Eminent Technology ET-2 Tonearm Owners

Well said John.   In an effort to contribute I want to give a shout out to the Medo AC0105 air pump.  It is rated at 7.11 PSI so it's only suited for those of us who have not upgraded to the high pressure manifold.  It is also rated for a 60 min duty cycle.  That aside, I have been using this pump for about three months and twice I have forgotten to turn it off when I went go bed.  It just keeps pumping along and my gauge says I'm getting about 8 PSI.   It is not quiet enough to be close by the listening position and does run hot.  However, in my experience, it is quieter than the famous Wisa.

I solved both issues by building a sound box with a plate fan in one end and vent in the other.  The box is built from mdf and lined with carpet padding both acquired from the audiophile dept. at Home Depot.  The plate fan is very quiet and purchased from Amazon.

I have about $125.00 in the whole project including the pump and a new PVC surge tank.

Anyone wanting more details, let me know.  

Regarding arm boards and optimal materials, it's very interesting to watch the diverse experience in idler drive plinths. A mixture of natural and slightly lively wood layers, combined with *some* more deadened materials, like *a bit* of MDF and maybe one layer of stone seems to yield very good results. Pure MDF not, neither Corian, synthetic stones, marble or metal is desirable. I think a considerable part of this experience should be considered when thinking about armboards. Solid wood and *maybe* a bit of acryl or alu smewhere should work well too.
Personally I'd seek other materials than overdamped polymers like Sorbothane - it's sounds like s*** as a platter mat, and it's audible wherever one uses it. Even natural rubber feet on speakers (or under analogue decks) sound IME sluggish. It's easy to overdamp surfaces and overtighten connections (not only because of eg. making cracks in the ET structure :-). Both result in kind of a deadened, "negative feedback" kind of unnatural sound.
Solid maple? A friend uses solid oak to very good effect for the adanalog arm.
For ET arms maybe solid sBruce is the optimal wood...?
An eminent discovery.

Pegasus
Regarding arm boards and optimal materials, it’s very interesting to watch the diverse experience in idler drive plinths. A mixture of natural and slightly lively wood layers, combined with *some* more deadened materials, like *a bit* of MDF and maybe one layer of stone seems to yield very good results

.
Pegasus Re: idler drives
When I was curious and going through a turntable phase, any thoughts of building a plinth for a stock L75 Lenco as a project were squashed after acquiring a Jean Nantais Lenco, and having a look under the cover.

JN Lenco

From my experiences, the idler design deals with the highest noise factor. I think the Lenco Swiss motor is art, but the wheel interface with the platter is not. Some go to extremes to contain resonances/vibrations. Looking at the pic in that link - JN found that huge voids are necessary under the armboards and motor areas; wide open to the bottom to help with containing/absorbing the resonances/vibrations. I/3 ? of the plinth is empty (air) - but it still weighs 100 lbs.

So now I have a dilemma. Frogman sending the extra arm board and Bruce sending the longer grub spikes. Ahhh, so many choices, so little time.

I wish all decisions were like these ones Harry .....:^)

Hi Chris! I accidentally grew up with a Lenco B55 (practically same technology as L70/75/78) and a Thorens TD 124. These were the first victims of my brothers and my audiophile interests - we dismounted and reassembled them. I was more impressed by the ingenuity and elegance of the Lenco - *and* I still remember the sound as very upbeat and vivid, memories reaching almost 55 years back! Much more so than my slightly lukewarm memories the TD124, I'm sorry to say...
The Lencos plinths empty rooms are not for controlling resonances - they are for ventilation, as the motor, a shaded pole motor, has very low efficiency and consumes *35W*...! I rather think that in the end this is more of a weak point than the idler wheel. My impression is that the vertical low mass idler wheel is (within the context of idler wheels) a very good idea. The weak point there is a) the steering of the wheel with kind of a rod with limited stiffness and b) the exact positioning relative to the conical axe of the motor. But...
Rehearing the L75 in a friend's (superb) system with modded Avantgarde Trio etc. etc., after years of listening to a Well Tempered Signature, then a Funk tt with Funk arm was a revelation - already with a simple plinth. Of all "real existing" turntable platforms it is in musical, timbral, dynamical and coherence terms almost in another league - and it is a "stone age" concept. It really was a jaw-dropping experience. ca. 1980 I *never* considered re-using a Lenco or a SL1210). I was a *real* audiophile, who had to use a belt-drive... I bought a Thorens TD 126 - one boring lifeless turnatble. Then came the Rega 2, then a Walker CJ55. Both really much better in musical & colour-terms, then the WTT Signature in my system too.
Funny how  I moved from "scientific" musical medicine back to "evidence based" or empirical musical medicine.
Today I use a much modded SL1210, which has a slight advantage in purity / stability of upper midrange timbres.
In Europe Pet Reinders is the Lenco "guru". I can do without gurus, though he has a good solution for the basic motor / bearing platform.