Eminent Technology Two tonearm Guy Lemcoe October 1991
"What's in the box, Guy?" asked Nicholas Potter, Santa Fe's sole purveyor of used records and CDs.
"CDs," I replied.
"Always glad to see 'em, especially the classical ones. Cleaning out the closet?" he queried.
"In a sense, yes. They don't sound so good anymore,"
"Because I've made some improvements to my systemtweaked my ET tonearm," I replied.
"That's the one with the air bearing, isn't it? The one you hook up to an aquarium pump?"
"Well, sort of. I replaced the pump with a high-pressure model, installed a new manifold in the arm, and added a damping trough and a dial indicator to it."
"Sounds like car repair. Did you put a Grado cartridge on, like you suggested I do with my setup?" he asked.
"Not quite. I'm happy with my Monster," I replied.
"By the way, Guy, my Grado sure sounds good."
"I thought you'd enjoy it."
"So, you don't like CDs anymore?"
"That's not the question. It's just that my LPs sound better now than they ever have," I replied.
"Read my upcoming article in Stereophile. By the way, got any new used LPs...?"
Bruce Thigpen's Eminent Technology Two tonearm is an engineering and design triumph offering outstanding performance at a modest cost. It is well known for its flexibility and adjustability, and graces many music-lovers' turntables. Upgrades (all retrofittable) have been offered from time to time, including rewiring of the arm tube and spindle with van den Hul silver. More recently, attention has been paid to the air bearing itself. The stock pump delivered about 2½psi at the arm. What would happen if this pressure was increased? Might not the bearing itself become more rigid? In addition, could a reasonably priced surge tank, or "buffer," be sold to ensure a non-pulsing air supply?
In response to these questions and apparent consumer demand, Herb Wolfe of Airtech Audio introduced to the high-end market the German-made, medical-grade WISA high-pressure pump and the Airtech surge tank/air reservoir (footnote 1). The pump is a high-pressure type with low flow. (The Takatsuki pump supplied with the ET 2 is a low-pressure, high-flow type.) Used with the Airtech tank, the Wisa pump delivers roughly five times (12psi) the air pressure at the arm. But the original ET 2 manifold was designed for air-flow rates and pressures different from those supplied by the Wisa. Will the benefits of increased air pressure be fully realized by just substituting pumps?
Well, yes and no. Yes, there will be a sonic benefit, but no, it will not be optimal. Even so, when I first installed the Wisa pump and Airtech tank in my system (the arm is mounted on a VPI HW19 brought up to the latest specit's a Mk.3.5, I guess), I noticed, in addition to a striking attenuation of background noise, a significant improvement in low- and midbass pitch definition. What before had sounded vague now took on unmistakable identity. For example, the kettledrum strokes toward the end of "Irish Boy" from the soundtrack album Cal (Vertigo 822 769-1) were resolved with more clarity, "weight," and speed than I had heard before. The placement of those drums on the stage was tangible, as was the canopy of air surrounding them. In fact, I could easily visualize the felt end of the stick as it struck the taut skin of the drumhead. This was indeed impressive performance; I spent hours playing album after album, discovering nuances of sound unheard up to that point.
Tighter, more extended and pitch-defined bass is not the only sonic improvement to be gained from changing pumps and adding the surge tank. Transients were rendered more dynamically, with less "smearing" than before. The initial attacks of such struck percussive instruments as drums, cymbals, and triangles were sharper and more clearly defined. More "snares" could be heard on snare drums. For example, Joe Morello's drumming (especially his delicate brushwork) on "Swanee River," from the Dave Brubeck Quartet's Gone With The Wind (Columbia CS 8156), was reproduced with stunning realism. (No apologies need be made for this 1959 recording!) Similarly, the leading edges of bowed strings had more "bite," sounded more resinous, and vibrated with more vitality than before.
I was particularly moved by the nuances of Gidon Kremer's bowing technique as captured in his stirring performances of Bach's Sonatas & Partitas for Solo Violin (Philips 6769 053, footnote 2). Due to an overall increase in transient speed, low-level resolution, and much better low-frequency response, coupled with a noticeable decrease in transient smearing and a general lowering of the noise floor, ambient information was conveyed with often startling effect. Hall sound became more pronounced on recordings which captured it, and sounds reflecting off side and rear walls were clearly heard. The canopy of air surrounding a symphony orchestra was picked up, as well as the envelope of air around individual instruments within that orchestra. Likewise, on popular music, the ambiences of different recording studios were discerned with almost photographic accuracy. And remember, all this with an apparent mismatch between pump and manifold!
Leave it to Bruce Thigpen to design a new high-pressure manifold which would complement the Wisa pump (footnote 3). Externally, the new manifold looks just like the old one. However, the new manifold is machined to closer tolerances, is 0.0007" smaller in inside diameter, and has smaller capillaries. The theoretical result of this re-machining is to achieve a higher air pressure at the bearing for a given amount of air flow. The result heard at the ears is an even better, more refined sound. The improvement, though not as great as that heard with the upgrade to the Wisa pump and surge tank, is still significant and worth the money. With replacement of the manifold, you can rest assured that the optimum interface between pump and arm has been achieved.
I found the Wisa pump slightly noisier than the stock ET pump, so greater care should be taken to isolate it from the listener. I placed mine in a closet in my listening room (where the stock pump had also been located), sitting on an old AudioQuest Sorbothane platter mat I had laying around. Pump and mat rested on a piece of particleboard on the floor. With this arrangement, nary a mechanical sound was heard. The only noise heard when the closet door was open was a soft, high-pitched whir. The surge tank was in the corner of the closet, out of the way. (It is not unobtrusive!) Since the Wisa pump doesn't have an on/off switch, it is advisable to plug it into an AC source with an in-line power switch. (I have a switch on the side of my VPI which controls a receptacle on the back into which the power cord from the pump is inserted.)
Installation of the high-pressure manifold is straightforward and should cause no problems. It may take some persistence to remove the original manifold, but keep applying steady pressure and the seal should break. Note: be sure to grease the gaskets on the new manifold before inserting it into the sleeve. Failure to do this will cause the manifold to "freeze" inside the sleeve, making subsequent removal for cleaning extremely difficult. Also, be sure to align the manifold according to the arrow and dots marked on top.
One of the features of the ET 2 arm is the relative ease with which one can change cartridges. The entire arm tube is easily removable with the cartridge in place and properly aligned. Installing another arm tube (with a different cartridge installed) takes about a minute. The arm tube itself is internally damped with foam. The spindle to which the arm tube is attached, however, is not damped, a condition which has been addressed with the introduction of the fluid dynamic damping trough.
When installing the damping trough, read the instructions over carefully. Make absolutely certain you have the trough positioned properly before pressing it up against the manifold housing. Once pressed firmly into place, it'll be harder than hell to get off! Don't get heavy-handed with the syringe either, or you'll squeeze more silicone than needed into the trough. Remember, it'll take some time for the fluid to settle evenly into the trough. It's much easier to add small quantities of the fluid than remove any excess. The paddle only needs to "kiss" the silicone for it to do the job.
Several advantageous functions of the damping trough are explained in the manual which comes with the kit. Perhaps most important is the discussion of low-frequency phase shift as a product of the resonant frequency of the tonearm/cartridge combination. Bruce Thigpen claims this "tonearm performance parameter" has not been discussed before. He also claims an "almost perfect low frequency phase response" for the ET 2 arm with the damping trough installed. Those inclined to view this hobby as a technical challenge might enjoy pursuing this hypothesis. I believe I understand the gist of what is being said and will leave it at that.
More obvious is the discussion of wow and flutter, and FM distortion, and the relation of both to disc-surface irregularities. Bruce believes wow and flutter derive from tonearm geometry, phono cartridge compliance with elastomeric damping, and surface irregularities in the LP. He does not believe this anomaly to be a function of the turntable. He presents several strong arguments, all of which made sense to me. If, as Bruce contends, surface irregularities (which result from the molding process used in making records) are the primary cause of rumble or random low-frequency noise resulting in tonearm/cartridge oscillation (of which wow and flutter and FM distortion are the end products), controlling these irregularities via the damping trough will alleviate the resonances induced by them and help eliminate the problem (footnote 4). In support of his thesis, Bruce claims up to a 50% reduction in (conventionally measured) wow and flutter, and includes a graph to illustrate his point.
I don't have the technical background to dispute these claims, but I do have a pair of ears that I trust. What I heard pouring out of the speakers after installing the damping trough sounded more like music to me than anything I had heard up to that point. There was an immediate sense of ease to the presentation which at once relaxed me and drew me deeper into the music (footnote 5). Solo piano recordings in particular took on a heightened sense of credibility. Gone was the slightest hint of pitch instability. The clarity of the piano notes (on good recordings) was stunning. My Keith Jarrett albums have never sounded better! Especially revelatory was the sound on Still Live (ECM 1360/61), recorded on stage at Philharmonic Hall in Munich. Jarrett's piano positively sparkles throughout the set, and the interplay between him, Peacock, and DeJohnette was brought forth with more urgency and dynamic contrast than I've heard before. Additionally, the sound of the applause from the obviously stunned audience sounded like individual hands clapping instead of rain falling on a tin roof.
I'm overwhelmed by the improvements wrought by these upgrades to the ET 2 tonearm; I urge every ET 2 owner to make these changes as soon as possible. Without them, you haven't heard the level of performance this arm is capable of. With them, the arm catapults itself into the next higher class of "Recommended Components." I've not heard many of the Class A champions, but I find it difficult to believe anything could sound significantly better. By the way, spend the few bucks to get the dial indicator and mount (footnote 6). Not only does it look sexy (in an industrial sort of way); it enables you to repeatedly hit predetermined VTA settings with extreme accuracy. Unfortunately, it will not determine those settings for you! It will, however, make the effort less daunting.Guy Lemcoe
Footnote 1: WISA audio pump: high-pressure, low-flow, diaphragm air pump. Price: $375. Airtech surge tank/air reservoir. Price: $200. Combined purchase: $500. Available from: Airtech Audio, 242 South Dean St., Englewood, NJ 07631. Tel: (201) 894-5500.
Footnote 2: I know these descriptions of how things sound to me may seem foreign to some of you, but if music and the instruments which produce it do not possess "personality," your hi-fi system is not doing its job! You're being denied the communicative aspect of musical performance which includes compelling, emotional expression. Music is a reflection of life, and its message is best described using the same vocabulary one employs in attempting to understand it.Guy Lemcoe
Footnote 3: The Eminent Technology high-pressure manifold costs $100 (with return of original pump and manifold). Eminent Technology damping trough; $95. Eminent Technology dial indicator mounting bracket; $25.
Footnote 4: The influence of the arm/cartridge's LF resonance on measured speed instability was explored in a seminal 1978 paper by B&K's Poul Ladegaard.John Atkinson
Footnote 5: I haven't often seen Dick Olsher swoon in the presence of recorded music, but I think I caught a glimpse of him succumbing to the voices of the Persuasions the other day in my listening room.Guy Lemcoe
Footnote 6: Teclock Model AL-911 dial indicator (cat. #06450068). Price: $26.95. Available from: MSC Industrial Supply Co., 151 Sunnyside Blvd., Plainview, NY 11803-1592. Tel: (800) 645-7270.