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Sunday, May 12, 2013

Beyerdynamic DT 1350

Disclaimer: This headphone is owned by Inks, who is indeed the greatest contributor of this blog.

Along with full-sized T-series models, Beyerdynamic DT 1350 is also a part of Beyerdynamic's proprietary Tesla-driver technology implemented line up. Although it is a portable supraaural design, the manufacturer emphasizes the headphone's professional monitoring quality sound.

The goal of Tesla-driver is to achieve 1 Tesla, or 1 weber, which is according to the BIPM, producing an electromotive force of 1 volt if it were reduced to zero at a uniform rate in 1 second. In other words, Beyerdynamic is trying to accomplish very high electroacoustic efficiency by increasing the magnetic power of the driver. According to Mario Gebhardt, Head of Development for audio products at beyerdynamic,
"In beyerdynamic headphones, “Tesla” stands for our latest system technology that is distinguished by a very powerful magnetic drive and clean reproduction with a low degree of total harmonic distortion ... With the Tesla principle, the magnet is mounted as a ring encircling the coil and this enables us to divert more energy to the membrane, which is where it is required."
Beyerdynamic's German patent, DE102009038593, indicates that the technology is comprised of a big annular "neodymium-iron-boron" magnet 120, which is situated at the outer rim of the voice coil, holding a base plate 110 and a cover plate 130, creating a massive magnetic system altogether, much bigger than that of any conventional dynamic transducer designs.

Moreover, the diaphragm 140 is made of a dual-layer compound foil, allowing "high inner damping of partial oscillations despite its low weight and contributes to the transparent, finely defined, and distortion-free sound".

In contrast to Sennheiser's ring-driver patentDE102007005620, of which the magnet is situated in the inner rim of the overhung voice coil, Tesla-driver technology has fewer components(lower production cost), a larger magnet(greater efficiency), and an underhung voice coil(emphasis in the bass quality). And these fundamental differences clearly distinguish the unique design goals the two German manufacturers are embracing, and ultimately, reveal Beyerdynamic's technical advantage over its arch-competitor.

PRO: The frequency response bandwidth well extended from 20 Hz up to 20 kHz, a long/warm decay in the low frequency range & effective leak control by a tight clamping mechanism.

CON: Odd-order distortion in the bass, perhaps due to the underhung voicecoil & Audible ringing at 10 kHz.

ON SECOND THOUGHT #1: Although the tesla-driver achieves a high sensitivity of 109 dBSPL/mW @ 1 kHz even with a 80 Ω driver, there's a good amount of distortion in the bass, which clearly contradicts what the manufacturer claims, suggesting the sign of false claim.

ON SECOND THOUGHT #2:  Unlike any other full-sized headphones, thanks to the dual-layer compound foil, DT-1350's resonance frequency is located in the mid-range, just like that of IEMs/earbuds. Although an amplifier is required to yield sufficient volume level, utilizing DT-1350's own impedance characteristic is perhaps useful to increase the mid-range vocal, which is slightly lacking in stock configuration, by 1 dB at most.


  1. Just a quick question. Have you heard anything with similar sound sig as DT1350? I kind of want something similar, but I'm not sure which headphone has similar sound sig.
    Also, have you heard about driver mismatch problems with the DT1350? I've heard it a lot.

    Anyways, great measurements, and thanks!

    1. DT 1350's sound is electrically flat, or raw-flat, meaning that the headphone is designed without any human HRTF in consideration. I know my modified T50RP sounds like that, but that's about all I know of.

      I don't think DT 1350 has a mismatch issue since the data from Innerfidelity, Goldenears, and my simulator basically share the same data. The claimed driver mismatch is most likely due to fitting issue, as the placement can greatly affect the sound itself with supra-aural headphones such as DT 1350.

    2. Thanks. I guess my next headphone will be something that sounds like DT1350 if I can find one.

    3. But how come innerfidelity's data show less distortion in the sub-bass??

    4. With DT 1350, I am afraid the level of distortion and the overall SPL in the sub-bass are determined by the degree of seal on the pinna. For instance, in order to achieve a vacuum-tight seal, I used agar.

    5. I disagree with the. Unit Variability issus DO exists with DT1350 models.
      As compared here
      And seal issues is pretty much debunked as the main reason