-Edit 17/4/09-

It has been some time now since I wrote this review. My opinions changed during my later tenure with this headphones, but not in any great substanciality. There are also, I know now, a smattering of inaccuracies. Most notable is the one about the nature of AMT motion. The animation in this review is in fact very inaccurate and I have removed it. I have also removed one other image in order to conform with new 25 images max per post limits which did not exist at the time or original posting. If you have questions it may now be an idea to email me than to reference this piece as an absolute.

PART 0: THE TITLE (In which our writer harbours delusions of grandeur and attempts to entice the unwary reader.)

The Ergo AMT: A story, a review, an adventure.

An eventual battle of Gods vs. Titans, man vs. machine, good vs. not so good but not actually evil but just so disappointingly under expectation it gives the appearance of evil. Of tree vs. chainsaw and eventually, of AMT vs. Electrostatic vs. Dynamic.

An exercise in finding a whole new approach to headphone reviewing by employing the kind of explanative and creative writing normally reserved for the like of Tolstoy, Shakespeare, Heller and Aristotle. A load of unabashed and shameless natural crop fertiliser disguised as somewhat vaguely well put together coherent option and analysis. As much a hoot to write as it might just be to read and perhaps even an important learning experience too.

As a note, those of you wishing to move straight to the sonic review part should fast forward to PART 7.


Click Here for full size picture.

PART 1: THE PREAMBLE (In which our writer discovers how to stretch a metaphor and tries to assure the readers of his impartiality, if not his honesty.)

This review has perhaps been rather a long time in coming. A deliberate effort of both self control, willpower and admittedly, some laziness on my part are responsible for this. I wanted to produce something of critical and analytical as well as literary merit (although I make no promises about my ability to properly use an apostrophe) and as such, took my time over it. Indeed, rather than exploding headlong -as I so often do despite the best ministrations of my doctors- into a premature ejaculation of initial impressions based upon over-excited and over-enthusiastic fondling and fumbling with a stimulating but admittedly unfamiliar rack ~An undesirable set of circumstances which would no doubt be all the worse for the several very generously mixed glasses of Gin & Tonic which naturally precede such messy and embarrassing outpourings of personality~ it seemed that self control was merited.

I thought it to be only right and proper therefore, that I should take my time over this endeavour. One does not ever wish to give a rise the possibility of the besmirching of ones lucrative career in writing comedy programmes for BBC Radio 4. Given that I may one day have such a job (at such a time as radio writers are flying their pigs to Broadcasting House) I decided that care and attention to the rack and all of its co-related attributes was the only way in which to guarantee the provision of complete satisfaction for the involved parties. There is after all, nothing quite as wonderful as that warm and intoxicating glow that one attains at the finale. That point at which the ink in the pen has just made its last stain on the blotting paper and you can bask in the relaxation of a job well done as you let your writers’ cramp ease away.

I wanted to write something which could really give a reader even only somewhat vaguely initiated into the world of headphone jargon and terminology (which I myself still have yet to fully come to comprehend at that native speaker level which many of us would probably love to have, where the syntax of technology and sound blends seamlessly into every written sentence.) a tangible appreciation of the different and disparate sounds which are involved. Something which would be helpful and informative, and with any amount of luck also be an interesting and perhaps even entertaining read too.

Doubtless there will be quite a few of you here familiar already with my personal preferences pertaining to both the aesthetics and the sound signature of headphones and also perhaps to some of my more acute or obvious musical preferences. I wanted to make it clear at the outset that insofar as the practical sonic review stage of this is concerned, that my personal fondness’s played no part in biasing my writing. I would never give any piece of equipment some sort of leeway credit because it stemmed from the manufacturing house of a brand I happen to have any consumer allegiance to. From such actions are the stuff of guilty dreams composed, and woe betide he whom might shalt invite such trespass upon his slumbering conscience.

The efforts that I shall make in order to avoid the kind of personally skewed descriptions of sound most commonly employed in phrases such as "the Sennheiser veil" may result in an articulate style which gives less of a familiar feel to the usual habit enlisted by other members who share their opinions in pieces of extended critique. I shall aim to remedy this with resort to the use of intra-descriptive, relative and comparative imagery. So expect visual and olfactory descriptions of aural stimuli when my abilities to form regularly coherent metaphor come into their inevitable difficulty.


PART 2: THE INTRODUCTION (In which our author discusses fuglyitis, tells the story of how and why he purchased the headphones and charges no royalty fees.)

Being a fan of what are prevalently regarded as the ugliest headphones ever fabricated is not as difficult as some may think, nor indeed is it something of which one should in any way be ashamed. Anyone who has ever bought a Grado SR-60 for use with their iPod, who has bought almost any Stax headphone ever made or who owned any pair of headphones during the seventies is most certainly guilty of a varying degree of fuglyitis.

And why not? I ask. In being the understanding, articulate, disparate and even on occasion, "wise" online gurus of the headphone world, should we not naturally be putting aesthetics after performance? We are not showing off slick and shiny motor cars here gentlemen and so there really is no need for the slick aerodynamic curves of a Porsche 911. Nor are we debating the merits of oils against watercolours with respect to the conveyance of minutiae of suggested detail in landscape painting. We are aware certainly of the benefits to be garnered by a piece of equipment which is appeasing to the eye, but know that really, to the Head-Fi initiate, deep down underneath in the workings is what matters, because it is the workings that produce the sound. The shiny exterior plastic is simply a casing, no matter how much gold leaf is applied, or how many diamonds are stuck on. Indeed, is it not so that one of the first things that the Head-Fi newbie comes to learn is that what goes inside the rather attractive design of the Bose Triport is what comes out of a bull. Whereas what goes inside the rather less attractive design of the Grado SR-60, the Stax Lambda or the AKG K340 headphones, is what comes out of a panning tray. A little bit of something very precious.

I have been a fan of the Jecklin Floats, arguably the grand kings of headphone ugly, since I first laid eyes on them in that infamous picture. When I got my first pair, it turned out that I loved their comfort and their sound as much as I loved their ridiculous design. Having bought my first pair (the Float 2) on eBay UK early this year, they arrived and turned out to be in a dreadful state of disrepair, with the foams crumbling and perished to the kind of consistency one gets when one leaves a vampire out in the sun too long. The thread I started about them (GENTLEMEN! BEHOLD! JECKLINS!) received more replies than any other I’ve ever posted since including the Phonodome thread, so you could say that they went down pretty well. I bought my second pair of Jecklins (the Float 1) not too long afterwards, also on eBay UK, and submitted them to a similar re-foaming process. They recently passed onto StewTheKing and I am sure that he will be converted to Team: Circumcranial fairly easily.

With such a Float bias in my mind, it was only inevitable that I should find my wondering shopping eye straying on a regular basis to their younger cousins, the Ergos. Produced by the same company, Precide of Switzerland, the Ergo range of headphones were the successors to the Float range and for several years, ran in parallel production. Naturally, they share many of the same design characteristics, most noticeable of these of course is the Darth Vader helmet appearance of the chassis, which stands in stark contrast to the more tried and tested “Two lumps on either end of a bendy rod” design utilised by… Well, by practically every single other headphone manufacturer in the world.


Click Here to see full size picture.

There are currently three headphones in the Ergo product range, as well as two headphone amplifiers. The Ergo1 and Ergo2 are both dynamic headphones which use neodymium magnets. Precide product information (of which there is actually precious little) on their website cites the merits of the very thin membrane diaphragm of the Ergo1 and its incredible performance at its low price point. The Ergo2 is hyped still further, its even thinner driver membrane allegedly producing, and I quote “...sound reproduction which is open, transparent and uncoloured, it approaches that of an electrostatic system.”. Every time I came into some ill-gotten pennies for surrendering to this terrible affliction some of us have the humour to call a hobby, they niggled me. "Buy me" they both squealed, jumping over the fences of my imagination like a pair of some terrible and frightening, genetically modified, radioactive, mutant zombie robot sheep.

How then, in the face of such powerful and oppressing mental imagery, did I manage to hold in my resolve? How did I manage not to blow the money on them, and instead spend it on far more sensible things like food and rent and beer and rare, mint condition first pressings of Mike Oldfield LPs? Simple answer: For all the curiosity concerning them, they aren't actually supposed to be terribly impressive. I say supposed because there really is precious little review literature available on these. The few reports on how they sound that I was able to unearth, mainly via Head-Fi and Google, suggested that the Ergo1 was disappointing for the price and that the Ergo2, while conversely quite good for the price (giving the HD600 a damn good run for its money I believe I read from one source), was not actually quite as good as its father, the Float 2. In lieu of such reports, it seemed that the Ergos would not really be anything of a gain for me as I already owned a pair of Float 2s. The dynamic Ergo headphones, apparently, are also best partnered with their matching headphone amplifier, the Ergo Amp1. Buying one of these would have added such extra expense (£170) to the purchasing price that I just wasn’t prepared to drop the cash on what might turn out to be a disappointment. So I just consigned all of them to the "One day once I’ve won the Lotto..." shopping trolley.

The Ergo AMT, which replaced the Jecklin Float PS2 electrostatic headphone system as Precides flagship headphone product, had also roused my curiosity, but at more than three times the price of the Ergo2 (£600 vs. £190) and four times the price of the Ergo1 (£600 vs. £149) and with a transformer box (now discontinued) or an Ergo amplifier, preferably the recently released Ergo Amp2 (£850) a prerequisite for being able to use it due to its proprietary connection jack (a unique four pinned plug) I shelved it along with the Orpheus in that little collection of headphones that all Head-Fi members have in their minds to eventually listen to, but realistically have no real prospect of coming into ownership of. Besides, who in their right mind would be interested in a headphone that garnered this sort of reaction from the great Tyll Hertsens?

-photo of Tyll removed-

The manner of how I came into possession of this oh-so-enticing piece of electromechanical gubbins is a disturbing and bizarre tale indeed. It is called the "Searching Head-Fi for “Ergo AMT” threads and finding one in the for sale forum, bookmaking the page, letting the bookmark gather virtual online dust, coming into spending money by selling my Stax 2020 system along with a large collection of old video consoles and games to afford it." technique. Aside from the foreseeable side effects, such as a brief internal debate over the merits of a better digital source (the enticing thing of beauty that is the Storm Digital DAC did entice me) rather than yet another damnable pair of headphones, the technique works pretty well, and as I'm such a lovely and gregarious chap I shall charge none of you chaps any royalties should you wish to employ it yourselves at any time in the future.


[PART 3: THE TECHNICAL STUFF (In which our author steps aside from his story and attempts to explain the science behind the AMT, some info on the Precide company and educates on the origins of confectionary based weather.)

So just what is the Ergo AMT? And what the hell kind of a name is AMT anyway? The answer to the former question is "A very unique headphone indeed." and the answer to the latter is "A very apt one, given what's inside them."

AMT is the acronym for "Air Motion Transformer" a unique type of diaphragm invented by the late great Dr Oscar Heil in 1973. Dr Heil was the man who among other things, invented both the FET or Field Effect Transistor (1934) and Heilstones (1952). The FET was in fact the first proper transistor. A transistor that relies on an electric field to control the shape and hence the conductivity of a 'channel' in a semiconductor material. Despite being developed first. The bipolar junction transistor (BJT) was usually manufactured instead due to the technical limitations of fabrication plants at the time. Heilstones are a particularly rare precipitation phenomenon, Heilstones are caused when upper mesospheric cirrocumulus clouds are subjected to a high intensity sucrose-cocoa ray. This causes them to suddenly release, in a short and heavy shower, assorted small chocolates such as Smarties and M&Ms.

Regular dynamic armatures work by passing an electrical current, generated by the audio signal, to a coil of copper wire which is located inside a matching channel inside a magnet. The magnet exerts a continuous magnetic field to the coil, which is attached to a (usually) cone or dome shaped rigid driver. This cone moves back and forward as the electrical signal passes through the coil, altering is magnetic properties so that it is being pushed in or out of the perminant magnets’ field. This pushing and pulling is what produces the sound by the motion of the driver. Almost all speakers today made are dynamic speakers with permanent magnets.

^Example Of Dynamic Driver Motion

Electrostatic armatures work by suspending a taught sheet of ultra thin Mylar plastic, micro-coated in an electrically conductive material (such as graphite powder) between two perforated metal plates (called stators). These metal plates have a high “biasing” voltage applied between them {on the diaphragm} (580volts in the case of modern Stax electrostatic earspeakers) and by inducing changes in the charge field applied to the stators, the Mylar is pulled toward one stator while being pushed away by the other, and vice versa for motion in the opposite direction. This means that because the driver is producing a mirror motive force and it s uniform shape, the audio output from an electrostatic driver is dipole, meaning that as much sound radiates outward from the driver in one driection as does in the other. It is because of this, that electrostatic speakers have been traditionally difficult to posision in a listening setup. Putting them up against a wall is a no-go because of the backwave. The push&pull system of operation also makes an electrostatic a fundamentally balanced system.

^Example Of Electrostatic Driver Motion

The various pros and cons of each driver, the nature of how they sound and the battles of opinion that exist between the camps on each side who love or hate one or the other I shall not delve into during this review because I do not want to go off topic onto something which is an area of continual debate among engineers and audiophiles. I just wanted to give the reader a succinct rundown on how the two most popular types of headphone driver operate in physical principle.

For those of you interested in reading more about the physical functionality of dynamic and electrostatic drivers or about balanced audio systems, I point you to Google and Wikipedia. For those interested in the comparative sound of each driver, you need do nothing more than a Head-Fi search on any phrase like “electrostatic vs. dynamic” in order to be rewarded with more results than you’ll be able to read through without taking a break for lunch.

The AMT operates on a different armiture principle to both dynamic and electrostatic drivers. Known also the AVT or Air Velocity Transformer, the AMT moves air in an augmented, semi-perpendicular motion using a folded Mylar sheet, structured around a series of aluminium struts positioned in a high intensity magnetic field. The diaphragm pushes back and forward from itself in a similar physical motion pattern to what you observe when an accordion is squeezed in and out to pump air though the reed chambers, albeit over an exceedingly smaller motion range.

===
In order to clarify on this definition, which my too clumsy employment of english and my incomplete technical understanding of the principles involved at the time of writing was not entirely correct, I am adding in a piece of descriptive text from the president of Precide himself, who wished to have this additional clarification after he read this review.

The unique design feature of the OSKAR A.V.T. which distinguishes it
from all other speakers is an extremely lightweight diaphragm, folded
into a number of accordeon-like pleats to which aluminium foil strips
are bonded. The Diaphragm is mounted in an intense magnetic field and a
music signal is applied to the aluminum strips.
This causes the pleats to alternately expand and contract in a
bellows-like manner in conformance with the music signal forcing air
under pressure out of the pleats and sucking the air in on the other
side, the airmovement is 5 times bigger than the movement of the
membrane, therefore also the velocity must be 5 time bigger.The total
moving mass is approx. 1 gram, we have therefore an almost perfect
transducer system. This principle can be demonstrated very simply by
taking a sheet of DIN A 4 paper with a surface of 616 cm2, folding it in
the center lengthwise and bending the long edges together to form an
opening of 5 cm on the one side. We imagine, that the upper and lower
part of the structure is closed and move each side 2.5 cm together. With
a frontal surface of 140 cm2, we have now moved 770 ccm of air, compared
with the 350 ccm of air moved by a flat diaphragm. Our transformation is
now 1:2.2, by making the triangle (top view) a square form, we doubled
the transformation to 1:4.4 The selected transformation ratio with the
Oskar A.V.T. is 1:5.3.
===


To illustrate as best I can in text, the driver moves thusly:

• /\/\/\/\/\/\/\/
• |||||||||||||
• \/\/\/\/\/\/\/\
• |||||||||||||
• /\/\/\/\/\/\/\/
• etc

To illustrate better, here’s animation number three:
-removed-

The result is a dipole driver with an extraordinarily rapid response rate, caused both by the extremely low mass of the Mylar driver, and by the far smaller motion range it undergoes on each “swing” compared to an dynamic driver. In this technical respect, it shares characteristics with the electrostatic driver.

The discernable motion of each of these diaphragm flexes is very small but because of the folded structure more air is moved than would be by a conventional cone or electrostatic driver of the same plotted surface area. As a matter of surface comparison, a standard one inch wide AMT strip has a functional driver area which is comparable to circle shaped dynamic cone with a diameter of eight inches. The folded driver design, combined with the small motive range, means that the AMT acts like a point source version of a larger driver, inherently resulting in lower distortion in sound reproduction. As a result of its motion pattern, the AMT "spits" the air out in a way which is compatible with what happens when, although you apply a small amount of pressure to an orange slice, the pip inside shoots out at high speed into the eye of the hard man at the other end of the bar, or if you are a better shot, down the barmaids top. The motion of the air as it leaves the diaphragm is in fact five times faster than the motion of the driver structure. Hence the name Air Motion Transformer.

The most common use for the AMT driver in consumer electronics today is as a midrange-tweeter in very high end (read: very expensive) multi-driver speakers, sometimes paired with horns, or in the case of Precides own speaker products, with an upward firing woofer driver. Precides own loudspeaker models are very faithfully based upon Dr Heils’ original designs. Which either means that the designs were excellent and merit no change, or that Precide are a bit lazy. In the tweeter market the AMT must compete against electrostatic, ribbon and dynamic dome tweeters. The AMT is, while apparently very good as a mid-tweeter or full tweeter, not commonly employed as much as one may expect lower down in the speaker market. This is mainly as a corollary of their dipole sound radiation, which makes enclosure in traditional speaker cabinets difficult without sacrificing sound quality or employing sound reflex baffles. The AMT can also reproduce sound right down into the low midrange fully competently, making design decisions regarding crossover points difficult.

What Precide have done in utilising these drivers for a headphone design is to run them at full range. The air motion transformer is unfortunately, mechanically unsuited to the clear reproduction of lower frequency sound. The AMT driver is usually employed to work at its best from anywhere between 300 and 700 Hz to 23 kHz and up. However, electrostatic drivers also face great technical difficulties in reproduction at the lower frequency regions without the resorting to using ever larger panel areas, so I was eager to find out just how well Precide manage in successfully utilizing the AMT for full range sound reproduction.


PART 4: OUT OF THE BOX (In which our author bemoans utilitarianism, cracks open an egg and finds things a bit heavy going.)

Post-purchase excitement always results in an impatient few days of pestering the local post office for details of why the parcel has failed to arrive with the kind of speed usually reserved for Vin Diesel race car movies. Whoever manages to invent the teleporter will have my eternal gratitude, although I suspect that even if instantaneous transportation of materials were a possibility, they would spend just as long going through the quagmire of governmental bureaucracy (read: The Post Office) as they would being transported by regular means in the first place.

Finally however, constant pawing at the letterbox yields the desired result, that sight that we all love and that our wives, girlfriends, flatmates or parents have come to despair: the bloody big brown box.


Click Here for the full size picture.

More mystical than the Ark of the Covenant, more precious than a pirate’s chest full of golden plunder, the BBBB is the most condensed physical manifestation of anticipation in existence after the Christmas tree present pile. The BBBB is the magical eggshell which once cracked can surely only bring the delicious yolk of excitement cocooned by the white of joy.

Cracking open this egg reveals two smaller cardboard boxes and a short set of wires.


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The crevices of the BBBB contain a veritable shipload of particularly bad tasting coconut Cheetos. Both stale and devoid entirely of their normal coconut flavour the Cheetos are a disappointment indeed, but the smaller boxes are not! One contains my shiny Ergo Amp1!


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A neo-gothic, monochromatic, utilitarian affair in black case on black chassis with black volume knob, black screws and small black on/off switch with what look like a little black LED that lights up black colour scheme. A looped set of Really Common Adapter sockets on the rear accompany the regulated DC power socket, two tiny recessed screwdriver-adjustable volume gain dials (one for each channel) and of course that strange but enticing AMT connection socket.


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The established 6.3mm stereo jack socket is to be found on the front panel. Why on earth the designers at Precide didn't put the AMT socket there too I have no idea. The notion that they would do it for any aesthetic reasons is to be dismissed out of hand given what their headphones look like.

My amp, naturally, has shipped to me with a power brick for those wretched two-prong North American wall sockets. Not to worry! In their infinite wisdom the tech gurus at Precide decided to make the power input requirements for their Amp1 completely compatible with the power output specifications for the standard Pro-Ject turntable wall brick. My Pro-Ject Xpression is soon unplugged and the Amp1 is rejoicing silently as my generous provision of delicious British electricity warms it gently.


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Any instruction sheet which opens with the words "Dear Audiophile" already has my endorsement. What a way to assure the new customer that the purchase they have just made cannot possibly be in error. But what of the other box?


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This one adorned not in standard utilitarian brown but with multiple glorious Technicolor photos of a pair of Ergo headphones. The pictures seem to be rather androgynous as regards which model they actually are. This is because the same packaging is used for all Ergo models, the only difference being which tick box on the side is marked in cheerfully coloured chubby children marker pen to indicate the exact contents. It would seem that even the packaging techniques and the highly accurate English translations from the Float era have remained the same even if the graphics have been given a facelift.

The box is surprisingly weighty, I put this down to the fact that the transformer for using the headphones with a power amplifier is inside along with the headphones. Lifting the headphones out reveals that it is in fact they which account for most of this mass. At a gnats whisker under 600 grams (as can be confirmed in the picture below) these are surely completely unsuitable for portable use even when forgetting the other limiting technological factors.


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Donning the headphones for a test fitting I am both surprised and delighted by how comfortable they are, the Darth Vader’s helmet design spreads the weight over a large area of the scalp minimising contact point pressure to, perceptibly, almost nil. The left and right driver cages of the headphones touch the ears gently with only a tactile and not a forceful sense of presence. The earpieces are lined with a comfortably soft cloth which seems remarkably similar to and almost certainly is, speaker grille fabric. The foam on the top of the headband is both soft and dense at the same time and has ability to grip onto things you try to brush across of in a manner which is reassuring, given that I had doubts as to how well they would stay in position on my noggin if I were to move about. The head foam reminds me in most ways of compressed neoprene, which is used among other things to make dry suits for diving and waterspouts. My father assures me however, that it is not. The AMT certainly gets the initial thumbs up for comfort.


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The foam also seems fundamentally less likely to be susceptible to perishing and crumbling as the foams on the Floats were so persistent in doing. The use of fabric on the earpiece covers (a modification which should be made to any restored Float) negates the possibility of foam perishing in this area entirely, and as such, also the risk of damage or wear to the drivers caused by foam particles crumbling through the cages supporting mesh and in to the driver assembly. The rear foam supports which help to stop the headphones flapping about on your head are positions behind the ears but do not come into contact with them, rather they press in on the rear sides of the cranium.

The outside faces of the driver cages have an open design, the gently waving canals in the plastic have fixed behind them another layer of the same speaker grille fabric employed on the inside. There is also a feature here that the old Floats, with their single-sheet-of-heat-moulded-plastic construction could fundamentally not boast: an adjustment for head size. Each driver cage can be moved up and down into any of a whole four positions using a mechanism that looks like what you'd get if you layered a couple of cogwheels out as flat bars, rounded the machined edges a bit and turned them into thermosetting plastic.

My initial tactile urges sated I leave the headphones on (what, after all, would I have to gain in removing them except perhaps my sense of self respect?) and rummage back in the box for the transformer. Taking it out, noting its bland, functional design and the fact is has only one switch (which, just for the look of the thing, I flick up and down a few times, cackling like some insane Transylvanian scientist as he sends the electricity surging through his terrible creation) I put it over on the Hi-Fi rack next to the Stax amp. I do not have a spare power amplifier, and even if I did, it probably wouldn't be suitable. The Ergo transformer boxes do not cope at all well with high powered loads and Precide recommends using them with the low power tube amps from Klimo whom I should mention by way of preserving honesty, are a partner company. I make a note of the fact that I still haven't got ahold of one of those little T-Amps and that what with them being so useful in situations such as this, I really should.


PART 5: SURGERY (In which our writer disassembles his new equipment, bemoans the weakness of hot glue, rediscovers some old friends and injures himself.)

Put yourself in my position. You’ve just blown all of your savings on a new set of headphones. You’ve got them ready to go, you can’t wait to hear what they sound like with Dark Side Of The Moon. What do you do?

Being the regular and respectable Joes you are, you’d have them on while you run and run to catch up with the sun. Not I. I reached for the screwdriver to perform some intimate and invasive investigation. Here are the fruits of my labours. Some high-res Technicolor shots of the innards of all this new gear.

First, the Ergo Amp1.


Click Here for full size picture.

The folded top cover casing is held in place by eight Allan bolts. Removing it reveals a set of working innards which were I not hoping to see something more visually stunning I would call neat and tidy rather than spartan. There is a master circuit board which is held aloft from the bottom of the casing, a few capacitors and whatnot and a large erect metal rectangle of some description. I was at least expecting a big meaty toroidal transformer and maybe some spicy bean tacos.

I have no idea what any of the things in there do with regard to pumping out music, so I shall just leave the more technically minded of you out there with a few more shots form different angles.


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Next up is the Ergo Transformer Box.


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The Transformer Box is just that. A switch box to transfer the output power from your speaker amplifier to your AMT headphones. The wiring principle is exactly the same as a non self-biasing electrostatic energiser. Signal goes in one end, into box, and if headphones are selected, out into the headphones. If speakers are selected, then back out again, and onto the speakers.


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Opening up this enticing little bundle of tricks leads to a bit of a disappointment for me. I was expecting some sort of fancy looking electromechanical engineering. Turns out, the transformer box is nothing more than a resistor network. Not as complicated as an electrostatic energiser by a long way. It’s also got some questionable build quality. Those components are stuck to each other in a rather haphazard way with what looks like glue gun glue and are only attached to the interior of the case by a sheet of double sided, padded sticky card. The foam in the roof of the case obviously stops the components from moving by pressing them into place. NOT a good piece of design this. It’s just asking for transport damage to happen.


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And happen it has. One of the wire coils has dislodged itself from where it is supposed to be soldered on because the glue has given way. The glue holding the two large capacitors has also failed and they rock back and forth independently on the sticky card.

An email to Precide is required in order for me to double check where that coil is supposed to attach to. It looked pretty obvious, but I didn’t want to make any assumptions which might prove disastrous later on. It was a few minutes work with a tube of Araldite and a soldering iron to fix the problem, but it was a problem which should not have occurred in the first place. Mounting those components onto a ridged board and using some proper glue would have prevented the problem from happening at all.

Inside the headphones.


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First we remove the outer part of the driver cage. Secured with four screws, the removal of the outer side allows the inner cage to which the AMT driver is mounted, to come free of the headband.


Click Here to see full size picture.

Here is where the magic happens. The folded driver is those vertical silver bars, which alternate weave around the aluminium strips. The horizontal bars are part of the magnet structure and let me assure you that the magnet in there is quite exceptionally strong. The driver is positioned slightly to the rear of the cage which will bring it into line with the ear once the headphones are worn. Were the drivers to be positioned centrally then they would lie in front of the ear when worn.

The metal grille to which the driver is stuck is the exact same as the drivers in the floats were attached to. When I say stuck, I do regrettably, mean stuck. The AMT unit is affixed to the inside of the cage by combination of sticky pad on the inside and some rubber pads and pressure on the outside. A design which would mean that the driver were actually rigidly affixed into the housing would be a better idea because it would reduce unwanted resonances, which even in a driver with a low a motive range as the AMT can still cause problems. Particularly as volume levels increase. The last thing that anyone wants, is for something to start rattling during the finale of their favourite song.


Click Here to see the full size picture.

A closer look at the AMT.


Click Here to see the full size picture.

A look at the opposite side of the AMT reveals that the magnet is applied across both sides of the driver and that the area of the driver is larger than it appears on the other side, blocked as it is by the padding materials.

Our detailed look inside complete, let us finally move on to the listening.


PART 6: THE SETUP(In which our writer introduces the combatants the AMT will face in the aural arena, gives a rundown on the rest of his equipment, lists the test music and shares a few predictions.)

I’ll be writing up my impressions on the sound of the AMT in itself and also comparing it primarily against the STAX Omega 2, with additional comment relating to the sound of the Sennheiser HD650, the Grado HF-1 and the STAX SR-202. The test setup will be a 4-way simultaneous setup. This is the normal way in which my setup is configured with the exception of the presence of the SR-202, which I borrowed from my dad for the purposes of this review. Testing using my analogue rig is sadly not possible because the power brick for my turntable has gone to the Ergo Amp1. The major system bottleneck for me is my digital source, which is an Audigy 2 ZS. Hardly the most highly regarded soundcard in the world, it is nevertheless what I am burdened with until such time as fate (and gradual expenditure) deem otherwise. Here then, are the equipment chains used.

Audigy 2 ZS -> NAD C352 -> Tape Loop 1 -> SRM-717 (loop out) -> Ergo Amp1 -> Ergo AMT
Audigy 2 ZS -> NAD C352 -> Tape Loop 1 -> SRM-717 -> SR-007
Audigy 2 ZS -> NAD C352 -> Tape Loop 1 -> SRM-717 -> SR-202
Audigy 2 ZS -> NAD C352 -> Headphone Socket -> HD650 / HF-1


I referred to a great deal of music in performing this testing (oh, the sacrifices I make). Here’s a fairly complete list of the CDs employed in alphabetical order, albums marked in bold type are used as primary references.

A Silver Mt. Zion - He Has Left Us Alone But Shafts Of Light Sometimes Grace The Corners Of Our Rooms
Air – Moon Safari
Alanis Morissette – Jagged Little Pill
Annie Lennox – Bare
Antonio Vivaldi – The Four Seasons
The Beatles – Abbey Road
The Beautiful South – Blue Is The Colour
Bo Hansson – Lord Of The Rings
Bon Jovi – Crush
The Bonzo Dog Doo-Dah Band – Gorilla (1995 Remastering)
Brian Eno – Ambient 2: The Plateaux Of Mirrors
Cavedog - Total Annihilation
Crash Test Dummies – Songs Of The Unforgiven
Creedence Clearwater Revival – Cosmos Factory
Daniel Beddingfield – Gotta Get Thru This
Deep Purple – In Rock (25th Anniversary Remastering)
Dido – No Angel
Dire Straits – Brothers In Arms
DJ Smuggy – Chronos (May 2006 Studio Mix)
Django Reinhardt & Stephane Grappelli - The Best Of Hot Club De France
Donald Fagen – Kamakiriad
-Morph the Cat
-The Nightfly
The Doors – The Best Of The Doors
Eiffel 65 – Cosa Restera
Einaudi – Una Mattina
Electric Light Orchestra – A New World Record
Eminem – The Marshall Mathers LP
Etta James – The Seven Year Itch
Eurythmics – Peace
-Sweet Dreams (Are Made Of These)
Fleetwood Mac – The Best Of Fleetwood Mac
Focus – Focus III
George Thorogood And The Destroyers – Haircut
Gnarls Barkley – St. Elsewhere
Godspeed You! Black Emperor – F# A# (Infinity)
-Lift Yr. Skinny Fists Like Antennas To Heaven
-Slow Riot For A New Zero Kanada
-Yanqui U.X.O.
Gorillaz – Demon Days
Gustav Holst – The Planets (London Symphony Orchestra DSD Recording)
Hank Shizzoe – Low Budget
Ibrahim Ferrer - Buena Vista Social Club Presents Ibrahim Ferrer
Jean-Michel Jarre - Chronologie
-Oxygene
-Solarnosc
Kate Bush – Aerial
Kenji Kawai – Ghost In The Shell: Innocence
Kraftwerk – Autobahn
Leon Redbone - From Branch To Branch
-Sugar
Lou Reed – Transformer
Luciano Pavarotti – The Collection Volumes 1 and 2
Ludwig van Beethoven – Symphonies 4&7
Maroon 5 – Songs About Jane
Melanie C. – Northern Star
Meredith Brooks – Blurring The Edges
Metallica – And Justice For All
Michael Jackson – Bad
-Dangerous
-Invincible
-Off The Wall
-Thriller
Mike Oldfield– Amarok (Tracked Version)
-Guitars
-Hergest Ridge
-Incantations
-Ommadawn
-The Songs Of Distant Earth
-Tubular Bells
-Tubular Bells II
-Tubular Bells III
-Tubular Bells 2003
-Voyager
Mike Scott – Still Burning
Moby – Hotel
Mozart - 4 Sonatas for Piano and Violin, Nos.18, 21, 24 & 26
Natalie Imbruglia - Left Of The Middle
Peter Cincotti – On The Moon
Pink Floyd – Dark Side Of The Moon
-PULSE
Prodigy – Fat Of The Land
R. Cajun & The Zydeco Brothers – No Known Cure
R.E.M. – Automatic For The People
-In Rio 2001
-Monster
-Murmur
-New Adventures In Hi-Fi
-Out Of Time
-Up
Radiohead – Kid A
Renaissance – A Song For All Seasons
Richard Ashcroft – Human Conditions
Rob MacKillop – Flowers Of The Forest
Rod Stewart – Human
Santana – Supernatural
Scissor Sisters – Scissor Sisters
Sigur Ros – ( )
-Takk…
Stax – The Test Disc
Steely Dan – Cant Buy A Thrill
-Gaucho
-Kay Lied
-Two Against Nature
Sting – Brand New Day
-Fields Of Gold
Taj Mahal – Dancing The Blues
Tchaikovsky – 1812 (Telark DSD Recording)
Tina Arena – Don’t Ask
Todd Rundgren – A Wizard, A True Star
Vangelis – Chariots of Fire
-Greatest Hits 2
-Mythodea
-Odyssey
The Velvet Underground & Nico – The Andy Warhol Album
The Waterboys – A Rock In The Weary Land
-Universal Hall


There are some other CDs which I used which will not be listed there . There are also some CDs listed there which did not attain particularly much in the way of play time for the purposes of this review but I thought worthy of including in the list. In short, I went through a pretty disparate mix, and the main exceptions in that list are the compilation albums and some classical stuff. You get the general idea though.

My predictions going into the test boiled down to this:

The Stax Omega 2 would be the reference by which everything else would be judged, being better at everything that was thrown at it than all other contenders. Such should be the expectation. It is after all supposed to be the best headphone currently in production.

The Ergo AMT would prove to be utterly and completely bass deficient by design. It would as a consequence lack aspects which are so essential to many types of music. It would also prove to be the worst headphone possibly applicable (maybe with the exception of the AKG 501) for the listening of dance, trance, house, drum and bass and other such subwoofer raping, nightclub dance floor filling drug enjoyable semi-pop music but would excell at less intensive catagories.

The HD-650 would thrive in its own separate arena, as its ability to provide visceral bass impact and a hammering sense of aural presence made it the more immediately pleasing choice for many albums. Although it would be hindered by its combination with the NAD, while the Stax and the Ergo had their own dedicated amplifiers, this hindrance would not be anywhere near the limitations of the Audigy.

The Stax SR-202 would, being powered by an far better amp than I previously used it with, nestle between the AMT and the O2, in terms of sound signature. Lacking the bass qualities of the O2 but also failing to provide the clear upper frequency accuracy I expect from the AMT.

Part of the way through writing the impressions section, my HD650s took a little trip. Specifically, I swapped them for a pair of HF-1s. There are upsides and downsides to this. The obvious downside is that I no longer had a pair of headphones I was using for review comparisons. The upside is that I have a new headphone (my first Grado) in the HF-1. And that I would also be able to use it to draw some further comparisons on sound.

I didn’t really know what to expect of the Grado sound, although I was terrified I might suddenly become a complete Grado convert, never again thinking that anything else would satisfy me for listening to Focus or Thorogood. (This later sort of turned out true.)

To reiterate, the primary cross-headphone listening comparisons were between the SR-007 and the AMT, although the primary review literature is on the AMT alone.


PART 7: THE GAMES BEGIN (In which our writer finally presses play, notes some of the main important aspects of headphone terminology, rediscovers some old favourites, reaches multiple eargasm, and comes to some pleasing conclusions.)


Palpable Bass

Loading up tracks for testing what we all test first in a new pair of headphones, the bass, my playlist ends up including tracks which do not feature in the above albums. Flat Beat, Zombie Nation, Dooms Night and Dragostea Din Tei being the primary culprits, but hey, whoever said I had to stick to some sort of rules eh? I’ll listen to whatever takes my fancy.

Let me start right off with the underlying honesty of the situation here before I start to warble. Bass on the AMT is without any question, a purely cerebral experience. The extension is rolled off more acutely than I have heard in any headphone of this calibre, (calibre, read: price) it does not however roll off to zero, it simply becomes tacit the further down the frequency registrar one goes. There is absolutely no employ of a mid-bass hump in the AMT in order to try and present a bass extension that does not really exist. ~I find this a brave and admirable thing for the designers to have done considering how easy it might have been.~ However there is no compensation in the proper way either, because the bass on the AMT is subdued. Quiet. Small. Refined. The bass goes deep, but very delicately and under the most supreme degree of control. Slam is all but non-existent, unless you go out of your way looking for it. This however, does not negate the existence of impact, of which there is an appreciable quality.

To clarify on the difference I think of between slam and impact: Slam is the tactile consequence precipitated by a volume of air causing a resonant effect in the ear. Akin to the impact of a large beater on a drum “BOOM”. Impact is the same beater hitting the same drum, except only the drum skin, like a tambourine strike rather than a drum strike. There is the same resonant surface, but no chamber. So there is still the same tonality and there is still the same sense of collision, but without the associated thump in harmonics.

Even electrostatics provide more in the way of bass punch than the AMT, however, all electrostatics that I have heard with the exception of the Omega2, do not provide quite the same understated uniformity in presentation of bass notes across the lower frequency range. The frequency response of the AMT rolls off in a way which provides for a very clean sound, without bloom, boom or bulge.

The overall effect of the bass slam and impact presentation in the AMT is caricatured for an example, when listening to thumping heavy tracks like Azzido Da Bass’ Doom’s Night. The AMT has a full, crisp and sharp delivery of the beat, but it is NOT an anorexic sort of presentation. While in sharp antithesis to the presentation of the HD650 which conveys the same song with the round, fat bouncing tone which its creators no doubt had in mind the AMT provides tone, extension, pulse, rhythm and a head bouncing groove. There is just something so much more cranial about the experience, its rather like having bass heavy music transmitted straight into your pre-frontal cortex without anyone bothering to make use of your ears first.

It is safe to say that the AMT will never ever win over any fans of the DT770. If perceptual kick in the bass is your thing, then you may learn to love the AMT presentation, but if tactile kick is your thing, you will have to look elsewhere. Despite its lack of motive slam, the impact of the bass is still appreciable. One is provided in clear definition the beginning, duration and end of each beat, one simply misses the detonation of air that is in general accompaniment with such sounds on conventional dynamics.


Conventional Bass

Investigating into bass important tracks with less emphasis on the bass as the primary character of the song; Donald Fagen’s Morph The Cat, Vangelis’ Mythodea Introduction & Movements I II & X, R.E.M.s’ Texarkana and Peter Cincottii’s St Louis Blues are conveyed in the lower frequencies by the AMT with a sparkling elegance which makes the HD650 sound constipated by comparison. The AMT brings a fresh perspective to such tracks with its satisfying cohesion to the sound signature with understated range dominance.

Texarkana was a pleasing experience for me because it was nice to have Mike Mills vocals and the strings sharing the soundstage so socialistically with the awesome bass riff. Morph The Cat for the first time sounds thin rather than fat, but I must absolutely stress that thin does not equate to lifeless, the track loses none of its drive or jive through the AMT, although it does debatably lose funk.

Mythodea Introduction suffers badly though, the entire track is composed of extremely low frequency bass rumble and effect, and listening with the AMT produces an experience which quite simply means you miss out on half the track. The bass roll off must dip sharply downward at somewhere below 100Hz. Unless the volume dial is cranked to the louder side of regular listening level, the pitch of Mythodea Introduction is beyond the AMT’s capabilities. Movement I is not so disappointing. One of my most treasured test tracks and an eargasm on every listen Mythodea I pulses with all the power of Holst’s Mars and with all the symphonic delicacy that a listener comes to expect of Vangelis composition. Played through the AMT I gain my first insight in to what it might be like to hear this piece performed live. The soundstage seems to extend outward from my head by several feet. I really am in aural bliss.

The AMT carries Mythodea I well, but repeat listening with the Omega2 brings an additional pulse in presentation to it which the AMT lacks. The same can be said, but to a lesser degree, of all of the other tracks I used for implicit bass testing, but not usually to the same degree. When up against the Omega2, which has quite possibly the finest bass reproduction of any headphone ever made, the AMT holds its ground well. Losing out only in terms of quantity when required, and in appreciable slam. The AMT does however, have a more subtle rounded roll to its bass response, whereas the bass on the Omega2 is quite appreciably lifted, at the very slight expense of its lower midrange.

Moving from musical bass onto male vocals we have the dulcet tones of Brad Roberts of the Crash Test Dummies as our primary participator. The album Songs Of The Unforgiven was recorded in a large old church and the blend of gigantic church organ with Robert’s rumbling, sensual baritone makes for the kind of ear sex that the censors have been trying to stamp out for decades.

The AMT brings a fresh experience to this album for me. The separate harmonics of the Vast Organ clearly spaced from the reverb and echo produced in its wake as the sound waves reverberate off the stone walls and back into the recording. Sound staging of minutiae in refracted audio such as this is not something that I had ever noticed in previous listening. On the track Everlasting Peace, one is acutely aware of the subtle differences in the tone of the original voice and the echoed voice, each tiny piece of gravel in Robert’s voice pours into the ear as if filtered through an extremely fine necked sand timer. Rather than the “’Eres your tonne of rocks boss, we’ll just drop them from the helicopter in this here giant sack.” Presentation of the HD650 or the comparatively crowded gelatinous delivery of the SR-202. Again, it is the Omega2 which is required to show the AMT who is boss. Providing all of the AMTs’ finesse in delivery but with the addition of polishing each piece of gravel with a soft cloth en route. Coming back for a repeat listening after getting my HF-1, Roberts voice does not agree with me. He sounds almost dehydrated. This may be an effect of the Grado treble spike or my unfamiliarity with a new set of headphones but I thought it bore mentioning.


Midrange

Female vocals are one area where the AMT really seems to shine out. Kate Bush’s Aerial has never sounded quite so sublime. The fine harmonics of her voice nuanced in the kind of way that puts me in mind of the perfect Gin and Tonic: Transparent, effervescent, sharp and smooth, and with a bite to the presentation which falls short of tang. Delicious. Orchestral score is intertwined together like fine rope, a superbly crafted singular strand the length of the piece, but if you wanted to, you could pick out even the smallest thread and separate it from the whole, and examine it in its own right. The ability to pluck an instrument from the mix in complex passages in this way is like being God handing out divine judgement on the masses before him. With a casual twitching of my ears, I have the power to obliterate entire oceans of rumbling crashing sound and pass individual blessing onto the lone sailor with his flute or violin.

And the invisible driver, the point source of musical information, the sound doesn’t seem to come through the air, it seems to pulsate through a pool of distilled water, giving the sound presentation of horns, strings and voices a most literally liquid presentation. The HD650 passes not through distilled water but though cookie dough, the HF-1 through alcohol and if the AMT is distilled water than the Omega2 is Perrier. Almost the same, but a lot more expensive and in a prettier bottle. There is nothing that I can hear on my setup which puts the Omega2 ahead of the AMT for midrange presentation in all its forms, allowing for the colouration from sound signature.


Treble

Imagine the basic Grado sound signature if you can. If you can’t, then you’re obviously far too new to Head-Fi, do a search. That Grado vs. Sennheiser clarity is in part there because of the treble spike in the frequency response of the Grado headphones. Now, imagine that sort of clarity in treble but without the frequency spike. All the enjoyment, none of the fatigue. That’s a start to understanding the treble reproduction of the AMT. A non-fatiguing, high clarity, non sibilant, non ringing, effortless high frequency reproduction. These drivers by their very mechanics are optimal for these frequency ranges and so it should come as no surprise that they do this well. Listening to Pink Floyd’s Meddle (Echoes), Jean Michel Jarre’s Chronologie or The 2001: A Space Odyssey OST albums. Or to the soprano passages on Vangelis’ Mythodea (Yes back to Mythodea, if you don’t have it go and buy it now!) Is a truly immersive experience. There is just this idea that everything that you are listening to has been polished to mirrored perfection by a team of small velvet clothed gnomes.

Treble on the AMT is the inverse of the bass in many ways. There is a discernable clout to high frequencies, this really is the “spitting” nature of the AMT driver. The fast transients combined with the mechanics are putting out high frequencies at high rates, the elimination of the motive sluggishness which dynamics suffer from gives the AMT a high end which is way ahead of the HF-1 and especially the HD650. Its also a more pronounced treble than the Omega2. It is however, after a long repeated listening testing. Not as refined. There is only the slightly tiniest amount of haze on certain female vocals which the Omega2 does not have. I blame this on the Amp1, or more likely, I’m simply finding something that might not really be there by this point.


Notes On Soundstage, Imaging, Instrument Separation and Aural Cohesion

One is stuck by just how spotless the AMT sounds. It seems to be taking a 16 carat audio signal from my soundcard and feeding me a 24 carat rendition.. When listening to Annie Lennox on Pavement Cracks the sound in visual terminology is passing through a window. With the Omega2, this window is of the finest crystal, invisible except at those angle where you look for it against the light. On the AMT, the window is made of the exact same glass, except it’s razor thin. There is almost no discernable transition from driver to eardrum in spite of the distance that can be apparent from the size of the soundstage. The presentation sometimes brings me to mind of the Soundbug. A device which you stick to any flat surface, the Soundbug will turn that surface into a speaker. Sticking the Soundbug to your forehead seemed to allow you to hear whatever you were listening to while bypassing your ears. The AMT can seem to provide this same experience, except without the central skull soundstage. Audio literally seems to move from front left soundstage to front left brainstage without any interim process. The general effect is of absolutely effortless presentation. The AMT is a contender for the invisible driver.

Provided that the recording is suitable. The soundstage on the AMT can be just absurdly vast. Listening to binaural recordings lends a whole extra degree of brainstage to that which is presented by a standard earbud, circumnaural or supra-aural headphone. It really increased my curiosity about the sound of the K-1000.


Eargasms And Aurgasms

Eargasm (or aurgasm as I prefer) testing was, as you might expect. A pleasant experience. I loaded up a playlist of six of my most favourite ‘gasmic tracks (Jupiter And Beyond The Infinite, East Hastings, Mythodea Introduction & Movement I, Hergest Ridge Part 2 and Ommadawn Part 1) and sat back and closed my eyes, opening them only on the few occasions (mostly between songs) where I would reach for my wine glass.

I have never been so utterly terrified by a piece of music as when I listened to East Hastings then. I couldn’t actually keep my eyes closed, I had to open them to reassure myself that it would be okay. When you watch a horror film, you shut your eyes to escape the fear, which music you have to open your eyes in order to obtain the same effect. An aurgasm it most certainly was not, but a life experience it certainly was. Thrilling. Each of the other pieces got an aurgasmic experience as well. Now, these are some incredible pieces of music, and ones which I know I love and which are moving and powerful, however, despite this, they do not always provide everything that you might want. The AMT was consistant in its ability to utterly and totally immerse me in the music to a degree which was even greater than the Omega 2. The reason being, I cant sit still for that long with the Omega2 without having to fiddle with the earpads when they become clammy during prolonged sessions. The same applies for the HD650, which was never so good at providing me with the out of body in the music experience anyway. The SR-202 also suffered from clammyitis. Score several billion points for the much mocked, super ugly form factor there!


Tweaking The Sound

The Ergo can be worn at a range of positions on the head, from having the rear pads in contact with the back of the ears to resting on the back of the head. Best results in sound, particularly relating to the bass extension, are obtained when the headphones are worn fully forward. The rear cushions just touching the back of the ears, and with the back edge running vertically. Bass quantity at the standard level can be increased further by gently pressing the two front bottom edges of the driver cages inward toward the chin. This also extends the bass response by at least an octave. It also comes at the expense of soundstage, which collapses from the intra-aural to the inter-aural. I imagine from the reports of other Head-Fiers that this is a similar effect to what happens when one switches from Grado bowl pads to flat pads I may look into some sort of detachable elastic chin strap to investigate the merits of such a position further.

As with any headphone, the AMT’s sound character varies with output volume. Very low level listening is hampered by the Amp1 which feeds the right channel less volume. ~The gain dials are set correctly.~ As volume increased, bass becomes more decided and the speed and drive of the headphones seems to enter optimum territory. Loud listening is an immersive experience, particularly with operatic and large scale orchestral or multi-instrumental compositions, or with complex or soaring electronic music. Listening at louder volume with bass heavy music, it is noticeable that the AMT simply isn’t being driven well enough by the Amp1. Distortion starts to creep in the low frequencies, and this is saddening, although perhaps expected.

Using the software bass boost does provide a new experience, but as with all EQ-ing, while benficial in some ways, it detrimental in others. Software induced bass response comes at the cost of the established sound signiture. The AMT gains bass but also gains bloat. I personally can live with it on certain tracks, but generally prefer it off. Others may beg to differ.

Back To The Bass

In the interests of purely scientific acoustic measurement, away from the personally skewed ramblings of someone unfamiliar with the terminology of differentiation, I fired up the NHC Tone Generator and attempted some purely scientific investigation into the exact nature of the bass behind both the AMT and the Omega2.

With the AMT, audible presence of bass tone starts to fade off around 120Hz and then plummets sharply at around 80Hz. It does however remain an audible aspect down to as low as 50-55Hz before rather suddenly fading into the background, turning up the volume at frequencies lower than this simply generates second order harmonics and hiss. Hiss being a fault of the amplifier and its high noise background. A characteristic of the Ergo Amp1 which is particularly noticeable when one inserts headphones with an impedance of below 75 Ohms into the 6mm jack socket.

Scrolling up through the frequency spectrum I stop at around 17500Hz, because once I start going higher than this I just cant hear anything. Ridiculously absurd high frequencies produce audible effects in the lower frequencies but I wont even pretend that that’s me somehow hearing them.

The Omega 2 begins an audible roll off slightly earlier at around 125Hz, becomes less discernable at around 60Hz and fades to background at around 35Hz. The Omega 2 however, will reproduce frequencies down below 10Hz if you turn up the volume. Hearing the kind of frequencies which are low enough to let you discern each motion of the driver is something that I have never been able to do before except on one occasion in a car audio showroom, and I left that with vibration white finger brought on by the wattages running through those subwoofers. The AMT will produce noise under the same circumstances, however it comes across as an unpleasant flapping sound rather than an actual discernable bass note, the noise floor behind them at this point also rises, although this is a fault of the Amp1 against the SRM-717, rather than with the headphones themselves.


Notable Strengths

Comfort. Soundstage. Speed. Control. Volume scaling. Female Vocals, Exceptional and astounding sound clarity. All of these traits in the AMT suggest that as a headphone armature medium, the Air Motion Transformer has a bright future for it if only other manufacturers are willing to take the time to invest in the product R&D to take it further.


Notable Limitations.

Aside from a limited bass response, an absence of slam and a silly form factor. These headphones have no limitations in my current setup. I look forward greatly to seeing how they scale further as I upgrade my source, cabling, and amplification. That double boxed, class A, Ergo Amp2 looks mightily intriguing. The Amp1 really is the limiting factor for the AMT, even more so than my rubbish soundcard. A regulated 18V power supply might do something to help. I shall have to email the chaps at Precide about that.


Conclusions And Afterthoughts

The Ergo AMT is a headphone which, I suspect is a love it or loathe it device. And the balance on that decision will depends almost entirely on the listeners acceptance of its lower frequency sound signature. The sound of the Ergo is clean, clear, controlled, quick, delicate and meticulous. It absolutely excels in the undistorted and resonant delivery of the female voice, of strings and of any well recorded material. It struggles with conventional pop music and with the more intensive kinds of rock. It is not a “fun” headphone. It is a “serious” headphone. Its an eyes closed, lights off, operatic, cerebral and intellectual odyssey through a multi-textured 3D landscape of startling subtlety. It provides all of the traits which so many listeners love in electrostatic headphones, with a slightly different flavour. It’s a fillet steak with port sauce. The Omega2 has cream peppercorn sauce, the SR-202 a Roquefort sauce. The HF-1 is a well hung piece of sirloin with horseradish and the HD650 is a T-Bone with mayonnaise. I guess that makes the Triport a tin of Spam.

To hear the Ergo AMT with the Amp2, or via the transformer box connected to say, a pair of Quad II mono-blocks, or even an Imp Amp would be something I would like most dearly. They are I suspect, despite already being quite astonishing, a well of potential which has not been properly tapped. I heartily recommend that other Head-Fiers take the opportunity if they ever have one, to audition this headphone. It is quite unique. Quite special. And sadly for us, quite Expensive. If you fancy going electrostatic and have a bit of money to spend. Then do the adventurous thing and go AMT instead. There are plenty of electrostatic owners out there. I’d love to personally pit the AMT against the SR-404 or the Lambda Pro. (If someone wants to lend me one I won’t be objectionable.)

These are not going anywhere. I’d sooner part with any part of my entire setup except the Omega 2.

I may come back and revise this in the future. I wanted to post it as it is because I thought that it was time it went up and it seemed to be good enough. That and because I wanted to get my 1500th post done with so I could go back to my regular trolling.

Id like to say thanks to Hirsch for selling me the Ergos. Thanks to MAGNOCTICOM for helping me out with the educational animations. And thanks to my dad for letting me borrow his Stax for the time I had them. Thanks for reading.

Oh yeah. Headphoneus Supremus. Joy.


*minor edits after posting* *driver principles descriptive amendment Oct 27 2006* *Title Edited for the PC loving 56 users 1/6/07*

Truely the work of a supremus in the way of headphones. I salute you, brave Douglas!

Very nice review! Your review makes me want to get a pair of AMT's, as I've been enjoying Ergo 2's.

Very little has been written about this headphone on Head-Fi and your review obviously fills a gap (especially for those who use the search engine when they wonder about something). I have heard the Ergo AMT in a shop and had mixed impressions. With the source material available in the shop, the AMT sounded really promising with an impressive midrange of the smooth kind. When I tested it with a few of my own CDs, I was much less impressed. It couldn't reproduce for example hard rock in a realistic manner, what I remember bass and impact was lacking seriously and the sound had a velvet character. I auditioned it with the basic amplifier model and the more expensive amplifier was not available in the shop at that time. What I remember that amplifier was rather inexpensive and it is possible that it didn't drive the headphone to its potential.

I think the AMT sound is in the same "family" as Stax RS-404 for example but the time between my auditions is far to long for a comparison of reasonable accuracy. AMT might be an alternative to electrostats for those who like that sound signature. It is definitely not an alternative for those who want the Grado sound!

I liked the ergonomics of the Headphone, lying on the head and not touching the ears, for the hour I listened but I haven't tried extensive listening. However, the sound signature is very smooth and AMT is a headphone that should be less prone to listening fatigue.

Magnificent review, truly Headphoneus Supremus material. Thanks for the most enjoyable and informative read I have had in this forum in long while.

Duggeh, your sense of humour, your ideas and opinions, and your overall writing style is always something to look forward to at Head-Fi.

You are a mastodon among tiny, tuskless baby elephants.

Judah Ben-Duggeh, you truly are the king of kings.

now we know why Duggeh has been a little quiet lately. The bar, gents, has been raised.

Bravo, Bravo.

I must say that the Ergo AMT and the preceeding review is missing one thing. I rousing round of Lily the Pink and a good pint!



[size=x-large]CHEERS[/size]

I remember seeing some swedish made speakerphones similar to this being sold in an audio shop's junk pile.

At first I was hesitant, but now I think I'll see if I can pick up a pair and hear what all the fuss is about.

Thanks for the review Duggeh!

Bravo Duggeh!

Quite a way to reach Headphoneus.

Now this is a review! My vote for featured reviews, especially seeing how there's so little information to be had on these headphones.

best review ever.

i might just get a pair of these for an early xmas present

Very nice review, and congrats on the Headphoneus Supremus! I also say that this goes under featured reviews.

Tahnks for the kind words guys. If the powers that be see fit to copy this to the reviews section I should be most pleased.

That is a great review Duggeh, worthy of being in the reviews forum. I think PM'ing an admin will get it there.