Overview

The Superlux HD681B is the bass-emphasized variant in the HD681 series, using 50 mm dynamic drivers in a semi-open enclosure. It is identifiable by dark-grey accents and targets users who prefer extra low-frequency impact for rock and gaming. Official specifications for the HD681 family and major retailers list 32 Ω impedance, 98 dB sensitivity, and a fixed single-sided 2.5 m cable (not detachable) [2][3]. Within the series, the “B” tuning increases bass relative to the base HD681/“F” variant positioning [2].

Scientific Validity

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Variant-specific laboratory data for HD681B remain limited as of the review date. We therefore apply a conservative 0.5 and supplement with series measurements (HD681) where appropriate. Reliable third-party measurements on the standard HD681 show: bass raised by about +5 dB with excellent extension, response within ~±3 dB from 100 Hz to 2.5 kHz, and treble peaks ~+10 dB above 6 kHz that are audibly sharp [1]. Distortion on HD681 at 90 dB SPL reaches ≈3.5 % (3rd) around 40 Hz, but falls <0.1 % above ~120 Hz [1]. Given the B-variant’s bass emphasis per manufacturer literature [2], neutrality for reference monitoring is limited.

Technology Level

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Conventional 50 mm dynamic drivers in a semi-open shell with a self-adjusting headband represent an established design. No special transducer topology, materials, or novel acoustic modules are claimed in official materials. The fixed single-sided cable [3] is functional but not advanced. Overall, implementation is competent yet non-innovative.

Cost-Performance

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Review-target price: 22 USD (representative U.S. street price). We searched for the cheapest equivalent-or-better alternative. The closest proven comparator is the Superlux HD681 (same semi-open design and user-facing functions; independent measurements available) [1][4]. In the U.S. market on the review week, HD681 lists at 24.30 USD, while HD681B is 21.50 USD [3][4]. As no cheaper product with equal-or-better functions and measured performance was found, CP is 1.0.

Equivalence note: Semi-open over-ear, 50 mm dynamic drivers, comparable series performance; third-party measurements exist for HD681 establishing baseline FR/THD behavior [1], while the B-tuning mainly increases bass [2].

Reliability & Support

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Warranty and parts support are retailer-standard. The fixed cable (non-replaceable) [3] can limit lifespan versus detachable-cable designs. Build is typical for the price; longevity varies by handling.

Rationality of Design Philosophy

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Prioritizing stronger bass within a semi-open presentation is a coherent trade-off for entertainment or casual monitoring. However, treble peaks reported in series measurements [1] and bass boost reduce accuracy for strict reference work.

Advice

If you want affordable semi-open headphones with extra bass for rock or gaming, HD681B is sensible. For more neutral monitoring in the same family, consider the standard HD681 (documented measurements) or the HD681F/EVO tunings; for isolation-critical tracking, use a closed-back model. Ensure a returnable retailer in case fit or unit variance does not meet your needs.

References

[1] DIY-Audio-Heaven, “Superlux HD681 – measurements (FR/THD)”, https://diyaudioheaven.wordpress.com/headphones/measurements/brand-superlux/hd681/, accessed 2025-08-20.

[2] Superlux, “HD681 Series (HD681/HD681B/HD681F) overview/specs (leaflet)”, https://images.thomann.de/pics/atg/atgdata/document/specs/218865_240434_240433_en_online.pdf, accessed 2025-08-20.

[3] Thomann USA, “Superlux HD-681 B”, https://www.thomannmusic.com/superlux_hd681_b.htm, accessed 2025-08-20.

[4] Thomann USA, “Superlux HD-681”, https://www.thomannmusic.com/superlux_hd681.htm, accessed 2025-08-20.

(2025.8.20)