Eminent Technology ET-2 Tonearm Owners

Hey Harry,
I'm glad you appreciate the tweak, and glad I could contribute something to this thread.
John

Hi Harry
got an email from Bruce that my I Beam is in the mail with some leaf springs. This is coming a little too early for me and is making me a little anxious as I am not home except for maybe 5 or so days, over the next 8 weeks. :^(

Have always been amazed when pulling off the I Beam/weights; by the amount of HEFT, there is in the armtube/cart without the I Beam/weights attached . Very heavy. Pulling off the balancing act with just one single weight and an MC cart. Very impressive. Significant vertical inertia happening here. The best bass.

For readers not aware the ET2 was built to go on many different types of turntables. The I Beam was made shorter to accommodate the different tables some of which came with dust covers. Bruce' new I Beam represents the Ideal length based on his testing. Look forward to trying it.
   
Harry - last year I got multiple yellow jacket bites - won't say where - it hurts just thinking about it -   when I tried to put some bolts into exposed holes in a steel roof only to disturb a nest. Felt like jumping at one point.

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Hi Eric (Bdp24)

what are ya'lls opinion of the Trans-Fi Audio Terminator in comparison? Just curious.

IMO. There are more design and build differences between air bearing tonearms, than between pivot tonearms. This is because each air bearing tonearm is very unique in how the air bearing is executed, and its air requirements.

Re; Transfi

Bruce' tonearm uses a captured air bearing. The film of air inside the manifold fully surrounds, encloses the air bearing spindle. 360. My understanding is Transfi is designed more like a sled on snow, a boat on water, as it rides on a film of air and is not enclosed. A very different design. Someone correct me if I am wrong.  

John - yes, yes I was remiss in not giving you a nod for this wonderful tweak.

Chris - Wish I could come off as a pro and tell you balancing was a snap.  Alas it was not. It took a good deal of time and patience to acquire a neutral balance  for leveling before adding the weight.

Interesting you used the word "heft" in describing balancing.  Heft is a good deal of what this upgrade added to my listening.  The sound is fuller without any bloat or loss of detail.  Indeed, detail was improved.  Not the kind of detail that is clinical but the kind that lets you hear fingers on strings and spit in the reed.  All in all very nice.  

Let me know what you hear with the long plank when you get back home.

Re yellow jackets, I've been stung 3 or 4 times since retiring here to "deep rural" and had no problem except the pain.  This time I had an anafalactic reaction and ended up at the emergency room.  I am now carrying an epi pen.  Ahh, the price we pay for shunning civilization.

A few thoughts regarding longer i-beam and leverage:
- While the captive air-bearing has advantages in stiffness, the ET design with stationary bearing has only one point with centered forces within the bearing along the arm travel. This "allows" some maximal leverage at the beginning and end of the travel.
- Having a short i-beam compensated with more weight on the i-beam side increases (lateral) leverage.
  Eliminating the leverage on the air bearing by using a moving air bearing has some advantages, but a drawback too:
  Either one needs an additional flexible air-tube, which increases vibration coupling between arm and tt chassis, and also vibrations within the air feed. 
  Or one needs an open bearing with less bearing stiffness, like the (very good) Adanalog MG 1 arm, or the many Ladegaard variations incl. the Trans-fi arm. (see below)
- It is desirable to keep varying leverage at a minimum, a)  on the air bearing as well as b) on a sprung subchassis. The latter will lead to varying lateral desiquilibrium, visible as increased "slipping" from a balanced middle position to outwards gliding at the start and end positions of arm travel.

- So a longer i-beam reduces the leverage on the bearing, and on sprung subchassis. It improves balance of the center of gravity along the bearing travel.  And it increases vertical mass, which often improves the sound too.

- Regarding "optimal" vertical resonance I did put up the idea, that (maybe) there is not much useful out of phase bass information below 100Hz - this might not be the case... as increasing the (out of phase) bass bandwith below eg. 15Hz, by lowering vertical resonance seemingly still is audible.
- However, there is an end to that, probably below 10Hz because of subsonic vertical garbage information with a maxiumum around 5Hz. This contrary to lateral resonance where the main problem frequency (correctable) is not higher than 0.75Hz.

- Trans-fi arm:
I trust several keen and independent ears, that this is a superb design, technically by design and subjectively by constant tweaking and improvimg.
- the stability/stiffness of it's "open" bearing is still very good by it's v-shape which forces centering of the air bearing by help of gravity.
- the vertical knife edge bearing is a very good and elegant design with no bearing chatter, and with selfcentering by gravity too.
- "optimal geometric design practice" followed by ET keeps the vertical bearing axis on the same height as the tracing / platter level, This reduces FM wow induced by vinyl warp,
-  However, this is not without a price: Lifting this tracing level has it's advantages too, leading to improved bass: Trans-fi and RS labs ar examples. This is, because putting the vertical axis in line with the cartridge cantilever ((ca. 20-30 vertical degrees)) eliminates vertical pull on the cantilever bearing, reducing vertical resonance of the arm activated by dynamic friction changes by tracking vinyl, and by variable friction...
No free lunch therefore for ET... and the above mechanism is rarely looked at. 

@pegasus 
As always your posts are insightful.
re the vertical bearing axis, as set up on the ET. Do you see any reason why this could not be lifted to 20-30 degrees? (Warp issues aside.)
This assuming there is enough travel in the vertical slide. I guess that the  platter would need to be very low relative to the armboard.
Have you tried this?
Results?

cheers