The
HD 558 climaxes my posts on the coverage of the Sennheiser HD 5XX series audiophile headphones having previously covered the
HD 518 and the
HD 598. Being the of the same product line, they all have a semblance in making and material. To begin with, they are all open back, high-end over the ear (circum-aural)
headphones featuring velour ear
pads and a leatheratte headband headset designed for extended listening comfort. Additionally, the velour ear pads provide for better sound channeling to your ear canal. This coupled with the open back design and an internal Surround Reflector, the HD 558 produces an
extended spatial sound
field. This makes it suitable for privately listening to music from your MP3 player and perhaps for use with your home theater entertainment system.
These headphones are supplied in a gloss black-colour with a layered honeycomb finish on ear cup casings.
Features of the Sennheiser HD 558
Open circum-aural headphones with E.A.R. technology
The Sennheiser HD 558 are full size headphones with earcups
fully wrapping around your ears and have been designed to give you
outstanding sonic accuracy and clarity while ensuring your listening
comfort for extended periods through Sennheiser's intuitive "Eargonomic
Acoustic Refinement" (E.A.R.) design. The E.A.R design ensures all
audio signals are directly into your lugholes while maintaining maximum
comfort.
DuoFol diaphragms are thin membrane films attached to a
voice coil. They are designed to create a wide sound stage with ultra-fast
response and rest times for improved sound transparency and minimal distortion. The size and shape of the diaphragms is ingeniously crafted to limit
intermodulation distortion. In simple terms, when an audio signal at a
given frequencies passes through an imperfect audio system, several
noise frequencies will be present at the output which are either
multiples, sums and differences of frequencies of the original audio
signal, though much weaker than the desired audio signal frequencies. This
distortion becomes significant when the volume is turned up!
Neodymium Ferrous Magnet and Aluminium Voice Coils
The permanent magnets adopted for the Sennheiser HD 558 are
highly optimized and field-strengthened neodymium ferrous magnets. This
coupled with lightweight aluminum voice coils provide an almost linear dynamic
response and efficiency.
The HD 558 are designed with open earcups that create a
spatial field - a perception of distance from the sound source. To
improve on this, the HD 558 is further equipped with a surround
reflector to provide an extended spatial sound field.
Velour Ear pads and Leatheratte headband
The HD 558 Ear pads are made of
velour fabric, which makes them have a smooth and tender feel to provide
extra wearing comfort during listening sessions. Its headband is lined
with leatheratte - an imitation of leather, to complete a luxurious and
comfortable headphone set.
Design attributes of the Sennheiser HD 558 Over the Ear Headphones
Just like all other models in the 5XX series, Sennheiser adopted dynamic
transducers with Duofol diaphragms for the HD 558 headphones. A dynamic transducer [call it a speaker], is able to produce sound because the changing audio current flowing through its voice coil creates a varying magnetic field in polarity, which interacts with the fixed magnetic field of the permanent magnet where the voice coil is suspended to generate a vibrating effect at the rate of the changing magnetic field. This vibration impacts the air around the cone, hence creating sound - music for that matter.
The permanent magnets adopted
in the HD 558 are similarly made from high performance field-strengthened
neodymium ferrous material to provide excellent dynamic response.
You should expect an almost linear response from the HD 558 headphones from as low as 15Hz to 28,000Hz. This range impressively blanks out our average ordinary audio range of 20Hz to 20,000Hz. Thus, the HD 558 has been designed for audiophile quality.
The input impedance is still the same from the Sennheiser
HD 518. The Hd 558 is rated 50 Ohms input impedance. This value is deliberately kept low by Sennheiser to ensure a quality output when used with modern home theater systems
and professional audio equipment, designed with low impedance
output headphone jacks.
The HD 558 ' sensitivity is of the same magnitude as the
HD 598. It is rated at 112 dB SPL at 1kHz for an amplifier input voltage of 1Vrms.
Total Harmonic Distortion (THD)
Total Harmonic Distortion (
THD) is a widely and intentionally misrepresented concept by most audio equipment manufacturers. The value of the
THD
ratio ideally should represent how much of the unwanted frequencies
(harmonics) a given audio system has at its output for an entire audio
signal range of say 20Hz - 20kHz. Traditionally, this is quoted by
manufacturers as measured for a single frequency. For the Sennheiser HD
558, this value of
THD is <0.2% at 1kHz, and 100 dB
SPL.
Dimensions and weight of the HD 558
The HD 558 is shipped in a product packaging that measures (L x B x H): 205 x 100 x 240 mm and weighs a net weight of 270 g.
A 3 meter, single sided and changeable OFC, 4-strand copper
cable, a gold-plated 6.3 mm stereo jack with a 3.5 mm gold-plated
adaptor and Sennheiser HD 598 headphones.
Buying guide
- The HD558 are an improvement from the HD 518. They sound better although some people may not at times tell the difference in performance. The headphones generally sound good for an open back design.
- The Sennheiser HD 558 wearing comfort is excellent even after extended use.
- Open back earcup designs normally have problems with poor Bass. But with the HD 558, the Bass is clear and just sufficient.
- Like all open back earcup designs, the HD 558 are always a distress
to the people around you because they allow music sound to escape from
the headphones, which is perceived as noise by others. So you cannot use
them while on your travels; on the Airplane for instance or in a public
place.
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