Headphone amplification has been experiencing resurgence over the past few years. Between the popularity of the iPod and audiophiles who desire a more intimate listening experience, combined with lovers of binaural recordings, the headphone market has been experiencing growth during the past year. In response to these events more manufacturers have been offering preamplifiers with headphone jacks while dedicated headphone amplifiers are becoming more mainstream.
Ray Samuels Audio produces various preamplifiers, phono stages and headphone amplification. Reviewed here is their basic Emmeline SR-71 headphone amplifier. They do offer other units, including tubes, though i was curious as to what could be offered for a an entry-level price of just under $400. Of particular interest was in the use of battery power! This eliminates the possible problems with power fluctuation, EMI/RFI, etc found within using the power company's offering.
While i will not delve too deeply into the specific parts and construction, the metal case feels extremely sturdy while the volume knob on the right moves smoothly. As seen above, the far left 1/8-inch stereo jack is for output while the other is for input. To the right of the metal volume knob is the power switch. Inside the unit, various power capacitors are mounted on the top of the board while the other side holds the chip-based amplification. The rear of the unit has a pair of easy to access screws for loading/changing the pair of standard 9V batteries. Unlike other units that require the batteries to be changed every 10 to 12 hours, the Emmeline SR-71 achieves from 50 to 70 hours for each pair of 9V alkaline.
Having taken a lesson or two from the battery G-ds after reviewing the Final Labs battery powered electronics, i have found that dry cell batters (also called 'Heavy Duty') can yield better sound than alkaline. My best guess of about 35 hours of amplification is achieved per pair of dry cells.
With an input impedance of 50kOhms, frequency response from 10Hz to 100kHz, and a gain of 6dB (250ma of current), the SR-71 can drive virtually all headphones. The additional power provided by the pair of 9V batteries, versus what some other manufacturers use (4AA or the like), allows the use of more powerful chip-based power amplification. Basic math... four times 1.5V equals only 6V for both channels as employed in other battery powered units versus Emmeline's 18V for the SR-71.
After careful listening with various headphones, including the Sennheiser HD600 (with Stefan AudioArt Equinox cable), various in-ear units, an old pair of Koss Pro.... Naturally the SR-71 was compared to various headphone amplifiers on hand including basic Headroom units and Skorpion's HV-1 OTL headphone amplifier as reviewed in January 2003. My overall impressions were very positive and overall listening was very enjoyable.
The benefit of using a stronger power supply augmented with capacitors was the ability to drive the headphones. This included bass-heavy music such as rock, techno and the like. Consider this the British equivalent of PRAT (race, rhythm and timing). Funk from Parliament/George Clinton/Funkadelic and the like did very well. It was leagues better than the few hundred dollar Headroom units on hand and was equal to the Skorpion. There was quite a bit alike between the Skorpion and the Emmeline SR-71. Within that review i wrote "Tonally, the HV-1 is on the accurate side of the fence over tube warmth or "lush". It is not a cold and sterile unit and to further clarify, harmonics seems quite good and precise over the rose-colored glasses variety. If you are looking to have added warmth to your headphone's sound, then i would suggest looking elsewhere."
What i will add is that battery rolling, akin to tube rolling (changing of tunes), the SR-71 was very musical with dry-cell batteries. Alkaline batteries produces, to my ears with my headphones, a bit more bass drive and upper midrange sharpness. Oh how we audiophile will try swapping anything we can to reproduce the music we love so dearly. Both the OTL Skorpion and SR-71 have a frequency range that extends well above 20kHz. The Skorpion is rated from 5Hz to 70kHz (+0/-3dB) whereas the SR-71 reviewed here is rated from 10Hz to 100kHz. And leads us to the highest octaves.
Bells, chimes, and cymbals had a wonderful shimmer not found in other units on hand. As a drummer/percussionist, this is usually where many music reproduction systems (in general) can either be enjoyable or annoying. For me, there is something about reproducing the uppermost frequencies that can either be enjoyable and relaxing, or annoying to the point of causing a headache. The SR-71 was extremely enjoyable and all day listenable.
As for right to left imaging, since the SR-71 is a true dual mono design i could not detect any major shortcomings. Of course this all happens within one's head, unlike using loudspeakers where one experiences sound within a listening room. Ray Samuels Audio chose a 'pure' design so there are no selectable listening modes to change the sound of the music. Some people find these other modes enjoyable while i generally find they add a layer of opaqueness, thereby adding confusion to my listening enjoyment. The usual 'less = more' design as it were.
Jazz and classical music was easily handled with aplomb including pipe organ and masses choir plus the usual audiophile faves from Miles Davis, Billie Holiday, Ella, etc. Massed stringed instruments were reproduced with an impressive amount of inner detail and delicacy. While perhaps not the very last word in microdynamics, the SR-71 is one heck of an amazing unit for under $400. If you desire more, Ray Samuels Audio does offer other headphone amplification -- with tubes -- though they are not battery powered.
As for dynamics, attack and speed, the SR-71 easily showed superiority to other manufacturer's basic battery powered units. It was not even close to my ears. This may be due, in part, to the stronger power supply, a good dose of power capacitors, a true dual mono design, and most important of all that the entire signal travels and very small length in total. By now virtually all audiophiles are familiar with products from 47 Labs (reviewed here) where an extremely short signal path was among the deign highlights. Since the Emmeline SR-71 is a small unit, with the entire signal-based electronics taking up only an inch or so of space, naturally the signal path is quite short. My guess would be that the total cable length you use to and from the SR-71 is over 100 times that of the signal length within the SR-71!
Obviously i was smitten by the Ray Samuels Audio Emmeline SR-71. There was much to like with the small form factor combined with a very usable battery life. iPod lovers can enjoy headphones that may need a bit more oomph to drive them. Add to that the obviously benefit of high quality portable amplification for other headphone uses and the SR-71 is a winner. Those looking to step up from the less expensive, plastic-wrapped battery powered headphone amplifiers may indeed step up to the next level in musical bliss. Of course in the end what really matters is that you...
Type: stereo headphone amplifier
Input & Output: 1/8-inch stereo jacks
Input impedance: 50kOhms
Input Sensitivity: 0.5 -- 4Vp-p
Frequency Response: 10Hz to 100kHz
Output Impedance: 16 Ohm at 2kHz
Output Stage Current Drive: 250ma
Dual Mono Design
Battery Life: with alkaline batteries is 50 to 70 hours
Emmeline By Ray Samuels Audio