Overview

The Drop + Grell OAE1 is a collaboration between Drop and Axel Grell, known for Sennheiser’s HD 580/600/650 and HD 800 series. Released in 2024, it uses sharply angled 40 mm dynamic drivers placed forward in the cups to approximate a “front-oriented diffuse-field” presentation. The concept targets a more speaker-like image via geometry rather than traditional cup acoustics.

Scientific Validity

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Third-party data shows mixed neutrality. Target compliance (RMS deviation): Bass 3.30 dB, Mid 2.13 dB, Treble 5.59 dB; FR consistency std. dev. 0.94 dB [1]. Weighted harmonic distortion is 0.25 % @94 dB SPL and 0.82 % @104 dB SPL (notably higher than class leaders at high SPL) [1]. Independent measurements report an impedance peak around ~5.5 kHz, which can exaggerate that region with high output-impedance amplifiers (e.g., OTL tubes) [2]. Results confirm the design’s imaging intent but also measurable departures from neutral tonality.

Technology Level

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The extreme driver angle and forward placement are uncommon in modern open-backs and executed with quality mesh and robust yokes. The approach is technically interesting, but measured outcomes prioritize spatial effect over strict neutrality; optimization appears incomplete.

Cost-Performance

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OAE1 price: 299 USD [3].
Cheapest equal-or-better comparator (function & measurement): HIFIMAN HE400SE, 109 USD (official store) [4]. It’s an open-back, wired over-ear with superior distortion (WHD 0.06% @94 dB; 0.11% @104 dB) and tighter treble compliance (RMS dev. Treble 2.52 dB; Mid 2.77 dB; Bass 5.3 dB) [5]. Also note Sennheiser HD 560S at 199 USD with very strong mid/treble compliance (Mid 0.93 dB; Treble 2.33 dB) and WHD 0.05% / 0.21% [6].
Calculation: (109 USD ÷ 299 USD = 0.365…) → 0.4.

Reliability & Support

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Drop lists a 30-day return window on the OAE1 page; explicit warranty terms for this model aren’t stated there at this time [3]. Construction is simple (wired, open-back, few moving parts), so baseline reliability expectations are average.

Rationality of Design Philosophy

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Targeting speaker-like cues by redirecting arrival angle is a rational hypothesis. However, available data shows trade-offs (notably treble accuracy and distortion at higher SPL) alongside the spatial effect, so the philosophy is interesting but only partly realized.

Advice

If you want a wide, “in-front” image and are willing to EQ and choose a low output-impedance amp, the OAE1 can be fun. For neutral playback and value, HE400SE (109 USD) and HD 560S (199 USD) both measure better in key areas at much lower prices [5][6]. Avoid pairing OAE1 with OTL/high-Z sources due to the reported impedance peak [2].

References

[1] RTINGS, “Drop + Grell OAE1 Headphones Review,” https://www.rtings.com/headphones/reviews/drop/grell-oae1 (updated 2025; accessed 2025-09-01).
[2] UnheardLab, “Review of Drop x Grell OAE1 Signature: style over substance?,” https://unheardlab.com/2024/10/28/review-of-drop-x-grell-oae1-style-over-substance/ (published 2024-10-28; updated 2025-08-11; accessed 2025-09-01).
[3] Drop, “Drop + Grell OAE1 Headphones,” https://drop.com/buy/drop-grell-oae1-headphones (accessed 2025-09-01). Price 299 USD.
[4] HIFIMAN Store, “HE400SE,” https://store.hifiman.com/index.php/he400se.html (accessed 2025-09-01). Price 109 USD.
[5] RTINGS, “HiFiMan HE400SE Review,” https://www.rtings.com/headphones/reviews/hifiman/he400se (accessed 2025-09-01). Distortion and target compliance values cited.
[6] RTINGS, “Sennheiser HD 560S Review,” https://www.rtings.com/headphones/reviews/sennheiser/hd-560s (accessed 2025-09-01). Target compliance and distortion values cited.

(2025.9.2)