Eminent Technology ET-2 Tonearm Owners

03-13-13: Ct0517
The Rockport and Kuzma tubing makes me think of my past experiences with my VPI JMW 12 tonearm. That tonearm’s wires are used as its antiskating method. Their positioning pushes the tonearm back toward the outside.

Could the tubing being in a loop at the centre of the Rockport and Kuzma arm, be acting as a type of dampener for the arms motion in both directions ?

03-18-13 John47
Mr Kuzma replies to MF

[quote]"A question of damping..."
........ There is, in fact, a level of effective damping on the Air Line tonearm. The cantilever suspension, and the air supply tube add damping. Our choice was for either too little or adequate damping; we chose the latter.

John47 - Thanks for confirming my assumptions with the Kuzma.

Dover - My ET 2.5 has the CF armtube and was the one I referenced in my post with the Benz Micro. So many variables here. Plus the specs I listed are for the stock cartridge – it is now a Ruby cantilever SS retip. I have no idea if the specs were changed when it got retipped. Does anyone know what a Ruby cantilever does over the stock Benz Micro one ? The cartridge came with the VPI TNT I bought years ago, and it needed a retip when I purchased it so I never heard it in stock form.

Richard – the triple leaf spring is tight but not 100% tight. It has a tiny bit of flex in it but you need to force it a little. If you hold it by the I Beam and shake it - it doesn't move. Still it is not as stiff as if you stuffed two toothpicks on either side.

Cheers

Re quality factor, Q. ... under, critically or overdamped systems, as they relate to the ET2. My running the arm at 12 psi is no accident. I addressed the Q factor of my arm years ago. And the bearing has no issues at all carrying the extra weight, even at this pressure.

I don't have any proof of this, it is just a recent thought. While higher or lower weight is obviously a factor, I think that the one leaf spring, two leaf spring plus number of weights thing, has probably a whole different set of cause and effect issues. So with reference to a rigid or sprung counterweight beam, it is probably an all or nothing event. In other words because we have the "potential" interaction of the swing frequency of the beam and the resonant frequency of the arm assembly, depending on the number of leaves and the number of lead weights used. It could be that tuning here with springs and weights (and their position) is at least partly to do with sorting this possible frequency interaction rather than just the weight or stiffness employed. Others may have already thought of this but, it is just an idea to put out there for comment.

1986, June as I recall, my first ET.

In '78 whilst studying Engineering at University I learnt a fundamental law of physics.

Q : How do you titillate an ocelot.

A : You oscillate it's tit a lot.

We didn't have Wikipedia in those days.

Hi Dover- ... interesting post. thanks
Wikipedia is ok ...Youtube can be

effective too?

I hate theory so the animation helps me alot; another reason I like posters here on the forum that talk to their direct experiences - not what if this or that.

I am no physicist and I am bad at math to boot. I hate formulae.

Btw – I have found myself the easiest what to find out about physics is to partake in a “hobby” that can kill you if you slip up. You learn really quick.

Ever track a car ......around an oval track that kind of sort of resembles an lp ?

Richard - re your last post.

.....So with reference to a rigid or sprung counterweight beam, it is probably an all or nothing event. In other words because we have the "potential" interaction of the swing frequency of the beam and the resonant frequency of the arm assembly, depending on the number of leaves and the number of lead weights used. It could be that tuning here with springs and weights (and their position) is at least partly to do with sorting this possible frequency interaction rather than just the weight or stiffness employed. Others may have already thought of this but, it is just an idea to put out there for comment.

Would not the rigid solution and the all or nothing event - be only applicable to a one cartridge guy and the specific cartridge cantilever needing to be – really stiff ?

As an end user I feel with the sprung counterweight it allows me to use all of my cartridges. Just a thought.

Also
In your custom ET2 setup – are you able to use higher compliance cartridges if you remove the lead from the spindle ? or are there other factors like a custom manifold involved ? that keep you from using higher compliance cartridges – sonic preferences aside for the moment ?
Cheers