Eminent Technology ET-2 Tonearm Owners

ET 2.0 spindle versus ET 2.5 spindle

I am focusing on the spindle /counterweight. I have some info to share.

It can be difficult from pictures telling the differences between the ET 2.0 and 2.5.

This makes it easier. Pictured is the

ET 2.5 spindle

Significant differences in weight and diameter.
19 gms ET 2.5 versus 11 gms ET 2.0.

Chris,

About 19 grams with the aluminum inserts which are machined from bar stock. The 2.5 tubing has about the same wall thickness as the 2.0.
brucet

Richard/Dover/theKong/Frogman others.

I find this significant based on the recent damping conversations. I will have more information coming from Bruce when he has time to discuss. I feel this info will enlighten us. The only clue I have been given.

"horizontal resonance to be above 2-3Hz but at least 4 to 5Hz below the vertical resonance"



TWEAK

I have also come up with something that I believe is significant as far as sonics are concerned and requires only a one minute adjustment. This is based on only one listening session but is so easy to try I had to share it.

Loosen the end cap bolt (not the leaf spring bolt we have been discussing) just enough to lower the lead weights, so that they are positioned at the bottom half of the spindle; when looking at the arm from the gooseneck side. Once done tighten end cap again.

This increases the VTF significantly.

You will need to adjust by moving the lead farther out on the I Beam. A good thing.

Cheers

Loosen the end cap bolt (not the leaf spring bolt we have been discussing) just enough to lower the lead weights, so that they are positioned at the bottom half of the spindle; when looking at the arm from the gooseneck side.

Hi Ct,

In all the photos I have seen on the Walker turntable, the counterweight set-up was below horizontal. So, I suppose that is intentional and offers some advantages, at least in that design.

I must apologize that due to my schedule, it will take me a while to have the time to do a thorough comparison on the counterweight set-ups in my system. I will report it here at once when I can complete the test!

Chris, thanks for the tip. I will try it and report back.

As we have been discussing the pros and cons of the decoupled counterweight on the ET, I have this question on my mind (admittedly a non-technical one) for a long time!

The ET uses leaf springs to decouple the counterweight so the arm doesn’t “see” the additional weight! To my thinking, this can only be possible if the counterweight actually doesn’t move during the initial movement (milliseconds?) of the arm, due to the compliance of the leaf spring. Then, after the arm has moved for a certain range, the counterweight would need to start “rebounding” to follow the arm.

If that is true, then would it create some delayed effect that could be detrimental to the tracking?

Or is my reasoning totally false?

Thekong - yes you are correct. That "rebound" as you call it has a resonance. The idea behind the variable spring rate and shifting the position of the lead counterweight is to place that resonance below the horizontal resonance of the arm so that the 2 resonances ( arm and beam ) do not couple together to produce a large peak at the arms resonant frequency.
All tonearms will have a lift or peak in response at their natural frequency. The tuning with the I beam ( decoupled ) is designed to reduce this natural bass peak at the resonant frequency of the arm to produce a flat bass response. This is illustrated in the graphs on Bruce Thigpen's website where he has published some of his test results.
The idea behind loosening the I beam that I outlined in my earlier posts is to lower this "rebound" resonance, by allowing the I beam to swing freely and also keep the horizontal arm mass low. Some wag above says you get no response below 30hz but that is not correct. You get a low fall off in bass below 30hz.
Rigidly coupling the I beam will increase the bass, adding more bass lift at the resonant frequency and beyond. If you run 30 year old Acoustat 2+2's in a room barely 10ft x12ft, listening position 5 feet from the panels and you like humpa humpa one note bass, then that is your ideal solution.