Eminent Technology ET-2 Tonearm Owners



Where are you? What mods have you done ?

I have been using these ET2's for over 9 years now.
I am still figuring them out and learning from them. They can be modified in so many ways. Bruce Thigpen laid down the GENIUS behind this tonearm over 20 years ago. Some of you have owned them for over 20 years !

Tell us your secrets.

New owners – what questions do you have ?

We may even be able to coax Bruce to post here. :^)

There are so many modifications that can be done.

Dressing of the wire with this arm is critical to get optimum sonics along with proper counterweight setup.

Let me start it off.

Please tell us what you have found to be the best wire for the ET-2 tonearm ? One that is pliable/doesn’t crink or curl. Whats the best way of dressing it so it doesn’t impact the arm. Through the spindle - Over the manifold - Below manifold ? What have you come up with ?
128x128ct0517
Speaking of removable arm boards and audiophile anxiety:

My (now “hybrid”) TNT 6 came with an arm board drilled for a SME V.  I was having difficulty getting a blank or predrilled armboard for my ET2, so I went ahead and had VPI drill the SME V board to accept the ET2, SME cutout and all.  I was eventually able to source two blank armboards which VPI drilled for the ET2 and for the Syrinx PU3 which I keep “just in case”.  Wouldn’t you know it, I was convinced that the arm board with the SME cutout sounded better and actually went back and forth a couple of times with the two arm boards to determine which actually did sound better; PITA.  Eventually settled on the new board without the SME cutout simply because it looked so much better 😊.

Happy New Year to all!
Post removed 
**** ET2 Yellow Sticky **** Cartridge Setup Guidelines ****

Tonearm Version _____ Armwand Version _______ I Beam/Leaf Spring Combo

General Guidelines.

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

Tonearm Version

ET 2.0 ___________________________ ET 2.5

Higher Compliance Cart ______________Lower Compliance Cart

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

Armwand Version

Aluminum __________Carbon Fiber _______Magnesium

High Compliance ______Medium__________Low Compliance


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

I Beam - Leaf Springs - (a higher mass cartridge needs more
counterweight mass, which in turn needs a stiffer decoupling spring).

Single Leaf Spring _____Double LS __________Triple LS ____

Low Mass __________Medium Mass_________High Mass

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

This info is endorsed by Bruce Thigpen

Hi Guys (Gals ?) This popped into my inbox this morning.
It is a rare listing for an ET tonearm that started life as 2.0, and was upgraded to 2.5 status. This means it has the bigger bore manifold and larger diameter air bearing spindle. 

It includes additional options which include single shot wiring. Anyone interested needs to realize that this tonearm will  require a suitable air source, able to deliver more than 19.0 psi to allow for a steady 19 psi.

As an FYI.
It comes with the original aluminum armtube only from the looks of it. The Carbon Fiber and Magnesium armtubes are a better match for the 2.5.  

Also be aware that Bruce now offers upgrades to the original design which include Solid Aluminum Base Mount, and Gooseneck (replace the CF),  and of course the longer I Beam which reduces the weights requirements in half.

Not affiliated with this ebay ad.

https://www.ebay.com/itm/333098302449?ul_noapp=true

Good luck to those interested. 


Are there any sonic benefits to the aluminium base and arm joint? Would like to know. I just received them in the mail!

Tim
@flemke ,

You're question does seem out of the ordinary since you ordered it before asking your question.

Happy Listening
Hi Tim (Flemke)
Both pieces will add weight to your setup over the Carbon Fiber.
(probably not recommended if someone is mounting an ET2 on a Linn LP12) 

You will be tempted to add the joint (Gooseneck) first (quicker to do), but to do proper "audiophile" observations for us, you should replace the mount first since it cradles "the whole enchilada". Then the Gooseneck 2nd. Doing two changes at the same time in ones system, breaks multiple audiophile rules.

But then again, if you are like me right now, just trying to make it past what is remaining of winter with some music; the last thing on your mind, may be to want to mess with your set up.

I have the new mount and what I consider a third party aluminum Goosneck, which I acquired if you remember my posts here, by way of New Zealand, courtesy of Richard Krebs.

My shiny Gooseneck, was IMO, a sort of inspiration for Bruce to do the Aluminum. I remember he really liked what he saw in the picture of what I sent to him. Mine is a bright silver and it does add bling to the setup if one likes that. I prefer that Bruce kept his aluminum pieces the same color as the rest of the tonearm parts.

Then again,

I read here on AudioGon somewhere, that someone once posted a question; Why do all these air bearing linear trackers need to look like oil pumping rigs ? He was obviously a bling fan.

ct0517,
I don't think Bruce would make anything that didn't sound right, so i bought the parts. I do remember reading about the joint  you have way back in this thread I think. I'll see if have time to swap out the parts and give it a listen. 

Tim
Very interested in any sonic impressions of the aluminum upgrades (?).  Thanks!
Porter Recording have on ebay this auction for their ET 2.0 on a Technics SP10 MKII, with obsidian plinth.

Interesting times.... not affiliated with the ad. Good luck to those interested.

https://www.ebay.com/itm/283415966095?ul_noapp=true

I wish I could report back some solid findings. I cannot. My personal life has been far too busy and I just could not pay attention that well. I do believe that I did put the arm back together better than it was. This could give me better performance on its own.
Has anyone thought of a way to construct a lift for the arm, like what they have for regular pivot tracking tonearms? I‘ve tried to come up with a way to do it, like rotating the tube at the end of play. Anyone have any thoughts or suggestions?
^^^^^

Mruggs2 - I haven't ....but....on another note. 

I am most intrigued by those brave souls who have actually removed the cueing mechanism in its entirety. I only know of one person that has reached this level. R Krebs.

The consumption of ? during music can increase bravery, but decreases the dexterity imo, needed to handle the naked armtube (void of linkages), which holds the precious. Or does consumption of ? actually help others calm down ?

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

I 'm breaking through
I'm bending spoons
I'm keeping flowers in full bloom
I'm looking for answers
From the great beyond

REM - the Great Beyond

*********************************************
Greetings and Happy July 1, "Canada Day" to everyone.
From the True North Strong and....still free.

@ct0517. Chris. are you trying to lure me back here?
Removal of the lifter mechanism affords a slight improvement in focus, image precision. I used a foam rubber block mounted on the plinth at the edge of the platter which the cart rested on when parked. And yes, stay away from any dexterity altering substances when using the arm sans lifter.

Substituting the carbon fibre goose neck for the aluminium one brings about a similar but larger increase in focus. One does loose some versatility though as it has only one "height" setting and it is of course heavier so lower compliance carts are  called for.

Cheers .      
Should read "Substituting the aluminium goose neck...…"

ie using the Al instead of the CF

Morning Joe has just kicked in. 

Cheers 
BTW if you are bold enough to remove the long lifter arm. Complete the task by removing the lever box and the short stick protruding from the goose neck. 
All of these things sing along with the music.

 Cheers 
Hi Richard -
nice to hear from you and thx for that info. Have not been active on the forum the last few months, so the only "luring" going on for me is with a crank bait or spoon. 8^0

Was just telling it like it is. You are the only one I can think of with this arrangement. Now the strange thing for me is that I have no issues putting a record down on a spinning platter, and then a clamp on top. The turntable is designed for this, and the platter is a smaller diameter than the record making it very easy to grip. (Picture the guy on TV flipping pizza dough) -  

But putting that armtube down on the record, and lifting at the end. One cueing mechanism please, for me. 

@mruggs2 - The best, smoothest, cueing mechanism I ever used was with the FR64s I used to own.

Cheers.

Chris.
Nice to be back.

"one cueing mechanism...." Totally agree, its is my finger.

If  anyone does remove the stick, don't forget to reset the VTF

Anyway horses for courses. 

Winter here, so not much to do but listen to music.
What's not to like.  


Regarding the JIG ^^^^

I have installed the ET 2.0 and 2.5 on a dozen ? different tables of various design. During this time I have removed and re-installed the tonearm in whole or part maybe 70? times - mostly due to cart changes.
Audiophilia Nervosa phase.  An AudioGon search on "Goldilocks and the Three Turntables, represents a milestone in a way for myself, and reveals much, in regards to my personal adventure. 
  
Now regarding the JIG itself. 

IMO - the key to an easy and successful installation is "Flexibility" in the "Jig" and the "turntable design".

I can share thoughts on what I mean by flexibility if anyone would also like to share here. I am on the forum sporadically through the summer more so later in the fall . Hope everyone is enjoying their summer - or winter - 8^0 - down under.

Cheers
Hi,

I am wondering if any of you is having troubles with water condensations in the air bearing section?

I got ET2 that I refurbished (changed manifold sealing rings, removed and cleaned really well the manifold as well as aluminum tube that rides inside the manifold, etc...) but have a repeating problem with humidity condensation.
Was first using original aquarium AT pump at about 2psi and then upgraded to Medo AC0110 which delivers about 10-12psi trough my "buffering tank".
I run even double filters on input as well as water separating filter and then even added a silica air drying filter; still get condensation visible in clear tube where air gets into the tonearm as well as getting bubbles coming out between the manifold and the aluminum tube.
Result is that this compromises how the arm glides and makes the needle jump the grooves when playing.
By cleaning everything with alcohol I can get it to work well again, but it will just soon return with same problem.
I am using AT33ptg2 cartridge tracking at 2.1g, all mounted on SP10-mk2 turntable.
 If anyone experienced similar problems and found a solution please share your advice as I am sadly at the point of removing ET2 and replacing with conventional arm....
@sary,

Does the Medo pump you're using run constantly? If so, this may be your main issue.
No, I switch it on just when listening. 
The fact to consider is that there is pretty high humidity over here, but this happens always, even on "dry" days...
The fact to consider is that there is pretty high humidity over here, but this happens always, even on "dry" days...

There is a challenge when one tries to run a full 360 degree air bearing in Mexico or the Amazon. Adding moisture to the air bearing will have the same effect, as adding water to the oil of a combustion engine.

This is not a good environment. The air pump system makes up IMO 50% (EFFORT not COST) in the set up of the solution.

Was first using original aquarium AT pump at about 2psi and then upgraded to Medo AC0110 which delivers about 10-12psi trough my "buffering tank".

This is not going to cut it unfortunately .You are trying to run a Porsche 911 at the track with snow tires.  

Recommend a pump system which eliminates the moisture at the pump, and a regulator / water separator near the air bearing, that allows you to see the PSI and moisture level near the air bearing.
How long is the air line - pump to air bearing ?  
Does the PSI get lower along the way. It is an indicator that water / moisture is getting in the line, if you are losing PSI. 




I use a bottle of pressurized air, this comes from an industrial gas tank company. It’s not "free air" anymore, but it holds for a pretty long time, at least with my ca. 0.7 Bar optimized high pressure bearing. I think it’s somewhere around 2-3 l/ min.
The bottle keeps 30 liters, filled with ca. 200 Bar at the beginning.
The quality of the air must be very good... ;-) It’s from the swiss alps. Try to order it to Mexico... !
Jokes besides, I think in Mexico you might get similar industrial air, and you might ask about the humidity of the air under normal air pressure situation ("exhaled" ;-)
@sary,

When I said "run constantly" I was referring to when you're listening. A possibility is to get a 5-7 gallon air tank and the necessary parts (air pressure gauge, cut-off switch, etc....) so the pump will operate long enough to fill the tank than cut itself off at a desired setting and then back on at a desired setting. The tank will have a drain valve and you most likely will still need your filter/s. I used a Motorguard "toilet paper" filter that worked wonders. It also serves to buffer any pulsing from a compressor. Using a storage tank also keeps the need for buffering, lower and saves your compressor and helps keep noise a non-factor.

Hello, OK, understand, might try the setup with storage tank in the future.

At the moment I got exactly following setup:

Medo AC0110, 4 ft of 1/8 vinyl hose, air filter/water separator, second air filter (disposable filter as per ET specs), silica filled humidity filter, another disposable air filter, 0.6 gallon buffer tank, 2ft of 1/8 vinyl hose connected to the arm.

With Medo pump I am getting about 10-12psi (0.7-0.8 bar) measured at the tank (about 2 foot of hose ahead of the arm).

I looked at possible compressed air air-dryers, but this solutions are really bulky and expensive...

Looked at possibilities to build a copper tubes system (or use a condenser from AC or refrigerator) where compressed air could
be cooled down so water can be separated but did not come with practical solution; has someone maybe try something like that?

At the moment, I get condensation everywhere; in my first water-separating filter, silica filter gets water saturated, I can see water in clear pvc hose entering the arm and finally I get water coming out trough air bearing.....

Might be that here in Hawaii is just too warm and humid for this type of arm?

Obviously, possible solution would be buying a bottled industrial air, but I guess it is just a bit over what I am prepared to go for; it is enough having to take cooking propane bottles to be refilled every so often :) 

sary
Looked at possibilities to build a copper tubes system (or use a condenser from AC or refrigerator) where compressed air could
be cooled down so water can be separated but did not come with practical solution; has someone maybe try something like that?

Sary
This is exactly my solution that I implemented many years ago. Do research on Timeter Aridyne - 3500, 3600, 2000 models.

End of the road - no fuss no muss, no filters, no traps, no bottles, just keep it in a separate room (hidden from the wife if need be) with the airline running along the baseboard to your setup. See pics 12 and 43 on my AudioGon virtual system. If I recall back the noise level is around 55-60 db.

You can buy them used on ebay.

https://www.ebay.com/itm/TIMETER-Instrument-Corp-ARIDYNE-3500-Medical-Air-Compressor-System-/2916073...



@sary,

Interestingly, your question regarding if any of us have tried a DIY cooled copper coil set-up... I did something similar when I had a constant running compressor...I had my plastic air line, coiled up in a cooler with ice water before it hit my regulator. It turned out to be a "fool's errand". The Motor Guard filter was a God send. Good luck. BTW, Mexico or Hawaii?

It is Hawaii; humid, but not crazy wet :)
While medical air supply would definitely be the optimum, it is a bit more than ready to commit at the moment; not the actual cost on ebay which is pretty reasonable, but space and shipping...

At the moment I went back to my Audiomods arm and while I think was preferring ET-2 there is lots to be said about simplicity of simply swinging and lowering the needle into the grooves; no more jumping even on demanding tracks....

I still want to re-visit ET-2 setup in the future and when looking again into my exact setup I guess there is logical explanation why there is water and most of it just at the air bearing.

Since I had Motor Guard Filter/water trap in front of the buffer tank, it is likely that the highest pressure in my system was just in short PVC tube run between the buffer tank and arm; there was no filter here any more.

Highest pressure would mean most condensation...

Now, I am thinking, if I would actually have a filter/water trap after the buffer tank and then have pressure regulator just in front of the arm problem could be much better?

Could someone who is using Medo AC0110 please share exact configuration (pump, hose, tank, filter, regulator,...) that works well; would love to give it another try.



Sary - the base ET 2 does not work with 2 psi - you need at least 3 psi. this could explain one reason for your skipping.

I have helped friends setup systems in the past. Regarding the regulator.

Type - Ensure your regulator comes with a water trap. Like this.

https://photos.app.goo.gl/eomCEWeVxLZxqn9U9

Location - as close to the air bearing as possible. Less chance of moisture getting in after air passes through it.

Usable gauge scale range - makes no sense for example, to have a 100 psi scale for measuring 3 psi which the base ET 2 requires.

Regulator Spring tension rate - higher PSI firmer spring rates to better engage/accuracy for the regulator, and the reverse, softer regulator
spring rates for lower PSI.

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

Regarding your comment on the convenience of pivot arms. Convenience will always win out in the end, especially as one ages. I have a Dynavector hybrid / pivot arm in my second room I use occasionally to test out records.
The key here with the ET tonearm / pump system is. IMO, to get a setup going that is as close to turnkey as possible. You throw the switch - no more fiddling.

My pump system lives in the back bowels of the house. A forgotten setup except when needed and then it is critical. Our Savannah cat has shown an interest and climbs up on it occasionally. Maybe I can teach her to throw the switch for me and really make it turnkey. 8^0

I purchased the big boy Aridyne 2000 with minimal hours a couple of years ago, for a good price, but the shipping and customs was high. You would not pay customs being in Hawaii. It is a backup for when my older smaller Aridyne gives up the ghost. But it keeps on going.....

Chris
Glad you got the Savannah settled in after all!
Try life with 2 Savannah and 2 Bengals.
Makes for fun vinyl times!
Ok interrupt over!
Hi Kevin - yes, she is settled in and in charge. New guests are amused watching her stare down a 90lb Black Labrador Retriever and have her way with him.
Felines and turntables - its make me shudder. With one swipe she can take out my drive system - string - easy to replace 8^0 , but the tonearm wiring or cantilever (much more expensive).

Greetings, all,

I know this isn't a for sale/wanted thread, but my ET-2, AirTech tank, Wisa pump, and cartridges were lost in a flood a couple of years ago. I've built a new house, have replaced most of the rest of my hardware (just found another Oracle Delphi II), but it seems that a complete ET-2 is rarer than an Acutex 420 in the Sahara desert.

Do you gentlemen know of anyone who might have one to sell? Am wondering if I should just buy a turntable I'm not interested in on Ebay just for the ET arm.

Many thanks,
Walt, who has a Medo AC0110 and big surge tank waiting....
Hello Walt
Sorry to hear about the flood. 8^(
when you say "lost":, do you mean in the literal sense, as in never found, or maybe went with the flood debris as part of the insurance process?  Reason I ask - Water cannot hurt an ET 2 - it can be cleaned up, parts sourced from Bruce, and Bruce can also verify operation of the VTA block worm gear. 

Chris 

Thank you, Chris. I've very much enjoyed reading your comments on this thread.

Here's the thing: I cleaned up the ET arm pieces after the flood and boxed them up for a very thorough cleaning later. That box and a few others disappeared from the "secure" storage facility I used at some point, so I want to go ahead and get another ET2 should one become available. 

Walt - I will private message you through AudioGon, if I come across the availability of one; as I am sure others will as well. Bruce may know somebody. . I would reach out to him. Appreciate your comments. Chris  
Chris, 

Does $288 + $200 shipping sound like a good deal to you on an Aridyne Timeter 3500 with fewer than 600 hours?
Hi Walt - it depends.
Is it a beige colored cabinet like in the links below - newer - as opposed to the older orange cabinets ?
I would not worry about the hours since they are hospital grade. They are all used to a certain hours / time period then decommissioned - leases etc.. A wholesaler will go into the hospital and buy XX of them with varying usage. These are the sellers on ebay and the like.

If possible ask the seller to open the back panel and send you a picture of the insulation. This is the part that can start decaying on the older orange ones. Is the insulation in good condition - not discolored or frayed, some of it falling off ?

If possible ask the seller to put a load on it - hook something up to it - and verify that the internal regulator turns smoothly. On older units this can get sticky from water hardness and not being used. This is an issue but not a showstopper,as you can just close it (the regulator) permanently - this puts the compressor on full out PSI mode - and add an external regulator instead. But the external one will cost another $50.
If the insulation is in good shape and the regulator is good then the $250 range is a good price. imo. They are $2500 us dollars new.

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

Shipping
For shipping it’s like a floorstander speaker so needs to go on a pallet.
I would do a search on medical whole sellers in your area. You might find one available locally or within driving distance and save on shipping.

As I am in Canada..... I got soaked on shipping costs for my 2000 plus duties/customs - the shipping ended up costing 4 times the price of the great deal I got on the unit. But my 2000 was like a ... picture a Barn find, very few hours and even the 12 volt battery was showing a full charge. But I am still using the 3500 - keeps on ticking. 8^0

The Compressor/Pump can be as we know an audiophile journey on its own. We have discussed here how to test ones pump.... for noise going into the audio system.

********************************************
Timeter Aridyne System- how it works - from their site

The system works by drawing and filtering ambient air through the air intake. The air is compressed to 80 psi and then cooled via the internal cooling coils which condense the moisture from the compressed air. The moisture is collected in the condensation trap and automatically drained into the evaporation tray. The cool, dry air is then regulated to 50 psi and delivered to medical devices through multiple outlets.

the 3500 model is $2500 us dollars new

https://www.global-medical-solutions.com/Allied-Healthcare-Timeter-Aridyne-3500-High-Flow-Medical-Ai...

the 2000 model is $3000 US dollars . It also has battery backup - so your turntable will slow down but your tonearm will not be affected saving the record from skips in a power loss situation.

https://mfimedical.com/products/allied-healthcare-timeter-aridyne-2000-medical-air-compressor

This article shows the differences between them

http://www.alliedhpi.com/images/z10-00-0081.pdf

Cheers Chris
I recently was returned to AMC (the analogue manic clinic.)
It started with staring at the cold black turntable and dust accumulating there on. We know that seeing dust & cleaning is dangerous to many in average predominantly female persons, leading to well known manic episodes. Where at some places undefined flying objects appear, in the latter case defined objects disappear in a flying mode. Including sometimes dear and important things. (I admit havin some messie traits).
The more serious part:
I had a fight with my London pony on the ET2.5 which has its damping trough inabled, but with moderate eddy current damping provided by a small magnet (far away from the wiring).
So I still intend.ed to model the complex spring mass interactions of the ET2 & ET2.5 and I asked Bruce Thigpen (once more) for the +/- precise masses involved with the ET2 & ET2.5, and quote his given data for completeness of infos on this board:

- original aluminum wand mass: 12 grams
- CF wand mass about: 19 grams
- magnesium wand mass about: 23 grams

- Joint insert into wand is 6.5 grams

- ET-2 spindle 23.5 grams
- ET-2.5 spindle about 30.5 grams.
(spindle figures are without wire or connectors)

From measurements, roughly:

the lowest vertical effective mass is

- about 12 gram, original wand with 7 gram cartridge,
- about 12 grams CF arm wand with 7 gram cartridge
- about 14 grams for mag arm with 7 gram cartridge.

- Vertical effective mass increases about +2 grams for the 2.5 spindle.

The lowest measured horizontal effective mass is

- about 30 grams, original wand and 7 gram cartridge
- about 38 grams, CF wand and 7 gram cartridge
- about 42 grams, magnesium wand and 7 gram cartridge
- Horizontal mass increases another +7 grams for the ET-2.5 spindle.

I try to let models follow, maybe some weeks from now.
The second part in my next post:
"Do the wrong thing!"
Having trouble with my London cartridges mechanical behaviour, having tried quite long, I concluded that I simply wasn’t able to apply enough damping, the thing was "meta-stable", although there were quite a few elements of greatness.
So, what do to do? I had as an interim replacement of my MC phono stage a Lehmann Black Cube SE in use for my London, set to MM cartridges. So staring into my not (...) empty cartridge drawer, I recognized a slightly dusty beauty lurking within:
A B&O MMC1, bought from a B&O dealer, seeing it’s lonesome place in a window, this was maybe beginning of the ’90s.
So out with London, in with B&O. Well... magnesium wand, ET2.5 spindle and whatever counterweight will be: "The wrong thing".
From time to time refusing correctness is indicated by your mental health officers: Yes, the horizontal resonance is around 3Hz, the vertical considerably higher but not visible. As you may have noticed in this thread, I have my counter-orthodox opinions in case of low horizontal resonance frequencies (not in case of vertical resonance).
Theories besides: This combo works absolutely *phantastical*, it digs deep into the grooves and is highly musical as well as very uncoloured and naturally liquid. It also has deep and quick bass. It stands out of the way in communicating the music and constantly bringing this amazing slightly shuddering feeling when you enter different worlds from LP to LP, hearing amazing musical, timbral, expressive nuances.
So my quintessence is: From time to time, try things that don’t work, as far as anybody knows. And be amazed by the unexpected joys of reality vs. correct thinking. It is indicated for mental health - and for sheer pleasure & guilt.
The MMC1 is one great cartridge – as probably the MMC2 is too - and it works in whatever ET combo, I have to assume.
This is probably thanks to the B&O engineers being *the* kings of precise engineering and damping in turntables/cartridges. Remember: The actual (eternally circulated) knowledge about optimal tracing and suspension tuning / damping of turntables comes from... the B&O stable. What great lab!
PS 1: Soundsmiths SMMC1 is the ca. successor of the MMC1, except that it uses a "massive" ruby cantilever instead of a small saphire tube (with superbly mounted paratrace diamond in the original MMC1).
PS 2: It "feels" to me like every cartridge with saphire cantilever has/had a very special quality I very much like: The Sumiko Talisman S, my "special" Jan Allerts MC 1Mk2 (and MC2 Finish) cartridges, as well as the MMC1. It is a grainless coherence and ultra-quickness through the whole range through midrange into upper treble. It’s a cantilever that kind of disappears from the mechanical formula.

pegasus
Having trouble with my London cartridges mechanical behaviour, having tried quite long, I concluded that I simply wasn’t able to apply enough damping, the thing was "meta-stable", although there were quite a few elements of greatness.
@pegasus
Without more detail, the carts "mechanical behavior" we know - is greatly influenced by the I -Beam counter weight set up,

Are you using a single, double or triple leaf spring ?

Long or Short I Beam, and are you set up for the highest vertical inertia ?

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

https://www.needledoctor.com/brand/London-Decca

Decca
• Output impedance: 2k ohms
• Dynamic compliance: 15x10-6cm/Dyne
• Channel separation @ 1kHz: >25dB
• Load impedance: 47k ohms

I don’t own a London cart. The Decca’s have medium compliance so just by the numbers alone they straddle between the ET 2.0 and 2.5 at 15 x 10-6cm/Dyne. Carbon Fiber or Magnesium armtube. I would set up on the Long I Beam. Double leaf spring set to the highest vertical inertia**. **Least amount of weights furthest out on the I Beam.
Try with no damping trough first. .

Hi Chris - thanks for your thoughts!
As you might remember I already owned the ET One and bought the ET2 about when it came out, and the physics behind interest me and I try to understand, master & use them since a long time... and I actually like to adjust & optimize the arm :-)

The London cartridge has a very uncommon combination of very high horizontal vs. very low vertical compliance. (ca. 40cu or more, vertical is below 10 cu). With conventional arms this leads to a one octave separation between horizontal and vertical resonance.
So, the cartridge does somehow the same "thing" with normal arms as the ET2 / ET2.5 or other tangential arm do with normal cartridges, (air bearing or mechanical passive arms) or the Moerch DP8 or the Dynavector arms: They split the resonance frequencies (of "normal" cartridges) too.
With such cartridges, I think Supexes were similar, you end up with two times the stretch of resonance frequencies - which is critical.
It results in an optimistic 12 Hz vertical resonance and 3 Hz or even lower horizontal resonance.
My London cartridge was restored and optimized by a swiss guy who learned / was trained & worked for Garrot Brothers. It has an even higher horizontal compliance than the usual Deccas (leading to lower VTF)

The lack of damping in the suspension (which provides a highly linear and probably also frequency-independent spring force) makes damping IMO a necessety. My small magnet is simply not enough, though it works very well in normal situations.

It sounded very good in pressings that worked. 
I use.d the new long i-beam, single spring, lowest counterweight far out (to bring this stiff vertical compliance to a rel. higher vertical mass).
And no it was not the low resonance of the i-beam / counterweight that made the thing slightly instable. And neither do I see a real indication that the low resonance frequency in itself was the problem:
The MMC1 has a similarly low horizontal resonance (ca. 3Hz) on my ET2.5 combo.
My feeling is also that other cartridges work more linear with wide excursions: They are more bullet proof, and "behave" better or / and are implicitely more damped.

It is BTW principally by no way easy to tune a tt suspension to fit / isolate a highly untamed vertical resonance of not far above or around 10 Hz from floorbourne vibrations.
@pegasus
(if you are disenchanted with your London) - Send it to me I will mount it and report my findings here. I have been curious about that cartridge for a long time. A good winter project and winter has come early here. 20 degrees Cel. below where we should be this time of year. So much for global warming. 8^0

@frogman
I think Frogman has one , an older version/ from what I remember? had grounding issues due to the common ground pin (3 pin) arrangement ? If he sees this maybe he can comment on the mechanical setup/tracking ability achieved - aside from the noise issues common to the older ones.

Is the damping trough a nice to have or absolute necessity with this cart. As we know the damping trough - slows - things down.

Hi Chris - yes I remember that frogman has direct experience with a Decca London, although not all Londons are created equal, you could try it. Although it also waits for being mounted in a Thales Easy arm... sending a cartridge between continents needs a bit of research how to do that in an economical way.

I think fluid damping is necessary with the Decca on the ET2 or 2.5.
Taking Bruces numbers, I doubt that "my" "heavy" setup will essentially change resonance characteristic compared to the lightest setup (in numbers: ca. 49g eff. mass with cartridge vs. 37g). It’s a not really considerable 30% difference, which results in ca. 15% difference in resonance frequency. Eliminating a major problem normally means considerable changes.
Ie. a 15% resonance frequency change is IMO usually less important than to introduce damping.
As the London Deccas come with a very "clean" spring with practically inexistant damping - which leads to some of its qualities, overdamping with it's sonic issues goes one or a few mile with that cartridge...
The Grado wiggle vs. London dance is a bit like senior gymnastics vs. voodoo dance.
I have NOT read through this ..'extensive' thread, but I wonder if anyone is still using the ET2 with a Linn table. Back in the day, this was a pretty common combo...and one that worked very well. Today's Linn is far more transparent and resolving than the vintage model that typically had the ET2 arm back in the day. So, another question would be how great the arm would sound on a current Linn Radikal D Klimax version..and if anyone has actually tried that?
Hi Davey, you’re outside of the fenced green pastures of audiophile correctness if you mount an ET2 or ET2.5 onto a Linn. But outside the fence, there’s life too!
Because the ET2 / 2.5 is not a heavy arm it’s feasible, probably needs "expert tuning" of the springs.
Caveats are two: The leverage of the arm tends to tilt the subchassis slightly from one side to the other when playing an LP from beginning to end.
And there’s a second issue that can be resolved with a Linn accessory / modification: The Bespoke spokes, that stop the subchassis from rotational modes, but leave the subchassis vertically decoupling.
This is crucial because rotational modes are only very mildly coupled to a radial tonearm (they counterhold the vast majority of these forces within the horizontal bearing, except for slight dynamic imbalances (in the horizontal plane).
With tangential arms thr inertia of arm and counterweight don’t compensate external forces. So rotational modes lead to slight, but constantly varying horizontal movements of the bearing and cartridge suspension, and therefore a subjective instability, in effect like a wobbly skating force. These modes are "tracked" because usually the horizontal resonance of the arm is below (or around, and not better,) the frequency of these rotational modes.
The Bespoke modification has some slight drawbacks, it seems, but it is in effect quite brillant and will work wonders in this (specific ET) situation.