[dlaloum]

Another question....

If this was a "normal" undamped 10" arm.... ie mid-high mass - the optimal cartridge compliance for the beast would be circa 10.... (eg: DL103)
With some variability and adjustability using heavier/lighter headshells.

But this is in fact a servo damped arm - and more than that it comes from the period when high compliance cartridges were very much the norm.... The cartridge that came new with the table had a compliance of between 15 and 18.... ie a mid compliance cartridge, but higher than optimal for an arm of that mass....

And of course this was the heyday of the V15 ... compliance 25, the AT12Sa 27, OM30 - 25

Seems like the table should be fine with higher compliances....

What cartridges do people find work well with these arms? - What compliances?

My focus is MM & MI cartridges (although I also have a couple of HO MC's)

In my current stable, the Jockeys include (well the arm is the horse isn't it!):

Shure 1000e / SAS  comp 22 + shure damper brush
AT440MLa Comp 18 (close match to original OEM cartridge compliance)
Signet TK6Ep with ATN440MLa stylus (p-mount signet)
AT12Sa - comp 27
Empire 999e/x comp 25
Ortofon OMP20 comp 25
Ortofon OM20 comp 25
Ortofon OM/OMP with Digitrac 300SE stylus - comp 25
Ortofon 320u - comp 25
ADC Integra with super XLM shibata - comp 40
Sony XL-MC104 - comp 20
Benz\Empire MC1 - comp 15?

- The high compliance theme is due to the Low mass tonearm on my other table (4g)

I will experiment throughout the repertoir over time... but where would it be best to start?

thanks

David

[Wayner]

I am the official AT440MLa pimp here at AC and for the money, is a stellar performer. It tracks well, is tolerant of arms out of it's compliance compatibility and has a fine line (shibata) style stylus. Pricing is all over hell, from $100 on Amazon to $200 at Music Direct.

My 2 cents.

Wayner

[dlaloum]

I was hunting for a stylus for my Signet TK6Ep.... and worked out with the help of forums like this one, that the AT102 p-mount family (of which the signet was probably the TOTL) shared the stylus mounting with the AT120/130/140/150 family....

This in turn led me to either a 150 or a 440 stylus.... and Until I know for sure whether I prefer the sound of the AT over the Shure (or vice versa) the 150 pricing was just too much. (The Amazon deal is not available to those of us outside of North America.... so I got to pay $30 extra in addition to the shipping for the priviledge of living in the Antipodes.... - still a lot cheaper than the local prices I could find)

As a bonus I got an AT440Mla cartridge body.... so I can compare the two bodies/generators/mounts with identical styli...

On the JVC all options are available - on the Revox I am sticking to P-mount for now...

The 440 needle is still brand new, virginal.... mounted on the Signet, ready for a ride....

The JVC received its spike feet today - forgot to pick up some bluetack so things are a little slidey what with the metal spike cups on the wood veneer.... should be ready to have a listen to the refurbished TT tomorrow... probably with the Signet TK6Ep/440Mla mounted!

thanks & bye for now

David

LATE NIGHT UPDATE... 1:30am...

Got the table on its tipitoes - got things connected up... put a black disckey thingy on the round silver thingy to spin.....

But now I am getting a weird "vibrato" effect.

Any ideas what might cause this?

Table spins - quartz lock speed light comes on... so theoretically it shouldn't be a speed issue..

the table still has a bit of movement in it (sorbothane hemispheres) - when the table moves (gets pushed a touch) the vibrato gets worse.....

Is it a mistake to put one of these on spikes? are they better of on Squidgy feet?

In any case there should not be such a strong "vibrato" regardless of the feet!

Would plasticine in the wrong place possibly cause this? (is it time to open her up and make sure there's no plasticine too close to the motor?)

damn - and I thought I would have a quick listen before bed..... I guess there's more to keep me from getting bored tomorrow.

[neobop]

David,
Kind of lost track of this thread. I figured you already had help from experienced JVC modders. What kind of spikes do you have? 6mm thread? Ready made cones, sharpened bolts? You've just entered my area of expertise. I put spikes on all my TTs. Even have tiptoes for my Sota.

The vibrato you're getting probably is from the feet/support. IMO There should no possibility for movement. But results are dependant on the shelf, stand or whatever supports the whole thing. I shun the use of any damping between the feet and the mass of the deck. If done properly, spikes will dissipate energy from the deck to the supporting shelf. Damping between the spikes and deck, defeats the effectiveness. This is mass coupling. It is the shelf or support underneath that sometimes has to be decoupled.

Ready made cones with short bolts usually have to be threaded all the way in or they will wobble. This defeats levelling opportunity, but it's necessary. If you're using metal discs as furniture savers, this is where you level by substituting ones of different thickness. I've started buying bolts of appropriate length and grinding down the head to make a spike. With these spikes you use a jam nut. This works out really well. On My Denon 1250 the bottom panel has a space around where the foot threads in. The jam nut fits perfectly in this space and results in zero wobble. Your JVC looks like it might be the same.
neo

[TheChairGuy]

But now I am getting a weird "vibrato" effect.

Any ideas what might cause this?

Table spins - quartz lock speed light comes on... so theoretically it shouldn't be a speed issue..

the table still has a bit of movement in it (sorbothane hemispheres) - when the table moves (gets pushed a touch) the vibrato gets worse.....

Is it a mistake to put one of these on spikes? are they better of on Squidgy feet?

In any case there should not be such a strong "vibrato" regardless of the feet!

Would plasticine in the wrong place possibly cause this? (is it time to open her up and make sure there's no plasticine too close to the motor?)

damn - and I thought I would have a quick listen before bed..... I guess there's more to keep me from getting bored tomorrow.

It's feedback - 98% likely.

Hard feet must be avoided....its sending energy back into the deck and that wallowy bottom board is acting like a moving speaker cone amplifying matters.

Nope, doubt you did anything wrong with the clay.  I think when you put squishy type feet back on, you'll see the vibrato greatly abated.

The trick on this deck is to get that feedback down....then the TT shines. It is a HORRIBLE problem, however, and takes some care to dial out.  Search for my topic on the JVC QL-Y66F here at AC a couple years ago and you'll save some time hunting for answers on the 'vibrato' you're hearing.

John

[neobop]

Difference of opinion here. The stock feet are probably squishy to some extent, so why not use them?

By all means, damp the bottom board. Also one of the benefits of the clay is filling the space inside so you don't have a big hollow cavity. The added mass is a benefit and makes the structure more solid/stable. But this doesn't seem like feedback. Hard to tell without actually hearing it, but it's probably the result of wobbly set-up - the whole plinth is moving, unstable. Feedback will make it howl if you turn it up. Regardless, using squishy feet is a band aid approach that results in squishy sound. You'll just have damped movement. There's a time to damp, and a time to couple or decouple. If spikes are solid, stable, you'll get much better results IMO, provided your platform or shelf is done right. As I said, energy is dissipated down the spikes. They are very inefficient transmitting energy up. But the underlying platform becomes more critical. Please don't compare wobbly spikes to squishy feet.
neo

[Wayner]

Let's discuss feet a bit more. Spikes are not diodes. They will transfer energy equally in both directions. To prove this, take a philips screw driver and put the tip on your furnace while it is running and then place your forehead on the end of the screw driver. You will feel every vibration of the furnace, conducted thru the screw driver. Maybe this is a slightly goofy example, but my home furnace was running and to prove a point to myself, I tried it and I could feel vibrations. While the cones make the table seem heavier (in pounds per square inch), They are ineffective, unless, as neo pointed out, the base that they sit on is massive.

That's why I, Technics, Sony and others lean towards the squisshy feet. They simply stop energy transfer. The Plasticlay will absorb any TT born energy and turn it into heat, the squishy feet will stop any energy transfer from the resting surface of the TT.

Wayner

[dlaloum]

OK.... I now have two apparently differing opinions both pointing at the same problem...

My floor is suspended woodconstruction.... and that is whereapun the tables must stand.

I have 4 lack tables - two set up as tables and two legless as platforms

Bottom is a platform on spikes, then table on spikes, followed by platform on spikes followed by table on sorbothane hemispheres.

The JVC is at the top, and the revox is in the middle.

DIAGRAM



    == JVC TT ===
    V large spikes V
====== Lack Table======
I                                    I
I                                    I
o        Sorbothane Domes  o
     Revox TT (suspended)
====== PLATFORM ======
v  small spikes                 v
====== Lack Table======
I                                    I
I                                    I
V small tall spikes             V
====== PLATFORM ======
V  small tall spikes            V




All the spikes are monacor, 2 sets of monacor small tall spikes (bottom platform, table), one set of monacor small spikes (middle platform), one set of large spikes (replacing the JVC feet on the table)

The Feet under the JVC are extended to the max to allow my phono pre to slide in under the table (only spot for it as I have shortened the cables to reduce capacitance). I need 5.5 cm (roughly 2" and a bit) for the phono pre.

The original feet, fully extended, were too short for the phono pre.

I think today's experiment may begin with moving the top Lack table with the JVC onto the floor directly (forget spikes/footers) leaving the table on its spikes and trying it out. If the Vibrato is still there - it is the spikes under the table!

Also I have to try with the under table spikes screwed down tight - there is movement in the spikes - and they should be rigid.... so another thing I have to try (if this step resolves it, then I will be out shopping for taller spikes....)

next step after that is possibly removing the Sorbothane Domes from the stack.... (I think?)

I do feel that with a suspended wooden floor, some form of damping is required - but presumable, soft squidgy is wrong for this table? (ie it needs to be firm?)
Turning it into a "suspended" table not an option?

I also have some ball bearing feet coming soon - when they arrive I will have a form of damping available that doesn't have "springing".

I'm still not clear as to what is optimal for this table - springy or rigid support? - and if springy then how springy?

[TheChairGuy]

I have always had solid supports for my non-suspended tables.

Almost all of them have sounded best with spikes from their bottom pointing straight down into a 3.5" maple butcher block.  Under that was the rack shelving (usually mdf)

Like neobop, I'm a fan of hard points under non-suspended decks....then draining into the maple block.

However, and this is a BIGGIE, the JVC QL-Y66F had tremors (I think that's the vibrato you hear) set up this way due to feedback issues

The biggest issue is the flappy bottom board - with hard feet / spikes, feedback energies that would normally drain into some soft squishy feet (like those that came with the table) are AMPLIFIED back into the deck and make the feedback issue worse.

You can see for yourself.  Take the floppy bottom board off and put spikes in the corners still left and see the difference in sound.

What I eventually came to prefer was, right under the table, some solid brass discs (the little cups that protect wood floors from spikes harm) and under that some silicone footers from Herbies.  That combo seemed to give the right combination of firm for best sound and allowed the feedback to be drained away.

You will see in my QL-Y66F topic a couple years ago...I damped the bottom cover with viscoelastic / rubberized spray, too.  This helped in addition to the jiggling legs.

I also found the combination of Vibrapod sitting on the maple table...with the vibrapod cone sitting on top of that (with the stainless steel ball of the cone under the JVC) was also a very good combination (and inexpensive)

So, soft beats hard under your JVC...but some workable combination of hard and soft under that table seems to work best. 

I live in a one-story house and as they have no basements, the floors are rather solid as the slab foundations aren't too far below the the floor of my listening room. Some additional care needs to likely be made to your jouncy floors there.

Regards, John 

[neobop]

I've lived with wood floors almost my whole life. From the get-go - wall brackets are the way to go. There was a big discussion about this some months ago. Bolt 20" brackets into the studs and lay a rigid board (shelf) across. Works like magic. Concrete floors are a whole other ballgame. If you could put up a bracket, maybe the shelf could be deep enough to accommodate the phono pre behind it.

Sometimes you can't put up a shelf. The spike/tower looks hairy, but could work with some modification. Spikes will not transmit energy equally in both directions for one reason. The mass of the TT. The more mass, the better it is. Touch a tuning fork to a block of granite and see what happens. It's surprising how much 6 lbs of clay helps you out here (good one John). I also think that braces inside a wood frame deck are a big help. Steel or aluminum is best for this, but wood braces, like inside a speaker cab, help enormously. This will stop the plinth from shaking.

I have one room where I can't put up a wall shelf. I've finally worked out a solution. I use a solid cherry wood end table on spikes. I use these spikes to level the table. They're screwed in as far as possible for that - the table shouldn't wobble. On top of the table, there's a wood platform that sits on cones, points up. This decouples the platform from the structure. The deck sits on that.
  ___  deck___
_v__________v____platform
__^_________^___end table
    l              l
    l              l
    l              l
    v             v 

Maybe 70mm sharpened bolts wold accommodate the pre? A large platform might do the same, without the long spikes.
neo

Edit: I just want to add - if you use a brace(s), having contact between 2 sides and the underside of the top, helps doubly. I recently added a brace like this to a cheap speaker that I modified. The brace went between the 2 sides and the inside of the baffle. Results were dramatic. I think it's probably the top of the plinth that's transmitting most of the offending energy. Cut your brace so it fits really tight, then glue it in.

Here's a great place to get hardware - all kinds of stuff. Even 2.5mm cart screws.
http://www.mcmaster.com/#metric-set-screws/=anpf4u

[dlaloum]

Good news.....

the simple act of shortening the spikes/cones and screwing them tight onto the base eliminated the Vibrato...

Just listened to Fantasia on there with Signet/440MLa - sounding good. (phew.... no need to panic)

now I can take the time to absorb the plethora of advice, and work out where to next....

I Do notice that the spiked TT is far more sensitive to any contact on the supporting table

I definitely seem to need some form of springing / sorbothane somewhere.... question remains where and how much. (Wall shelf is not currently an option)

The Lack tables have a great reputation as lightweight damping platforms - they are hollow using a box structure.... some people have filled them with foam - which would give them more mass.

The table is now up to around 13kg (given that I added 2.5kg of modelling clay) I probably have room in there for another 500g at a minimum... and maybe as much as another Kg...

Right now my squidgy layer is 2" domes.....  I think it is too springy/soft.... and there is insufficient weight on it to bring it to its optimum (20 to 30% compressed) state.... I also have smaller hemispheres as well as 5cm pads 0.5cm thick - the pads would provide a much more controlled lateral motion with springing primarily in the vertical axis, and that springing would be more limited (0.5cm rather than 2.5cm of sorbothane with the current dome)

Alternatively I may just wait for the ball bearing feet (ball bearing between two metal holders - allows micro vibrations to be dissipated through ball movement) - but this is unlikely to help with the lower frequency vibrations.... ie the part of the spectrum where the springy stuff works best.

Neobop - my original thinking was to set up something similar to your diagram, but with either the ball bearings or a fairly firm set of sorbothane feet between table and platform.

More for tomorrow....

bye for now
David

[dlaloum]

Update:

the Sorbothane hemispheres are gone - replaced for now with Sorbothane pads - more dampy less springy - this reduced movement... the Vibrato is definitely gone.

The Cones are bolted tight now - right up against the baseboard - and the phono pre is on the cupboard next to it (very awkwardly perched I must say)

Played a couple of LP's and it is sounding good!

Tried to run my lightest cartridge/headshell (OM20 without additional weight) and the arm would not balance at such a light weight....

Can an alternate counterweight be used ( a lighter one!) ?

This would of course also lighten the entire arm..... good for my high compliance cartridges!

Is the counterweight a standard thread / diameter?

I've worked out that the lightest weight it will balance seems to be around 13.4g (headshell with cartridge mounted)

The OM20 on my lightest headshell can get down to around 8.5g...

With an appropriate counterweight that might shave between 6g and 8g from the tonearm mass.... making it much more appropriate for some of my cartridges.

I also ran F/R (pink noise + FFT RTA analysis) test - and found that the Shure 1000e/SAS had identical behaviour to what it does in my Revox - except below 50Hz... where the Revox provides a flatter more extended Frequency Response (down past 18Hz)... I need to do more testing with the JVC - but the fact that the arm makes a difference to the measured performance in the LF area is interesting.... - I will test it further soon.

bye for now

David

[dlaloum]

Hi Folks,

The JVC has been running well - no small part due to your input.

I mentioned a while back that I was going to try to reduce the effective mass of the tonearm, and was looking at ways to do this.

Ultimately - to keep things simple, it came down to having multiple Counterweights.

Lowest effective mass is achieved by having the counterweight as close as possible to the pivot, and choosing the lightest possible counterweight that can go close in - while balancing the arm.

ie: a lighter counterweight pushed further out to balance a heavier headshell/cartridge results in a higher effective mass than a heavier counterweight closer in.

The default setup of the QL-Y5F, with its 110g counterweight, results in an effective mass (when balanced with a 9g headshell and 5.5g of cartridge/fixings) of around 20g.

I managed to find 2 more counterweights that fit this arm (14mm inner diameter) - one is 89g and the other is 97g.

At the lowest possible mass, I can - with an OM cartridge (2.5g), low mass headshell (5.5g), and the 89g counterweight get the effective mass to somewhere around 13g.

This makes a substantial difference in cartridge matching.

It also opens up new options - previously the arm would not balance with a headshell / cartridge combination weighing less than 13.4g - now I have tested a headshell/cartridge combo weighing 8.7g.

With high compliance cartridges like the OM30 (30cu) this moves me from having a resonant frequency of between 6 & 7 Hz to now having a resonant frequency a touch over 8Hz. Still not a perfect match - but moving from the "problem" zone into the "acceptable" Zone.

For those of you running high compliance (primarily MM / MI) on mid-mass arms, this is a viable solution.
The new counterweights do not match the look of the table - but they do make a difference to its operation. - And I have extended the range of compatible cartridges for this table substantially in the process.

bye for now

David

[neobop]

At the lowest possible mass, I can - with an OM cartridge (2.5g), low mass headshell (5.5g), and the 89g counterweight get the effective mass to somewhere around 13g.

David,
Thanks for posting your results on mass reduction. What a difference!

I do something similar with my 20g arm, although it looks a little crude. I replaced the stock 11.4g headshell with a Technics or another light aluminum one that weigh around 7g. Then I got a car hose clamp and put it around the counterweight. This is a screw on type clamp. I put the screw assembly on the bottom. It's a PIA when setting the VTF, but it weighs around 15g and I get the counterweight as close to the pivots as possible. I figure this reduces eff mass to somewhere around 15/16g. Anyway, now some medium compliance carts like the AT-15SS sound good on there, when I wouldn't even considerate it before. Other slightly higher cu carts like the M20FL Super or a 440ML sound better on a lower mass arm. With the stock headshell it really is best suited for lower compliance carts.

What is that 5.5g headshell? That's really light. Also, what are your thoughts about the effect on mass, of moving the counterweight close to the pivot without mass reduction at the headshell?

neo

 

[Wayner]

The correct way to measure tonearm mass is to remove the counterweight (along with the cartridge) and that is the mass of the tonearm. You have actually added mass to the the tonearm assembly's counterweight which is on the other side of the horizontal pivots, and it has not really changed the mass of the tone arm or the resonance frequency. The measurable mass of the tonearm is the forward weight of it from it's pivot forward. You'd have to use a digital scale to measure the weight of the empty arm.

Wayner

[neobop]

Wayner,
This question came up on another forum. An arm designer said that adding mass to the counterweight will increase eff mass slightly. Moving the counterweight forward will improve moment of inertia. Can't remember about effect on mass, maybe negligible.

Changing mass at the cartridge end will have the most effect on eff mass. Actually weighing an arm w/o counterweight will not yield accurate eff mass. He said that this has to be calculated. I am curious about David's results using a test record.
neo

[Wayner]

Well, according to this article, the method I described is what they (who ever wrote this) said.

http://www.speakerbits.com/speaker-repairs/about-cartridges-choice-of-cartridge/article-26.aspx

As I suspect, there are as many opinions on the correct procedure. I can see it both ways, thinking that additional weight has to affect the resonant frequency in some way, but I can also see how the mass on the back side of the horizontal pivots is null.

Wayner

[dlaloum]

Hi Wayner,

there's a lengthy discussion of tonearm physics at
http://www.vinylengine.com/phpBB2/viewtopic.php?t=24136

I used the discussion to create my own spreadsheet, but then LuckyDog on that forum published a much easier to use version...

Effective Mass has to do with the moment of inertia at the Stylus.

The counterweight has a measurable impact - a heavier counterweight closer to the pivot point will result in lower "Effective Mass" than a lighter counterweight put further out.

So to get a real idea of the EM - requires weighing the counterweight, as well as the headshell, cartridge and bare arm, measuring arm length (pivot to stylus is a critical spec for all arms so that one is usually published!)

Just measuring the arm with headshell and cartridge mounted will give a reasonable approximation - but it requires a bit more maths / physics to get closer to the real figure.
(Whether going that extra mile is worth it to you is a whole different question!)

Having a model that allows estimation of final EM is very useful before buying a cartridge, headshell or stylus.... you will have some idea of how the system would come together.

I intend to verify my efforts using test record measurements - but I am not there yet. (I only got the new CW's fitted yesterday!)

Neobop
The lightweight headshells I have range from 5.5g (Lo-D plastic headshell - weighed without wires... wires add 0.36g, screws another 0.42g), 5.8g for a black plastic (no name on it, also ex wires), the ADC LMG-1 magnesium headshell I have weighs in at 6g, the standard pressed aluminium ones that are quite common tend to be around 6.7/6.8g, standard Technics is around 7.3g. (I spent a bit of time hunting for the lightest possible options - would love to find something even lighter.... )

When trying to match a high compliance cartridge on a "standard" S-Arm (ie not a low mass arm) - every bit of mass counts...

I am trying to find some nylon screws to shave another 0.2g off...
The stainless steel screws weigh substantially more than the aluminium ones (Nagaoka screw sets are good, light aluminium)

My other problem as mentioned earlier - was that although I could get the headshell/cartridge down to 8.7g (OM cartridge with weight removed) - the arm would not balance at that weight as the std CW was too heavy.
With a lighter CW, the 8.7g combo works.
I was hoping to be able to try an Ortofon Concorde on there (6g!!) - but even my new lightest CW (89g) is still to heavy for that, and the original Concorde I have has no overhang adjustment, and the overhang is wrong on my arm. - So it is up on fleabay looking for a new home. 

I previously could not balance my ADC integra either (12.3g) and now I can!

So the main EM reduction gain is at the headshell/cartridge/fittings level (which is measurable using the rule of thumb of arm without CW).
But an ultra light combo simply won't be possible on a lot of arms without a lighter CW.
(I now have 38 redundant CW's does someone want one?)

And a CW which is too light (and therefore ends up further out on the arm to balance the arm) will increase the Effective Mass.... so there is a matter of balancing CW weight/position to get the best result.

Does anyone know of where I could find 70g or 65g CW's with a 14mm inside diameter (same as Technics SL1200...)?
If I can find a slightly later Ortofon Concorde, (with the overhang adjustment - but not the later heavy 15g version) I would still like to give that a try - and to balance that would require a CW lighter than my current lightest. (Current CW's are 110g, 97g, 89g)

I am currently discussing and checking the EM spreadsheet model (which will involve test record measurements - soon) - on the thread linked above.

My most optimistic estimates have moved EM from 18/20g down to 12.7g - which is still too high for my ADC SuperXLM... but great for the Ortofons, ATs, and Shures.

One of the other experiments I plan on doing is to see what difference the JVC's electronic Q damping makes at differing levels - I believe a little bit is essential - but at what level does it become overdamped? - That is unclear....

Although there is a scientific article in a 70's edition of the BAS newsletter that has all the relevant formulae laid out - bit heavy for me!

Bye for now

David

[neobop]

Hi David,
Thanks for refreshing my memory about the MOI/eff mass thing.

Perhaps you have a machine shop somewhere nearby? Maybe a buddy with a lathe? Having all those CWs you could have some modified or even custom made if you need a different inner diameter. I'd probably put a couple to the old grinding wheel and make some sparks. Cosmetics aren't a high priority with me though. If I modify something and it sounds noticeably better, but looks bad, those looks tend to become endearing.

It seems to me there are considerations other than mass when it comes to headshells. I only have one arm with a standard SME type removable headshell, so my collection is small. But with mass reduction, you're often stuck between a rock and a hard place. Light weight ones tend to be less rigid and could sound worse, IMO, than another that's a little heavier. Some people use different types like ceramic, magnesium, carbon fiber etc for different carts, regardless of mass. I wonder how much their subjective evaluations are effected by mass/synergy. I'd think that could work both ways too. At what price mass reduction?

You seem to have some impressive results in that area. I don't doubt your ability to optimise a parameter like that, but I do wonder about your feelings concerning the sound quality of some of the lightest shells. I would tend to take the easy way out and try a less compliant cart.

I almost forgot. I know they're not nearby, but nylon screws are here- you might have to buy 50 or so in one size, but they're not that expensive - You'll have to check size available. They might only have M2 or M3 and not M2.5 in a particular style/material.
http://www.mcmaster.com/#metric-machine-screws/=batlcw

neo

[dlaloum]

Hi Neo

totally agree about the Headshell potential impact on sound - separate from the mass issues...

But figuring out and understanding the parameters of TT optimisation requires working through the separate variables one at a time.

And at some point I will need to work through a series of identical weight headshells of differing materials and designs to see what the difference is.

There is more to headshell selection - the issue there being micro vibrations, vibrational damping and transmission.... Investigating that would also involve looking into the impact of different shimms/dampers, damping treatments on the arm, (blob of pasticine on the arm?) etc...

Vibrational energy transmission is facilitated at interfaces between materials of similar density - and there tends to be more reflection of energy between materials of differing density.... Then there is damping properties of materials - and in that area, plastic (plexiglass, acrylic) has very good damping properties - which is why some platters & plinths use it in their construction... differing woods absorb/reflect/refract vibrations in different ways - and hence the benefits of either wooden cartridge bodies, or wooden shimms between cartridge and headshell.

As you say - I have also read many reports of differing sound caused by headshell changes. But no one I have read has actually tried to identify or quantify how those changes occur and why. - Which (AGAIN  ) means headshell experiments are done as a stab in the dark.... - so how can one tell what headshell will provide optimum results for a given cartridge/arm/table combination?
And I definitely include arm and table in that set of variables, as when talking about Vibrational energy we have to talk about the entire system - possibly including stand too...

I am considering this side of things - but right now, my first objective was simpler - enable me to balance the arm with the integrated headshell (tick), and preferably allow a reduction in arm effective mass (tick).

Latest review of my calculations show I was being optimistic - my gains are probably circa 4g reduction in arm mass.

In reality what I've achieved is extending the arm's flexibility in terms of lightest to heaviest range available.

I will report results in terms of sound in the near future - and post samples (inspired by DaveyW's efforts)

Bye for now

David

P.S. was hoping to pick them up locally (nylon screws).... not worth a huge effort for 0.2g...