SRH-1540

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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.

descriptors2

post separation
Shure SRH-1540

OLYMPUS DIGITAL CAMERAThe Shure SRH-1540 headphone is a closed over-ear headphone.  It has rather common looks but feels and looks luxurious, sturdy and well made.
It’s comparable to the Beyerdynamic DT1770 in price and build quality.
The MSRP is around €500.-

The measured headphone is used and was kindly sent in for measurements.

The headband can be easily adjusted. This is done by metal sliders. The part that touches the head consists of 2 thin pleather covered strips. The measured headphone is used and the pleather is already flaking. The foam inside is pressed together so one may have to replace the strips now and then. The headband feels comfortable.

The pads are replaceable and made of perforated (fenestrated) Alcantara leather. The SRH-1540 comes in a nice hardcase with a set of spare HPAEC1540 pads. The pads feel very comfortable with plenty of room for most earsizes and shapes.
The memory foam pads feel soft and provide a good seal.

The clamping force is average.  One can keep these headphones on the head for many hours.

The cups cannot swivel and tilt very far but just enough so they sit properly on my slightly smaller than average head.

The cable that came with this headphone is 1.8 meter. Actually the headphone comes with 2 of those cables. No idea why they did not opt for a longer and shorter cable (with or without inline remote/mic. The length is quite suited for usage with desktop/home equipment and can also be used with portable gear. It may be a bit short for listening in a comfy chair connected to a stereo system and a bit long for portable usage.
The cable has colour coded (red and black) gold-plated MMCX connectors. These connectors are also used in the Shure IEM models and the SRH-1840.
The cable is smooth and just slightly microphonic. There is 3.5mm TRS connector with a screw-on 6.3mm adapter. One can use this headphone on balanced amplifiers when using an aftermarket balanced cable.

With its 286 g (without cable) it is a lightweight headphone which helps with comfort for longer listening sessions and keeping it in place when moving the head around.

The overall looks and quality feel is excellent (personal opinion on the looks). The efficiency is high enough and the impedance (46 Ω) is friendly for most music sources. This headphone will play quite well and loud enough from most phones. It has a high power rating (1W) so you won’t blow it up when connected to a decent headphone amplifier.

specifications:

Type: Over ear, closed
Usage: Home/studio/portable
Driver type: dynamic
Pads: replaceable fenestrated Alcantara with memory foam.
Inner pad dimensions: height: 60mm, width: 40 mm, depth: 26mm.
Foldable: No
Headphone connector: MMCX connector, color coded
Cable entry: dual sided, split cable.
Cable: 1.8m smooth vinyl 3.5mm TRS + 6.3mm adapter
Driver size: 40mm, not angled
Power rating: 1W
Max. Voltage: 6.8 V
Max. current: 150 mA
Max. S.P.L.  128 dB
Impedance: 46 Ω
Efficiency: 99dB/mW (112dB/1V)
Weight: 286 g, cable adds 35 g.
Clamping force: medium
Colour: black, silver and carbon accents.
Accessories: extra pads, extra cable, 6.3mm adapter, hardcase.

Sound description:

The sound is warm and bassy as in not ‘tight’. With certain recordings it can sound boomy. With popular music the sound is full and not boomy or bassy. At somewhat higher levels you do get a tactile feel when subbass is present. The amount of bass is quite seal dependent though. The bass is quite well textured and, although elevated, of good quality.
Mids are neutral and never sharp. The mids are not very forward nor jumping at you. Polite and not emphasized would be a fitting description. This headphone is not very dynamic sounding but certainly not compressed either.
The treble is present and not sharp at all, slightly on the suppressed side of neutral.
The headphone is lacking ‘air’. Cymbals etc. lack ‘shimmer’ and sound rolled-off.
Highs are nicely detailed though and not coarse or overly smooth.
Suited for low SPL level listening. At higher SPL bass may be overwhelming.

measurements

Below the frequency response of the SRH-1540 (Left, Right)FR SRH1540
Channel matching is quite good. Just some very slight (inaudible) deviation below 60Hz and around 7kHz. The specifications say 5Hz to 25kHz. It starts to roll-off above 12kHz though and is around -20dB around 25kHz. At 20kHz it is still around -6dB so only a bit subdued.
The bass is elevated by about 6dB. The elevation around 150Hz is responsible for the boomy bass. (see top of this page for explanation). The mids (200Hz to 6kHz) is neutral with a slight warmish ’tilt’ (+2dB@400Hz to -2dB@4kHz). This tilt, combined with the boosted lows and roll-off above 12kHz gives the overall sound a bassy warmish/full character.
This also makes the SRH-1540 quite suited for monitoring purposes, just not suited for mixing.

compared to

As most people are interested to see how it compares to other well known closed headphones.  Below a couple of plots that show where they differ tonally.

Below the SRH-1540 versus the SRH-1840srh1840 vs SRH1540
There is a substantial difference between these two models. Aside from the SR1840 being open the tonal balance is very different. The SRH1840 certainly is not the open version of the SRH1540. Tonally both headphones are ’tilted’ in the opposite direction.
Warm/bassy with soft treble and clear/neutral with the correct amount of treble.

Below the SRH-1540 versus the DT-1770SRH-1540 vs DT-1770
The DT1770 is not elevated in the lows but bass is somewhat disattached from the mids (dip around 220Hz). Also the treble of the DT1770 is a LOT more pronounced.

Below the SRH-1540 versus the DT-770 SRH-1540 vs DT-770 ProThe DT770 is a lot cheaper and a bit more neutral yet the bass quality of the SRH1540 is better. Treble of the DT770 also is quite elevated compared to the SRH1540.

Below the SRH-1540 versus the Ether-C FlowSRH-1540 vs Ether-C Flow
The Ether-C flow, is a lot more ‘neutral’ sounding and even though it tops out at 18kHz it is a lot airier and ‘brilliant’ sounding. The mids of the SRH-1540 are a bit more neutral though.

Below the SRH-1540 versus the Sony MDR-1ASRH-1540 vs MDR-1A
The MDR-1A is a bit bassier and warmer sounding. It also has more ‘sparkle’ up top in the treble. The SRH-1540 is the more realistic sounding one.

Below the SRH-1540 versus the Meze 99 classicSRH-1540 vs Meze 99-classicThe 99 Classic also is elevated in the bass but also a bit ‘muddier’. For both headphones a similar effect is seen. When you listen to one of these headphones the brain ‘accepts’ the tonal balance and one doesn’t find these headphones overly warm but more of a pleasurable ‘warm sounding blanket’. The 99 Classic has a lot less clarity though. Treble of the 99 Classic is better extended and slightly more present.

Below the SRH-1540 versus the MH-40SRH-1540 vs MH-40
The MH40 is further extended/present the subass but also clearly ‘muddier/fatter’. In mids and treble the quality of the SRH1540 is better quality though.

Below the SRH-1540 versus the NighthawkSRH-1540 vs NighthawkThe Nighthawk is not really comparable and a lot ‘darker’ and less clear/detailed sounding. The relatively elevated and extended treble make the Nighthawk not ‘rolled-off’ sounding, just ‘dark and full’. The SRH1540 is better the more realistic sounding one.

Seal

Seal can be an issue with closed-back headphones. Breaking the seal such as improper fit on the head, means a loss of (sub)bass. Below the effect of different levels of seal breach are shown.seal 1540
Perfect seal, Seal broken with a thin arm (temple) pair of glasses, seal broken with thick armed glassesseal broken using a 6.3mm TRS plug. A perfect seal  is not needed. Using thin armed glasses won’t affect the LF response of this headphone very much. Breaking the seal a bit further (hairs, thick armed glasses or poor placement) results in less elevated and earlier roll-off in the sub lows.

output resistance / damping-factor

As this is a dynamic headphone the frequency response might be amplifier output resistance dependent when certain higher output resistance amplifiers are used.
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 11.1dB 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. R120 -11.1dB
This headphone does react to a higher output resistance by increasing the bass even further. The headphone thus will sound muddier on high output resistance amplifiers.
This headphone should be driven by amplifiers with an output resistance below 10Ω

Below the distortion measurements of the SRH-1540. Below the Left channel.dist LThe plot above is in a dB scale, below the same measurement but in a percentage scale.dist L percentThere is quite a lot of 3rd harmonic distortion (indicating compression) below 200Hz.
5% at 50Hz is reaching audible levels. Above 500Hz the distortion is reaching low levels.
NOTE: The actual 2nd harmonic distortion above 300Hz may well be lower than 0.2%. A shortcoming (measurement limit) of my measurement rig.

Time domain measurements

Below the CSD of the SRH-1540 (Left and Right are superimposed)CSD SRH1540There are 2 very short lived and not sound degrading resonances visible at 6.5kHz and 11kHz and some low level lingering at around 3kHz. The ear itself also resonates a bit at around that frequency so is not problematic. The closed cup is most likely causing the small attenuation of frequencies below 1kHz.

Another form of looking in the time domain is the spectrum plot. The amplitude is color coded and both the time scale and frequency scale differ as well.

Below the spectrum plot of the  SRH-1540 (Left channel) Spectrum L SRH1540
Here too we see the energy below 500Hz is lingering a bit. chances are this could be improved with some damping in the cups (speculation). The 3kHz amd 6kHz resonances are also visible in this plot.

Below the step response with a dB scale (so not similar to an oscilloscope plot which has a linear scale).  The step response (Left and Right channel over-layed) step SRH1540
The bass extension is quite good. The rising edge reaches -3dB and is slowly climbing to the same level as the mids and lows at around 300μs. This is indicative of ‘rolled off’ treble and less ‘crisp’ sound lacking in ‘sparkle’. ‘Attack’ in music signals is located around 3 to 5kHz and is at 0dB so while lacking ‘sparkle’ it is not lacking in clarity.

Square-wave and impulse response

Below the 40Hz and 440Hz square-wave response as well as a 100μs DC impulse.
SQR SRH1540This is for the Right channel only.
The 40Hz square-wave shows there is roll-off in the lowest frequencies but not severe.
The 440Hz squarewave is quite good. Not much ringing and no overshoot. The slight rounding off also shows the lack of ‘sparkle’ and definition in cymbals/violins which sound like you are sitting in the rear of a concert hall instead of in the middle or more towards the front. One is not ‘missing’ sound but it’s a bit on the ‘tame’ side.
The measured signal otherwise closely follows the applied signal.
The impulse shows excellent impulse response. The measured signal, however, doesn’t reach the target level indicating the treble is a bit ‘subdued’ in level.
There is no overshoot and also no undershoot. The signal has the correct shape. This means treble quality is high and there is enough resolution/detail but a bit low in level.
There is some reasonably well damped ringing visible at around 6kHz.

compression issues

The Shure SRH-1840 showed non linear behaviour. The excursions of the membrane are not following the applied signal exacty when the amplitude increases.
The SRH-1540 also has somewhat similar issues but not as bad.

First a linearity measurement for the Edition XX (ignore the 50, 100 and 200Hz spikes/dips which is picked up hum)Lin Ed XX.pngWhat is shown above is the measured frequency response between 10Hz and 30kHz at different SPL. 95dB, 85dB, 75dB, 65dB and 55dB.
The plot below is the same measurement but with all traces overlayed.
Lin Ed XX overlay.pngWhat can be seen is that the frequency response is the same at all different levels.
This is the case for most headphones. Below the € 20.- Superlux HD681 for instance.Lin HD681 overlay.pngHere we see some slight compression (-1dB) at 92dB SPL (around 45Hz).

Below the response of the SRH1540 at 90, 80 and 70dB SPL overlayed.linearity tonal balance difference 70,80, 90dB.png
What can be seen here is that till 80dB (which is actually 90dB for the bass frequencies) there is no compression visible yet, or at least not significantly.

Below the response of the SRH1540 at 97, 90, 80 and 70dB SPL. Because bass is boosted in the SRH-1540 by approx. 10dB the test below is done using EQ.
Bass is lowered and upper treble is boosted so we get a fairly flat response to start out with.linearity 70,80, 90, 97dB EQ'ed.pngAnd of coarse below the overlayed frequency responses.linearity tonal balance difference 70,80, 90, 97dB EQ'ed.png
Do note the different scales of the plot above which is now 2dB/div where above all plots are 5dB/div.
As can be seen the shape of the response (bass relative to mids and treble) differs at different amplitudes. This means at low listening levels there will be more bass than at higher listening levels. This is caused by non-linearities at higher excursions of the membrane. We hear it differently because of equal loudness countour effects.
Anyway… this should not be there and can be seen as a design error.
There is nothing to see till we reach go above 80dB SPL. At 90dB SPL some compression is already visible. It is less than 1dB and bass extension is not affected. At 97dB SPL there is a 2dB reduction in the bass area. Not something to really worry about but should not be there and is a sign of over-damping.

This is also visible in the distortion plots shown below. Note the distortion measurements are made without EQ. At 70dB SPL there is no distortion visible. At least the ‘grass’ visible at the bottom of the graph is the noise floor of my measurement rig. At 80Hz the ‘distortion’ is below 0.4% Do note that at 80Hz the bass reaches levels of 80dB while the rest is at 70dB.
SRH1540 distortion @ 70dB (60Hz).png

Below at 80dB SPL above 200Hz there is no distortion visible. At 80Hz the 3rd harmonic distortion increased to 0.7% and can be considered inaudible.SRH1540 distortion @ 80dB (60Hz)

Below at 90dB SPL the 3rd harmonic distortion (80Hz) increased to 3%. Above 300Hz (mids and treble) the distortion is below 0.2%. (This is the limit of my testrig for 2nd harmonics)
Note: while measured at 90dB bass levels are already at 97dB
SRH1540 distortion @ 90dB (60Hz).pngThese are effects that I do not see that often when measuring headphones and seems to be a design issue. Levels below 5% are not considered audible when listening to music). These are audible when listening to pure tones at this level.
The SRH-1540 driver performs much better than the SRH-1840 and is the better headphone.

The SRH-1540 reacts pretty well to EQ and measures (and sounds) better with it.
Below the SRH-1540 stock and with some (basic) EQ.SRH1540 EQ'd.png
The sound is pretty good, free of distortion and clear and extended sounding in the treble.

pads

As Shure has different pads for different headphones and pads can (but not always do) change the sound it would be fun to see what SRH-1840 and SRH-940 pads would do with the sound when fitted on the SRH-1540.padsWhat is obvious here is that the sharp dip at 8kHz seems to be caused by the pad. The other 2 (velours) pads do not show this dip. The SRH-940 pads can be used as an alternative for the Alcantara pads. They are a bit less deep through. Mids and treble is the same but there now is a bit more pronounced hump around 150Hz.
The SRH-1840 pads clearly cannot be used. All lows/bass is completely gone.

summary

The Shure SRH-1540 is a warmish neutral headphone with somewhat elevated and tactile bass. Recordings with the correct amount of bass sound a bit ‘fat’ as in not ‘tight’.
Pop and Rock recordings sound quite full and pleasant through this headphone.
The mids are detailed and warmish/neutral. No dynamic nor forward mids with a lot of clarity. Instead a not exaggerated mids without any harshness or shrillness.
Treble is present and detailed but slightly subdued. Lacking in treble extension/air.
Cymbals and violins sound overly polite. As if one is listening to a concert from the back rows.
This headphone does react good to EQ and one can EQ out the 150Hz hump and add the treble above 12kHz.

The comfort is very good and one can wear this headphone for long periods.
Those looking for tight bass and ethereal sound should look for the open SRH1840 instead.

This is a closed headphone but the attenuation of outside noises is not something to write home about. Not that suited for commuting/plane usage.
Recommended for low level listening/relaxing with music and monitoring.

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