Adding mass to a tonearm. Best principles?

[stevec67]

Let's keep it simple.
where do I add the weight.

As I said earlier, add it at the headshell. Balance it up with the counterweight. All this effective mass stuff is about not letting the tail wag the dog. A high compl iance cart (=floppy) can go on a drinking straw and won't flop about. A low compliance (stiff) cartridge needs something solid on it or it will be able to do its own thing.

Now imagine I am trying to restrain your arm with say a broomstick. So I strap it to your arm and it stops you waving your arm about. The other end sits on the ground. Now then, is this broomstick going to be more effective if I add a weight, say a breezeblock, at the end by your arm or by the bottom end, next to the ground? There's your answer.

 

[Rockmeister]

Sometimes it pays to be thick. Good breezeblock metaphore. Got it now

 

[misterdog]

PTFE tape to prevent marking/adhesion.

Self adhesive lead strip for window glazing.

Self amalgamating silicone tape stretched over to secure and remove any resonance.

Weigh lead tape, apply on 1/2/3 points along arm length.

Blu tack for short term trial to prove effectiveness of theory.

 

[Jim Audiomisc]

An eighth of an ounce in fact...

Ounce?! You'll be talking scruples and pecks, next. 8-]

 

[chartz]

Weren't we just here yesterday, Jacques?

Too low and the possibility of oscillations/mistracking on warped/rippled records; too high and lowest recorded frequencies boosted, perhaps inaudibly, but wasteful of amplifier power, and possibly leading to driver damage at high levels.

Yes we were! BUT I can't see any cone flapping with regular low power drivers. You might think this has to do with my using QUAD amplification? But WAIT, no, my Technics SU-A4/SE-A3 have no capacitors—and therefore can let DC out, and no flapping either.
Still no explanation then? Perhaps the 600,000 ctS damping fluid (recommended by TT Basics) in the trough does that, I don't know.
But hey, the mucic flows nicely anyway.

 

[fried]

Ounce?! You'll be talking scruples and pecks, next. 8-]

Or 9 bars.

 

[sq225917]

A proper metal head shell weight, between cart and head shell, is the way to go. Make sure it's perfectly flat.

 

[Craig B]

Yes we were! BUT I can't see any cone flapping with regular low power drivers. You might think this has to do with my using QUAD amplification? But WAIT, no, my Technics SU-A4/SE-A3 have no capacitors—and therefore can let DC out, and no flapping either.
Still no explanation then? Perhaps the 600,000 ctS damping fluid (recommended by TT Basics) in the trough does that, I don't know.
But hey, the mucic flows nicely anyway.

Just to be clear, I wasn't suggesting that your particular tonearm/cartridge resonant frequency case must necessarily be causing a problem.

Hydraulic damping does indeed make a massive difference wrt resonant peak amplitude, and, therefore eliminating any negative affects of same, though.

 

[Craig B]

A proper metal head shell weight, between cart and head shell, is the way to go. Make sure it's perfectly flat.

Agreed, and credit to @moffer in post #15.

These are beautifully turned out (4.4g) and stack well...

 

[stevec67]

I got a free weight like that with my xenon dl110.

 

[Mike Reed]

As I said earlier, add it at the headshell

A proper metal head shell weight, between cart and head shell, is the way to go

Okay, putting all the above info. in this thread into practical use, adding weight to the headshell to achieve more eff. mass to suit a specific cart. is as effective as getting another arm designed and made at that weight; yes or no in purely practical terms (forget costs etc.) ?

This is not hypothetical as I find myself in exactly that position but this thread has made me think.

 

[misterdog]

Simple way to add/subtract a small amount of weight is to use different mounting screws.

https://www.sound-smith.com/accessories/ez-mount-cartridge-screws

 

[Alex S]

We had that a page back. It’s such a good idea I’ve ‘liked’ it again.

 

[sq225917]

There's no easier way than the headshell plate/weight.

 

[Alex S]

Well different screws are since you don’t even need to change VTA.

 

[Craig B]

Personally, I'd rather the business end of my tonearms not look like medieval thumbscrews.

 

[stevec67]

Okay, putting all the above info. in this thread into practical use, adding weight to the headshell to achieve more eff. mass to suit a specific cart. is as effective as getting another arm designed and made at that weight; yes or no in purely practical terms (forget costs etc.) ?

This is not hypothetical as I find myself in exactly that position but this thread has made me think.

Yes, all things being equal. But they're not.

a new arm will have different characteristics. It's a different design.

The only way I can think of adding effective mass to an arm without DIY and without using another design is to swap a fixed headshell SME 3009 for a removable headshell version. They sound identical but the removable HS version is heavier (the collar) so better with MCs.
However it really is as simple as adding metal to the headshell end. Do this any way you like, or use blu tak, washers, screws and nuts, whatever.

 

[Mike Reed]

Personally, I'd rather the business end of my tonearms not look like medieval thumbscrews.

Should help with those torture tracks though.

new arm will have different characteristics. It's a different design.

Well, of course. Maybe I should explain in detail. My 12" PU7 is happy with my Proteus and, when I had it mounted on that arm, so was my Urushi. The Koetsu wasn't as happy on my 12" Ace Anna unipivot; possibly (?) because of format synergy. I'd like to re-mount my Urushi after lying idle for 2 years+ on the unipivot just to assess it, having got used to the Transfig., which has been digitally checked out to be pretty well set up, and sounds it!

Both arms are around 14g eff. mass, which is as near as N.A. and Johnnie of A.O. can guess. If I can add that 5 or 6 g to the Ace Anna, it should at least be a better match, so I'm not really worried about aesthetics. I was contemplating a heavier arm (another unipivot but at 19g), which would be a hefty investment, because I might swap out my K. for another low compliance jobbie.

Someone here is going to say "change cart's round" or simply "take the Proteus off for a rest and put the K on the gimballed arm" but setting up cart's (even with my Dr. Feickert) is very tricky for me, esp on my rear (unipivot) arm because of eyesight, along with dotage. Answers on a postcard?

I like the heavy screw idea, but they'd need to be around 3 g each ! Is that possible?

 

[stevec67]

So try the K on the Notts arm and add a weight under the cart, as seen earlier. Then if you no likey the PU7 goes back on. That's minimal changing around.

 

[Craig B]

Depending upon length, stainless M2.5 thumb screws will be circa 3g each. Rather than pay $40. to an outfit like Soundsmith, any industrial fastener shop can provide these on the cheap.

Come to think of it, I've never been asked to pay more than $2 for a couple of fasteners from any of the shops round here.

P.S. Best to check screw size/length and thread pitch carefully; especially so, for cartridges with threaded mounting holes (Proteus?). And ask for matching nuts; they always like it when you ask for those.