et-2 damping trough-good idea or not?

Hi Frogman/Raul - hope this helps a little. I needed the rehash. Let’s try to understand this better and hopefully in words that anyone reading this can understand.

So we know it’s a resonance, vibration hobby - playing records. As far as the tonearm/cartridge combination mechanics on their own - it’s a spring system, with a natural occurring frequency -Resonant Frequency. Thinking about a tuning fork helps. A stiff tuning fork resonates high. Like a stiff MC cart with its low compliance cantilever. A "less" stiff tuning fork resonates lower - like a less stiff MM high compliance cart.

This shiny piece of black vinyl record is not perfect as we know. Non-centered center holes that cause speed and other issues, warps, scratches..... but if we look closely when the record spins, surface irregularities exist. Bruce discusses this in the damping trough manual. These irregularities are not part of the cutting process, but the molding process in making the record. You can see the small ripples on the surface as the record turns. These ripples excite the "natural resonant frequency" of the tonearm/cart. combination being used.
We want these resonances (which are not in the recorded music) to remain well below 20 hz where we can’t hear them. When a tonearm and cart are badly matched - resonances will rise and could and do cause problems. if the system is resolving enough it will be heard.
Bruce did measurements and found most tonearm/cart combinations give rise to the frequency some as high as 8db with high Q. Ok this is technical. Applies to speakers also, and this number would not be tolerated there. Yet no one has ever discussed it with vinyl play. 8^0... Anyway, the result of this resonant rise, he called the "Effects" - and they can be subtle and sometimes not so subtle - reproduced on our systems.
The Effects can cause a phase shift. Put simply the time the low frequency signals come from the tonearm/cart, are slightly shifted from the mid-range frequencies within the audible range, and substantially shifted up to several periods of resonance. Bruce measured near perfect low frequency phase response when the original ET 2.0 was used with the damping trough.

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The first ET 2.0 with "aluminum" armwand came out when MM’s were popular. So.....1) aluminum armwand with 2) MM cartridge, and 3) single leaf spring. The three are a good match in resonant natural frequency. Then stiffer lower compliance higher resonant MC’s arrived, and the damping trough was introduced.

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TAKEN FROM THE DAMPING TROUGH MANUAL
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Please note that the tonearm now responds much more slowly due to fluid damping.

A low frequency sweep was performed twice on the tonearm, once without the damping trough and once with the damping trough. The cartridge used was of very low compliance and the tonearm was set up so that a high amplitude high Q resonance existed. The results of the test show a reduction in the amplitude of the resonance of about 8 dB (horizontal). Not shown is the vertical resonance which was 15Hz with this cartridge and was reduced about 2 dB.

https://photos.app.goo.gl/oWHujb7CygwLU8SC7

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In due course Bruce introduced the larger bored out ET 2.5 (lower resonant frequency air bearing manifold) with Carbon Fiber and Magnesium armwands were introduced, along with the double and triple leaf (stiffer leaf) springs to deal with stiffer higher resonant MC. So - Likewise the ET 2.5 with Magnesium wand mated with double or triple leaf spring, mated to a high compliance MM is a bad match.

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The first ET 2, the 2.0 version. with "aluminum armwand", and low compliance MC cart produces higher resonances - and is a bad match. Frogman confirmed this with his findings here.

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There are folks on the ET2 thread that are using an ET 2.0 with aluminum wand and MC and single leaf spring, and do not have a damping trough. Most have made other mods - either to the headshell or armwand to compensate. So anything is possible but we really do need details on gear setup here, when people give their opinions. For it to be helpful to other people. This is not plug and play. Vinyl never was in the higher end. 

Remember we have no idea what lies downstream of the turntable in peoples homes and how the rest of the audio chain matches up to what is before. This helps to explain the infinite opinions on this forum.
This link in the ET2 Tonearm Owners thread, shows the setup to be followed for MM and MC carts - endorsed by BruceThigpen.
We called it one of the yellow sticky guidelines

https://forum.audiogon.com/discussions/eminent-technology-et-2-tonearm-owners/post?highlight=yellow%...

Dear @ct0517  @frogman  : I understand the issue of tonearm/cartridge resonace frequency.

"""  Please note that the tonearm now responds much more slowly due to fluid damping.... """

That could affects in some way the freely cartridge stylus ridding the recorded LP surface but for forgman " overdamps " with the other wands but aluminum where is an improvement.

That does not makes " click " for me with foundation in my premise in my first post here.

I don't know you but I need to find out a different explanation/reasons for that " behavior " because resonat frequency can't explain it at least for me. Why in the same scenario where only changed the wand something has an " improvement " and something " an " overdampiong "? this is the subject of what I need an explanation because I'm ignorant about with that tonearm/cartridges combinations.

R.

@rauliruegas

Raul - firstly - what I like to keep in mind for myself. It helps me is this.
All around us are materials that have their own resonant frequency. Now when something is made - with multiple materials, like a tonearm or a cartridge, the resonant frequency becomes that of all the materials, and it depends on what percentages of each material that went into making that tonearm or cartridge. We then join those two - tonearm and cartridge - we get another resonant frequency, and then they interface with something - in this case the vinyl record.

When they are put against a moving vinyl record which is not perfect, and has imperfections I discussed previously - like the ripples; these imperfections, since this is a vibration resonance activity - EXCITE - the resonances. You can see how much in the graph.

That could affects in some way the freely cartridge stylus ridding the recorded LP surface but for forgman " overdamps " with the other wands but aluminum where is an improvement

Look at the graph in my previous post. It describes this scenario. That was a low compliance cartridge set up to produce a lot of resonance with the aluminum armwand. The oil trough smoothed out the resonances. It helped. Now if the carbon fiber or magnesium wand was used instead with the trough, because of these armwands lower frequencies the damping trough would probably have been too much. The results would not have been good and I believe this is what Frogman experienced.
Maybe Frogman can elaborate here if what I am saying is off.

Dear @ct0517  : Through my audio years I learned that well damped tonearms designs always performs and sounds better that non-damped ones.

I remember at least the experiences with 3-4 of my tonearms: Micro Seiki MAX, SME V and Audiocraft where all gives you the posibility to handle damping through silicone oil.

MAX 282: I started to listen it with out the external silicon damping and was just great using any of its 3 diferent arm wands.

One day I put silicon in the tray to look what happens with and what I listened did not like me: suddenly the sound losted " life ", gone in the dark side near severe dull response.
I was disapointed and return to listen with out silicone oil.

In those times I owned too the Audiocraft unit and made the same with similar results, I did not like it with more damping.

Latter on and with more attended events of live music and with experiences seated at near field position I came back to my MAX unit and try again the silicon oil and left that way for 2-3 weeks because after the first week I started to appreciated the true advantages of the damping silicon oil.

Where I listened the first advantage was precisely in the bass range that came tighter, precise, not bloated and with no overhang and this makes that the overall frequency ranges stays truer to what I listened in a live event. The Audiocraft experiences were similar.

Through the time the tonearm damping is a must for me. I own/owned non-damped tonearm as the FR/SAEC and differences for the bad/wrong are truly high vs damped tonearms.

But guess what? several/many audiophiles prefer non-damped tonearms or not very well damped ones.

It's almost imposible to overdamp a tonearm because is extremely dificult to stop/inert the horizontal movements due to LP off-centered, the friction forces generated at the stylus tip and the inner oriented vector generated for th LP spin velocity. Overdamping could means problems with cartridge ridding that we can listen it as a mistracking often events and with my very good damped tonearms the good tracking cartridges even are better trackers and I tested with several LPs like the Telarc 1812 where you can listen with more clarity and precision the cannon shots so the harmonics developed are more open/cleAnsed and this helps A lot to the whole frequency range: bettter overall quality level performance.


The SME uses magnesium build material that's very well self damped material and even that the optional silicon oil external damping always sounds better than with out silicon oil.

The Townshed TT is the more radical example of tonearm damping becuse it happens at the nearest position to the cartridge you can do it and you can hear its very high advantage in the damping regards.

Yes, the damping works diferent with diferent tonearm build materials. Aluminum is more resonant than magnesium so we can hear higher improvements in aluminum than with magnesium but even with magnesium or other less resonant materials always we can listen the damping advantages and its whole benefits.

That we can like the more with out than with is something that I experienced and truly convinced I was way wrong.

I have experiences with other tonearms and results are similar when are well damped and when are non-damped.

For the people, normally, the non-damped are more alive with more detail and better HF but all these alive and the like are only additional generated distortions/resonances/vibrations.

The ET2 designer knows very well what I'm talking about as Townshed too.

In the analog rig our enemy are: resonances/vibrations/generated distortions, so we need the best damping we can in the TT it self, arm board, tonearm, cartridge and the LP surface contact.

I don't know if you remember that Sumiko had on sale a very flexible and low weigth belt-like that was used in helicoidal way around any tonearm wand to function as an additional damping and guess what: it works wonderful !!!!


My advice to the OP is: go a head with the ET2 damping trough.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

At the headshell is the most effective location to apply a damping system to a tonearm/cartridge, for reasons explained in the writings on the design of the Townshend Audio Rock turntables, currently out-of-production. But the Rock is not usable with linear tracking arms, only pivoted ones.