Eminent Technology ET-2 Tonearm Owners

An interesting set of articles on the ET2 with a little discussion of resonance in tone arms.

http://www.stereophile.com/content/eminent-technology-two-tonearm

I have not thought much about the actual mechanics and physics of turntables and arms but some of what I read does not make much sense to me. Perhaps someone can help me understand better.

Folks talk about "draining" energy to the earth or some other place of stability as if it somehow removes the effect. This does not make sense to me. If a tone arm resonates at some frequency it seems to me that it must be moving. That movement will eventually be damped by some mass, i.e. the movement will become undetectable. The resonance will if no longer being excited die out as the energy is dissipated as heat energy raising the temperature of the resonating part.

The damage from an audible perspective would seem to me to come from the movement. For the cartridge to reproduce what is in the groove it needs to be absolutely fixed relative to the groove. If it moves relative to the groove then that movement becomes part of the electrical signal as there is no way for the cartridge motor to know if the cartridge is moving or the cantilever is moving.

What I think Bruce is saying with his measurement technique is that if you can sense movement in the headshell of a tone arm, which is what you are doing by placing another stylus / arm on the headshell as it plays a record, that movement has to be counterproductive to the faith-full reproduction of the information in the groove.

FROGMAN... you didn't, I will be glad to clarify my statements when needed. I get on my high horse some and I thank you for pulling me back down a notch. I get too passionate about audio as everyone can see.

APbiii - here’s some interesting data on resonances from Reed.

I am sure Bruce probably has files and files of tests as well.

>Resonance Testing

Some more of their research.

Magnetic Damping - and Antiskating
I find it very interesting that pivot arm manufacturers are openly discussing the "possibility" of mechanical noises caused by regular antiskate in pivot arms.

In Reed's owns words.

"This model features magnetic antiskating technology which eliminates the possible noises brought up by the traditional mechanical antiskating."


Magnetic Antiskating & Damping

Since no one has spoke up about the ET2 magnet yet - I will say I have left it on. I guess we need to experiment with how big it can be and not effect things. My magnet is placed on the pedestal where the air bearing spindle exits. My wires now exit the arm tube and go straight down away from the Spindle. I would post a pic but I am not able to yet.
Cheers

DOUBLE LEAF SPRING I-BEAM -
Frogman thank u so much for turning me on to this.
For the small amount of $ we are talking about here I can’t stop myself from telling you guys that you should have Bruce send you:

Two I beams with the factory single leaf spring on them. They are around $15 each.

Plus three leaf springs on the side(loose).

From this you can make one double and one triple leaf spring I Beam to try out.

You probably have a single spring version already.

Have a look at what kind of condition your existing I beam /Spring is in. You may just want to replace it as well. If you have a single spring you should see damping material on the one side that was put on at the factory. This is a folded aluminum shim with inert material similar to silly putty according to Bruce.

I have just assembled a straight double leaf spring super glued together, started listening and really like what I am hearing. Bruce said no damping material is needed with the double spring and he has not tried the triple spring.

Frogman - 3 I beams in the waiting ? Single, double, triple spring versions based on the type of cartridge you want to put on ? Is this a silver bullet or one of them with this tonearm ?

Using the minimal amount of weights as far out to the end of the IBeam as possible.

Magnet in place for damping (thank u Dover)

Cheers