Campfire Audio Clara: how much amplifier do you need?

The Campfire Audio Clara is 13.3Ω with a sensitivity of 115.3 dB/mW, which is 134.1 dB/V. To reach 100 dB SPL — genuinely loud, louder than most people listen — it needs 0.03 mW, or 20 mV across the drivers.

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, 280 have at least 10 dB of headroom and another 0 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

Impedance13.3 Ω
Sensitivity115.3 dB/mW
Sensitivity (voltage)134.1 dB/V
Power for 100 dB SPL0.03 mW
Voltage for 100 dB SPL20 mV
TypeIn-ear monitor
Easy to drive — anything will do it
All 280 sources at 100 dB SPL into 13.3Ω
Comfortable 280Enough 0Marginal 0Not enough 0
Cheapest portable source that does it
$9 · USB dongle · +26 dB headroom
Cheapest desktop amp with 10 dB to spare
$75 · desktop DAC/amp · +33 dB headroom

Sensitivity here is in dB per milliwatt. Why the unit matters.

Where this sensitivity figure comes from

Campfire Audio does something unusual: it publishes 94 dB at 94db @ 1 kHz- 9.95 mVrms, an SPL at one specific drive voltage rather than per milliwatt or per volt. That is convertible — at 13.3Ω that voltage works out to a known power — and the 115.3 dB/mW above is the result. It is a real figure, just stated in a way nothing else in this database uses.

Campfire Audio prints the impedance as 13.30Ω @ 1kHz, not as a bare number. Everything on this page is calculated with the nominal 13.3Ω, and the rest of that line is quoted here rather than tidied away, because how a figure is qualified is part of the specification too.

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

What is printed there, and what it is worth

As it is labelledAs printedToleranceStandard
Frequency Response5-20 kHznot printednot printed

Campfire Audio prints 5-20 kHz for the Campfire Audio Clara, under the heading “Frequency Response”. Source: campfireaudio.com.

No tolerance is printed with it, so “5-20 kHz” says nothing about how loud this headphone actually is at 5 Hz.

Only what the maker printed; maker by maker.

Power, voltage and current by listening level

LevelWhat it isPowerVoltageCurrent
85 dB SPLquiet background listening0.00 mW4 mV0.3 mA
95 dB SPLnormal listening0.01 mW11 mV0.8 mA
100 dB SPLloud listening0.03 mW20 mV1.5 mA
105 dB SPLvery loud0.09 mW35 mV2.6 mA
110 dB SPLpeaks on dynamic music0.30 mW63 mV4.7 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 13.3Ω 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 13.3ΩHeadroomVerdict
FiiO SnowSky Tiny AUSB dongle$2237 mW+31 dBComfortable
FiiO SnowSky Tiny BUSB dongle$2257 mW+33 dBComfortable
Tanchjim Stargate IIUSB dongle$4068 mW+34 dBComfortable
ddHiFi TC35ALUSB dongle$4687 mW+35 dBComfortable
ddHiFi TC35AirUSB dongle$4687 mW+35 dBComfortable
Fosi Audio N3Bluetooth receiver$5057 mW+33 dBComfortable
Hidizs SD2USB dongle$5029 mW+30 dBComfortable
iFi GO linkUSB dongle$5929 mW+30 dBComfortable
Kiwi Ears Allegro ProUSB dongle$6028 mW+30 dBComfortable
ddHiFi TC35Pro (Mountain2)USB dongle$6627 mW+30 dBComfortable
DUNU DTC 480USB dongle$7027 mW+30 dBComfortable
EPZ TP35 ProUSB dongle$7047 mW+32 dBComfortable
Aiyima A2 Prodesktop DAC/amp$7562 mW+33 dBComfortable
ddHiFi TC35Pro (Eye2)USB dongle$7627 mW+30 dBComfortable
ddHiFi TC44 Pro E2USB dongle$99104 mW+35 dBComfortable

The three ways a source goes wrong

Hiss. At 134.1 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 42 dB SPL in these headphones — clearly audible in quiet passages. Check your own source.

Output impedance. At 13.3Ω these want a source output impedance below 1.66Ω to satisfy the one-eighth rule; 41 of the 192 sources that publish one miss it. Check yours here.

Similar headphones

Compared with its stablemates: vs Andromeda 2020 · vs Ara · vs Chimera · vs Solaris 2020.

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