Eminent Technology ET-2 Tonearm Owners

I'm a (very) long time user of the ET2 arm, I owned the ET one before. I still find the arm superb!
I have a first comment, others might follow.
The question of resonance frequency is mostly re-cycled from some sources, that did a lot of calculations a lot of time back. That's OK, but there is one aspect missing IMO.
The main signal is cut laterally, one can safely assume that if there are very low frequencies on an LP it is cut *laterally*. The main disturbance laterallyis off-center records (0.55 Hz).
The off-phase info is cut vertically. The off-phae low frequency part is not doing anything helpful in normal rooms, so usually the LF signal below ca. 100Hz is blended to mono.
This leads to severely different optimal resonance frequencies horizontally and vertically. More will follow.
Let it be said that my most memorable analog experience in the 70's was a FR64 & FR7 combo - it had *decidely* "suboptimal" resoance frequency, ie. far below 10Hz. It sounded better than anything else I heard at that time, and I still the *bass" and ambience of that front end. There's a physical reason for it, I think.

I remember this combo clearly because it was visible that it had rel. low damping and an unusually low resonance frequency. I knew and was used to tonearm/cartridge combos with "correct" resonance frequency. This one was incorrect - and sounded better than anything I had heard (in the low-mid frequencies, in dynamics and resolution).
If "correct" resonance frequency would be the main reason for optimal or non-optimal sound, such suboptimal resonance frequency should have almost destroyed any potential of good sound. (that's what I thought then).

The normal warp & rumble zone is usually quoted between 2 to 5Hz - it leads basically to vertical accelerations. If one assumes that there are no important signals to be traced below 20 Hz or even below 50Hz (because the big excursions involved in low freq. creates problems for the cutting head *and* the cartridge. And because even in big listening rooms it is difficult to reproduce phase differences in LF) one places the optimal *vertical* resonance frequency between 5 and 20, or more radically even below 5 and 50Hz.
-> Vertical optimum is around SQR(5x20)=10 Hz or even SQR(5x50)=21 Hz
(so long so good, so often heard).

Horizontally there is a main disturbance at 0.55Hz (33.333rpm/60"), maybe 0.75 Hz (45rpm/60"). But there is a good reason to extend extraction of musical information like ELF reverb etc. down to at least 5Hz - if possible. Cutting and manufacturing LPs has several modes of creating vertical disturbances but only one or two horizontal issues: Off-center records (which actually could and should be corrected) and horizontal bumps on the cutting lathe - rare (but I have one such record in thousands of LPs).
So there is a moderate, but constant excitation/acceleration on 0.55Hz (basically correctable) and a useful extended LF range down to 5Hz which leads
to an
-> optimal horizontal res. frequency of SQR(0.75 * 5) = 2 Hz

I agree that low horizontal res. frequency is not without problems (with highly off-center records). But preventing this problem with much higher (ie. standard) horizontal res. frequency means loosing very worthwile ELF information (which, as said above, is cut mainly in the horizontal plane.)

So the *often" alluded main "achilles heel" of air bearing arms is actually an advantage, in an "objective", physical sense. About the same time, I drew these thoughts up on paper, I found the new Mörch arm which does *exactly* follow these reasonings, with superb result. It couples the cartridge to a *very* high horizontal mass. Experiments show that the rigid coupling of that horizontal mass vs. the cartridge is sonically important.

The ET 2(.5) and other air bearing arms have the same high hor. mass advantage "built in for free".
The decoupled counterweight of the ET 2 gives simply more freedom with problematic pairings of cartridge, arm and off-center records.
Maybe, when it is not necessary, blocking the decoupling could have advantages sound-wise.

BTW in my experience it is extremely important to have both the platter and arm *extremely* well levelled in the horizontal plane. Side-forces on the cartridge cantilever lead to plummy bass. Probably because a variable pull with varying tracking friction on a laterally deplaced cantilever gives dynamically varying side forces - which might energize the horizontal resonance. It sure is very audible. In my setup it is important to check regularly, floating the arm with two equal blobs of Blue-Tak on both sides of the arm, one at the backside of the arm, the other on the counterweight.

Hello Pegasus

Two posts that imo generate very good thought. I need to first say that ever since this ET2 thread started I get a special feeling in my gut whenever a long term ET2 owner posts in this thread for the first time. Especially when it is his first post on audiogon. Remember how this thread started - "Where are you guys ?" IMO - anyone that has owned ET2(.5) for a significant period of time, has been through a huge RE:LEARNING process with their records and how to play them, especially if your main tonearm before was a pivot arm. So welcome to this thread which I now see is about to touch 1/2 million views soon. Who knew ?

When you say

The main signal is cut laterally, one can safely assume that if there are very low frequencies on an LP it is cut *laterally*. The main disturbance laterallyis off-center records (0.55 Hz).
The off-phase info is cut vertically. The off-phae low frequency part is not doing anything helpful in normal rooms, so usually the LF signal below ca. 100Hz is blended to mono.

The normal warp & rumble zone is usually quoted between 2 to 5Hz - it leads basically to vertical accelerations. If one assumes that there are no important signals to be traced below 20 Hz or even below 50Hz (because the big excursions involved in low freq. creates problems for the cutting head *and* the cartridge. And because even in big listening rooms it is difficult to reproduce phase differences in LF) one places the optimal *vertical* resonance frequency between 5 and 20, or more radically even below 5 and 50Hz.
-> Vertical optimum is around SQR(5x20)=10 Hz or even SQR(5x50)=21 Hz
(so long so good, so often heard).

Horizontally there is a main disturbance at 0.55Hz (33.333rpm/60"), maybe 0.75 Hz (45rpm/60"). But there is a good reason to extend extraction of musical information like ELF reverb etc. down to at least 5Hz - if possible. Cutting and manufacturing LPs has several modes of creating vertical disturbances but only one or two horizontal issues: Off-center records (which actually could and should be corrected) and horizontal bumps on the cutting lathe - rare (but I have one such record in thousands of LPs).
So there is a moderate, but constant excitation/acceleration on 0.55Hz (basically correctable) and a useful extended LF range down to 5Hz which leads
to an
-> optimal horizontal res. frequency of SQR(0.75 * 5) = 2 Hz

It is my understanding that bass below 100 hz is mono as well. Your comments make me curious whether you have been involved in the lp engineering/mastering side at all ?

Do you still own the ET1 ?

The decoupled counterweight of the ET 2 gives simply more freedom with problematic pairings of cartridge, arm and off-center records. Maybe, when it is not necessary, blocking the decoupling could have advantages sound-wise.

A profound thought that IMO can only come from a long time owner with direct experiences. Indeed the ET2(.5) can accept all cartridges I have thrown at them so far, From extreme high compliance Sonus Blue Gold to the XV1 although the 2.5 by design is happier with heavier MC's. The problem is learning how to use the counterweight/springs does take time and patience. I am past the swapping of cartridges stage and have now settled in and just love listening to my music.

BTW in my experience it is extremely important to have both the platter and arm *extremely* well levelled in the horizontal plane. Side-forces on the cartridge cantilever lead to plummy bass. Probably because a variable pull with varying tracking friction on a laterally deplaced cantilever gives dynamically varying side forces - which might energize the horizontal resonance. It sure is very audible. In my setup it is important to check regularly, floating the arm with two equal blobs of Blue-Tak on both sides of the arm, one at the backside of the arm, the other on the counterweight.

Agree, in fact Bruce should have shipped ET2 (.5) all out with a pack of Blue-Tak.

For me it is the audio wonder tweak. It holds, it dampens, it can even clean your stylus....

Cheers

CT0517 - For me it is the audio wonder tweak. It holds, it dampens, it can even clean your stylus....

Blue-Tak audiophile tip # 115.

Put a very small touch of Blue-Tak on your "audiophile" screwdriver tip. You know the one with the Cocobolo handle that is used to put the cartridges on and take them off. Presto ! you will never lose another screw in the carpet. Your wife will never hear you utter the words " Damn ! I just lost one of the screws, and now only have one like that one left ..they were a special one of kind pair buy from xxxx ".

To this very day I am too scared to vacuum in the immediate vicinity of my analog rig for fear of hearing tinkle, tinkle, tinkle, tinkle, in the vacuum cleaner dirt holder. Screws from years past.

I think there is a couple ET2 leaf springs down there too :^(

all the leafs are brown... the fall is coming.. :-)
Yes Blue-Tak is something to have around, and I use it (I'm swiss :-) on my jewelers screw driver - when I remember...

No, I wasn't in LP mastering / cutting, but I have a profound interest on the electronic & physics side of that hobby. I make recordings of concerts at our place, and did some recordings already in the 70's with a semi-pro JVC portable cassette-deck from my brother.
And I did a few Magnepan modifications for customers, and made new low-diffraction panels, and calculated all new crossovers for MG3 and MG 3.3s.

I had to trade in the ET1 for the ET2, so I don't own it anymore, contrary to the ET 2 it was slightly crude in set-up and detail solutions - but it worked very well.

My main messages about the arm (which I always loved) are as follows:
- If the bass is off, it's probably the set-up (side level or maybe a too softly springed counterweight stud).
- If I only touch the VTA adjustment a bit on *my* ET2 - the side-leveling is severely off. If it's not, I was lucky. To check is better than to believe...
- The "critical theory" against air bearing arms, and specially the ET2, stands IMO on very shaky feet, as I tried to show above. If there is a structural problem it might be the slight elasticity in some of the joints.
- subchassis turntables have two main problems with an air bearing arm:
- the lever mechanism of the shifting mass offsets the subchassis (-> increases sideforces)
- The needle drag problem, ie. the varying friction with tracking, potentially sets up rotational forces in the subchassis, with every arm. This leads to a slight instability in the subchassis and pitch uncertainties. But it also kicks air bearing arms in a different, very undesirable and quite audible way: Side-ways. (Much more audible than a radial tonearm, where the kick goes much more along the stable axis needle to arm bearing).
So one gets both problems - the bass instability and the pitch instability.
But it's still feasible and it can sound very good.
- In my book of experiences, every screw that creates a touch more grip than needed to keep a joint or a connection from gliding, introduces quite severe grades of transistor-feedback sound. I understand this as a necessary minimal torque, but every further bit of torque is like tuning the screw up, in the sense of a steel string. Tune these down & out, and they ceae to resonate. It is less storage of resonant energy. So my ET 2.5 runs with minimal torque on all screw connections. It sounds less artificial and more integrated to my ears.

My ET 2.5 sits now on a partially spring suspended Technics SL1210 with some modification on the electronics. With a very old, original AT OC7, which sounds very, very good here. I know, it shouldn't :-)