腸,你們好  
 
我和king論及如何找出null point,找出null point在唱針路徑上的位置祇是開始,  
最終目的是利用這2点null point來决定唱針尖及針杆是否更正確地安裝,  
網上www.enjoymusic.com所提供的,我覺得未能達到我的要求,只能和跟唱臂附送的tool差不多.  
 
我不是要null point的數據  
 
 
 
ivanto
12-10-18
10:54:09
回覆 (1949): Null point calculation
 
 
You may well choose to be precise up to 1/10 of a millimeter if that should put your mind to rest. All these  
measurements and calculations, however, are based on one grave assumption, i.e. the diamond stylus would  
be cut perfectly with the utmost of precision. This is far from the truth and here lies the irony too —the more  
expensive your cartridge is, the more awful the diamond shape is likely to be!  
 
At the end of the day, everything boils down to the art of compromise. Kong is absolutely right. There is no  
point to insist on the ultra-accurate. The 2 null points are nothing more than dead reckoning or, as the moral  
goes, asshole hitting the right stick.  
 
If you’ve done everything you can and still find audible distortion coming out from your most treasured discs,  
no worries mate, here is the remedy:  
 
When audible distortion is heard at the outer most grooves, move the cartridge aft. If shattering sound  
happens at the midway between the 2 null points, move forward. Period.  
 
 
limage
12-10-18
10:12:09
回覆 (1948): Null point calculation
 
 
Now these are the arguments and measurements for the technical minded:  
 
“It's obvious that a rigid pivoted arm must swing in an arc and therefore can't possibly track radially. What's less obvious is the precise relationship between the resulting tracking error and the corrective offset/overhang geometry of typical arms. A prevalent mistake is to assume that it's the tracking error that must be minimized. Actually, it's the tracking distortion, which happens to be directly proportional to the tracking error but inversely proportional to the radial distance of the groove from the spindle. Consequently what must be minimized is the ratio of the tracking error to this radial distance. The correct way to formulate the basic mathematical question about optimum lateral tracking geometry is therefore the following: with a tone arm of given effective length, and over a total recorded area of given maximum and minimum radii, what combination of offset angle and overhang will yield the smallest possible peak values of the ratio of tracking error to groove radius? Not a seventh-grade problem in geometry, that one, although any competent mathematician could give you the correct solution. No one bothered until 1941, when H.G. Baerwald did the job once and for all. Our table of alignments is based entirely on his definitive work, which should have eliminated forever (among other things) the untutored practice of jockeying for zero tracking error at the innermost groove, a la SME. Correct alignment results in two zero-error points, the first about one third of the way into the recorded area, the second close to but still a small distance away from the innermost groove. And with optimum offset angle and overhang, these zero-error points are fixed, regardless of arm length, as long as the maximum and minimum radii of the recorded area are specified. (For exact numerical values, see table.)”  
 
 
limage
12-10-18
10:09:31
回覆 (1947): Null point calculation
 
This is how the Graham jig works
thekong
12-10-17
18:16:38
回覆 (1946): Null point calculation
http://www.enjoythemusic.com/freestuff.htm  
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this looks good enough. in fact ivan did something similar but manually.
drwkng
12-10-17
18:07:57
回覆 (1945): Null point calculation
 
The Phantom’s jig is specially design and can only be used with the arm. It actually fits over the headshell allowing alignment to be done with the arm wand detached from the base. The 2 markings (not null points) are for aligning the stylus back and forth on the headshell. It is a big tolerance if you can move the stylus back and forth at the headshell by 1mm and still conform to 1 of those curves. That's why I say ultra accurate protractor is probablyt not needed!  
 
Check out whether the Excel spread sheet in the following page helps. It gives the null points, but not printing the whole arc protractor!  
 
http://www.enjoythemusic.com/freestuff.htm
thekong
12-10-17
18:00:44
回覆 (1944): Null point calculation
On the jig, there are 2 markings for 2 different alignment curves. These 2 markings are rough 1mm apart!  
----------------------------------------  
Thats call plan B!  
 
The trouble is i do a few protactors too. So, which one is Plan A?
bobui
12-10-17
17:38:05
回覆 (1943): Null point calculation
Now, my Graham Phantom comes with a custom alignment jig. On the jig, there are 2 markings for 2 different alignment curves. These 2 markings are rough 1mm apart!  
 
----------  
this is what ivan showed me but with one curve. as per the formulat, the two null points are dependent on the arm length, offset and overhang. so the idea is to set up the arm to get the overhang first. based on this, a curve can be generated with markings on two null points.
drwkng
12-10-17
16:45:23
回覆 (1942): Null point calculation
 
To be honest, unless it is arm specific, I believe a basic protractor is enough.  
 
I am very skeptical about the ultra-accurate protractors, which some advocates claim can vastly improve vinyl playback!  
 
Now, my Graham Phantom comes with a custom alignment jig. On the jig, there are 2 markings for 2 different alignment curves. These 2 markings are rough 1mm apart!  
 
Obviously, the 2 alignment cures have their pros and cons, so which alignment curves to choose would depends on you LPs and preference (where on the LP can you tolerate more distortion). Unless you only have 1 LP, your preferred alignment curve would probably change from LP to LP.  
 
Even with a normal, not-so-accurate, protractor, I believe it is not hard to achieve a +- 0.5mm accuracy, which represent the difference of the 2 marking on the Phantom jig!  
 
Add to it that your LP collection probably have many different sets of outer and inner track radius; the ultra-accurate would probably serve no purpose unless you only listen to a single LP, or even a single track on that LP!  
 
thekong
12-10-17
15:52:38
回覆 (1941): Null point calculation
 
 
BTW, I have made my own protractor. You can have mine for a trial if you want. Come to pick it up this Sat-Lunch then.  
 
 
limage
12-10-17
15:12:42
回覆 (1940): Null point calculation
 
 
Ivan To,  
 
If that's your concern, it is very easy to make your own template which can easily be fabricated from an  
ordinary file card.  
 
Simply mark off three points on one of the printed lines anywhere near the middle of the card. From left  
to right, the second point should be 66.0 mm from the first and the third point 120.9 mm from the  
first (not from the second). Then punch a spindle hole of 7.2 mm diameter through the first point. If you  
wish, draw two perpendiculars to the printed line, intersecting it at the second and the third point.........  
 
For further details, you may look up the discussion from Dr. Feickert's thread here on Page 2 of the index,  
back off to page 5 along the thread.  
 
 
limage
12-10-17
15:06:39
回覆 (1939): Null point calculation
 
Something like this?  
http://www.conradhoffman.com/TemplateGen.zip
thekong
12-10-17
14:08:48
回覆 (1938): Null point calculation
after talking to ivan to, the program is not correct. what he wanted is to have the program calculate the 2 null points and print out a diagram with parallel lines marked on those points so that he can use it set stylus orientation. so back to the drawing board. .
drwkng
12-10-17
13:30:22
回覆 (1937): Null point calculation
 
>…some claims that the relatively high horizontal moving mass may cause a deflection at the cantilever, therefore making some constant (relatively) tracking error through the whole LP! <  
__________________________________________________________________  
 
About this point, I wonder whether Ivan To has any equipment that can measure the amount of cantilever deflection on a linear tracker as compared to a pivotal arm! I would think such equipment is not really that high-tech, right?  
 
thekong
12-10-17
13:12:16
回覆 (1936): Null point calculation
 
Actually, as the skating force depends on the modulation of the LP groove, you will have constantly changing skating force when playing a normal music LP.  
 
Tracking error may have a slight effect on skating force, as difference stylus designs may have slightly different drag with different amount of tracking error.  
 
So, any anti-skating force applied is nothing but an approximation. The result you get from any test record may not really apply to real world situation!  
 
But then, since there is skating force for sure in any conventional pivotal arm, I suppose a small amount of anti-skate is better than nothing, at least in theory.  
 
thekong
12-10-17
12:49:46
回覆 (1935): Null point calculation
In theory, linear trackers don't have skating force at all, so no need for anti-skating!  
---------------------------------------------------  
 
Thats very good to know. This anti-skate issue is probably the one and only puzzle in LP set up that really bug me. I am not saying i fully understand all the mathmatical principals in LP playback but in terms of the variables I can see(knobs and adjustment entitle the LP owner to mess around with in an average LP set up), this anti-skate is just so.......bloody..........utterly........annoying.  
 
 
Now, I can forget about the idea of adding an anti-skate in my Terminator. Silly me! Diawok would kill me!  
 
bobui
12-10-17
12:08:16
回覆 (1934): Null point calculation
 
>Linear tracking in theory is better in terms of minimising the anti-skate force required. <  
___________________________________  
 
In theory, linear trackers don't have skating force at all, so no need for anti-skating!  
 
thekong
12-10-17
11:50:55
回覆 (1933): Null point calculation
The skating force is induced by the offset angle of the cartridge  
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Thanks for the correction! That also imply Linear tracking in theory is better in terms of minimising the anti-skate force required.  
 
=====================================================  
 
I always have doubts on Decca base on my very limited bad experience..... but now I know clearly where the goal post stands.  
-----------------------------------------------------------------------  
 
Dont be shy la, icefox! You have accumulated plenty of experience with Decca. In fact, u did take me to listen to your below posted system at Yu sir. Very nice lor!
bobui
12-10-17
11:25:36
回覆 (1932): Null point calculation
Talking about arm that's like a Naim Aro........  
 
Edwin and I have a couple of masterclass sessions with Yu sir playing with Decca cart in this setup............. simply sublime....... the best vinyl sound I have heard.  
 
I always have doubts on Decca base on my very limited bad experience..... but now I know clearly where the goal post stands.  
 
The arm in this setup is like a Naim Aro in modern execution with lot of problems in the Aro fixed.
icefox
12-10-17
11:04:57
回覆 (1933): Null point calculation
 
 
Provided it really works without encumbrances, US $8,900 is nothing when compared with any high end product these days!  
 
limage
12-10-17
11:01:12
回覆 (1932): Null point calculation
 
The following is a brief description by Schroder himself:  
 
> The position of the pivoting bar (that holds the actual tonearm) is governed by a frictionless magnet/guiderail arrangement. The pivoting bar revolves around a preloaded ceramic hybrid bearing which accounts for nearly zero(~2-3mgr) additional (rolling)friction, for a total that's still about half of what you'll find in any arm equipped with ball race bearings.<  
 
I think the arm base has to move, although only for a very short distance, to accomplish linear tracking. But as it use a pivotal point for the arm base movement, the moving mass should be way lower than a conventional air-bearing linear tracker!  
 
Maybe diawok can arrange a demo unit?  
 
However, instead of US$6000, the introduction price seems to be US$8,900, and that is getting serious!  
thekong
12-10-17
10:50:36
回覆 (1931): Null point calculation
 
 
bobui,  
 
The skating force is induced by the offset angle of the cartridge and is proportional to modulations of the groove.  
Hence, the higher the recorded level, the higher the skating force. That's why it is wrong to adjust anti-skate by  
using blank tracks. This force is also higher when tracking weight is increased.  
 
Tracking error has nothing to do with the skating force apparently.  
 
limage
12-10-17
10:40:55
回覆 (1930): Null point calculation
@@
icefox
12-10-17
10:35:24
回覆 (1929): Null point calculation
So............ elegant!
icefox
12-10-17
10:33:17
回覆 (1928): Null point calculation
 
 
I wonder how this Schroeder works since there is no levers to continuously move the headshell like other designs do.  
 
Does the arm base move? If it does, then the same problem similar to parallel tracking arms may set in, albeit the moving mass would be 10 fold higher.  
 
limage
12-10-17
10:19:57
回覆 (1927): Null point calculation
The Schroder LT is nice! Actually a bit like the Naim Aro!  
 
Anti-skate, below sum up how I understand it. Scream at me and share with your thoughts and make correction please.  
 
1. The pulling force to the spindle is in proportion to the speed.  
2. The anti-skate force needed to pull back the cartridge from the spindle is proprotion to the tracking weight in use.  
3. The tracking error is one other major factor that determine the pulling force.  
4. When the stylus wear out, the trackability decrease and thats when the anti-skate start becoming more important for maintaining proper tracking between left and right channel.  
5. If the tracking error is a vital part that determine the level of pulling force, the only chance an arm has in reducing the pulling force is when you have a linear tracking arm.  
6. If you kind of agree point 5, then the material use in an arm has very little to do with the level of pulling force  
 
bobui
12-10-17
09:48:11
回覆 (1926): Null point calculation
 
Oh yes, I would also like to see limage setting up one of this Schroder LT in his den!  
 
It may sounds crazy, but when comparing to some other super arms, the cost of this Schroder actually looks reasonable!  
 
I am sure diawok can get a good price on it! :-)  
 
thekong
12-10-17
08:23:30
回覆 (1926): Null point calculation
I am planning to see Fank Schroeder at the European Triode Festival next month, so I guess I could bring the arm back with me for Master Limage 8^)
daiwok
12-10-17
08:19:57
回覆 (1925): Null point calculation
Talking about null point and tonearm, I wonder why no one mentioned about this.........  
 
I like the idea of it being a linear tracker but being a pivot arm without the need for those pumps and surge tank and things like that.........  
 
I would love to see limage being the first user of this arm in Asia....... looking at limage's very methodological and disciplined approach in vinyl playback I am sure this would be the match in the heaven for him..... (could be a wishful thinking)!  
http://www.analogplanet.com/content/new-schr%C3%B6der-tangentially-tracking-pivoted-tonearm
icefox
12-10-16
22:52:28
回覆 (1925): Null point calculation
On anti-skate: tracking force aside, the effectiveness mass (arm tube length x mass) of pivoted arms is another issue. Some guys here in Toronto have 12 inch pivoted arms with ebony arm tubes. Zero anti-skate always sound more natural and lively.
davidchan
12-10-16
22:51:57
回覆 (1903): Precious broken cart
daiwok,  
 
呢件真係娘到爆!!!!
icefox
12-10-16
22:47:18
回覆 (1924): Null point calculation
 
 
' Interesting to note that two of the very few manufacturers of both cartridges and tonearms opt for heavy horizontal moving mass tonearm designs. The flagship of ClearAudio is, of course, a linear tracker. '  
_____________________________________________________________  
 
I believe the Clearaudio tonearm horizontal moving mass is less than most of the air bearing design, due to its very short arm tube and the mechanical bearing has less mass than the air-bearing. The greater bass weight of the Clearaudio can be due to the constant contact of the bearing wheel with the arm-rail.  
Though linear trackers/pivoted arms have their ups and downs, I prefer linear trackers from my experience. They have bigger soundstage, more instrumental separation, better focus and more air.  
kh33
12-10-16
19:12:05