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This player is well equipped. There are analog outputs (line and headphone) plus two mini USB ports. One of them can be used to connect the player to a computer to download music files. The other also connects to a computer but this time is for streaming DAC use. There is a color display showing file data like name and other ID information but no cover art. It shows word length but not sampling frequency. The player comes with an external battery charger.
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Ergonomics are obviously not a priority. The device fits nicely into a palm but the user interface is not as friendly as it could be. There is one ‘easy’ manipulator however, the push button in the middle which starts and stops playback.
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Tech specs:
D/A chip: TDA1543
LPF op-amp: OP275, OPA2604
Headphone amplifier op-amp: OPA2107
Frequency response: 20Hz - 20KHz
Distortion: 0.09%
S/N: 92dB
Stereo cross talk: -74dB (line out)
Headphone amplifier
Output level: 1.1v at 32Ω; 2.2v at 150Ω
Max output: 30mw at 32Ω,; 26mw at 150Ω
Size: 62 x 103 x 26.5mm or 2.4 x 4.05 x 1.04”
Weight: around 200g
On-board memory: 16GB flash
Battery time: 9 to 10 hours
I/O: Headphone output; line output; USB data exchange; USB DAC input; SD card slot (up to 32GB)
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HiFiMan EF-5: This is the current top device in this manufacturer's portfolio intended to drive all its planar headphones from the HE-4 I reviewed here on to the top-line HE-6. It includes two identically sized chassis for the power supply and amplifying stage.
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The latter is easily recognized by its FullMusic 12AU7 double triode that works as an input buffer. There is also a quite powerful input stage with OPA275 chips driving powerful output transistors (four per channel covered by large golden heat sinks). The amplifying stage is mounted to a small PCB that plugs into the main board with golden pins. A miniature Alps pot handles volume.
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The main PCB in fact is a very advanced power supply section. There is a switch on the top that allows to choose between high and low gain. The latter should be suitable for most headphones. On the front there is on/off button, a headphone jack and a small knob for volume control. The amplifier is fed from the DY-1 power supply equipped with IEC socket. The output voltage is selectable between 16 and 18 V AC. Inside is a large toroidal transformer.
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Technical data:
Op-amp: OPA275
Tube: FullMusic 12AU7
Frequency response: 20Hz – 30kHz
THD+N: < 0.2%
S/N: >95dB
Input impedance: 50KΩ
Output signal strength: up to 15 volts at 32Ω
Input: RCA
Output: ¼” headphone jack
Dimension: 110 x 50 x 270mm
Weight: 3kg including packing
Included: 12AU7 tube, DY-1 power supply compatible from 110v to 240v
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HiFiMan HE-4: As the company’s Mr. Fang stated in these pages elsewhere, “…our planar headphone project started in early 2009. Because one can source the very best magnets right here in China, we decided to create a high-end planar headphone. Our first prototype was only 4 ohms and we had to add a resistor to the driver to make it work with headphone amplifiers. Then we learnt how to print a thinner voice coil onto the Mylar diaphragm. The thinner the coil, the higher the impedance. The HE-5 was 25 ohms, the HE-5LE is 38 ohms.”
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The HE-4 has exactly the same impedance. Mr. Fang calls the HE-4 the single-ended version of the HE-5LE with a very similar sound signature. Because the magnets in the HE-4 are 50% smaller than those in the HE-5LE, the HE-4 is much lighter (350 g). The design sports a Grado-type fixed leather-clad padded bridge. With the headphones come three sets of 3m cables that plug into the ear covers with nice gold-plated plugs. One of the cables sports a 6.3mm plug, one a 3.5 mm 4-pin plug for your mobile phone and the third one a plain 3.5mm plug. If you want to use a different after-market cable from the likes of Cardas or Oyaide, HifiMan includes a set of spare terminations for your rolling pleasure.
Technical data:
Frequency range: 10Hz - 60kHz
Impedance: 38Ω
Sensitivity: 86dB
Weight: 350g
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opinia @ highfidelity.pl
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