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NO SMOOTHING is applied to the shown plots. Most measurement sites have some smoothing applied which ‘irons flat’ sharp peaks and ‘wiggles’. I do not use smoothing because some info about sound quality is lost when plots are smoothed.

Aside from a small correction of the microphone itself also some correction in the lowest frequencies is applied to the plots to compensate for the perceived loss of bass when using headphones. This is described HERE in more detail.
A ‘horizontal‘ frequency response curve on the shown frequency response plots on this website thus indicates a perceived ‘flat’ tonal signature.

ALL measurements are made with a good SEAL on a flatbed measurement rig.
The shape of your head, bone structure, pad size, pad ‘softness,  (compliance), hair or no hair and or wearing glasses may (drastically) change the frequency response of some headphones, so… your personal experience may differ substantially from these plots.

Frequency response (tonal balance) is the most sound-determining aspect of headphones. A horizontal line shows audible neutral response in the plots on this website. Deviations in different severities at different frequency bands have an effect on the sound character.
The bigger the deviation the stronger the effect.

Below an aid to help determining the sound character of headphones with relation to the frequency response.


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Audeze Sine (closed)

This Audeze Sine is a closed orthodynamic headphone. There is also an open version of this headphone (not measured). The design and feel is nice. It folds so is quite compact in case you want to take it along. Travel, commuting and portable usage is what this headphone is all about. They sound (and measure) the same, so I am told. The headband has soft pleather padding and feels comfortable. The room for the ears is a bit on the small side. For most people it will be an over ear but for some it may be (partly?) on ear.
It retails for around €550.- in Europe. This is quite expensive for a travel companion in the eyes of many casual listeners.
It can be connected via a special cable (CIPHER cable) , for an additional €50 which includes a 24 bit DAC and DSP and gives much more functionality when using this cable. This cable can be connected to the digital output of Phones etc.
For the measurements this cable isn’t used. The standard 3.5mm TRS jack cable (with special connectors on the headphone side) is used. This means the DSP and what it can do for the sound is not measured. Only the headphone itself in passive mode.



Type: Over ear, closed
Usage: Portable, commuting, office and home.
Driver type: orthodynamic
Pads: leather
Foldable: Yes
Headphone connector: 3.5mm TS
Cable entry: dual
Cable: 2.5m 3.5mm TRS (+ 6.3mm adapter) to 2x 3.5mm TS (mono) in a proprietary shape or 2m balanced cable with 2x 3.5mm TRS or CIPHER cable (for Apple only).
Driver size: 80mm x 70mm
Max power rating: 6W
Max. S.P.L. > 120dB
Impedance: 20 Ω
Efficiency: 94dB / 1mW
Weight: 300 g.
Clamping force: medium/high
Accessories: Soft carrying pouch, 6.3mm adapter

Sound description:

Will be added later on


Below the frequency response of the closed Audeze Sine (Left, Right)

FR sine

The frequency response is remarkably flat. Just a very mild (+3dB) bass boost around 200Hz and a +10dB treble boost. One large dip at 8.5kHz which in reality is not there as I suspect it’s a measurement error (nulling due to the large driver) and excellent (realistic) performance on the upper mids/lower treble. That small dip around 7kHz is most likely completely masked by the treble peak.
This is one of the better measuring headphones.

output resistance / damping-factor

As this is a low impedance orthodynamic headphone the frequency response would not expected to be output resistance dependent when certain higher output resistance amplifiers are used. Still, when measured from such an amplifier it turned out there there is a substantial resonance going on at 2.5kHz.
To test this the headphone is measured via a low impedance amplifier (0.2Ω) and a high impedance amplifier (120Ω). On a higher output resistance amplifier the output level will be considerably lower. To compensate for this the amplifier is cranked up to the same level (at 1kHz) as the low impedance amplifier. This way the plots are overlay-ed and it is easy to see how the tonal balance changes.

Right channel only, driven from 0.2Ω and 120Ω amplifier.FR Sine 120
As can be seen the difference is negligible over the entire frequency range except between 1.5kHz and 4kHz. it will become a bit ‘thinner/sharp-isher’ sounding. Fortunately I do not know of any portable sources with output resistances this high. The effect on a 10Ω output R amp will be max +1dB and inaudible. On a higher output resistance amplifier (some specific desktop amps) this 4dB peak would become audible.

Below the distortion plots of the Audeze Sine: (only Right channel shown)
The distortion products are shown in dB.

DIST sine R


As can be seen in the plots there appears to be a high amount of distortion in the bass.
Well … measurements lie at this moment because what you are really seeing in the grayed area is leakage of ambient sounds. This headphone was measured at ears-unlimited-logo where substantial background noises were present in the demo room at that time. There were people in the room talking and walking around. Real performance is (much) better in reality than shown on the plots. Expect about the same performance here as the EL-8. I may re-measure it in the future when the opportunity arises.


Below the CSD of the EL-8 Titanium (Left and Right channel are superimposed)

CSD sine

Aside from some short-lived ringing at around 2kHz, 3kHz there is not much to worry about. Not an exemplary performance though.

CSD sine 120
Above the CSD of the Sine (right channel) via a 0.2Ω output resistance amplifier and also when connected to a 120Ω amplifier.
Here too the effect of the 2.5kHz resonance is visible.

Below the spectrum plot of the Audeze Sine.

spectr sine R


This plot too shows some small issues around 800Hz and between 1.5 and 3kHz.

By lack of oscilloscope shots (not enough time to measure that) below a step response plot of the Audeze Sine. (Left channel)
step sine L
This is an excellent step response. It does show some ringing but is short lived. The freguency response is quite even. The 200Hz ‘bump’ is also seen here in the form of the small bump around 1ms. Below the Right channel.

step sine R


The Sine is a headphone that measures pretty well. It does have some small issues as shown in the measurements but the audibility of it remains to be seen.
The response is quite even. Maybe too flat in the (lower) bass when commuting. A little boost is desirable in that case. Some tone control or the CIPHER cable, which will give you even more options for tuning the sound, will be helpfull here.
Recommended for portable usage.
Do try to fit them before you buy when you have a larger than average head or ears.

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