Gathering at NWA

[Marco]

Hi Ali,

Did you see my reply here, regarding arm geometry: http://theartofsound.net/forum/showt...289#post523289



Marco.

P.S Barry, I've noted those recordings for future buying reference - cheers!

[Ali Tait]

No missed it, cheers for the heads up.

[Dominic Harper]

Just for your info, I did set up the DH1 to Baerwald in your Techy Marco.

[Barry]

The arm Marco uses is the Ortofon AS-212S : http://www.ortofon.com/products/hist...ducts/as-212s; a now discontinued product.

From the above link it can be seen the arm has an effective length of 231mm, with an offset angle of 22° and overhang of 15mm. The recommended radial null points are 58.5mm and 114.5mm.

Curiously this geometry corresponds to neither Baerwald, Löfgren nor to that of Stevenson. Using the equations quoted in http://theartofsound.net/forum/showt...earm-alignment, we can calculate the following: -

For Baerwald (IEC) geometry: offset angle = 23.86°, overhang = 17.97mm and the radial null points are at 66.0 and 120.9mm,

for Baerwald (DIN) geometry: offset angle = 23.28°, overhang = 16.31mm and the radial null points are at 63.1 and 119.2mm.


For Löfgren (IEC) geometry: offset angle = 23.86°, the overhang = 18.48mm and the radial null points are at 70.3 and 116.6mm,

for Löfgren (DIN) geometry: offset angle = 23.28°, the overhang = 17.42mm and the radial null points are at 67.4 and 114.9mm.


And finally for Stevenson: the offset angle is 22.57°, the overhang = 15.8mm and the null points are at 60.33mm and 117.0mm.

Comparing the latter figures with those quoted by the manufacturer, it can be seen that the arm geometry is closest to that of Stevenson. The manufacturer’s recommended null points are correct given the arm geometry, but do not correspond to the Baerwald values as used on most alignment protractors.

So whilst it would seem Ortofon have chosen their own geometry, the arm/cartridge alignment will be optimised if their recommended null points are used.

[Marco]

The arm Marco uses is the Ortofon AS-212S : http://www.ortofon.com/products/hist...ducts/as-212s; a now discontinued product.

Soz, Bazza, yer is wrong... I use an RS-212D, as shown here: http://www.ortofon.com/products/hist...oducts/rs-212d

The AS-212S, shown here: http://www.ortofon.com/products/hist...oducts/as-212s is similar, but different in that it is a "Static-Balance" design, whereas the (more expensive) RS-212D is a "Dynamic-Balance" design. It outlines briefly what that means on the Ortofon website, but whether the difference is audible, I'm not sure.

I bought the RS-212D because I liked the look of it better! Here are both the 9 and 12-inch versions (the 'RS/D' designs, shown below, just look more 'solid' than their 'AS/S' counterparts):





I agree with your calculations, and have always found that Japanese arms perform optimally when set-up for Stevenson.

Marco.

[Marco]

Just for your info, I did set up the DH1 to Baerwald in your Techy Marco.

Yup, and of course, it sounded superb. However, one wonders how much 'more superb' it would've sounded, had it been set up for Stevenson, in order to align with the geometry that was used to set up the arm?

Marco.

[Dominic Harper]

My personal preference is Baerwald, but when using a SPU you are limited because of lack of adjustment at the headshell, ie you cannot adjust overhang or offset. You then need to rely on the manufacturers recommendation for spindle/pivot distance in relation to tip to pivot distance, plus arm geometry (off set designed into the arm wand).
If a cartridge and headshell are employed which has some adjustability( headshell slots ) then most alignment variations can be investigated and prefered one employed.
There are no rights or wrongs here, just personal preferences.

[Dominic Harper]

I agree with this IF the arm is using a cart such as the SPU where no adjustments can be made, but also refer to my other statement about personal preference.

I agree with your calculations, and have always found that Japanese arms perform optimally when set-up for Stevenson.

Marco.

[Marco]

My personal preference is Baerwald, but when using a SPU you are limited because of lack of adjustment at the headshell, ie you cannot adjust overhang or offset. You then need to rely on the manufacturers recommendation for spindle/pivot distance in relation to tip to pivot distance, plus arm geometry (off set designed into the arm wand).
If a cartridge and headshell are employed which has some adjustability( headshell slots ) then most alignment variations can be employed and prefered one employed.
There are no rights or wrongs here, just personal preferences.

I absolutely agree. However, as I tend to use Japanese arms, exclusively, my own personal experience has shown that adopting Stevenson geometry is preferable, even with a DL-103 at the helm (fitted to a headshell with slots in it)...

Much depends at which point on the record (beginning, middle or end of side) you wish to minimise distortion the most, which is largely the point of having the various geometry options

Marco.

[Barry]

Soz, Bazza, yer is wrong... I use an RS-212D, as shown here: http://www.ortofon.com/products/hist...oducts/rs-212d

The AS-212S, shown here: http://www.ortofon.com/products/hist...oducts/as-212s is similar, but different in that it is a "Static-Balance" design, whereas the (more expensive) RS-212D is a "Dynamic-Balance" design. It outlines briefly what that means on the Ortofon website, but whether the difference is audible, I'm not sure.

I bought the RS-212D because I liked the look of it better! Here are both the 9 and 12-inch versions (the 'RS/D' designs, shown below, just look more 'solid' than their 'AS/S' counterparts):





I agree with your calculations, and have always found that Japanese arms perform optimally when set-up for Stevenson.

Marco.

Sorry Marco, the two arms look similar with the 'cube-shaped' bearing housing. Personally, I prefer static balanced arms as these do not use springs which can ring. As long as the TT is level and one's records are flat, there is no real advantage to dynamic balancing.

But I digress, both the RS 212 and AS-212 have identical geometry. To realise the optimum performance, the arm must be set up so that the radial null-points are at 58.5mm and 114.5mm. I assume Ortofon supply a protractor with these null-points marked.

If you try to set the arm up according to Baerwald you will have to skew the cartridge in the headshell by ~ 1.5 degree, as well as increase the overhang by ~3mm.

Ortofon/Jelco designed the arm to have a particular geometry which does not correspond to either Baerwald or Stevenson. There is nothing wrong with this, it's just to set the arm up as designed, you can't use arm alignment protractors that are marked with either the Baerwald or Stevenson null-points. The errors in doing so are small, and probably inaudable - but if you are going to do the job, you may as well do it properly. As one supermarket says: "every little bit helps".