Thanks to their Tesla technology, the Beyerdynamic T51i will brighten audiophile listening sessions while, unfortunately, remaining in the shadow of more popular headphones from the same brand.
Akin to Sennheiser with its HD 600 series, if I say Beyerdynamic, you’ll probably think DT 770 PRO, DT 880 PRO, DT 900 PRO X, DT 990 PRO, and so on. Now that those iconic headphones have been discussed, dissected, praised, critiqued, and compared online ad nauseam, the idea of another article on one of them might make you sigh.
However, you’re in luck, as this analysis will cover a lesser-known, undeservedly overlooked contender from Beyerdynamic: the T51i.
Occasionally, after conceiving a particularly successful and innovative product, a manufacturer will create another one, often more affordable, using the same trickle-down technology. This is the case with the T51i, the least expensive Beyerdynamic headphones incorporating the Tesla technology used in the DT 1990 and both flagships, the T1 and T5.
In a nutshell, Beyer’s Tesla technology endows the headphone drivers with a higher magnetic flux density, intended to improve detail rendering and spatiality, even in a compact design like the T51i.
- Headphone Design: Closed, on-ear
- Transducer: Dynamic
- Impedance: 32 ohms
- Frequency Response: 10 Hz- 23,000 Hz
- Nominal SPL: 111 dB
- Power Handling: 100mW
- Max. Sound Pressure Level: 131 dB
- Weight: 174g (without cable)
- Cable: 1.20m-long (4ft) 2.5mm mini-jack non-detachable plastic cable with stereo jack 3.5mm & 6.35mm adapter
Upon delivery, the headphones reside inside a nicely padded cloth carry case, which is protected by a regular compact cardboard box. Due to the multiple layers, unpacking the T51i is like excavating the smallest Russian doll from its bigger counterparts.
A velcro fastener with the Beyerdynamic logo opens or closes the carry case. While this stylistic choice exudes a rather relaxed and casual lifestyle feel, it doesn’t coincide with the more upscale, modern look of the T51i.
Additionally, the small-form factor of the padded and layered carry case, though optimized for convenience and portability, doesn’t shelter the headphones against sharp and heavy objects, especially if other accessories, like plugs and adapters, are already squeezed in there!
From the small on-ear rotating cups to the high sensitivity, the T51i are clearly designed for convenience and portability. Their sleek, understated, and minimalist aesthetic will appeal to those who value noble materials like metal and leather.
Since plastic is scarcely used, their overall build feels sturdy and durable, especially at this price point.
They resemble a tiny, more stylish Beyerdynamic T5. Unfortunately, the cable is non-detachable and rather flimsy.
The cables constitute the weak link in the otherwise excellent build quality.
Thanks to the closed metallic earcups (another specificity of the tesla technology) and the thickness of the leather ear pads, the passive noise cancellation blocks the sound quite efficiently. I’ve used the T51i on an airplane, and they reduce the engine rumble by 60-70% – more than enough to enjoy music without deafening oneself.
In terms of comfort, the Beyerdynamic T51i simply excel. At less than 180 grams, their weight is almost negligible.
If it wasn’t for the slight clamp force and the leather pads, one could forget they are wearing headphones.
One drawback, however, is that the leather can get warm on the ears after a few hours of listening. In brief, the T51i headphones exude quality, durability, and style, but is the sound on par with those physical attributes?
Beyerdynamic T51i Sound
First, thanks to their low impedance (32 Ohm) and high sensitivity (111 dB), most of the T51i’s full sonic potential can be unlocked by your phone, tablet, laptop, etc. So no need for extra dongles or full-blown amps the size of a desk heater.
The T51i impart a detailed, immersive, immediate, and musical sound without emphasizing a particular frequency.
The clear delineation of each instrument from right to left contributes to their excellent imaging. It is primarily noticeable in big orchestral ensembles, like John Williams’s score for Encounter of the Third Kind.
Many of the tracks emulate a Pendericky-like orchestral cluster, in which dissonant chords from many instruments are played simultaneously in a crescendo, while others, like the wind section, are arpeggiated. Due to the long decay, one can easily discern the violins on the left, the violas on the right, and the ethereal flute, in the center, bouncing around.
Perhaps due to the closed-back nature of the T51i, the inherent lack of openness and airiness somewhat limits the soundstage depth. Hence, the foreground and background instruments seem a little closer to what they would actually be on stage.
For example, in Bernstein’s primal and gritty interpretation of the Rite of Spring with the New York Philharmonic, the earth-shattering timpani and harsh brass section, located in the back, appear closer to the front. However, rest assured that this idiosyncrasy doesn’t truly diminish one’s listening pleasure, especially in this price bracket.
Speaking of the Rite of Spring conducted by Bernstein, that recording alone showcases a pair of headphones’ ability to reproduce the timbre and fullness of instruments as well as its transient response, dynamics, and attack. I’m happy to report that the T51i succeed on all fronts!
Though not subterranean, the bass is substantial enough to provide a certain kick and weight to the sound. For example, through the T51i, percussion instruments, like timpanis, drums, and even lower octaves on the piano, exert – when the recording allows it – a liveliness and fullness that enhance the listening.
Of course, though largely sufficient for most music types, the bass doesn’t produce a seismic roar that will rattle your skull. The sub-base is “suggested” rather than there.
Articulate and natural, the midrange is quite agreeable and doesn’t leave me longing for anything. The T51i don’t succumb to some of the flaws that plague many similarly priced closed-back headphones with either passive or active noise cancellation: a boxy sound due to a boost in the lower midrange and a metallic and unnatural tonality (aka the Audio Technica MRS7NC).
Since the T51i don’t adulterate the sound or inject any particular coloration, the midrange on a good recording is reproduced pristinely. For example, in the seemingly close-miked Norah Jones’ album “Come Away With Me,” the T5i perfectly convey the fullness of her voice and recreate the smoothness and sense of proximity captured by the recording. In brief, everything sounds right!
While Beyerdynamic have had a penchant for a prominent treble in some of their more popular headphones, the T51i don’t follow that trend. Akin to the midrange, the high frequencies are detailed, natural, and not overbearing. No harshness or edginess occurs.
In other words, if the recording is decent, the highest C on piano or the highest G on clarinet won’t pierce your eardrums.
I couldn’t, in good conscience, omit the comparison with another similarly-priced marvel of German engineering: the Sennheiser HD 600 (2019 version).
Vs. Sennheiser HD 600
On the surface level, both headphones differ vastly. While one pair is mostly constituted of metal, the other is plastic. One is on-ear closed-back, the other over-the-ear open-back. One is slender, the other bulky. One will blow your ears off in high gain, the other most likely won’t. The list goes on…
However, despite their significant divergence in design and build, surprisingly, the comfort remains excellent on both.
Their sound profile also shares many similarities.
Both headphones create an intimate soundstage with a sense of proximity, giving the impression that the music was recorded in a studio.
If you yearn for a spacious, airy presentation, neither will satisfy you. In fact, that feeling of closeness magnifies nuances and other qualities or flaws in your music. While the soundstage depth is limited on both headphones, thanks to the open design of the HD 600, the music inherently appears slightly less cramped and a smudge clearer.
In terms of imaging, the HD 600 slightly outperform the T51i. The latter conveys a marginally more polarized instrument placement while the HD 600 manage to position instruments from right to left with a more distinct center image. However, this only becomes apparent after obsessive A/B comparisons through tens of pristinely recorded orchestral music. A casual listener won’t notice.
Bass, midrange, and treble display similar attributes on both headphones. Nonetheless, the HD 600, once again, come on top, by a hair, regarding the instruments’ timbral accuracy and the overall smoothness of the sound.
Don’t let those small dissimilarities deter you from considering the T51i. Most of them are hardly noticeable unless you feverishly swap one pair of headphones with the other.
If you enjoy the HD 600 sound signature, the T51i are a good closed-back alternative.
Where to Buy
The Beyerdynamic T51i headphones appear to have lived in the shadow of the much more popular DT series (DT 770 PRO, DT 880 PRO, DT 990 PRO, etc.), revered by audiophiles and professionals alike. Yet, their performances have stood the test of time and rivaled several current, more expensive closed-back headphones.
Additionally, the T51i still hold their own against old open-back classics, like the Sennheiser HD 600. The minor variations in sound quality are largely offset by the Beyer’s finer build quality, aesthetic, and versatility (thanks to the noise isolation and the low impedance making an amp unnecessary).
In brief, from their ease of portability to the very balanced and coherent tuning, the T51i headphones offer a complete package that belies their price point.