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Old 2nd October 2006, 08:10 PM   #1
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Default ball neo arm pivot..

just saw this site and it looks that the armpivot is a neo ball magnet. Have a look.
moray james
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Old 3rd October 2006, 11:48 PM   #2
lancer is offline lancer  Singapore
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Saw it in the flesh. One piece of engineering I must say. Heard it playing as well and was impressed with it.
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Old 10th October 2006, 03:38 PM   #3
Fox is offline Fox  Netherlands
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I have made such an arm specifically for the Denon Dl-103. It has an adjustable effective mass between 11 and 15 grams.
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Old 10th October 2006, 03:40 PM   #4
Fox is offline Fox  Netherlands
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And another one ...
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Old 10th October 2006, 03:57 PM   #5
hacknet is offline hacknet  Singapore
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hey! super looking arm you've got there!

how did you vary the effective mass?

and what material is your arm made of?

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Old 10th October 2006, 09:59 PM   #6
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Default ball neo arm pivot

Really impressive bravo.How it sounds on the TD125?
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Old 10th October 2006, 10:00 PM   #7
EC8010 is offline EC8010  United Kingdom
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That's a very tidy piece of work. (And nice photography.)
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
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Old 11th October 2006, 03:34 AM   #8
EUVL is offline EUVL  Europe
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very well made.

I wonder whether you are using steel bearing balls and have the magnet inside the arm tube ?

Also did you make a dimple for the ball to sit on ?
And what is the purpose of the ball on the lower side which is not touching the arm (damping) ?

Sorry for the lists of questions. Could not help being curious.

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Old 11th October 2006, 10:06 AM   #9
Fox is offline Fox  Netherlands
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Default Arm details


Thanks for the compliments. Here some more details about the arm.

It is 10 inch long, the armwand is made of two layers of carbon tube. The "bearing house" is made of aluminium and the other parts of stainless steel. The lift is OEM-Rega as you probably already figured out.

Inside the armwand at the pivot point rests a neodym ball-magnet. The ball-magnet on top of the armtube locks very tightly to the magnet in the arm. The arm is very able to move in all directions freely. The ball-magnet under the armwand functions indeed as a damping-device.

The effective mass is adjustable by means of the small stainless steel tube between the pivot point and the headshell. I have measured the difference it makes and the effective mass is adjustable between 14-18 grams (this differs from the effective mass as posted above but at the time of posting I did not have my drawings at hand). Naturally, any movement of the effective mass adjuster should be compensated by a movement of the counterweight.

The arm is complex in its use. The azimuth, VTA, damping , effective mass and what have you are adjustable. There are many parameters to adjust, so you can imagine that I am all but finished figuring out what the optima are soundwise.

Speaking of which! The arm replaces my Incognitoed OL-RB250 with custom counterweight and VTA-adjuster (see picture attached). With the Rega-arm the Dl-103 did not sound very well to my ears. I even experimented by adding weight to the headshell (as much as 11 grams!) buth the Rega and the DL-103 are not meant to each othert IMHO. The rythms were OK but the treble was harsh. With my DIY-arm the DL-103 really shines. It is as if a veil is lifted. The sound is exceptionally detailed (in the treble as well as in the bass-department), very smooth and very dynamic. Surface noise is also much lower than with the Rega. Go figure!

In the mean time I have finished my Pass Pearl with Ono MC-pre-pre to replace my tube phono pre and MC-step up transformer and this meant another leap in performance. I am as far to conclude that the conical stylus of the DL-103 should by no means be regarded as a weakness of the cart in the sense that it limits the amount of detail that comes through. It also tracks the inner grooves suberbly.

The arm goes along very well with my Thorens TD125 MK2. The bearing of my Thorens has been polished and re-oiled two years ago by stuff sold by Joel Boutreux at (Germany). Due to this measure the dynamics and detail of the turntable changed for the good. A year ago I replaced the LP12 springs again with the original ones and this resulted in an increased bandwith. It turned out that the LP12 springs make the mids too warm. To cut a long story short: the TD125 is a great turntable in the sense that it allows my DIY-arm and Denon cart to shine.

All the best,

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