EPZ: what they publish

This page does not review anything EPZ makes. It counts one thing: how much of what this database says about their products came out of their own documents, and how much had to be worked out or left blank.

Impedance is almost always printed. Sensitivity is the one that goes wrong, because a decibel figure means two very different things depending on whether it is per milliwatt or per volt — about five decibels apart at 300 Ω and eighteen at 16 Ω. The conversion is here.

• Converted from per volt — 1: the maker prints a figure per volt, converted here with dB/mW = dB/V − 10·log₁₀(1000/Z)
• Unit not stated — 3: the maker prints a decibel figure with no reference unit, so it is shown as printed and flagged rather than quietly converted

Power decides whether it gets loud enough, output impedance decides whether it tilts the response of a multi-driver in-ear, and the noise figure decides whether you hear hiss with sensitive ones. All three fit on one line of a spec sheet; most of the industry prints one of them.

EPZ publishes a power figure at a stated load on 2 of 2, output impedance on 0, a noise figure on 1. Of the 8 power figures this site displays for them at 32, 150, 300 and 600 Ω: 2 printed by EPZ at that exact load, 6 worked out by holding output voltage steady across loads.

Rather less than half of what this site says about EPZ came from them. The rest is arithmetic, and it is marked as arithmetic on every page.

The rule used here is the same for every maker and is described on the manufacturer index. Every figure behind it can be opened on the product page it came from, with the document it came from linked.

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