variable mass tonearm

Bibio

Member
2009-03-08 3:36 am
would a tonearm become a variable mass tonearm if one were to cut a slot in an arm tube and fit a weight inside the arm tube with a bolt holding it in position so one could slide the weight up and down the arm tube?

my reckoning is that sliding the weight up towards the yoke would allow for heavier cartridges while sliding it towards the headshell would allow for lighter cartridges.

or am I being stupid again.. lol
 

prairieboy

Member
Paid Member
2010-11-22 2:31 am
The SME series III allowed for variable mass by adding, or subtracting, lead weights in the counter weight. They were added to the front of the assembly, with the remaining space in the counter weight assembly filled by 'hollow' plastic spacers.

So, I'd say you aren't being stupid at all, just perhaps didn't have the best way to do it.
 

Bibio

Member
2009-03-08 3:36 am
ok further to my silly idea. how about the same weight but used as the VTF. so you would attach the cartridge then balance the arm with the sliding arm tube weight at the back of the arm but use the stub weight to balance. once balanced then slide the arm tube weight to desired VTF. that way the armtube would always be the correct mass for the cartridge.

i suppose working out the correct weight for the internal balance weight would be the headache.
 

Bibio

Member
2009-03-08 3:36 am
Mayware Formula 4 arms had a sliding weight which made the equivalent mass adjustable. Hit images.google.com and you'll see how they did it.

yes same idea but mine would be internal so i guess it would work :)

The SME III with high compliant MM vintage classics such as Grace F-9 sounds absolutely fabulous ;)

do they
tbh, i'm not a lover of S shaped arms
 

ChrisG139

Member
2012-03-08 5:39 pm
The Funk Firm's F6 has a similar arrangement to the Mayware -the cylindrical weight can be moved up and down the arm tube. Not sure why you would want to mess around with this though. There are many other variables which are more significant in my view.
Chris
 
Something like this?

Tonearm with sliding weight on armwand, Abis.

Mockingbird-Audio_Abis-SA-1.jpg


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Funk Firm F5 tonearm

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Old school tonearm, Audio Technica AT-1005.

$T2eC16V,!ycFIdRdtTfzBSb7pGzLS!~~60_57.JPG


[IMGDEAD]http://www.retrohifi.co.uk/at1005.gif[/IMGDEAD]
 
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Yes, variable mass tonearms can be build.

However, they are usually not that practical as you might think. It is not easy to build a really low mass tonearm; most tonearms with a removable headshell already have an effective mass of 15g or so. 15g is already considered medium mass and adding to that is most of the time not required (and can be done with a heavier headshell).

Building a 7-8g eff. mass tonearm and make it variable mass would be great, but doesn't exist as far as I know.

Finally, don't forget that the position of the counterweight will also be very different for low mass and high mass tonearms. For the low mass tonearm it will need to be very close to the pivot, which is also difficult mechanically.

Hannes