Dual 510 overhang measurment

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Iloveali
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Re: Dual 510 overhang measurment

Post by Iloveali » 01 Feb 2019 14:51

if the plastic gauge isn't around, then use a modern protractor and set to approx 60mm from disc centre - 58mm to 60mm
That's fine but how do I convert the protractor that measures 66mm and 120mm to achieve 58mm?

danmanch
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Re: Dual 510 overhang measurment

Post by danmanch » 01 Feb 2019 15:19

This helped me a lot getting my 510 sleds aligned correctly....

https://www.ebay.com/itm/Pats-Audio-TK- ... :rk:6:pf:0

DSJR
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Re: Dual 510 overhang measurment

Post by DSJR » 01 Feb 2019 20:16

To use 60mm on a gauge, measure the distance from the centre along a line to the 'point' these protractors provide (if 65mm for example) and mark the 60mm position.. Rega arms use 65mm as their null point and Linn/SME today use 60mm in their gauges.

Apologies for not describing it properly. Probably best just to use the printed gauge linked to above.

JaS
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Re: Dual 510 overhang measurment

Post by JaS » 01 Feb 2019 20:24

FWIW the Chpratz Protractor makes it easy to align to any null point from 60 to 150mm

https://www.vinylengine.com/ve_download ... ractor.pdf

Iloveali
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Re: Dual 510 overhang measurment

Post by Iloveali » 01 Feb 2019 21:26

Thanks to both, that's a interesting protractor. I figured out how to make it 60mm on the shure. But to my other question, how do I know where to put the protractor? Prior to adjusting overhang. There's has to only be one right spot.

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Re: Dual 510 overhang measurment

Post by DSJR » 02 Feb 2019 12:16

The protractors I used have a hole that fits over the spindle. the 'hatching marks' are usually big enough to use different distances from the centre of the spindle hole for you to scribe a fine line. There's only one place along that 'line' to mark the 60mm position.

I'll try to take a shot of what I'm talking about (I use a Linn gauge which just happens to use 60mm as SME ones do these days) and post it to my gallery if that's any help, as I don't use a third party image host these days.

As I said, the Dual arms are fixed in place, so no need for 'arcs' or the outer null position as you might need if setting a new tonearm up to a blank arm board. Dual also got the offset angle of the headshell correct too for this tonearm efective length, so the ONLY thing you need to do is to set the overhang which is pretty similar for most cartridges these days I think.

I'm sorry for not being able to explain it more clearly. It's SO damned easy to do and all my stash of cartridges line up in their carriers either half way in the slots or often slightly forward of this position, with one or two nearly fully forward. Remember, this is always an approximation based on an arbitary figure for the inner groove distance on LP records, and we all know how different this is from LP to LP. Standard elliptical styli are pretty damned forgiving I've found and really, the quality of the diamond itself is the most important, as an old coal-like 'nail' as most were in the 70's will sound sh*t irrespective of how carefully set up it is.

Iloveali
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Re: Dual 510 overhang measurment

Post by Iloveali » 17 Feb 2019 13:40

Thanks, i must still be missing something, i have protractor measured out to 60mm. So know my question is where to put the protractor. In theory i can put the protractor in multiple places and still alighn the stylus based on moving cart foward or back. What I'm not getting is where is that ONE spot that the protractor goes to force correct overhang. Is this where you measure up the protractor line coming from spindle with the pivots to spindle measurement. Ex. I don't start setting overhang until the protractor line measures 221mm from pivot?

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Re: Dual 510 overhang measurment

Post by DSJR » 17 Feb 2019 18:09

Protractors usually have a hole in them which fits over the record spindle and there's what I call hatching lines with a mark, sometimes at 65mm or on my old SME protractors I found, at 60mm precisely from disc centre. The rest kind of fits together and there should be a mark to place the stylus while you look to ensure the cartridge is roughly square to these lines. The 510 may be different, but the 12** headshells and certainly the 10** ones are slightly tapered from back to front, so the front of the shall needs to line up, checking the cartridge body each side. I appreciate it's more fiddly than the original Dual gauge and if you can get a 'printed' version of the original gauge on eBay, maybe that's the best way to go in all honesty.

DSJR
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Re: Dual 510 overhang measurment

Post by DSJR » 17 Feb 2019 18:15

Forget the outer, it's of no use to you at all here. Measure 60mm, you have a nice line exactly on that mark I see around three back from the 65mm mark. Get a pin and prick the 60mm line where it bisects the line from disc centre and voila!

Iloveali
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Re: Dual 510 overhang measurment

Post by Iloveali » 17 Feb 2019 23:33

Dsjr- thank you so much for all the effort in your responses, i do greatly appreciate it. I understand all the basic stuff about the protractor. I wasn't explaining my question right, when the protractor spindle hole is affixed to the spindle and 60mm is set, in regards of moving the protractor side to side(away from tonearm, towards tonearm), where is the proper spot. That's what I have always been stumped on.

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Re: Dual 510 overhang measurment

Post by Iloveali » 17 Feb 2019 23:38

20190217_172402.jpg
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So im trying all suggestions to see what results they yield, including this, in lieu of no gauge, i tried to replicate dualcan' s image.

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Re: Dual 510 overhang measurment

Post by DSJR » 18 Feb 2019 10:34

Mountain - molehill - sorry..... It's NOT worth going OCD over I swear :D

You can happily use the 65mm point on your gauge as pictured, I think it's equivalent to 1mm further forward in the slots I remember.

Yep, just checked and adjusted on my 701 for confirmation. 65mm from disc centre is 1mm or so further forward than setting to 60mm - AND IT'S INAUDIBLE!!! I'm using an ADC ZLM right now with a slightly fussy 'swept' elliptical tip that's more sensitive than the standard elliptical in the XLM III Improved model...

Iloveali
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Re: Dual 510 overhang measurment

Post by Iloveali » 18 Feb 2019 15:25

dualcan wrote:
26 Jan 2019 16:06
Hi,
The stylus is aligned on the cart sled TK14 or 24 via the gauge.
In lieu of this gauge, here are the actual measurements of the stylus' position, once aligned:
gallery/image/28633
Regards,
k
Hey dualcan, one last qustion. For the depth measurements in your photo, you have A, B. What one is the correct depth?

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Re: Dual 510 overhang measurment

Post by dualcan » 18 Feb 2019 20:07

Hi,
The gauge gives the minimum stylus distance from cart floor as "a" and maximum as "b". With this tolerance I usually stick to stylus tip/contact just under b.
Keep in mind, this alignment is static and theoretical as the varying disc thicknesses and record warp will come into play. If you use a extra platter mat, it will again affect the angle, and that's the reason for the a/b tolerance on the gauge.
Regards,
k

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Re: Dual 510 overhang measurment

Post by Japi Roelofs » 18 Feb 2019 22:03

I have been following this thread with interest. The one thing Dual manuals don't disclose is the overhang figure. The 'Ebay protractor' that was shown on the previous page seems to have it though. It says it's for a variety of Dual models, that supposedly have the same arm length. I looked at a Test Report from an old German hifi magazine (check the link here — sorry, it's in German) for a Dual 701, that has the same effective length and offset angle as the 510. The overhang figure of 18.9 mm, and spindle to pivot distance of 203.1 mm are mentioned there too. Can we assume they are correct? Who knows... in that same test report it is said that the null points are at 61.5 and 124 mm though. That doesn't correspond with the null points of the Ebay protractor. Interesting...

So let's assume the overhang figure is right. We now have these parameters:

Effective length: 222 mm
Overhang: 18.9 mm
Spindle to pivot: 203.1 mm
Offset angle: 25° 20'

Is it possible to make a custom arc protractor using Conrad Hoffman's program? Let's see...

Regular alignment methods and groove radius sizes all give a different outcome. The only way to make it so that it corresponds with the specs given by Dual is to use Baerwald / Lofgren A alignment, and a set of custom groove radius sizes.

Being the obsessed fool that I am, I worked the numbers and came up with these parameters, to be used in Conrad Hoffman's program:

Spindle to Pivot Distance: 203.1 mm
Inner Groove Radius: 57.643 mm
Outer Groove Radius: 158.885 mm
Alignment method: Lofgren A

The result looks like this:
Dual 510 arc.JPG
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So this is the same protractor as the 'Ebay protractor'. The position of the null points is a little bit different, but we're talking less than a hundredth of a millimeter here. Even more fiddling with the groove radius numbers might correct that. The numbers are weird anyway, especially the Outer Groove Radius which is way out of the actual disc size. What's up with that?

I guess the only way to figure out if it is really correct, is to very accurately measure the spindle to pivot distance yourself. Not an easy task...