Eminent Technology ET-2 Tonearm Owners

Hi Dover,

It would seem to me that the constant corrective motion of the arm to compensate for LP production imperfections, either lateral or vertical (warps), would involve some degree of "overshoot" and, thus, generate some stylus/groove misalignment due to inertia and that a properly implemented damping system would reduce this overshoot while having minimal impact on the initial transient response, ie using a minimal amount of the damping fluid such that the paddle only skims the fluid's surface (per Frogman).

I would not argue that the use of damping is a sonic tradeoff in practice and would not be desirable in a world of perfect LPs and ultra-stable resonance-free cartridges, but perhaps it is a desirable solution in our real world of neither?

Dave

Dlcockrum

Precisely

Dlcockrum
Yes I agree that damping may be required in some cases, and that running the paddle at the surface would be best. That is how I set the paddle with the Townsend TT.

However, the application of damping should be a last resort. In my experience many folk have applied damping to cure a "resonance" that has resulted from poor set up eg VTA, tracking force, etc and could have been removed by careful set up and in the case of the ET tuning..

I have used electromagnetic damping on my ET2 as discussed earlier in this thread. The damping is created by eddy currents which are only generated when the arm moves relative to the magnet.

I have run the ET2 for 25 years and found that the higher compliance cartirdges such as my Shure V15vmr benefitted most from electromagnetic damping.

With lower compliance cartridges such as Madrigal Carnegie, Koetsu, Denon 103 and Benz Micro fluid damping slugs the sound in my experience. Bear in mind that I run a decoupled counterweight assembly rather than a sprung counterweight - this has the advantage of keeping the ET2 horizontal mass as low as possible. As your friend Frogman has found, running the counterweight decoupled has produced quicker, more transparent bottom end in his system.The set up procedure he described above is the same as I have used.

A little history here -

If you read Bruces manual and patents he starts with a low mass arm, and then brings the effective horizontal mass up very gently by providing variable spring rates on the decoupled counterweight. This is formulated to keep the differential resonances between horizontal and vertical in sync with the compliance of the cartridge and the Q of the system. The Q is related to the dampening of the oscillation - the use of magnetic dampening will shift this slightly. Very small adjustments can give quite dramatic changes to the sound, especially in speed, transparency and articulation.

Krebs approach has been to load up his ET2 with 30+ grams of lead. He has also removed the decoupling spring from the I beam. Effectively he has added some 60g to the horizontal mass of the ET2. It is no wonder that he has changed his mind after 20 years and is now using fluid damping. Mass increases inertia and has no dampening properties. The high horizontal mass he is running has increased the side forces on the cantilever by over 300% when the arm moves back and forth increasing cantilever flex and distortion.

Quote from Thigpen

If the weight is coupled the system resonant frequency would be extremely low, a resonant frequency at 3Hz with a significant rise in response (6-12dB) results, which would affect tracking slightly because of the asymmetric position of the cantilever, we opt for splitting the horizontal resonance frequency into two points and lowering the "Q" which improves tracking.
More important than tracking, the intent was to reduce the modulation effects of low frequency energy (FM and AM) that increase distortion in the cartridge

I note that DGarretson has been experimenting with his Terminator tonearm. The Terminator in standard form has a much higher horizontal effective mass than the ET. DGarretson has reduced the horizontal mass quite substantially by reproducing some of the parts and yielded significant improvements.

12-01-13: Richardkrebs
H F Dover.
Still....relative to the groove.
Everyone else understood what I meant.

Thank you for that feedback. I'm surprised the results from the Eksen Research survey were available so soon.

Slaw - As I was curious I sent an email to Jun-Air on weekend when I saw your post.
Their help desk was open this morning.
I received a response. fyi.
Just great customer service btw.

Re: A Jun-Air 16-25 w the moisture trap/container option.
When the compressor reaches it's max setting, it cuts off and immediately starts expelling air.
Can you offer any advice in how to troubleshoot this problem.
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Hi
It sounds like a unloader valve is sticking.
Thanks, Garry
Garry Unrath
Technical Assistance/sales
Ph. 269-926-6171 ext 1114
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Thanks Gary
How would you recommend fixing this ?
Replacing a part or maybe opening it up - can the valve be lubricated in some way?
Chris
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Hi Chris
First I would try cleaning out with electrical contact cleaner. If that does not help I would suggest a new one, part number 6973080.
Thanks, Garry

Do you mean to tell us all, they have Home Depots in Canada???

yeah - you know the damn stores are everywhere - at least 70-100 in Ontario
There are 10 within an hours of drive of me incl. one 7 mins away by car (or 45 mins away by horse & buggy)

Regarding the Timeter pump - can't recall which model you have.
Mine is the Aridyne 3000. There is no brass lip to wear.
It has a hours counter on it that when reached - hospitals are required to replace them.
They are cheap on ebay and the quality of air is the best I have ever experienced.
Its a 50 psi pump that I steal 19 psi from and the rest going into the atmosphere.
Because of this and with some of the funny posts hear lately,
I am thinking of hooking up an extra line for myself this winter - you know -
for when the posts crack me up to the point of having trouble breathing.
Its around 60-65 db exposed and not closed in so it needs a separate room.