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Published: Jul-07-2017, updated Dec-13-2021

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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 planar-dynamic on-ear headphone. Its design and quality 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.  The headband has soft leather padding and feels comfortable. The room for the ears is a bit on the small side. For most people it will be a partly on-ear but. For kids they may well be an over-ear.
It retailed for around €550.- in Europe (no longer available from 2020 it seems). This is quite expensive for a travel companion in the eyes of many casual listeners.
It can be connected via a special (Apple only) 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 i-Phones.
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.

The frame is aluminium and feels sturdy. The cups are covered with leather as is the headband. There is 35mm in height adjustability.
The cups can tilt and swivel plenty in all directions so getting a good fit should not be difficult.
The pads are ‘ear-shaped’ and small in size. The cup size itself is also small.
Inner pad dimensions are height: 45mm, width 33mm, depth 11mm.  What was Audeze (or more precisely the BMW i8 team) thinking ?
Clamping force is on the high side so one’s ear gets pressed down on its edges which is becoming quite uncomfortable after a short time. Not suited for those wearing glasses at all. This becomes painful quickly.

Fortunately there is a cure for this from Vesper Audio in the form of much better pads. This improves sound and above all comfort a LOT. On the left Vesper Audio pads (VA pads in the article) and on the right the original pads.
These pads are made in White Russia are highly recommended and as the are custom made (and you can select all kinds of leather, foam, angled or not, coloured or black) they are not available from stock so takes a lot of time to arrive. Well worth it. It turned a, to me, unusable and not great sounding headphone into a comfortable, easy to drive portable headphone with a good sound quality.
The configuration of the pads above is: black real whole grain leather+memory foam, 25 mm thick. These compress quite lot so maybe order 30mm.

The cable… this is another ‘odd’ thing about the Sine. It is 1.2m and has a flat (tangle free) soft silicone feel to it. It terminates in a straight 3.5mm TRS jack and on the other side has strangely shaped connectors that stick into the side.
Try to get a replacement cable for that ! (they probably exist though).
The connectors in the headphone are 3.5mm TS (mono) connectors that are angled and have L and R markings on it. No idea why Audeze didn’t opt for 3.5mm TRS jacks. In that case it would not be needed to label the connectors and could let the headphone determine if it receives L or R info. Audeze is not alone in this though.
The plugs go into the back with the wires angled forward.

The headphone comes in a box with preformed foam and a pouch for transport.
Cups cannot collapse into the headband but can fold flat. Still takes up quite some volume but not much height.


Type: On ear, closed
Usage: Portable, commuting, office and home.
Driver type: planar dynamic
Pads: leather
Foldable: Yes
Headphone connector: 3.5mm TS (angled proprietary)
Cable entry: dual with L/R markings
Cable: 1.2m 3.5mm TRS 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: 45mm x 50mm effective area
Inner Pad dimensions: depth: 11mm, Width: 33mm, height: 45mm, ear shaped.
Max. power rating: 1W
Max. voltage: 4.6Vrms (13Vpp)
Max. current: 220mA
Max. S.P.L. > 127dB
Impedance: 21 Ω
Efficiency: 94dB @ 1mW
Sensitivity: 111dB @ 1V
Weight: 320 g.
Clamping force: medium/high
Accessories: Soft carrying leather pouch, 6.3mm adapter, manual/warranty

Sound description:

The problem here is that the sound is seal dependent. As these are partly on ear this means most people will not be able to get a good seal and thus the sound description may differ from person to person.
To me the sound was a bit ‘honky’ and bass extension was not great. The treble sounded a bit subdued rolled off but did have some upper treble. I had to press it to my ears to get a more balanced sound.
The measurements below will show the difference when measured with a perfect seal (easy to do on a flatbed) and when using an ‘on-ear’ adapter used or on-ear headphone measurements.
The sound is quite dynamic and the headphone can play very loud yet continues to sound good.
Stereo imaging is not the greatest but it certainly does not have a super wide nor narrow ‘headstage’.


Below the frequency response of the closed Audeze Sine with a perfect seal (Left, Right)

The frequency response is remarkably flat. Just a very mild (+2dB) bass boost around 200Hz and a -5dB upper mids/lower treble dip. A small upper treble/air boost above 12kHz.
Nice and linear as it measured it did not sound like the plot above. Usually the correlation is very high.
So I decided to re-measure but using an ‘on-ear’ adapter (not  a real pinna shape) and measured again.

Below the frequency response of the closed Audeze Sine with on-ear adapter (Left, Right)This is more to how it sounds to me. Lows slightly rolled off, a bit ‘nasal’ and with a bright-ish sound yet muffled in details.

As this headphone isn’t really usable to me I decided to look for alternative pads that fit this headphone. Due to the odd shape of the cups and I really wanted over-ear pads I stumbled upon Vesper Audio (VA).
Below the frequency response of the closed Audeze Sine with VA pads (Left, Right)
Good bass extension, great comfort, Still a small ‘lift’ around 200Hz and a dip around 5kHz. The pinna most likely ‘fills’ this in a bit.
Upper treble, however, is now way to high and gave a sharp ‘edge’ to the sound. This, however, can be corrected by use of a filter (see further down the article).

compared to

Below some measurements comparing the Sine fitted with VA pads (no filter) with other closed headphones.
On this plot the Audeze Sine VA is compared to the Audeze EL8-closed.

These headphones have a clear relation. The EL-8 has a bit more bass response and clarity but also some ‘sharpish’ treble up top.

Below the Harman target hugging AKG K371 vs the Sine VA.The ‘lower bass boost’ from the Harman target is easily seen. This means the Sine is not as exaggerated in the bass but rather neutral. Those preferring elevated bass are better of with the K371. Both have a small dip around 4kHz (partly filled-in by the ear) but the upper treble of the K371 is not elevated.

Below the AKG K550 vs the Sine VA.This is not very different from the K371. The Sine VA being a bit more neutral in bass and mids.

Below the AudioTechnica ATH-MSR7 vs the Sine VA.

These are not too far apart in sound. The peak around 8kHz (MSR7) is ‘sharper’ sounding than that of Sine VA. Both can be ‘fixed’.

Below the studio ‘classic’ Beyerdynamic DT150 (fitted with velour DT100 pads) vs the Sine VA.

Above 2kHz there are some differences. The Sine VA is the more ‘hifi’ sounding version from these headphones.
The Sine is much better looking, the DT150 is very utilitarian (butt ugly).

Since we are in the prof Beyerdynamic headphones below the DT250-250 vs the Sine VA.Those familiar with the DT250-250 sound may well like the Sine VA.

Below the cheap Takstar Pro82 in the lowest bass setting vs the Sine VA.The Pro82 has a bit more bass (even in this lowest bass setting) and is a bit more forward. Clarity on the Sine VA is a bit better. Treble quality of the Pro82 isn’t as good (more grainy) than the Sine VA.

Lastly the Shure SRH1540 vs the Sine VA.The SRH1540 has elevated (and a bit boomy) bass but great mids with treble at the proper level.

output resistance / damping-factor

As this is a low impedance planar dynamic 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 an amplifier with various output resistance of 0.2Ω, 10Ω, 32Ω and 120Ω. The higher the output resistance the lower the output level will be due to its low impedance (21.5Ω measured). 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. For 10Ω a 3.3dB boost was needed, for 32Ω an 8.1dB and for 120Ω a 16.1dB.

Right channel only, driven from 0.2Ω, 10Ω, 32Ω and 120Ω amplifier.
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 when the output resistance increases. Fortunately I do not know of any portable sources with high output resistances.
This unusual ‘bump’ at 2.5kHz is not caused by the driver. There is an equalisation circuit in there that removes a 6dB peak the driver has. This filter works well with low output resistance amplifiers but becomes less effective at higher output resistances.

The linearity test showed no surprises. FR measured at 100dB SPL, 90dB SPL and 70dB SPL showed no changes so excellent linearity. Measured using VA pads and the treble filter

can be an issue especially with closed-back headphones. Breaking the seal (improper fit on the head, hairs or glasses) usually means a loss of (sub)bass. Perfect seal, seal broken with a thick arm pair of glasses and seal substantially broken by slightly lifting the bottom of the pads which can occur when not properly seated. This is measured using the VA pads (no filter)As can be seen seal is very important for a good bass extension.

Below the distortion plots of the stock Audeze Sine VA: (Right channel)The distortion products are shown in dB.dist Sine VA R

The same plot but shown in percentages.Please ignore the 50Hz spikes. the testrig is picking up mains hum. The 2nd harmonic distortion in reality is lower than shown. We are looking at the measurement limit of the used microphone. The distortion around 5kHz is there but disappears below 80dB SPL.

Below the CSD of the Sine VA (Left and Right are superimposed)

No problematic areas are observed. Some folks feel the Group Delay plots are more conclusive. Such a plot is shown below and also shows no problematic behaviour.

Below the spectrum plot of the filtered Audeze Sine VA.

This plot too shows very little problems.

By lack of oscilloscope shots (not enough time to measure that) below a step response plot of the Audeze Sine VA. (Left and Right overlaid)The sharp rise and subsequent drop are caused by the treble peaking around 12kHz.
Below the step response of the Sine VA but with the filter, the sharp peaking is gone.
Bass extension is excellent as the horizontal part barely drops.

passive filter for Vesper Audio pads

When using the Vesper Audio pads that ‘convert’ the Sine from a rather uncomfortable on-ear headphone to a far more comfortable over-ear headphone those pads show an audible upper treble peak which give an overly ‘detailed’ sound with a sharp ‘edge’ on the sound. To remove this peak without affecting other parts of the frequency response nor treble extension the filter schematic below can be used. For those that can not build this the filter can also be ordered here.

Audeze Sine filter schematic

The filter removes the treble peak as shown below using the Vesper Audio pads.

The sharpness is removed without affecting the treble extension.

square-wave and impulse response

Below 40Hz and 440Hz square-waves and 100μs impulse response of the Sine with VA pads and filter, stimulus (and target) and measured response.
SQ Sine modif


The Audeze Sine (closed version, there is also an open version) is an expensive ‘design’ headphone made with luxurious materials.
Alas, form factor/design was deemed more important than comfort. The high clamping force combined with the too small to be over ear and too large to be on ear pads make this headphone not a comfortable one. The seal breach which is easily possible due to the pad size and the way the pads press on the outer side of the pinnae makes a good seal difficult if not impossible. This can make this headphone sound different to different people. Given the price point it is disappointing.
Fortunately one can get high quality after-market pads that turn this headphone in a comfortable over-ear headphone.
This changes the comfort and ensures a good seal and sound quality can be had.
The Sine with VA pads and filter sounds very dynamic and realistic. No overblown ‘Harman bass’ and excellent tonality.
Its high efficiency and low impedance make is suited to be driven quite well directly from a phone or other portable devices.

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