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Eminent Technology ET-2 Tonearm Owners


Where are you? What mods have you done ?

I have been using these ET2's for over 9 years now.
I am still figuring them out and learning from them. They can be modified in so many ways. Bruce Thigpen laid down the GENIUS behind this tonearm over 20 years ago. Some of you have owned them for over 20 years !

Tell us your secrets.

New owners – what questions do you have ?

We may even be able to coax Bruce to post here. :^)

There are so many modifications that can be done.

Dressing of the wire with this arm is critical to get optimum sonics along with proper counterweight setup.

Let me start it off.

Please tell us what you have found to be the best wire for the ET-2 tonearm ? One that is pliable/doesn’t crink or curl. Whats the best way of dressing it so it doesn’t impact the arm. Through the spindle - Over the manifold - Below manifold ? What have you come up with ?
ct0517
dover
2,303 posts
 
12-09-13: Richardkrebs
Depending upon the counterweights used and the weight of the cartridge, this total can approach 100 grams. The same ball park as my arm.
You have stated in earlier posts that you added 30g of lead to your ET2 plus lead to the headshell and replaced the original plastic counterweight beam with an M10 threaded rod. You have strongly advocated adding more mass to the ET2.
It is simply not possible to add 30 plus grams of lead and arrive at the same net weight to an unmolested ET2.

With my low compliance Denon 103 weighing 9 gms I could balance the ET2 with 35g at the counterweight giving a total mass of around 79 grams. ( That would be about 43 gms using your maths ).

Re your comments on transmissibility -
03-14-13: Richardkrebs
Shown here is a link to the Math on driven harmonic oscillators, a mathematical representation of an arm/ cartridge assembly. It shows in both formula and graphical terms what I have been trying to say. The Math is a bit of a struggle but fortunately the graphs show the results.

en.wikipedia#Driven_harmonic_oscillators
I have pointed out before, the model you refer to applies to a harmonic oscillator like a pendulum. You are incorrect if you think that this represents a cartridge.

The arm/cartridge/record interface has 2 fulcrum points -
The stylus point around which the cantilever pivots, constrained by the groove.
The cantilever suspension point, about which the cantilever also pivots, but which is partially constrained by the rubber suspension damping.

The forces involved are double ended - you have the groove applying a force to one end of the cantilever via the stylus. The other end of the cantilever has forces being applied from the arm motion.
The 2 forces are not in sync because there is a suspension joint between the cantilever and the arm.

In order to conceptualise this, think of 2 people holding a pipe and each one trying to move it sideways out of sync with the other. That is what the cantilever experiences. It is not a pendulum and it is not a harmonic oscillator.

The Wikipaedia example you have chosen does not apply.

Rather than get lost in fanciful mathematics the bottom line is that the cantilever flexes when faced with an eccentric record, even more so with added lead mass.
I quote Bruce Thigpen directly
the cartridge will "see" .55Hz mounted in any tonearm, more so in one with higher horizontal inertia
I don't think Kuzma means the stylus does not deflect at all at .55Hz, that would defy physics
Postulating that the cantilever does not flex with an eccentric record and that adding mass has no impact defies physics.
ct0517's avatar
ct0517 OP
2,041 posts
 
Hi Richard

" spring cleaning ? "

I wish. its freezing here.
where to put the Christmas tree for best room acoustics in a shared room ?

I am interested in your I Beam testing/findings.

Is your manifold a standard low pressure one ?
If so consider including tests that use just enough PSI to make the spindle float and work as Bruce designed.
I think Dave's recent observations on music presentation when PSI is run higher on a regular LP 2.0, show how much we change change things up with PSI. This will change your findings/results.

I am also interested to know what your and others definition is of a really eccentric record ?

I believe we are all different in what we will tolerate as far as this is concerned.

Wouldn't it be nice if someone came up with a record making machine that could produce holes in vinyl - LIKE A CD.

Looking at the way the groove looks.

http://embrangleroot.files.wordpress.com/2012/08/tumblr_m7ob01afye1qlixleo1_1280.jpg?w=614

Now add an off centered hole to that mess.
richardkrebs
427 posts
 
Chris.
Yes spring has sprung here. BBQ's, Boating, Fishing, and company with great friends watching long sunsets over a glass of wine. I suspect that it was the change in temperature that precipitated the o"ring failure.
I am using a HP manifold at around 18 psi.

HF Dover.
I knew that you would bring up the added weight question inside the spindle. The 30 gm adder was a guess based on 16 year old memory. Clearly my guess was well overstated. I will be removing this when I do the swing arm counterweight test to bring the arm as close to stock as possible. The 95 gm total, arm and cart weight, is accurate. This depending upon c/weights and cart used by others, being more or less the same as a standard ET2 using a mag wand.



For further discussion on how every ET2 on the planet requires the cartridge to push sideways the total arm weight when tracing an eccentric record, please read below....


> Bruce.
> I have been thinking about the horizontal effective mass of your ET2 and have a question please.
> The horizontal effective mass calculation you give in the tech section of the manual shows an arm mass of 30 grams which is then added to the weight of the cartridge to give total horizontal mass. This calculation ignores the weight of the counter weight since it is decoupled via the leaf spring.
>
> My question is around the horizontal effective mass seen by the cartridge when tracing an eccentric record. The resonant frequency of the counterweight spring assembly is 2-5 hz and the lateral tracing frequency of an eccentric record at 33 rpm is 0.55 hz.
> At 0.55 hz the transmissibility would be approaching 1, even with a counter weight spring frequency of 2 hz.
>
> This would therefore mean that the cartridge "sees" all of the counterweight weight when tracing an eccentric record?
> Thus the effective mass at this low frequency, 0.55 hz, would be the total weight of the arm and cartridge including the beam and the weights it is carrying.
>
> Many thanks
>
> Richard.
>
>
Richard,

Below the counterweight decoupling frequency cutoff ~ 2hz, the effective mass becomes the total mass. Then you have another resonance freqeuncy to add to the mix which is typically much greater than .55Hz.
So yes, it sees all of the mass below 2Hz, but the combination of those masses results in a cantilever resonance above that frequency. You should see the arm move back and forth with the eccentricity of a record at .55Hz as opposed to deflection of the stylus.

I hope this helps and thank you very much for the interest.

brucet

john47
50 posts
 
Why do you keep (repeatedly) trying to prove the arm designer wrong?
harold-not-the-barrel
895 posts
 
Chris,
We are children of the revolution, the swirling 1960´s and we "speak" the same language. We have certain respect to our past, and it´s music itself. The super groups we listened when we were kids will be our musical heritage till the end of time.
The turning point for me personally was in 1974 when I used to listen FM radio and I occasionally managed to record some strange and quite extraordinary music to my PHILIPS radiorecorder (at the time I didn´t have a record player !) I captured "Shine on Brightly" by Procol Harum, "Meddle" by Pink Floyd, "Brain Salad Surgery" by ELP and "Starless and Bible Black" by King Crimson on tape. And "Twin Peaks" by Mountain as well, probably the heaviest/fattest bass sound ever put on vinyl. Thanks to Felix Pappalardi, the great late producer, band leader & musician. Of course, we kids listened the pop music too.
But I hadn´t any idea where this all will lead in next year. My dear dad bought me my first stereo system. The finest part of the sale was a bonus, the double album "666" by APHRODITE´S CHILD, would you believe ! Oh yes, the mighty music composed by Vangelis & sung by Demis Roussos who has a very unique and beautiful voice. This stunning music blew this kid´s mind away and never looked back ever since.

But it still took 26 years to find another musical treasure hidden in time, the fantastic Classic Italian Progressive music. In 1973 Alphataurus the Mighty Dove abandoned manking in frustation & anger because of commersializing the music culture. But mankind still has hope as we saw the triumphant return of Alphataurus in 2011 as documented in "Alphataurus Live in Bloom"

http://www.ebay.co.uk/itm/LIVE-IN-BLOOM-ALPHATAURUS-VINYL-NEW-/370760653864?pt=UK_Records&hash=item56530e9c28

And resulting a Renaissance in Prog Music, especially in Italy after all the years ! Another gem:

http://www.btf.it/dvd/prog-exhibition.html

Another thing I regard you as a sir is your TT, The Platine & ET-2. I think it´s a very special combination. In fact, you are running a double air suspension system turntable truly.
This unique and very sophisticated techique you are using proves that you take audio and music VERY seriously and you truly respect the things you love.

Furthermore and as for an extra suspension, I would suggest you to try a Reso-Mat made by Vic himself. IME over the years it is a true bargain in audio. In my system the improvement in audio guality & quantity is really huge.
It´s due to it´s feature that vinyl sits freely and uncompressed on vinyl spikes that allow resonances vanish into air and not bouncing back to vinyl and rearching stylus. Many things in mechanics are simple, also this. It works !

http://www.ebay.co.uk/itm/RESO-MAT-TURNTABLE-PLATTER-MAT-FOR-TECHNICS-SL1200-GARRARD-401-/181111989567?pt=UK_AudioTVElectronics_HomeAudioHiFi_Turntables&hash=item2a2b1da53f

Btw, thaks us showing the way to the record groove, I actually haven´t seen it so clearly before ! What a revelation !

Cheers
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