Tangzu Zetian Wu: how much amplifier do you need?

The Tangzu Zetian Wu is 16Ω. The shop listing this figure stands on prints a sensitivity of 100.0 dB and never says whether that is per milliwatt or per volt, so this page reads it as per milliwatt — on that reading it needs 1.0 mW to reach 100 dB SPL, or 0.13 V across the drivers. If the figure is really per volt, it needs far more.

That puts it in the easy category. A phone, a laptop headphone jack or the cheapest USB dongle will drive it to painful levels. Of the 280 sources in the database, 275 have at least 10 dB of headroom and another 5 have enough. The cheapest portable source that does the job is the Apple USB-C dongle (US) at $9.

The two numbers that decide everything

Impedance16 Ω
Sensitivity (printed with no reference unit)100.0 dB
Sensitivity (voltage) (if the figure is per milliwatt)118.0 dB/V
Power for 100 dB SPL (if the figure is per milliwatt)1.0 mW
Voltage for 100 dB SPL (if the figure is per milliwatt)0.13 V
TypeIn-ear monitor
Easy to drive — anything will do it
All 280 sources at 100 dB SPL into 16Ω
Comfortable 275Enough 5Marginal 0Not enough 0
Cheapest portable source that does it
$9 · USB dongle · +12 dB headroom
Cheapest desktop amp with 10 dB to spare
$75 · desktop DAC/amp · +19 dB headroom

This maker printed a decibel figure and no reference unit, so the number above is shown exactly as printed. Everything below reads it as per milliwatt, which is the commoner convention on a sheet that omits the unit — if it is really per volt, this headphone is about 18 dB harder to drive than the rest of this page assumes. The converter explains the difference.

Where this sensitivity figure comes from

Tangzu, as the shop reproduces it, publishes a sensitivity of 100 dB and does not state whether that is per milliwatt or per volt — the spec sheet simply stops at the number.

Both readings are given here so you can judge for yourself. If that 100 dB is per milliwatt, the figures on this page are right as they stand. If it is per volt, the real sensitivity is 82.0 dB/mW — 18 dB lower at 16Ω — and everything above understates what these need by that much. The per-milliwatt reading is the one shown, because it is the more common convention on a spec sheet that omits the unit; treat it as an indication rather than a specification.

One caveat about the source. Almost everything in this database comes from a document the maker published. This entry does not: the figures above stand on someone else's product page — Concept Kart, a retailer — and not on any page Tangzu publishes. Shops usually copy the factory table faithfully and this one may well be exact — but a shop can also carry an old revision, and if Tangzu changes the number there is nothing here that would notice. It is the weakest provenance on this site, which is why it is written on the page rather than left in a footnote.

Tangzu's own catalogue no longer carries this model; it lists a later Legend Edition, which is a different earphone with different drivers and is not a substitute for it.

Source: conceptkart.com. How this data was built.

What the shop lists, and what it is worth

As it is labelledAs printedToleranceStandard
Frequency Range20- 20khznot printednot printed

Concept Kart, a retailer, lists 20- 20khz for the Tangzu Zetian Wu, under the heading “Frequency Range”. Source: conceptkart.com. No document published by Tangzu carries this figure, so it is the shop's number, not the maker's.

No tolerance is printed with it, so “20- 20khz” says nothing about how loud this headphone actually is at 20 Hz.

Only what the maker printed; maker by maker.

Power, voltage and current by listening level

LevelWhat it isPowerVoltageCurrent
85 dB SPLquiet background listening0.03 mW22 mV1.4 mA
95 dB SPLnormal listening0.32 mW71 mV4.4 mA
100 dB SPLloud listening1.0 mW0.13 V7.9 mA
105 dB SPLvery loud3.2 mW0.22 V14.1 mA
110 dB SPLpeaks on dynamic music10 mW0.40 V25.0 mA

Most people listen between 75 and 85 dB; the 100 dB row leaves room for peaks.

The cheapest sources that drive them with room to spare

The 15 cheapest of the 280 sources here that reach 100 dB SPL into 16Ω with at least 10 dB of headroom and no known hiss or output-impedance problem with these headphones. All 280 sources, judged for these headphones.

SourceTypePricePower into 16ΩHeadroomVerdict
FiiO SnowSky Tiny AUSB dongle$2245 mW+17 dBComfortable
FiiO SnowSky Tiny BUSB dongle$2268 mW+18 dBComfortable
Tanchjim Stargate IIUSB dongle$4082 mW+19 dBComfortable
ddHiFi TC35ALUSB dongle$46105 mW+20 dBComfortable
ddHiFi TC35AirUSB dongle$46105 mW+20 dBComfortable
Fosi Audio N3Bluetooth receiver$5069 mW+18 dBComfortable
Hidizs SD2USB dongle$5035 mW+15 dBComfortable
FiiO BTR13Bluetooth receiver$59120 mW+21 dBComfortable
iFi GO linkUSB dongle$5935 mW+15 dBComfortable
Kiwi Ears Allegro ProUSB dongle$6034 mW+15 dBComfortable
ddHiFi TC35Pro (Mountain2)USB dongle$6633 mW+15 dBComfortable
iBasso DC03 ProUSB dongle$6949 mW+17 dBComfortable
DUNU DTC 480USB dongle$7033 mW+15 dBComfortable
EPZ TP35 ProUSB dongle$7056 mW+17 dBComfortable
Tanchjim SpaceUSB dongle$7062 mW+18 dBComfortable

The three ways a source goes wrong

Hiss. At 118.0 dB/V these are sensitive enough to reveal a source's own noise floor. The noisiest source in the database, the Schiit Mjolnir 3, would put its hiss at roughly 26 dB SPL in these headphones — clearly audible in quiet passages. Check your own source.

Output impedance. At 16Ω these want a source output impedance below 2.00Ω to satisfy the one-eighth rule; 35 of the 192 sources that publish one miss it. Check yours here.

Similar headphones

Compared with its stablemates: vs Fudu Verse 1 · vs Li Zhi · vs The King Wukong · vs Tianpeng.

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