Overview

Lizer Lab JIJUMA is a Japanese eartip series built around a metal phase-plug and venting scheme intended to shift perceived sound from “in-head” to a more frontal position. The current JIJUMA-BRASS generation is advertised with a larger tip opening and a shorter plug than earlier models, and it is sold at around 39.90 EUR before shipping in the EU and via Amazon Japan [1][2]. The company markets the concept as an “out-of-head localization eartip” and lists related patents [2][3][4].

Scientific Validity

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There is no independent, controlled ABX/blind data verifying a reliable “out-of-head” effect for JIJUMA-BRASS. One third-party post reports a ~15% increase in a clarity metric (C80) on one IEM when using a related JIJU-series tip, which suggests measurable acoustic changes but does not establish audibility across users or programs [9]. The third-generation description (larger phase-plug aperture, fewer shell holes) is plausibly impactful on frequency balance, yet transparent-level results for ear-coupled devices require broad, consistent measurements that are not available here [1]. Patents describe the hole/plug mechanism that aims to alter reflection timing toward the tragus, but that is still a hypothesis for localization without corroborating listening tests [3][4].

Technology Level

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Multiple granted patents cover Lizer Lab’s ear-tip structure (phase plug, forward-firing venting) [3][4]. The current JIJUMA-BRASS iteration is documented as having a larger plug opening and shorter overall length versus prior versions, indicating iterative engineering and material change (brass) [1]. As an accessory-side approach to HRTF manipulation, the idea is original within eartips; however, industry adoption is limited and competing approaches (conventional geometry, foams, horn/short-stem silicones) remain more common.

Cost-Performance

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Price basis (review target): 50 USD (approx.; EU listing 39.90 EUR before shipping) [1].
Cheapest equivalent-or-better option: SpinFit CP100+ silicone eartips at 13.99 USD (2 pairs, current US retail) [5]. These provide the same user-facing functions (secure seal, broad IEM compatibility) and typical silicone-tip passive isolation suitable for music listening [5][6].
Calculation: 13.99 USD ÷ 50 USD = 0.28 → rounded 0.3.

Reliability & Support

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Lizer Lab is a small Japanese maker selling primarily via Amazon Japan and periodic crowdfunding; an English-language support/warranty framework is not clearly published [2][7][8]. Brass plug parts should be mechanically robust, but long-term RMA/MTBF data are not available. Distribution exists through EU resellers as well [1], which is positive, but after-sales expectations remain modest compared with major accessory brands.

Rationality of Design Philosophy

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The design targets a real limitation of IEMs (in-head localization) using a physically motivated vent/plug structure described in the patents [3][4]. That is a rational hypothesis. However, emphasis on strong “front localization” outcomes without standardized listening tests or multi-unit measurements risks over-claiming. From a measurement-first perspective, cheaper silicone/foam tips already achieve core benefits (seal/isolation), so the premium is difficult to justify until controlled evidence shows consistent, audible superiority [6].

Advice

Consider JIJUMA-BRASS only if you specifically want to experiment with front-localization concepts and accept uncertain outcomes. For most readers, mainstream tips like SpinFit CP100+ (13.99 USD) or Final Type E (widely available, low cost) offer predictable seal, comfort, and tuning changes for far less money [5][10]. If you proceed with JIJUMA, check nozzle size compatibility (≥ Φ5.5 mm noted by an EU reseller) and anticipate import/shipping costs [1].

References

[1] HiFi-Passion (EU retailer), “Lizer Lab Jijuma Brass” — price & 3rd-gen description (enlarged plug opening, shorter plug), accessed 2025-08-19. https://hifi-passion.de/EN/Lizer-Lab-Jijuma-Brass/HL02535.1
[2] Lizer Lab (official site), top page & purchase link (Amazon JP) describing “out-of-head localization” eartips, accessed 2025-08-19. https://lizerlab.com/
[3] JPO via Google Patents, JP6271795B1 “イヤーピース” (ear tip) — vent/tragus/phase-plug concept, accessed 2025-08-19. https://patents.google.com/patent/JP6271795B1/ja
[4] INPIT case study (JP), notes Lizer Lab patents JP6271795 and JP6621166, accessed 2025-08-19. https://chizai-portal.inpit.go.jp/supportcase/2020/02/post-863.html
[5] Audio46 (US retailer), “SpinFit CP100+ Silicon Eartips (2 Pairs)” — 13.99 USD current list, accessed 2025-08-19. https://audio46.com/products/spinfit-cp100-plus-silicon-eartips
[6] SoundGuys explainer (general), “What is noise isolation?” — context on passive isolation and spec ambiguity, accessed 2025-08-19. https://www.soundguys.com/what-is-isolation-12506/
[7] Lizer Lab (official X/Twitter), note on Amazon sales openings (JP), accessed 2025-08-19. https://x.com/lizerlab
[8] Makuake project page, “JIJUMA-HORN” campaign information (recent model activity), accessed 2025-08-19. https://www.makuake.com/project/jijuma-horn/
[9] audio-sound @ hatena (JP) — article referencing C80 change with JIJU-series tip (indicative only, not ABX), accessed 2025-08-19. https://www.ear-phone-review.com/entry/product/LIZER_LAB_JIJU_JET-2
[10] Amazon JP search results & listings for Final Type E (typical low pricing in JP), accessed 2025-08-19. https://www.amazon.co.jp/s?k=final+type+e

(2025.8.19)