Question about tonearm placement: Micro Seiki MA-505L on DDX-1000

Mr. Yamaha

Mr. Yamaha

Not so much Yamaha lately...
Hello guys, I have a question about the resposition of a MA-505L arm on a Micro Seiki DDX-1000 turntable. Everything is so variable with the arm board, the tonarm itself and this table that I'm a bit lost. Mostly because I think the rest placement influences the course of the anti-skating mechanism from first groove to the lead-out groove.

I'm talking about this angle:

IMG_3712.jpg

As you can see, the back of the arm points a bit to the right, because I like the way it looks like this. But the question is, is this correct.

Now about the anti skating mechanism. It alters the bend of the small wire that realizes the tracking force. So when the arm moves to the spindle, the angle of the bend gets sharper. That is where I'm starting to doubt the arm placement, because in the way it's placed now, it could applies too little anti-skating.

Close up, arm in rest position:

IMG_3715.jpg

Lead in groove:

IMG_3716.jpg

Lead out groove:

IMG_3717.jpg

The service manual does not say anything about this.

Any help or suggestions would be great :bigok:
 
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If I understand the question you should be OK with the anti in any position you want. Lets see if I have my geometry correct. You have 3 fixed pivots. So to get the NULL points correct you make sure the 2 red lines are the correct in there distance. This will give you 6 different points with the 3 fixed mounting positions. Because the platter is a circle I Would THINK the pull would be equal with any of the 360 degrees positions around the platter. The arch of travel should be the same regardless of where you put the starting point ( determined by the pivot to spindle and effective pivot to stylus lengths) the 2 red lines.

Or maybe think about the platter moves in a circle. There is no start or stop position. So if you had a arm on a pod you could get a starting point from the 2 red lines then draw a circle from there. Now you could position the arm anywhere around the new circle and everything else remains the same.

If I am not correct hopefully someone will chime in. The debate on null points and anti skate will go on forever but I think the mounting positions are pretty black and white.

I had a normal length ma 505 for 40 years. I modded it alot. If you are a tweaker I would try a new direct coupled counter weight. It change the sound more than you would think. It is truly one of the top arms of the past.

Enjoy the ride
Tom
 
TomWh said:
If I understand the question you should be OK with the anti in any position you want. Lets see if I have my geometry correct. You have 3 fixed pivots. So to get the NULL points correct you make sure the 2 red lines are the correct in there distance. This will give you 6 different points with the 3 fixed mounting positions. Because the platter is a circle I Would THINK the pull would be equal with any of the 360 degrees positions around the platter. The arch of travel should be the same regardless of where you put the starting point ( determined by the pivot to spindle and effective pivot to stylus lengths) the 2 red lines.

Or maybe think about the platter moves in a circle. There is no start or stop position. So if you had a arm on a pod you could get a starting point from the 2 red lines then draw a circle from there. Now you could position the arm anywhere around the new circle and everything else remains the same.

If I am not correct hopefully someone will chime in. The debate on null points and anti skate will go on forever but I think the mounting positions are pretty black and white.

I had a normal length ma 505 for 40 years. I modded it alot. If you are a tweaker I would try a new direct coupled counter weight. It change the sound more than you would think. It is truly one of the top arms of the past.

Enjoy the ride
Tom
Click to expand...

337alant said:
Did you look on Vinyl engine Tone arm data base
https://www.vinylengine.com/tonearm...ohlo=&ohhi=&search=search&amlo=&amhi=&cw=&mp=

It has a Pivot to spindle distance of 270mm
Null points at 38.7 & 171

Turntable data base
https://www.vinylengine.com/turntab...earch=search&control=any&auto=any&changer=any

Alan
Click to expand...

Hello, yes all other points are correctly adjusted: null points, pivot to spindle and overhang. I'm only concerned about the arm base position, because the position of the arm looks to have a direct impact on the angle of the anti-skating mechanism. So when the arm base is turned more to the right (away from the platter), then the arm is more rotated towards the spindle then when the arm base is more placed to the left, thus giving it more anti skate. The angle of the anti skate system is changed when turning the base.
 
I'd rotate it so it has minimal antiskate force coming in at the leadin groove.

I also have this table - didn't know it's supposed to have a platter weight!

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Aerobat said:
I'd rotate it so it has minimal antiskate force coming in at the leadin groove.

I also have this table - didn't know it's supposed to have a platter weight!

y4m6hzn2567RktQ-jA87WVXQWzsYotpkuHPHOxY92pBJc-ustetWAFCmT7jhaokg0RLcwR4UWwNm14t_g66hW2-CHCY2bbgdpkZF4CV_BVncnzGhH07BP9z6y_ndNkcYgV595yThTF9AP9v3Pk4zYc0Aj6A167MSnyL5EDR07B3S1molIapAIbsQz3zGOrxEQ8bbmxvClbTXdup3AeglJEgxA
Click to expand...

Thanks, nice looking arms! When I do like you say, then it's very close to the platter in rest position. Not sure whether that's right. The weight is the optional Micro Seiki ST-10, made from gunmetal. Can be found regularly on Yahoo Auctions or the Bay.

In the mean time I found this in the Japanes manual of the MA-505 (smaller variant). I think this answers my question. The angle between the line spindle to pivot and the arm in rest position must be between 62 and 75 degrees. Correct interpretation?

Micro1.JPG

Micro2.JPG
 
With this info I connected a small thread from spindle to pivot and from pivot to headshell centre. I measured the angle with a triangle ruler and found out the angle was 56 degrees. So that's not within the range. So I turned the arm to the position where the angle is 65 degrees. I don't like how it looks, but it's according to specs.

Before:

IMG_3756.jpg

After:

IMG_3757.jpg

IMG_3758.jpg

Mystery solved I guess? :cool:
 
Looks good to me. Photo of mine for reference. The weights are going for $200, yikes!

y4m8gDoZgAxPD_kwou9olWBsB9GxYbMuvG5TQIaG23mJ2i3TiWfqmL-5aaaLbW6TNRsffPe8mnjD7Jw3BUTGXMkmqEAHUyujf2TKPjCYzp3M0UTQFL43TdzBJWUGaTp2xO_vzIbISxqpybh-hYw_oJiQJ6BWTU22xREWPCVB-FmBQWcWRyqhTfQLUO55jchLF1DagZWm2SDeN18xEM3mYd9eA
 
The Jelco 370 was mounted using the specified pivot to spindle distance and an alignment template printed from a generator. As far as the angle of the arm I just eyeballed it.
The VPI arm was aligned using the VPI jig, it doesn't specify a pivot to spindle distance that I know of.
 
I hope I'm not too late to help.

The pivot to spindle distance (PTS) is 270mm for the MA-505L.

It is 222mm for the MA-505.

You can place the pivot anywhere on a circle that is 270mm from the spindle. It is best to get it as close to 270mm as you can, but +/- 5mm will be OK.

I have two MA-505 arms. I have found that the provided antiskate (AS) adjustment is not sufficient, especially for the heavy, low compliant cartridges and the Lofgren A alignment in favor today. I had to remove the black adjustment knob. You can see the details on the Vinyl Engine website Forum. When this arm was released, cartridges with low mass, low tracking force, Stevenson alignment and very high compliance were the rage. The Grace cartridges were highly recommended. The MA-505 can accommodate heavier, low compliant cartridges very well. But you will need to add weight near the headshell.
 
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