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Confocal

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About Confocal

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  1. The parameter to say how much the stylus is 'aligned' to the groove (it is better to say, how much the stylus is tangent to the groove) is expressed by the "Lateral tracking error". This 'error' is important because is the source of a distortion. The lateral tracking error is determined by three parameters that fully describe the configuration of the turntable : tonearm effective length, overhang, offset angle (please see on the web the description of these parameters). On the ST150 user manual there is only the effective length of the tonearm, so it is difficult (let say impossible) to say something about the lateral tracking error. We can say only that the s shape tonearm typically are better in terms of tracking error respect a straight tonearm with the stylus in line with the shell (offset angle=0). But, I repeat, to say a correct information regarding the tracking error, it is important to know the three parameters I reported above or, of course, the error itself (typically declared by the manufacturer). So, a straight tonearm with a good combination of the three characteristics (effective length, overhang, offset angle) can be better than a S shape tonearm in terms of lateral tracking error! To calculate the tracking error there is a formula (please see my post http://forum.gibson.com/index.php?/topic/112489-tracking-error-on-194mm-effective-length-straight-tonearm-t120/). The tracking error it is not constant during the playback. It change depending the position of the stylus between the outer and inner grooves, i.e. the distance between the stylus and the center of the disk. Typically we can say that the error is low when it is less than 1 or 2 degree. I hope I was clear. Regards.
  2. After some years the rubber/plastic on the top surface of my T.120 (around the plate and the command buttons) is very sticky. Bad, bad feeling when you touch this surface. I would like to underline that the usage of my T.120 was not very intensive and always in my home (no dust, no smoke, like in a club for example). The problem now is how to try to replace or to clean this surface. On the web there are some people that suggest something…but I am not sure these are good methods. Any professional and previously proved suggestion is well accepted!! Thank you! Bye bye from Italy.
  3. Just after the initial use of my T.120 turntable some years ago, I heared a strong noise at 50Hz (the mains frequency here in Europe). The best way to ear it was: - stylus on the disk (pulling up the stylus from the disk, noise was less) - plate not running (no other noise) - no vibration from the desktop where the T120 was placed (for example, no PC external disk on the desktop, no other vibratin sources) Switching on and off the motor switch there was not any change, the noise was there! The 50Hz noise was very loud! Not acceptable from a Stanton turntable!! No way to reduce it. For years I used the turntable with this noise but recently I decide to make something. I start to investigate and after a lot of tests, I found that the reason was not of electromagnetic type but of mechanical vibration type. The mains internal trasformer was the source of that mechanical vibration. I opened my T.120 I removed the transformer and placed it outside the turntable. I will make an external box for that transoformer with some custom connection, but for now it is all on the desktop! (see attached photo). Now, the noise is totally disappeared! It is clear that the insulation rubber placed on the plate that fix the trasformer inside the turntable case (see the red arrows in the second photo) was not sufficient to filter all the vibration generated by the transformer. Or, the trasformer is to much vibrating for this type of application. At the end some important declaration: 1) I know that opening the turntable the warranty was 'broken' 2) I know the risk of electric shock with this kind of work. Please, note that the parts I removed and reworked are very dangerous parts when they are connected to the mains. The voltages on these parts can be DEADLY. I am an electronic eng. so I know how to work in a safety way. 3) WITH THIS POST I AM NOT SUGGESTING TO DO THIS TYPE OF REWORK TO SOLVE THE PROBLEM I HAD ILLUSTRATED ABOVE. I MADE THIS THIS POST ONLY TO SHARE MY EXPERIENCE ABOUT THIS 'DEFECT' AND TO KNOW IF OTHER PEOPLE EXPERIENCED SIMILAR 50 HZ NOISE. IF YOU HAVE THE SAME PROBLEM, DO NOT MAKE ANY RE-WORK LIKE THIS ONE. IF YOU DO SOMETHING LIKE THIS, IT WILL BE UNDER YOUR RESPONSABILITY. PLEASE, CONTACT THE STANTON SERVICE.
  4. First off all, I am sorry for my basic english. English is not my first language. A very theorical but serious issue. In the user manual of my T.120 Stanton turntable is declared a maximum tracking error of 3 degree. Recently I have studied something related to the tracking error argument. There is a formula (see figure, attached) that quantify the tracking error when are known the effective lenght of the tonearm, the overhang and the angle between the stylus plane and the effective lenght line. d: distance of the stylus from the disk center hole o: overhang ε: lateral tracking error β: offset angle le: effective lenght of the tonearm I applied this formula to T.120 and I found that this error is very huge : from 15° to -15° coming from the external grooves to the internal grooves. See the graph in figure attached. I was very surpised, so I made a countercheck. I found and downloaded from the web a particular tool (an image to print on a piece of paper) useful to measure the tracking error, and with my great surprise, this tool has confirmed the calculations I made previously. It means measures on my T.120 are the same I calculated by the formula. Now, I am thinking with a reasonable belief, my T.120 has a tracking error very high. How is it possible that a great brand as Stanton declare a tracking error less than 3 degree instead 15 degree? There are only two possible explanation: the specification of this tracking error by Stanton is wrong or I am in wrong! If someone can explain something about this argument, I will appreciate a lot. Thank you for your attention and bye bye from Italy.
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