Stax SR007t Mark II

Electrostatic Earspeakers

Price: $2,400

SRM-007tII Vacuum Tube Driver

Price: $2,000




Dynamic versus Electrostatic headphones

In general, headphones, or earspeakers, have one advantage over conventional speakers – the room acoustics or the peaks and nulls that occur due to the room reflections and standing waves do not affect them.

The dynamic headphones are similar in design to the most commonly found dynamic speakers. The mini headphone driver (diaphragm with attached voice coil) moves through the static magnets when the audio signal passes through: moving air or producing sound corresponding to the input signal.

STAX developed the world’s first electrostatic headphone and produces some of the best electrostatic headphones and amps.

According to Stax, “The electrostatic transducer adopted in the STAX Earspeakers consists of two parallel-arranged fixed electrodes and several microns thick (less than 2 microns) high-polymer film diaphragm suspended in the middle of the electrodes. The low-mass film diaphragm is supplied with the biasing voltage from the energizing adaptors or from the driver unit.”

“When the fluctuating voltage of the audio signal is applied to the electrodes, the diaphragm is pulled by the electrode which has the opposite charge of the diaphragm's and simultaneously pushed by the other electrode which then has the like charge of the diaphragm's.”

“The continuous flow of alternating voltage in interpretation of audio signals causes the diaphragm to vibrate in faithful compliance with the amplifier output without time lag, assuring undistorted sound waves. This is why the STAX electrostatic Earspeakers sound so good.”


This figure shows the driving mechanism of the Stax Earspeakers. From a practical point of view – electrostatic headphones need electrostatic headphone amp or at least a transformer that can connect to a power amp. Dynamic and electrostatic amps and headphones cannot be used interchangeably. For more about electrostatic speakers, read the review of the Sander's 10b ESL system, Stereomojo's 2008 Product of the Year. See the link at the end of this review.


SRM-007tII is a balanced amp driven by dual triode tube 6FQ7 (6CG7). It has both balanced and RCA inputs and can simultaneously power two STAX SRS-007MK2s effortlessly. The volume pot is one of the smoothest I have experienced. These are the most comfortable headphones I have ever tried. The earpads are fully adjustable to the shape of your head and are made of genuine sheepskin. The look and feel is clean and luxurious like no other headphone.





Type :Push-Pull Open Back Electrostatic Headphone
Frequency Response :6 - 41,000Hz
Impedance :170k Ohms (10kHz)
Sensitivity :100dB / 100V r.m.s. 1 kHz
Bias Voltage :580V DC
Left & Right Channel Identification
:Left (L) and Right (R) indicators are provided at the cable entrance points on the Earspeakers. Left channel cable is marked with a solid Line. Right channel is marked with a dotted Line.
Ear Pads :Crafted from high quality sheep leather for durability and comfort.
Cable :Low capacity wide format, PC-OCC (Pure Crystal Ohno Continuous Casting) 2.5m/8.2ft


First impression

When Stereomojo publisher James Darby gave me an opportunity to review the updated headphone system from STAX, I was thrilled. A few months before, I was able to borrow STAX’s lower range headphone system and although I really enjoyed its open presentation on jazz, I felt as though it clearly lacked in bass.

But when I first hooked up the 007 Mark II, I heard something special. First thing I noticed was the presence of bass that was lacking in STAX’s starter series. I had read the Mark I review as well as user impressions in online forums about the lack of taut bass. If anything the Mark 2 addressed it and I could head bass clear and present – no complaints here on bass.

The midrange is where most of the music is and that is where the Omega 007 Mark II really shines. They produce the lushest and smoothest vocals of any headphone system to which I have had the pleasure to listen. They made all vocal recordings enjoyable – audiophile or from the 70’s.

So that leaves us with the high frequencies. They provide the detail but are slightly roll off on the top and are not the last word on air around the instruments. But they provide a very immersive, out of the head experience.

When I asked my wife for her impressions, she said they created the impression of surround sound that she really liked. Further she did not have any quibbles about the look, feel or sound – so hopefully this means II will soon have STAX system of my own in the house. They create a very pleasant house sound that is rich and easy on the ear. Their presentation is different from most dynamic headphone systems. I can definitely hear the benefits of tubes here that tubes generally lend to the headphone systems. Mr Tats of Yama’s Inc. said that the stock tubes in the amp are the current production Electro Harmonics and the amp would have to be sent back for re-biasing if the tubes were to be changed. I wish I had a chance to listen to the STAX system after swapping the current EH tubes with some NOS tubes, I’d imagine it would open up on top provide some more air around the instruments.

I was not able to reach any useful conclusion doing the A-B Testing Switching between the Stax headphone and amp combo and my re-cabled Sennheiser and recabled AKG 701’s with Solid State and tube headphone amps. In short I found that there are more similarities between the Sennheiser 600 and AKG 701, though they sound so different, than there are similarities between the Stax and either of the two dynamic phones. I had to stop doing A-B, not because I did not hear the difference, but because I want to connect with Stax and listen to what they were saying and get used to their voice. Stax have denser or richer sound. They may not provide the microscopic details but sound relaxed and very enjoyable.



MK I vs. MK II Earspeakers

Mr. Tats sent me both MKI (brown) and MKII (black) Earspeakers at my request. In my conversation with him, he told me that the newer model has improved imaging and bass response. The leather pads in the newer model are not as soft and luxurious as the new ones. Mr. Tats mentioned that these phones really take about a year until they continue to break in or continue to sound better. He said that eventually the leather pads would break-in too but they are not as soft as the old one by design to give better bass response among other improvements. The differences may be minor but they are there.

I believe in the positive effects breaking-in any audio gear – electronics, cables or transducers. Bob, the president of New York Audio Society says that takes about a year for any audio gear to fully break-in. I, the publisher of Stereomojo, say Bob the president of New York Audio Society is mistaken and that there is no rule of thumb for every audio component, unless that component IS a thumb. For me, there is no question that new audio components require some time to break, burn or settle in. Almost every serious designer will tell you the same thing. They will also usually tell you what that time period is. It can range from a few hours to hundreds of hours.

It is an ongoing issue in the audio industry as well as the audio press. See "Dirty Little Secret"

sidebar - publisher.





Here are my listening impressions. You’ll notice that some CDs are better known for their musicality while others for a certain aspect of audiophile or recording quality.



Kind of Blue - Miles Davis - So What

The more I listen to So What the more I enjoy it and it was no different this time – what I was pleasantly surprised by was the texture and quantity of the bass response.

Time Out - Dave Brubeck -  Take Five

Stax gave a very smooth presentation that was foot tapping rhythmic and very enjoyable.

My wife said there is something sweeter about it and while the conventional headphones were trying to create a surround sound – the Stax actually created the surround sound environment. I’d call it a more immersive and involving experience.


Diana Krall - Live in Paris - I Love Being Here with You

This track is making me fall in love with these Stax. I was impressed with them from the very first day I heard them and I knew they were special but I had preference for my existing reference gear. It has taken me some time to start love them. Stax created a very expansive arena with a nice attack. The bass response and quality is very unique – it is neither better not worse – but different from what I am used to. The bass is definitely more tubey – but very tuneful. Some people call the Solid State fast bass as accurate some prefer the tubey slower bass, with more low level harmonics as musical – by which they mean more real. So one is real and one is accurate. Is it a matter of choice of words or listening preference?



The Singing Bowls of Tibet - Alain Presencer

This CD is all about “Tone”. It is a very good attempt at reproducing sounds from Tibetan bowls that are made of an alloy of eight metals: gold, silver, copper, tin, lead, iron, zinc and bronze. The craft that went into the casting over the past 1000 years has produced bowls of great beauty and, at times, unfathomable sound. The STAX produced a very meditative experience with tonally colorful and reverberating sounds. On this CD, they produced an extremely immersive experience that transported me to an exotic place and helped me connect to my inner space.


Still on the Air - Toshihiro Akamatsu (Three Blind Mice) - Still on the Air

This CD for me represents “Air” around the instruments – this is where the STAX fall short. If the STAX SR-007 II have one thing coming in the way of them becoming one of the best headphone system would be that they do not portray the space or air around instruments as convincingly as good speakers or some other high end headphone systems do. It seems like STAX made this compromise of giving up the last bit of air for making this headphone system extremely musical and least bit analytical.


The Rain - Ghazal

ECM label is known for it minimalist approach. This is beautiful and very natural blend of Persian and Indian Classical instruments Kamancheh and Sitar with Tabla and some interspersed vocals. STAX delivered this blend in a way that very easily drew me into intimately set live recording. The Kamancheh retains its earthy tone while Sitar plucked the heavenly chord. It is very hard to record and reproduce Tabla properly due to its range and texture. Even though Tabla is mostly in the background, STAX conveyed the texture in a very convincing manner. I thoroughly enjoyed this CD through STAX or should I say I thoroughly enjoyed STAX through this CD. The leather earpads are so comfortable and the headphones in general exert minimal pressure on the head and around the ears, combine that with their utter musical, lush and immersive presentation – they drew me into music and made me forget that I was listening to headphones.


Eric Clapton - Unplugged - Signe

This recording captures the emotion of a live event but the recording is on the hot side of the spectrum. SR-007 II just transported me to the best seat in the house. It does a good job making poor recordings listenable and even enjoyable – that is one of its biggest strength. Just listen to whatever you like to listen to – not just the audiophile recordings. By the way the guitar came across with plenty of detail and the STAX nailed down vocals like nothings else. This CD is a tough test to pass and STAX passed with flying colors.


Friday Night in San Francisco

This dazzling pluck my heart strings every time I listen to and it was no different now. This is one of the most enjoyable Live CD's for me and it was just as if not more enjoyable through STAX.


Scheherazade, Rimsky-Korsakov, Op. 35 Final movement

There is so much drama, suspense and change of scene on this track. Living Stereo’s recording is full of dynamics Reiner’s reading is full of flair and color. STAX kept up the pace with the full blown orchestral attack from bass to strings to wind instruments to drums. Fantastic!



The Stax SRS-007MK2 Electrostatic Headphone System is very special and produces an incredible sound. They are extremely enjoyable and are closer to the warm and lush side of neutral, a more preferred side for most when compared to the cold and dry or analytical side of the neutral. I had a hard time comparing them to the dynamic headphones, they just sound so different. Do make sure you have sufficient time before you set up an audition and just listen to the STAX for a couple of hours. One needs to get accustomed to their unique and and so easy to listen to presentation.

At $4,200, these are certainly not for everyone, but neither is a Lexus or Mercedes, and that is the class of quality about which we are talking with the Stax. These are recommended for those that listen to their music almost if not completely exclusively through headphones; or as Stax calls them, earspeakers. Of course, they cost more than many pairs of conventional speaker, which for many people is just fine since they believe that listening via 'phones eliminates the major impediment to truly accurate home listening - the room. For apartment dwellers, phones allow you to crank them without worries about cranky neighbors. Of course,this is really a headphone system since it includes a very fine headphone amp. There are several dedicated headamps that sell for $4,000 by themselves. So, investing in a state-of-the-art system such as this makes sense for a whole lot of people.

Bear in mind that the amp is not tube roller friendly. Changing them out requires a trip back to Stax.

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