Overview

Pentaconn COREIR Brass integrates a nickel-plated brass core within silicone eartips. It comes in S/MS/M/L sizes (color-coded: S=Black, MS=Blue, M=Yellow, L=Red), two pairs per pack, and fits 4.5–5.5 mm nozzles. A colored silicone cushion prevents collision between the metal core and the IEM nozzle. The maker cautions that metal parts may detach under excessive force and warns users with nickel sensitivity.

Scientific Validity

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As of today, there are 0 published third-party datasets (FR/THD/isolation) demonstrating measurable advantages for COREIR Brass over common silicone tips. Independent research shows that ear-tip type/fit can alter ear-canal acoustics and perceived response, but there is no product-specific evidence that a brass core yields superior, repeatable results. With no quantified improvements (0 dB reported gain, 0 isolation delta reported), we adjust from the 0.5 baseline to 0.3.

Technology Level

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Build execution (metal insert, plating, size coding) is neat, but the underlying method—embedding a standard metal insert in silicone—is only moderately sophisticated and not notably novel for the category.

Cost-Performance

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Comparator (equal-or-better on function/fit)

• Pentaconn COREIR Brass: 49 USD (JP reference 3,850円)
• SpinFit CP145 (2 pairs): 10.99 USD (JP reference ≈1,375–1,530円)

Computation (USD basis, 1-decimal rounding): 10.99 ÷ 49.00 = 0.2.
Both are silicone tips for 4.5–5.5 mm nozzles and include 2 pairs; with no verified performance gains, the large price gap drives a poor value score.

Reliability & Support

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Materials and warnings (possible metal detachment; nickel sensitivity) are clearly disclosed. Retailer warranty examples include 1-year coverage. Durability and support look industry-average.

Rationality of Design Philosophy

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Maintaining the “sound conduit” shape is plausible in principle (preventing bore collapse), yet audible benefits are unmeasured. Marketing claims around brass and “fidelity” are not substantiated by product-level data, hence a neutral score.

Advice

If you’re optimizing value and consistency, start with SpinFit CP145 or comparable mainstream silicone tips. Tip-dependent changes largely track fit/seal and bore geometry, so trialing sizes remains more impactful than paying premiums for unverified material claims.

References

• Pentaconn official (COREIR BRASS page: specs, caution, 3,850円)
  https://www.pentaconn.com/view/item/000000000070
• Pentaconn official shop (accessory list showing COREIR BRASS 3,850円)
  https://www.pentaconn.com/view/category/accessory
• Linsoul (COREIR Brass product page, 49 USD, specs)
  https://www.linsoul.com/products/pentaconn-coreir
• Bloom Audio (SpinFit CP145, 10.99 USD)
  https://bloomaudio.com/products/spinfit-cp145-premium-eartips
• Amazon Japan (COREIR BRASS local price/specs reference)
  https://www.amazon.co.jp/dp/B0CBRBZBBS
• Research paper: acoustics of instant ear tips (ear-canal acoustics & occlusion differences)
  https://pmc.ncbi.nlm.nih.gov/articles/PMC9592182/

(2025.8.19)