Eminent Technology ET-2 Tonearm Owners

Ct0517: Regarding my arm and for which pressure it was designed.... I found a receipt stating "high pressure manifold", remember, this was way back when this option was first introduced. This and the fact that I am getting optimum sound from exactly 18.5psi, to me, confirms the fact that what I'm hearing correlates to this discussion.
Again, FWIW.

Wow, when I post, I post!

If this has been addressed in the past, I apologize... I notice some choose to "hang or mount" their counterweights from the top of the I-beam. I choose to hang mine from the bottom.
In the past, (a long time ago), I A-B'd these settings and preferred the way I do it. From my logical standpoint, I would think hanging the counterweights below the center of gravity, from the spindle's point of view, would be the preferred method. Any takers?

Well, it's 2:20 EST and no response.

My last post. I feel if we aren't referencing a specific lp, how in the heck can we continue to go on as if there is something else as our reference?

We can go on and on about this and that but in the end we come back to the music. I'm feeling that this is what some may be afraid of?

Dover.
I quote directly from your post of 03-13-13

*********On an eccentric record the acceleration will be the same for each arm –
0.0024metres / (1.8 sec x 1.8sec) = 0.00074 metres per second squared

The horizontal effective masses of the 3 arms mentioned in this thread are:

Kuzma has been quoted as 100g
Terminator 80g
ET2 25g

The force on the cantilever is as follows:

Kuzma = 0.1kg x 0.00074m/s2 = 0.000074 Newtons
Terminator = 0.08kg x 0.00074 m/s2 = 0.000059 Newtons
ET2 = 0.025kg x 0.00074 m/s2 = 0.000018 Newtons

Summarising then you can see that the increased mass of the Terminator and Kuzma arms increase the lateral forces on the cantilever by 300-400% over the ET2.

Now Krebs has modified his ET2 by adding 30gm of lead to the spindle. This adds 30g to the effective mass of the "ET2. Krebs also couples the counterweight ( no spring ) which adds another 30g to the horizontal effective mass.

So Krebs has increased the horizontal mass of the original ET2 from 0.025kg to 0.085kg.
The Krebs modifications have increased the lateral forces on the cantilever by over 300%**********

Dover
You stated in this post that the ET2's effective mass as seen by the cartridge WHEN TRACING AN ECCENTRIC RECORD was 25 gms.

This is not true. The effective mass of an ET2 below FR is the total mass of the arm including the weight of the counterweight. Depending upon cartridge and wand used this will be in the order of 75 to 95 gm. I say again, the leaf spring does not flex due to the action of tracing an eccentric record, so it does not lower the effective mass at these frequencies. The lateral forces imposed on my cartridge due to tracing an eccentric record are much the same as those imposed on a cartridge mounted in a standard ET2, Terminator and Kuzma. If the cantilever is flexing when tracing an eccentric record in my set up it is by definition flexing with a standard ET2 as well.

I am sure that others are finding this line of discussion tedious and for that I apologise.

Slaw.

Thanks for the info. I will take a look at M-30 M-60. Does this have an air bleed as well? I am already using a combination 3 micron filter and water trap.

Richardkrebs,
You are wrong. You continue to put up an argument for adding lots of mass to the ET2 and removing the patented decoupling methodology of the counterweight. Your argument is based on a strawman hypothesis that only focuses of frequencies below FR. Bruce Thigpens exhaustive testing does not support your view. You continue to ignore what is happening above FR when the decoupling reduces the horizontal mass, and your horizontal effective mass is 300% higher than a standard ET2 ABOVE FR.

You claim that 300% higher horizontal mass above FR ( ABOVE FR ) and removing the decoupling is of no consequence. Bruce Thigpens testing that he has documented on his website clearly shows that you are wrong and the problems of increased resonance when the counterweight decoupling is removed are documented.

Your claim that high horizontal mass has no consequence suggests that Shure, Ortofon, David Fletcher ( of Sumiko ), Alisdair Aitken ( SME ), Bruce Thigpen and virtually every tonearm and cartridge manufacturer has got it wrong. Record grooves are cut at 45 degrees, both vertical and horizontal mass matter. You cannot increase horizontal mass ( ABOVE FR ) by 300% and expect no change.

In this thread Dgarretson has reduced the horizontal effective mass of his Terminator and yielded significant improvements in speed and resolution. Frogman has further decoupled his counterweight and yielded significant improvements in speed and resolution, more bass notes he says. I have tested fixed and decoupled counterweights some 30 years ago when the ET2 replaced the ET1, and yielded significant improvements with the decoupled counterweight even with very low compliance cartridges.

Bruce Thigpen has documented the problems of high horizontal mass as have Shure with their white papers on tracking.

None of your claims that a rigid counterweight and increased mass are supported by proper documented testing. Your argument is entirely based on theory, and it is flawed. Your maths that you quote continues to ignore the fact that the decoupled counterweight splits the fundamental resonant peak into 2 smaller peaks ( as demonstrated in the Stereophile review and Bruce Thigpens testing ) that has benefits of lowering distortion in the audible spectrum ( ABOVE FR ). You have used mathematical arguments that are not fully representative of the cartridge/arm resonant and tracking behaviour and are taken out of context.

I would suggest that you should buy a Kuzma arm which has been designed from the outset with a high Horizontal mass and has a fixed counterweight if you wish to throw away the advantages of the ET2 with its design goals of maintaining as low a mass as possible and minimising resonant peaks in the ultra low bass & minimising tracking distortion through the employment of the patented decoupled counterweight system.