Eminent Technology ET-2 Tonearm Owners

Hi Chris (?) the compressed air bottle is a 200 atmospheres 60 liter steel tank. It provides "air DC" (to my arm & head) :-)

Wires: the Audio Consulting wires are twisted single strand 0.15mm silver wires with thin isolation. I dress them carefully (two L/R separated looms in a circle of almost 245 degree with ca. > 15cm diameter) going up from the arm in 90 degree to ca. 4cm above & behind the arm, slowly turning > 200 degree and back to vertically down. I measured the forces applied by the elasticity and weight of a single winding, it's around 0.05 gm. This is audible - if one does not correct for it. But I tune the downforce by ear anyway. The forces are low, and less in the horizontal plane. The end effect is what the arm does: It still skates off very slowly outside the middle 5cm to the inner and outer grooves.
The wiring works actually very well (far better than the original wiring), and I prefer to keep the wires twisted for hum compensation. Some time I used 0.07mm single strand copper wires, the applied slightly less force but sounded IMO worse.

Did you really check for absolute levelness after changing the VTA position, finding *no* change in side balance?
The imprecision is shurely on a very low absolute level, but not low enough in my case. I found out the hard way, by ear that there was a problem.

Dover, thank you for the link to the MIT video. Very interesting, and I was particularly impressed by how their designs are guided by music theory. As I said before, the conceptual parallels between the audio hobby and music making are many.

the compressed air bottle is a 200 atmospheres 60 liter steel tank. It provides "air DC" (to my arm & head) :-)

hah hah - I like your sense of humor Pegasus.

Like wise when needed, I sneak some Arizona like air from my Timeter pump. It is after all located next to the treadmill. (But its on its own circuit - heh - heh)

Did you really check for absolute levelness after changing the VTA position, finding *no* change in side balance?
The imprecision is shurely on a very low absolute level, but not low enough in my case. I found out the hard way, by ear that there was a problem.

Firstly Pegasus if I put myself in your shoes based on this problem, if it is really bothering you there are three options that I can see.

1) As you have sensitive ears, try a properly set up double spring I Beam. As you know especially with heavier stiffer LOMC cartridges, the single leaf spring I beam can be taxed more and induces more horizontal movement with eccentric records. The stiffer double spring does not do as good a job of damping the spindle on eccentric records but is what you should be using with heavier lomc's. The manual does not discuss this. If there was an updated rewrite of it the single, double, triple spring I beams would be a chapter on their own - imo.

To play records on an ET2 with a single leaf spring an eccentric record must not have a runout of more than 1/8 inch (from the manual) . The stiffer double spring would make this number a little less - imo. take note.

2) Send your ET2 to Bruce to check it out. He will tell you if it is within spec/tolerances for the year it was built.

3) Switch cartridges to one that doesn't reveal your particular issue to your ears. This is after all about enjoying the music right ?

I can change VTA anytime and I again do a quick gravity test with the handy
BlueTac Pancake which makes the arm free float. No movement at VTF 0, we are good. That is my test. I have these Blue Tac pancakes for whichever cartridge is on there. you start small, add a little on top till the arm floats like a teeter totter with two same weight people on it. Do you remember the uneasy feeling of being on a Teeter Totter as a child, with someone your same weight; and holding the teeter totter in a balance ? Remember if the other guy jumped off quick and you hit the ground hard ? The gravity test is no different, same principle. But the ET 2 has the ingenious holding cue arm for when you take the Blue Tac weight off the lead weights.

I need to also qualify something and I have mentioned this before here.
My ET 2.5 is a more recent build 4 or 5 years? not sure now - a custom build by Bruce and the manifold/spindle has tighter tolerances than my HP 2.0.
Let me better explain this.
With the air off sliding the spindle in and out of the manifold is much stiffer on the 2.5 than the older 2.0.
My ET 2.0 is also a HPM (High Pressure Manifold) - but it will still play with only 7 or 8 psi. in fact it will play with over 30 psi and no air hissing is heard and the inlet air tube does not blow off. It is a custom build obviously and it was bought used. My newer 2.5 needs 19 psi no questions. So here we have another example of the way Bruce constructed and changed his tonearms differently either by the buyers request or just as time went on. We know for instance that Bruce went to the 2.5 to meet the demand of lower compliance MC's. that has been discussed here before.

So how old is your ET2 ?

09-09-15: Bdp24
The discussion of a musician's sense of time brings to mind a singer whose timing drives me nuts, and you hear him at many audio shows---Willie Nelson. I don't mind a singer having flexible or elastic phrasing (pulling ahead of or falling behind the pulse of the band), but he jumps so far far ahead it creates anxiety!

By the way, when you hear a recording in which the drummer (or entire rhythm section) seems to be dragging, it's not necessarily of his/their doing. In doing session work, I have found many singers to have trouble "waiting" for the beat coming towards them while over-dubbing vocals to previously recorded backing tracks, and end up "rushing". Don't blame the drummer!

Bdp24 - welcome to the thread.
Could this be a case of some singer "beat deafness", or maybe "weed" influence ?
This could be fun if you could point to some youtube examples that illustrate this?

if I may ask; So as a drummer, has it been your personal experience that the "beat" guys get the best chicks ?

Good to have another back row guy here to balance out things. :^)

Cheers

Hi Chris, BTW the pressurized air bottle is true. :-)
I forgot to answer an earlier question of yours: I prefer to use less counterweights farther out on the I-beam. I prefer it because this way the center of gravity of the arm is more centered along the bearing, and because I have less lever forces on my semi-springed subchassis. It helps to float the arm better across it's way.
It also reduces the maximum lateral mass, effective at "DC", below the resonance frequencies of arm/bearing and I-beam/counterweight.
Less counterweights farther out in effect tunes the I-beam / leaf spring resonance lower down. In the end, this is a more important aspect than the leaf or counterweight looked at separately I think.
I went through many such tests during the 80's and beginning of nineties, taking some of them up in the last years.
I didn't like the single leaf springs with my medium to low compliance cartridges, I preferred the double spring ones - I don't think I have a triple leaf I-beam.
There is another aspect of the I-beam, which is critical / sub-optimal: The weights are not centered around the I-beam, ie. it exerts an offset torsional force on the leaf. This means that any vertical movement of the arm activates a hidden torsional resonance, which slightly modulates tracking force. The vertical axis is the one axis, where you want *absolute* "true inertia", and as few resonant modes as possible, including arm resonances, as it affects the critical downforce.
My feeling is that the stiffer beams control this aspect better than the single leaf beam.
I always preferred the I-beam leaf with a bit more damping than originally provided, using BluTak.

For balancing I move two Blue-Tak "saddles" along the I-beam, and the arm lever extension, to keep lateral forces equilibrated.

My ET2, now with ET 2.5 bearing is an early one. I ordered the bearing for around 0.8 bar (ca. 11 psi) and it still runs OK with ca. 3 psi. Though below ca. 6 psi things go audibly downward, the magic disappearing somehow. In fact the ET 2.5 has "simply" more surface and is therefore already stiffer, but the price is a higher lateral mass, probably 10g more.
Sending the arm from Switzerland to the US - and parting from it - would probably affect my sleep... not in the best way. :-) It works good enough... I'm Just checking lateral balance after adjusting the VTA.