Tonearm Tweak

[jls001]

A (fairly old ) tonearm tweak that's claimed to drastically improve detail retrieval from your gimballed arm:

AudiogoN Forums: Strange Tonearm Tweak. Long

Idea is to add two small lead weights to the axis of vertical bearing so as to increase effective horizontal weight, while keeping the veritcal weight constant and tracking force also unchanged. The increased horizontal weight reduces the tendency of the arm to move (unnecessarily) in the horizontal axis. The principle seems to be similar to using fluid-filled damping troughs (think Townshend Rock, but at the arm pivot and not at the headshell).

I would encourage folks to try this mod out. It is cheap, reversible and claimed to produce real results.

PS: this mod is intended for medium to heavy arms using low compliance cartridges. This is not useful for light arms used with high compliance carts.

 

[entsurgeon]

Someone pls make sketches/diagram and explain. Got over my head. Would like to try it. My tonearm though is featherweight- project 9cc carbon fibre. With 2m red I guess this may not b for me. Eh?

 

[jls001]

Someone pls make sketches/diagram and explain. Got over my head. Would like to try it. My tonearm though is featherweight- project 9cc carbon fibre. With 2m red I guess this may not b for me. Eh?

Googlebaba says your arm is low mass arm (as, at 8.5 gms effective mass, it is less than 10 gm - which is the generally accepted cut off mass for low mass arm), but I can't figure out the compliance of your cartridge, but assuming that it will be mid to high compliance. Usual pairing is:

1. low mass arm -- mid to high compliance carts
2. moderate mass arm -- moderate to low compliance carts
3. high mass arm -- low compliance cart

If you fall in category 1 above, this tweak is not for you, as the tweak is basically for overcoming the lateral movements of low compliance cantilevers.

 

[entsurgeon]

Cantilever is in cartridge. Low compliance means lower travel/movt of coil vs magnets. Eh?

 

[sachu888]

Someone pls make sketches/diagram and explain. Got over my head. Would like to try it. My tonearm though is featherweight- project 9cc carbon fibre. With 2m red I guess this may not b for me. Eh?

Hi,
2M read is med to high compliance cart(20 m/mN) suitable for your low mass arm.Ortofon OM 10/20/30 would be more better choice as they have compliance rating of 25 m/mN.
Sonus Blue(discontinued) is another great high compliance cart,(50 m/mN)for your arm.

Regards,
Sachin

 

[jls001]

There is a good explanation of the meaning of cartridge compliance here:

Tonearm/Cartridge Capability

To paraphrase, the tone arm is a "mass" acting on the cartridge. The resistance of the cartridge (or more specifically the resistance of the cantilever part of the cartridge - that little piece of boron or any other exotic material like ruby or sapphire crystals on which the diamond stylus is fixed) to this mass is the "compliance". A "springier" cantilever will have higher compliance, and needs less tracking weight to make it track properly. On the other hand, if the "springiness" is less, it is said to have lower compliance and need more tracking weight to make it faithfully trace the groove. Hope that clears the doubt about compliance and cantilever.

PS: the use of magnet or moving coil doesn't have any relation to the cartridge's compliance (AFAIK. But I could be wrong in my understanding of this esoterica - will be happy to be corrected)

 

[jls001]

Despite using a high compliance cartridge (Shure M97xE) and a high mass arm (3009 Series I non-improved), I just couldn't resist the thought of not trying this tweak. So spent Sunday evening thinking, thinking and thinking how to make this lateral weights. I even went to a few sports shops hoping they'd stock fishing weight. Came back empty handed and thought some more. Finally decided to use the ground pin of electrical connector as that's easily available. So fashioned a means to fix it to the horizontal pivot point of the arm.

Outcome: after rebalancing the arm (as my implementation of the tweak increases slightly the weight of the arm on the arm tube side), audio seems cleaner and detail is a wee bit better. Also discernible is a better defined bass.

Will post pics tomorrow. I have never seen pics of the original tweak on audiogon (and that was for Origin Live Silver arm, I think), so what I had done is probably a bit different from the original recipe but the idea remains the same.

 

[jls001]

Viewed from the side: the angle subtended by the two weights is not equal. That's because I had to grind down the thickness of the black plastic after a test fit. The screw of that goes into the tonearm was quite short and could not go in far enough to hold the black plastic as well as the tonearm's pivot assembly. So rough grind resulted in some awkward angles.




Here's a bird's eye view:


Here's a close-up:


Uploaded with ImageShack.us

Note the angle of the weight. It is pushed up a bit towards the arm tube to avoid it touching the record cueing hydraulic device. Ideally the weight should be on the same plane as the arm tube so as not to disturb vertical mass distribution of the arm.

Further scopes for experimentation:

a) use different weight. I don't know how much is the current weight. I have no way of mesuring it. I thought of fashioning it out of metal, then acrylic, etc, then the idea of using electrical ground pin came to my mind :lol: The original audiogon thread suggested using 12-13 gms weight (lead fishing weights). I don't know for sure but I get a feeling the weight I used is less. Need to figure out how to add more. Will also try using lower weight (live and neutral pins of a 3-pin electrical connector, which are slimmer and shorter than the ground pin, come to mind).

b) reduce the length of the plastic links so as to bunch up the lateral weights closer to the plane of the horizontal pivot.

 

[entsurgeon]

go to any dentist friend who makes artificial dentures. ask him to give you wax from wax plates. these plates are used to package the acrylic teeth set for making dentures. this wax is soft and sticky. will hold weights , could be easily fashioned into newer shapes by bare hands. when removed it wont leave scratches/marks. and different weights could be tried for best results.

 

[issigonis]

go to any dentist friend who makes artificial dentures. ask him to give you wax from wax plates. these plates are used to package the acrylic teeth set for making dentures. this wax is soft and sticky. will hold weights , could be easily fashioned into newer shapes by bare hands. when removed it wont leave scratches/marks. and different weights could be tried for best results.

>>>

An apt example of cross subject fertilisation!
Terrific.

Regards

 

[Dr.Bass]

entsurgeon, your PM Inbox is full. I am trying to contact you but PMs dont go. Please clear your inbox and contact me.

Sorry guys, please carry on

 

[murali_n]

Hi all,

Another method would be to fix balls from bearings, to be fixed using blue tac, or the clay used in modelling (color clays ). In this method the weight can be adjusted by increasing the no of steel balls.

N.Murali

 

[jls001]

I have since increased the weights - added one live-neutral pin of 3-pin plug to each side. It sounded better to my ears with the added weights. Initially, the extra weights were glued (with masking tape) at the same distance as the main weight. Then I moved the extra weights to protrude more from the main weight. This has the same effect as increasing the weight (principle of leverage as discovered by Archimedes a few millenia ago!) After this change (protruding more than main weight) I hear even better detail retrieval, but I am hearing some harshness in the trebles. Will listen some more using familiar records to be sure. Will have to try to figure out the sweet spot.

@murali: can you please explain more about your idea of using ball bearings?

 

[entsurgeon]

@jls, not ball bearings . bearings from the disassembled ball bearing.

 

[omishra]

BTW can we use weights which are used for wheel balancing?

 

[jls001]

BTW can we use weights which are used for wheel balancing?

I think those weights are made of lead. So it may be a good option. Let me try some friendly neighbourhood tyre balancing shop if they will sell me some. Even the fishing weights which I was initially searching for are usually made of lead. Only caveat here is one must be careful while handling lead (being poisonous). Also, it will need quite a bit of reshaping, drilling appropriate sized holes to fix it to the arm, etc. May be a project for next weekend. This week I am going to force myself to complete the Hypnotoad.

 

[jls001]

@jls, not ball bearings . bearings from the disassembled ball bearing.

The cylindrical bearings may work if we can figure out a way to affix it.

 

[Finyl Vinyl]

Pretty interesting.

Questions: How much did you have to increase the dial of your pitch control. I'm sure that you will need additional torque to drive the stylus through a groove. Could this be the reason for the harshness?

Suggestion: Fishing weights tend to be ungainly. Why don't you use soldering lead with fishing line dipped into it just before cooling? You can add or subtract as you desire. I used some of it to add extra weight to a shaving razor.