STAX SRM-500T Valve Headphone Amplifier
The STAX SRM-500T is the entry into the world of STAX valve energisers for their remarkable earspeakers. The combination of the SRM-500T & the SR-L700 MK2 Earspeakers is something you really must hear. For under $6K you have a system which rivals loudspeaker based systems costing tens of thousands.
For many years, enthusiasts have raved about STAX valve energisers and preferred them as being the most natural partners for their wonderful earspeakers. The SRM-500T proves the point resoundingly. Everybody who hears this wonderful driver with any of the STAX earspeakers, especially the sublime SR-L700 MK2, finds they cannot stop listening to music. One track leads to another as they explore their music collection with fresh ears. Ears that are caressed and beguiled with the most natural sound many have ever heard. This energiser is far from the least or the most expensive in STAX's range but it just may be the sweet spot when it comes to cost vs. performance.
The input stage of the SRM-500T features a simple two-stage circuit using low noise FETs that are hand selected while the Class-A DC amplifier configuration eliminates coupling capacitors throughout the signal path. Very good quality high-voltage dual triode 6FQ7/6CG7 valves are employed in the output stage of the SRM-500T. This helps give this energiser such a rich and natural sound right across the audio spectrum and across all genres. From rock to jazz to electronic and classical the SRM-500T enables you to listen and enjoy music over a long period of time with zero fatigue
Inside, carefully selected high-quality audio grade components are employed for the main circuit which contribute greatly to the overall tonal quality. High-quality relays are placed close to the input terminal to realize the shortest signal path and the quality of the circuit board, wiring and soldering are beyond reproach.
The controls on the SRM-500T are a pleasure to use. The volume control uses a custom-made double axis 4-gang volume pot to allow smooth control of both volume and balance. The front panel metal controls are precise and solid giving great confidence in the quality of construction. Two STAX earspeakers can be used simultaneously with dual PRO level outputs provided on the front panel.
Around the back there are 2 inputs so you can connect a couple of sources at once. There is one set of balanced XLR inputs and one set of RCA inputs. There is also, conveniently, a parallel output so you can feed the selected source back into your amplifier if required.
Why Electrostatic Headphones?
Electrostatic headphones operate on a different principle than conventional "dynamic" or "moving coil" designs. In a conventional headphones there is a coil of wire inside a magnet, generally glued to a stiff cone or dome that's held in place with a springy suspension. This makes in more difficult to re-create detail in playback due to mass. Or to put simply there are more heavy moving parts.
Pioneered by STAX in 1959 – an electrostatic design works by placing a static (non-moving) electric charge on a film that floats between two perforated metal plates. When audio voltages are applied across the plates, static cling and repulsion causes the entire film to move by itself. This film is so thin, it effectively weighs less than the air around it, and has no resonances or energy storage which leads to distortion inherent in moving coil speakers.
These factors are one of many reasons why STAX electrostatic Headphones sound so much better than conventional designs. During play back the listener is experiencing minimal interference from the headphone speaker itself, in turn bringing you that much closer to the original artist's performance.
About STAX
STAX was founded in 1938 in Japan. In 1959, STAX developed the world's first electrostatic headphone and introduced the SR-1 in 1960. Today STAX continue their tradition by offering the finest headphones for both professional and audiophile applications. STAX refers to all its headphones as "Earspeakers". Such Ultra-High-Fidelity devices for reproducing music can only be compared with the best cost-no-object loudspeakers, not other headphones. The term "Earspeaker" is, therefore, more descriptive of STAX's contribution to today's most advanced level of sonic transduction. STAX is a company with more than 80 years of history and a persistent pursuit of Hi-Fi and Hi-Res audio reproduction. It has always focused on electrostatic technology and has almost become synonymous with electrostatic headphones.
STAX SRM-500T Review
"The STAX SRM-500T was paired to the STAX SR-L700 MkII, one of its natural matches, though the STAX SR-L500 MKII, and the STAX SR-L300 are also considered the natural companions of the STAX SRM-500T if not its BFFs.
As with all STAX electrostatic headphone amplifiers the midrange is yet another place where the magic lives and it is always beautifully rendered. The STAX SRM-500T handles the midrange beautifully in how it renders timbre, tone, and texture in a rather sublime manner. The SRM-500T offers good transparency, though it is not quite as good as those STAX electrostatic headphone amplifiers above it. And therein lie the sacrifices that must be made for keeping to a certain price point. Yet despite this, its midrange performance is rather exceptional, as well it should be. Those entirely new to the electrostatic world may well be entranced and en route to becoming a citizen of another world.
The treble is very natural, completely free of any sibilance or harshness or grain. Resolution is also quite good and cymbals will resolve as cymbals and not the irritating "Schchccccccsssh" sounds that come from components that render this upper band poorly to horribly. And there are systems and components from the very inexpensive to the prodigiously expensive that err with regard to this one simple requirement—let cymbals be cymbals and not as a friend would say, "The sound of paint cans spraying paint." The STAX SRM-500T, however, passes this test with flying colors!
The STAX SRM-500T, like its siblings, sports a rather traditional design - clean, purposeful, minimalist - with an anodized, aluminum facade and a gray-coated, steel body. The SRM-500T's top features two, small, vented, convex mounds, directly above the two 6FQ7/6CG7 internal tubes, for cooling. These mounds sit between the cooling vents for the SRM-500T's interior.
The STAX SRM-500T is diminutive, well executed, and built to last, which so very many STAX energizers have apparently been built to do—to last. The SRM-500T's design is straightforward and clean and purposed—it plays music beautifully.
No doubt, the SRM-500T was STAX's way of saying this was constructed for those new to electrostatics, for whom it may serve as a beacon to a world that is immensely charming, musical, and communicates as if a breath of fresh air. There will also be those, who see the STAX SRM-500T as but the point of entry to this world. Their sights will, no doubt, lead them farther into this incredibly beautiful, transparent, and detail rich electrostatic world.
We, AudioKey Reviews, highly recommend the STAX SRM-500T for those new to electrostatic headphones and amplifiers, as it will serve as either a longtime companion, perhaps for most, while for others, the first friend in a journey across an electrostatic world where a more 'kindred' musically adept electrostatic friend may, indeed, be found. Happy world hopping and happy befriending!" AudioKey Reviews
Out Take On The STAX SRM-500T Valve Energiser
I had a few minutes spare the other day to check out the STAX SRM-500T energiser and decided to plug the SR-L700 MK2 earspeakers in and take a listen. Just as well we weren't too busy because I totally lost track of time and ended up playing a whole string of tracks as I kept delving into our music library and coming up with more and more undiscovered gems that I had never even thought were well recorded, much less audiophile material. But everything sounded so good! Not in a rose tinted glasses sort of way either. I could still tell which tracks were decently recorded & mastered and which weren't but, in reality, I stopped caring. I was more interested in just enjoying the music – the sheer musicianship on offer from all sorts of artists. The telepathic vocal interplay on CSN's Wooden Ships, the cavernous scale János Starker's coaxes from one cello on the Bach Cello Suites, the way Ella Fitzgerald & Louis Armstrong finish each other's musical thoughts on Ella & Louis, the explicit primal quality of Stevie Ray Vaughan's guitar on Tin Pan Alley, the hypnotic manic driving beats of the first Chemical Brothers album etc, etc, etc. One track inevitably lead to the next as if the whole thing was scripted but it was really the musical qualities of one track suggesting a transition to the next and the next. Such is the seductive power of STAX in general and this wonderful valve amplifier in particular. Maybe it's time you took a listen?
Main Features & Specifications
- Design: Vacuum Tube/Valve Amplifier for STAX PRO Earspeakers
- Use with these STAX Earspeakers: STAX SR-L300, STAX SR-L500 Mk2, STAX SR-L700 MK2
- FET Input + vacuum tube output hybrid DC amplification
- Newly Designed Vacuum Tube Output Stage
- Custom-Made Low Noise Dual FETs
- Pair of 6FQ7/6CG7 pre-installed Vacuum Tubes
- Frequency Response: DC to 90 kHz
- Gain: 60dB
- Harmonic Distortion: 0.01% or less (1kHz/100Vrms output)
- Input Impedance: 50kΩ (RCA), 50kΩx 2 (XLR)
- Maximum Output Voltage: 300Vrms (1kHz)
- Bias Voltage: DC580V
- Operating Temperature / Humidity: 0 to 35 Degrees C / less than 90% (non condensing)
- Input Terminals: Stereo RCA, Stereo XLR
- Output: Stereo RCA parallel output
- Power Consumption: 38W
- Dimension (WxHxD): 195 x 102 x 376 mm
- Weight: 3.4 kg
- Manufacturer's Warranty: 1 Year
Note: Features & Specifications Subject To Change Without Notice. E&OE.