Eminent Technology ET-2 Tonearm Owners

Thekong

Thanks for sharing your experience. I agree with Fremer.
Thigpen does appear to hold patents on the decoupled counterweight.
Whereas Walker uses a fixed counterweight at 45psi in the Proscenium, Richardkrebs advocates using a fixed counterweight, adding additional lead weights and running a relatively low pressure of only 12psi in his ET2.
In my view his modifications increase inertia and increase the loading on the cantilever suspension when side forces from eccentric records are presented to the stylus. He employs no dampening to control this increased mass. Once it moves there is more induced cantilever flex from overshoot. This is way outside Bruce Thigpens original design concept of low mass and decoupled counterweight and should in no way be construed to be an ET2. There is always the risk of cartridge and or record damage with Richardkrebs added mass-low pressure approach.
Richardkrebs advice in a previous post for those concerned about possible cartridge and record damage was, quote

People are free to try, it is entirely their choice. Install an alternate cheap cartridge, play a record you don't like, if you are that worried about damage to same.

This advice is probably about the only thing that Richardkrebs and I could agree on.

very interesting discussion guys.

I am personally going on over 9 years with the ET2’s – never had a problem with a cartridge.

I think I represent a typical music lover – meaning - I own xxxx records. At any one time there are xxx in 4 or 5 rows on the floor against the wall in my room that get cycled.
Now none of them are eccentric enough to cause the spindle to move around like crazy. Most of the time I can barely see any movement in the spindle at all. I’d have to look really hard.

Very interesting discussion on the various air bearings. It should be noted that of the ones mentioned so far , the Kuzma and ET2 I believe are the only two that can be mounted on any TT. There is the Terminator too (it seems from pictures/videos to occupy alot of space on the TT?) Maybe DG can elaborate? Its a BIG DEAL in my book to not be TT dependent. And fwiw - Any tonearm comparisons should be made imo mounted on the same table as this is a hobby about resonances and vibrations.

So I have to ask here - Richard, Dover, Kong, others ..... what kind of records are you guys actually playing that you are so worried about eccentricity of the record ?

I refer back to this post with data from the ET2 manual.

http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1325551242&openflup&372&4#372

Specifically the wording.

This means that any given cartridge works against lower horizontal forces in the Model Two tonearm (.1 gram or less) compared to a conventional arm (.2 grams/gram vtf). These figures apply if you use records that are not severely out of round. If you like to play severely eccentric records, ones with runout of greater than 1/8”, then we suggest you use a low mass pivoted arm.

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Richardkrebs - We went on to talk about potential problems with cantiliver flex. His response was the resonant frequency due to the combination of a typical low compliance cartridge and horizontal effective mass was in the region of 2.5 -3.5 hz.(this has been published by them elsewhere), this is well above the 0.55 or 0.75 hz for 33 or 45 rpm eccentric records. Therefore the cartridge does not "see" this movement.

Richard , so as shown above, Bruce has measured the lower horizontal forces in the Model Two tonearm (.1 gram or less) compared to a conventional arm (.2 grams/gram vtf).

Are you able to get us the actual “lower horizontal force number” in the Kuzma Airline from Mr. Kuzma.

I am very interested in this number – this is where the tire hits the road to me, no ?
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I have to admit something here to everyone as well, since I have been giving the discussions we have had thought.

I really like the fact that the ET2 does not put any constraints on me as far as the type of cartridge I can play, anytime and anywhere.
I can put on a Sonus Blue Gold with a single leaf spring,
• Dynamic Compliance: 50 x 10-6cm/Dyne.
• Tracking Force Range: 1.0 to 1.5 grams.

than switch it over to a triple leaf spring beam with my XV1. Is this flexibility not worth something ?

sorry for the following asterisks but this "IBM dos like" based forum does not allow for bolding and colors.

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Is there another tonearm in existence that allows for the above to occur regardless of cost ?
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btw - If I do find a record I like alot - that is so off centered (runout of greater than 1/8” as Bruce says)
and cannot be replaced. Why not just drill out the center hole and use a heavy weight on it ?

Richard/Dover/Slaw - is this not possible ? You guys have discussed drilling out of holes before....

Cheers

correction last post - I am in my 10th year now with the ET2's. When this thread started it was 9 years. lol.

The ET2 gooseneck – the part that connects the armtube to the spindle is made from Carbon Fibre. I asked Bruce about making one in aluminum. It can be done in a special run if there is enough interest.
I told him I would find out how many are interested. If you have an interest you can contact me at
bcpguy(at)bell(dot)net

Cheers

Dover.
If the cartridge does not have a (damped) spring inside, please explain to us what causes the cantiliver to return to its rest position.

My discourse on resonant frequency IS the whole point, since the resonant frequency is set by the horizintal mass of the arm plus cartridge AND the cartridge's compliance.( plus some other complications around the systems overall rigidity) The system has a resultant resonant frequency which takes into account the stiffness of the cartridge's suspension. Below this resonant frequency the cartridge is able to move the arms weight, start it and stop it, without cantilever deflection. I do not need to talk to cartridge manufacturers to confirm this. Do the math.

Chris, I do not worry at all about playing eccentric records, nor do I worry about hanging my Shelter Harmony on the end of my arm. I have had one cartridge failure in 35 years of this hobby and this was caused by my son using it as a chisel to make a nice tangential groove on a record.( maybe he didn't like my choice in music) The other cartridges have simply faded away after long and fruitful lives.

While making some assumptions around the rigidity of the cantilever, wand and goose neck, my spring/weight analogy is valid.

Right at the start of my involvement in this thread, I said that my arm had been optimised for low compliance carts. Chris, in doing this I have compromised its versitility regarding cartridge selection. High compliance carts are out. Low compliance carts are individually adjusted using different counter weight shim washers.
I made this compromise in the pursuit of sonic performance.