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Uni-Protractor Set tonearm alignment

Looks like Dertonarm has put his money where his mouth is and designed the ultimate universal alignment tractor.

Early days, It would be great to hear from someone who has used it and compared to Mint, Feikert etc.

Given its high price, it will need to justify its superiority against all others. It does look in another league compared to those other alignemt devices

http://www.audiogon.com/cgi-bin/cls.pl?anlgtnrm&1303145487&/Uni-Protractor-Set-tonearm-ali
downunder
john_gordon
116 posts
 
Thuchan,
I didn't say you, personally, accepted everything Dertonarm said. I was making a general point.
I am always willing to discuss things, and admit when I'm wrong, the operative words being "discuss" and " wrong".

you said
The (analogue) world is like it is, some good developers and failed ones.
Mostly the failing guys do have a motivation to define the world and tell the succesful developers what they seem to have done in a wrong way.

believe me, I do know producers of tonearms and even turntables who do understand the theoretical implications of proper alignment but they do not really care about it.

Success or failure in hifi and good and bad developers do not necessarily correlate. Making money from a product doesn't mean it is good, merely that a lot of people buy it, and vice versa.

My, and many other's, experience is that often a good product can fail because someone who can influence the market decides it should fail - it's all part of the way markets work... probably best to stay out of it (or, vice versa, as given by your example above,...!)

J
john_gordon
116 posts
 
Dertonarm

Glad to see you have responded to my post (via T Bone). Why did you do that? I am willing to discuss the SME issue directly.

You said
Given the fact that the mounting hole in the SME V is not really intended to allow anything like a "cartridge offset angle" (which in tonearm geometry not really exists at all - other as by wishful thinking)...

please read my post to Peter re the conflation of headshell and offset angles and why this is confusing.I am assuming you mean cartridge mounting.

...one can assume that it's designer did so by good reason...
That is a fair assumption, but only if you give a fair analysis of why they might have done it that way.
...As this mounting hole is (to the regret of many of it's owners past and present - including me ..) not really an elongated one either...
Patently not, given it has no slots. Why would this be?

...the effective length is - at least in theory and designer's intention - pre-determined as well...
No. The alignment chosen, ie Baerwald/LofgrenA IEC, is predetermined. The effective length is nominal.

...Setting the "cartridge offset angle" other than the offset angle of the tonearm's headshell does produce an additional break-down torque in the tonearm's static model - i.e. an additional force vector.
This is a plain mechanical fact - thanks to Isaac N. ...;-) ....
This is vague. What do you mean by "break down torque" and why would it be additional if the overhang remains the same? The stylus merely rotates, the groove tangent remains the same, therefore the vector towards the centre remains the same. The only change could be due to the stylus, which may or may not increase the force along the groove tangent depending on the stylus profile.

(re Issac Newton - I have heard he had a great hifi, but maybe Einstein's was better on the super fast transients... (just a joke))

That additional break-down torque does of course influence the skating force.
In what way, by how much?

Now you get to the point:
Now is the SME V designed and constructed strictly following Löfgren A IEC (Baerwald)?
According to it's designer's it is.
According to it's technical parameters it is too.
Can one adapt the SME V to different alignments by moving its slide carriage? It was not intended to adapt to different alignments, but to different position of stylus relative to the mounting hole of the SME V.
Granted, though Lofgren B IEC is much easier than with a slotted headshell - no need to loosen the cartridge, just slide the base.

...The moving of the SME carriage does alter P2S and adapt's the effective length to different distances - in cartridges - between the mounting hole and the stylus.
Correct

Thus being able to retain the original Löfgren A IEC alignment is was calculated to.

Thank you for agreeing.
But why not just say you were wrong, or had expressed yourself badly, previously?

As Piet Hein, the Danish scientist/philosopher/poet said:
The road to wisdom?
Well, it's plain
And simple to express:
Err
And err
And err again
But less
And less
And less.

geoch's avatar
geoch
354 posts
 
Dear Daniel, for second time in this thread you state :
+++[ "Setting the "cartridge offset angle" other than the offset angle of the tonearm's headshell does produce an additional break-down torque in the tonearm's static model - i.e. an additional force vector.
This is a plain mechanical fact - thanks to Isaac N. ...;-) ....
That additional break-down torque does of course influence the skating force." ]+++

I'm sorry for I'm not in a deep embarrassed position and have the nerve to ask you about such widely known physics.
I have a question for you (and it is a genuine one, due to my ignorance) :
The Talea, Schroeder, Clearaudio Satisfy are designed with adjustable arc on their rudimentary headshell. The Simon Yorke has circular headshell which does not shows any preference in cartridge angle. Moreover, there are some circular cartridge bodies also! How does the Newton's law applies there?
The antiskating force is always an adjustable issue and in no way the value of it can determine a fault on design. The fact that most of tonearm designs can not provide this feature by the right way, thus gradually increasing antiskating force, it does not giving the wright to anyone to acuse the cartridge's twisting on headshell.
Please tell me what I'm missing ? The cartridge is always slaved by the arm which is slaved by it's pivot point, so, there is no any relationship with cars moving freely on a road and are coming to take a close turn while having 100m/h
I'm sorry for asking but I really want to know better.
Thank you in advance.
George
dertonarm
1,042 posts
 
Dear George, that now is a question/comment worth being addressed.
The Talea, Schroeder, Clearaudio, SY and before them other tonearm designs ( Well Tempered et al) did use this smart trick for good reason.
By this design feature they avoid a pre-determined offset angle and thus are much easier to adapt to different alignments (calculations) without trade-offs due to the alternation of a "pre-determined" offset angle by a cartridge's body aligned in a different angle.
Circular bodies further reduce the problem, but - unless they follow the Ikeda or DECCA/London cantilever-less principle - there is still the line of the cantilever which should be in line with the offset angle.
If we have a cartridge body other than circular, the problem get's worse and if the cartridge's body and its cantilever aren't in line with the headshell's offset angle, we will get another force vector - i.e. a second breakdown torque and thus an alternation (not necessarily an increase!) of the skating force the tonearm can ( NOT must!) apply to the stylus/groove contact.
Before I address your statement regarding skating force and "anti-skating", please clarify what you think skating force is and where it comes from.
There are a very few pivot tonearms out there with apply practically zero skating force to the stylus.
Cheers,
D.
geoch's avatar
geoch
354 posts
 
"There are a very few pivot tonearms out there with apply practically zero skating force to the stylus."

Why are you mention this? Are they having an advantage over the rest tonearms? I thought that as the friction increases towards the center of the LP, we can not assume the skating force as a constant value and so, we must apply an increasingly antiskating force anyway. I'm I get it wrong?
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