Sonic Encounters -- Stax Earspeakers

Stax Earspeakers

This week, Sonic got invited to join a test of the legendary Stax electrostatic headphones, or Earspeakers as the Japanese manufacturer quaintly calls them.

Sonic got to hear two models – the top-of-the-line model SR 009 with a tube driver stage unit and the more affordable SRS 2170 system (headphone/earspeaker unit and driver unit). The top-model is priced beyond US$7,000 in our town with the driver unit.

The background of this test started with a debate with two fellow audiophiles on the ideal reproduction system. The debate turned on what to do about the last mile – that is our speaker/room interface and the path to our ears.

A room can be conducive to musick reproduction or it could be your worst enemy. One audiophile says damp it, Sonic follows Micahel in saying control and use the energy in the room – the room is your speaker and in any struggle between the speaker and the room, room wins. Then the discussion ran to DI (Direct Injection). Musicians DI electric guitars, basses and keyboards to eliminate studio physical effects in recordings, so what about the parallel of this idea during playback, where we DI the musick to our ears using headphones. No room acoustic problems of overhang, excessive damping, wrong dimensions etc because there is no room.

Who's Stax?
They are not to be mixed up with the US Stax record label, but a venerable Japanese company with roots back to 1938. Over their history, they made microphones, cartridges, tonearms, CD players, amplifier and the acclaimed ELS-F81 electrostatic loudspeaker. Their most enduring product line is their earspeaker/headphone systems with their first model rolling out their factory door in 1960.

Stax earspeakers don’t plug directly into a headphone jack but work through a driver stage – a box with a volume control – that provides the bias voltage for the electrostatic drivers and takes the signal normally from the REC Out of a preamp (it can be driven from a headphone jack though). This is an improvement from earlier Stax earspeakers that had to be driven from the main amplifier’s outputs and had a switch to route the signal between the earspeakers and the in-room loudspeakers.

The 009 have round earpieces while the 2170 have the oblong earpieces that are visually more recent Stax-like (their early earspeakers were round, I am told).

The earspeakers are open back and if you cupped your hand over them you can get a wa-wa effect like the blues harmonica players get with their harps.

We listened on a system that with a digital front end using a CDC belt-drive CD player and tube electronics.


The 009 and 2170 are fairly comfortable for the 30 minutes Sonic tested them, not heavy, or did they make my ears sweat. External noise sealing is not great so when other people in the store tested loudspeakers, we (Sonic and other testers) had to sit it out.


Headphone Drawbacks
Whatever headphones do right, there are drawbacks. You got to put up with an object clamped round your head. The soundfield swings around as you turn your head. You get some odd effects of the music being in your head and not “out there, ahead of you”.

Sonic has owned a couple of headphones and never really liked them very much for these reasons. Of course, there are systems like the Dolby which uses processing to push the soundstage out front of you but I have not heard these so I cannot say how effective they are. There is also the binaural system which can be very real – recording withy microphones in a dummy head (often a dummy head and torso) – but lacks software. You no can buy Handel, Haydn or Led Zeppelin in binaural.

The Listening Test
Sonic tested with Handel’s Water Musick (Pinnock/Archiv), of course there was other musick, mostly fusion jazz which I am neither familiar with or enamoured.

Assuming both earspeaker systems were fully run in and settled, the 009 was very flat in frequency response so much so it sounded almost bland. It sounded extremely transparent, with every detail in the recordings audible. I could hear how voices and instruments had been recorded separately and “dropped in” in the mix.

On the other hand, the 2170 had more treble bite and upper bass projection that Sonic can to relate to from hearing live recitals of violin and celli. Over the brief test period, this model sounded a bit closer to what I have experienced of live musick but the test period is too short and too many things are variable that could tip things in favour of the 009s.

The transient speed of both earspeaker were of an order on par with or beyond the best electrostatics and horn loudspakers. Tonally both were very pure.

The bass of both were extremely tight, smoother that many in-room speakers and went down deep. And true to Sonic’s earlier expereinces of headphones a jazz trio CD had the piano go through my head ear to ear while the bass was on my skull just above my left temple and the drums/cymbals a couple of inches above my right temple.

On both models, I can hear a clarity and detail that I have not heard without excessive brightness. I can hear ambience from the recording venue but the absence of a physical room makes a big difference. I could hear how much a room adds to the sound in terms of excessive ambience, ringing, overhang in the bass or in other cases overdamping.

With the Stax, I got huge clarity and bass extension with a “dryness” in the bass that tells me the room is gone. There is ambience, reverb, echo effects even when not listening at excessive volume levels. On recordings I know well, the Stax earspeakers showed me how much my room was contributing to the sound at my ears.

The Debate
For all their limitations, headphones direct inject what is the musical signal right into our ears. A loudspeaker/room combination is unable to reproduce a recording of an instrument or voice in an acoustically dead space, like speech in an open field or an anechoic chamber while a headphone system is able to reproduce such a signal FWIW.

What then is the approach we Tunees should take?

We listen in rooms. We treat our rooms and we don’t want “dead” rooms. Should we use headphones as a reference to guide us as we tune our rooms?

Also, will platforms, racks, cables, canopies from Michael benefit headphone listeners? The tune trilogy appears to show they will.

Michael, what’s your take on this:

a. Can headphones be a reference standard for a hifi system?

b. What if we built up a system that is grounded mechanically and electrically tuned with Michael’s wonderful wood, racks, cables and cones but drove headphones instead of loudspeakers?

c. Will the differences when top tuning equipment, tightening or loosening bolts and racks be audible through headphones?

d. How would the tune trilogy work with earspeakers? Are speakers in the room required?

Sonic

Hi Zonees

What some audiophiles may not be clued in is that the frequency response of many headphones, even acknowledged reference standard ones, exhibit frequency response deviations that will be unsettling if seen in loudspeakers.

Go have a look around Head-Fi.org and such places and you will find many quality headphones with deviations of more than +/- 5 dB in the the very audible 3KHz to 10 KHz range.

The square wave response from a number of these things do not resemble square waves at all, more a fast rise with some ringing and a fall away like a ski slope. OTOH, Quads and some of the Magneplanars will, in the right test microphone positions, reproduce a recognisable square wave.

I also read a view in the professional magazine Sound on Sound where the engineers pointed out that the perception of headphone bass varies from listener to listener due to sealing, earpiece and ear shape interface.

Also earspeakers tend to exaggerate pan potting of images across the soundstage.

So to the professionals, headphones are a useful check on a mix but not a reference tool. For tunees, they may also be a good reference check. Go see my post today on my thread of what I did after wrestling with a "simplified system" for nearly a month. My conclusion was influenced partly from the test of the Stax Earspeakers.

Sonic