Eminent Technology ET-2 Tonearm Owners

Frogman
The less compliant double spring usually yielding a more controlled, defined sound with tauter and faster bass. More compliant springs have produced sound that is generally fuller, but less-well defined; fuller mids and lows, but less-well integrated highs.

Frogman your observations mirror mine. Here are some personal impressions in my specific 2 rooms.

BTW - Bruce has confirmed to me that adding a double spring raises the resonant frequency of the I Beam Counterweight.

Two rooms set up with an ET2 and ET 2.5.

First room

The ET 2.5 is in a room with gear that I am able to pressurize easily and hear the bass nodes by walking around all on fours. I can locate where the bass is fullest and over powering. I can also find the spot where the nulls are. By experimenting over 19 years with multiple speakers I have found for this room only; the spots that give me minimal resonances at my listening chair, based on where I position the speakers. A key to my own audio madness 1) a dedicated room and 2) a listening chair that can be moved forward and backward multiple feet to adjust for soundstage/sweetspot differences between differently engineered music sources (whether they be on lp, cd, or tape) and different cartridges. Anyone that has ever heard a 420 str for the first time is aware of the stark differences in soundstage presentation it provides. I had to move my nearfield listening chair back a few feet from the first listen to the 420 str. What if your chair is up against wall.....

I prefer the double spring in general in this first room. The bass is tighter as you say – mids and highs are clear, the bass nodes don’t last as long with the double spring. The triple spring was even more extreme in this regard. It became too lean however as I posted a couple of posts back.

Second Room – much larger (adjacent to room one)

An ET 2.0 setup with gear that provides for full sound through the mids and highs, but needs help with two subs for the lowest octave with certain music. They are Quad 57 speakers. I cannot pressurize this room no matter what I do – reason is - firstly the space is too big and open and 2) my wifes TV room is close to it above and adjacent to it a ways. :^(

I prefer the single leaf spring in this second room. The bass is fuller as Frogman said, but in my case as the space is larger it allows IMO for bass waves to dissipate, not bounce around causing problems. This also means harder surfaces can be used in the room to allow for clearer highs.

For me the room/space dictate our preferences above everything else.

TORQUING OF THE ET2 LEAF SPRING USING DOVERS METHOD

I untorqued the single leaf spring in room 2 last night per Dovers recent post and the sound seemed to get even more fuller. The change was noticeable. I will experiment more with this.

Dover thanks for this detail it is really appreciated.

Heath Robinson Belt Drive

I really like Grantn's sense of humor :^)

Welcome to the thread Grantn.

I have learned alot from Richard and Dover in the last few weeks.

Cheers Chris

03-23-13: Gnnett
When I look at the pictures of RK's arm I do not see an ET2. It is something specifically crafted and tuned to his system. It is not a universal tonearm. A little bit like the highly modified ET1 that Lloyd Walker uses actually.

Grantn – I thought your observation was a really interesting one.

You mentioned the ET1. It has a very interesting history.

As a reference point here I feel it is important to understand the transition from the ET1 to the ET2.

Especially since we have been debating Rigid versus Sprung I Beams/Counterweights.

ET1 - is Heavier and Rigid

ET2 - Lighter and Sprung

I skipped through the ET1 manual from Bruces’ site.
Anyone interested in Tonearm Resonances and Testing of Resonances should see pages 49 and onward. It is much more detailed than the ET2 manual in this respect and the tests apply to all tonearms in general.

So why did Bruce to go from an ET1 to an ET2. Do the design and specs themselves tell enough story?

There are big differences between the ET1 and ET2.

Actual tonearm tube/headshell weight is more on the ET1.

The small counterweights on the ET1 are actually the large size on the ET2.

The spindle weights are the same.

************************************************************
ET1 specs.
Spindle Weight 14 grams
Tonearm Tube Weight 14 grams / Headshell weight 5 grams
Counterbalance Weight 15 grams small 30 grams large.

************************************************************

ET2 specs
Spindle Weight 14 grams
Tonearm Tube Weight 11 grams
Counterbalance weights 5 grams small and 15 grams large.

************************************************************

Has anyone heard an ET1 versus ET2 ?

Cheers Chris

For me the room/space dictate our preferences above everything else.

Just to be clear - my statement is very "biased" and it is based on my personal audio hobby experiences over the years.

cheers

My view on a stereo system is that it is just a machine. Actually lots of machines chained together to give an output based on inputs. As such it is logical and the output is predictable provided we have sufficient understanding of the machine. ( none of us have sufficient understanding )
What we are talking about here is a small part of the machine. The coupling, decoupling of a counterweight on a linear arm.

Frogman and Dover say that they prefer a loose connenction and one leaf spring.
Chris says that triple springs produce a sound that is too lean.
Rockport, Walker, Kuzma and I say that there should be no spring at all.
I believe ALL of the above statements as I think that they are actually saying the same thing along a continuum.
It all depends upon the voicing of your system and our biases, and we all have biases.
Also an improvement can actually sound worse as it can expose more clearly problems elsewhere in the machine chain. Sometimes when we open the window wider, we do not like what we see. We then need to work on the new "view" to correct a previously unseen problem. It does not mean that the original change was wrong
I have said that I don't think that it is a good idea to have a mass attached to two dissimilar springs who's resonances are in the same neighbourhood. The transmissibility graph I posted shows the potential nasty consequences of this. At least a 6 x seperation of the two resonant frequencies would a target.
Using one spring lightly coupled to the spindle pushes the resonant frequency down below the arms core resonance. This is good. (As Frogman points out, there may be other factors at play here with the loose screws.) Double or triple springs push the resonant frequency above the core resonance which is also good.
We have to be carefull when using stiffer springs that we don't move too close to the audio spectrum, since the same transmissibility graph data will bite us. We also have to be carefull that we do not go to low with lite springs since we get close to eccentricity frequencies again with possible nasty consequences. So what if we pushed the resonant frequency up above the audio spectrum. We have no risk of any of the issues I raise here.
My early fixed counterweight designs resonated somewhere in the midrange. It was easy to hear adding a nice, but not accurate bloom to voice and midrange instrumemts. If my system was not already "full" in this range I may have stopped experimenting, thinking that the arm was acurate. Increasing its rigidity more, pushed the resonance above the frequency of audibility. This is desirable and is the final logical progression to the tests that have been listed in this thread.

Gnnett. Do you live in AKL? It would be nice to meet. You can contact me directly via my web page if you wish.

Richardkrebs:
Yet again I have to address your gross assumptions and misunderstanding of the principles of the ET.

Richardkrebs
Frogman and Dover say that they prefer a loose connenction and one leaf spring. Chris says that triple springs produce a sound that is too lean.
Rockport, Walker, Kuzma and I say that there should be no spring at all.
I believe ALL of the above statements as I think that they are actually saying the same thing along a continuum.
It all depends upon the voicing of your system and our biases, and we all have biases.

This is absolute rubbish. You are implying that the decoupling and non-decoupling are both valid, when they are not. With the ET2, the outcomes are entirely different and Bruce Thigpen has tested and measured these. The decoupled methodology employed by Bruce Thigpen is designed to minimize horizontal inertia and ensure the resonance of the I beam and counterweight remains below the horizontal resonance of the arm. The rigid coupling of the I beam and counterweight that you advocate is contrary to these stated design goals. Your comment about voicing the system to biases is as presumptuous as it is incorrect. An experienced listener can hear changes in transient speed and accuracy of timbre and timing irrespective of the system. That is how a system should be tuned.

Richardkrebs
Double or triple springs push the resonant frequency above the core resonance which is also good.

Your statement contradicts research and testing by Bruce Thigpen, and I quote the following email from Bruce Thigpen published above:

Bruce Thigpen
Chris,
You always want the horizontal natural frequency of the counterweight to be less than the cartridge/arm resonance, this is the case 98% of the time.
The natural frequency of the I-beam/leaf spring depends on the thickness of the spring, the amount of weight, and where the weight is on the beam. The natural frequency goes down as the weight moves further out on the beam which is where we want it to be.
brucet

Richard, clearly you have not done any testing to support your guesswork, otherwise you would have found that 98% of the time you are wrong.
If you bothered to read the manual you would see that the double spring is for low compliance cartridges and should be used with the minimum counterweight pushed further out on the I beam to position the resonance of the I beam and counterweight BELOW the horizontal resonance of the arm.

Richardkrebs
I have said that I don't think that it is a good idea to have a mass attached to two dissimilar springs who's resonances are in the same neighbourhood.

Again, if you bothered to read the manual and Bruce Thigpen’s website, the decoupled counterweight is designed precisely to achieve this. Furthermore on Bruce’s website he has provided extensive test results proving this.

Richardkrebs
The transmissibility graph I posted shows the potential nasty consequences of this.

I have already explained to you in great length that the mathematical model you refer to, "harmonic oscillators", which you pulled out of wikipedia, does not apply. Let me help you. Read my post of 03-14-13, the first sentence begins

Dover
Richardkrebs
OK now I understand where you are going wrong in your thinking.

Richardkrebs
At least a 6 x seperation of the two resonant frequencies would a target.

Where did you pluck this number from? Why 6 times? Please don't use an incorrect mathematical model again when you attempt to explain.

Richardkrebs
We also have to be carefull that we do not go to low with lite springs since we get close to eccentricity frequencies again with possible nasty consequences.

Bruce has completed extensive testing and provided clear guidelines on the use of the light spring. He has calculated the resonances and provided extensive guidance. What testing have you done, or is this purely speculative guesswork on your part yet again.

Richardkrebs
My early fixed counterweight designs resonated somewhere in the midrange.
Increasing its rigidity more, pushed the resonance above the frequency of audibility.

Have you tested this? What resonant frequency did you measure?
More guesswork?

Richardkrebs
This is desirable and is the final logical progression to the tests that have been listed in this thread.

You persist in arguing your unfounded case for fixing the counterweight.

Arrant nonsense.

To remind readers I repeat:
The decoupled methodology employed by Bruce Thigpen is designed to minimize horizontal inertia and ensure the resonance of the I beam and counterweight remains below the horizontal resonance of the arm. The rigid coupling of the I beam and counterweight that you advocate is contrary to these stated design goals.
Once again, we go round the block for the umpteenth time.

Bruce Thigpen has calculated, tested and measured precisely the resonances of the decoupled I beam and counterweight with a wide variety of cartridges from low to medium to high compliance to determine the level of decoupling required to optimize the cartridges performance.

How many times before you get that decoupling is an integral part of the ET2 design and how the arm is engineered to optimize performance. You are clearly out of your depth. You persist in misapplying physics and just don’t seem to be able to comprehend the design. Do you run your car on 3 wheels?

You have resorted to implying that readers who have tried removing the decoupling and found it to be detrimental are either fixing up defects in their system or have biases. That is an arrogant assumption, and reflects poorly of your estimation of the contributors to this thread.