SRH-1840

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published: Jan-22-2020, updated: Aug-06-2022

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.

Shure SRH-1840

The Shure SRH-1840 headphone is an open over-ear headphone.  It has rather common looks but feels and looks luxurious, sturdy and well made. The rear of the driver remains hidden behind dampening cloth.
It’s comparable to the Beyerdynamic DT1990 in price and build quality but not in sound.
The MSRP is around €550.-
It does look like an open version of the SRH-1540 but it is a completely different sounding headphone.

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  velour. The SRH-1540 comes in a nice hardcase with a set of spare HPAEC1840 pads. The pads feel 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 2 cables that come with this headphone are 2.1 meter. 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.
Strangely enoung the cable is slightly different in length and geometry from the SRH1540 cable.
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-1540.
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 268 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. Just a few grams lighter than the SRH-1540.

The overall looks and quality feel is excellent (personal opinion on the looks). The efficiency is lower and the impedance is higher compared to the SRH-1440 (65 Ω). This headphone will play decently well but maybe not 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, open
Usage: Home/studio
Driver type: dynamic
Pads: replaceable velour with memory foam.
Inner pad dimensions: height: 60mm, width: 40 mm, depth: 21mm.
Foldable: No
Headphone connector: MMCX connector, color coded
Cable entry: dual sided, split cable.
Cable: 2.1m smooth vinyl 3.5mm TRS + 6.3mm adapter
Driver size: 40mm, not angled
Power rating: 1W
Max. Voltage: 8.2 V
Max. current:  120 mA
Max. S.P.L.  118 dB
Impedance: 66 Ω
Efficiency: 88dB @ 1mW
Sensitivity: 100dB @ 1V
Weight: 268 g, cable adds 40 g.
Clamping force: medium-low
Colour: black and grey.
Accessories: extra pads, extra cable, 6.3mm adapter, hardcase.

Sound description:

Slightly light on the bass but not lacking in bass or bass extension. Bass sounds realistic and very natural/realistic. Bass ‘snaps’ in the correct amount when listening at somewhat louder listening levels.
The mids sound polite and not emphasized, so no ‘forward’ nor highly ‘dynamic’ mids. Just non intrusive and clean mids. No chances of listening fatique.
The treble is not accentuated and on the correct level. There is enough ‘air’ but ‘sparkle’ is slightly lacking. There is a very slight but not disturbing ’emphasis’ on sss-ess but not so much one could call it sibilant. Just a bit unnaturalness in the treble.
This could be called a neutral and realistic sound just a touch light in the bass when one likes ‘Harman bass’ sound. For those enjoying jazz and classic music it is just about right.

measurements

Below the frequency response of the SRH-1840 (Left, Right)
Channel matching is exemplary. Bass rolls off gently but sounds very good in quality.
Another thing that stands out in these measurements is that there are no dips or peaks between 10Hz and 5kHz. This makes the overall sound really ‘natural’. There is a slight and narrow peak around 8kHz (+5dB). It is audible and can be EQ’ed out without affecting the perceived amount of treble.  Also the treble does not have alarmingly high dips or peaks. Above 13kHz the overall level drops but because the roll-off is gradual and merely -5dB at 20kHz this, just like the bass levels) can easily be EQ’ed back in.

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-1840 versus the SRH-1540
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 without peaky treble.

Below the SRH-1840 versus the DT-1990 (analytical and Balanced) pads
The DT-1990 has a bit better bass extension and level. With the balanced pads there is a considerable difference in amount of bass more closely to the DT-990 where the Analytical pads are closer to the DT-880 (so is more like 2 headphones in one).
The Beyer sounds a LOT clearer/sharper than the SRH-1840 which has the correct amount of treble and does not need EQ/filtering as the DT-1990 does. The DT-1990 (even filtered) has much better extension, more ‘air’ and sparkle.

Below the SRH-1840 versus the DT-880 The DT-880 is a lot cheaper than the SRH-1840 and just like the SRH-1840 is a bit light (not bass-shy) on the bass and also has great (as in realistic) bass and mids.
The main difference is that the DT-880 has elevated treble with more treble extension, ‘air’ and sparkle. A bit too much of is though but with some EQ this can be corrected.

Below the SRH-1840 versus the HD-600
The HD-600 is often seen as the king of neutral sound. As can be seen theHD-600 has a slightly more bass extension as the SRH-1840. It is not an obvious difference though, both headphones are more similar than different in this area (that is when it comes to level)
Both headphones have excellent tonal balance. The HD600 does not have the 8kHz peak and much smaller ‘wiggles’ in the treble and better bass extension as well.
In treble quality the HD600 is just a bit better. The SRH-1840 is performing quite well in the treble department though.

Below the SRH-1840 versus the HD-650
The same story as for the HD600 above but the HD650/HD6XX is having slightly more warmth/bass.

Below the SRH-1840 versus the HD660SThe HD660S has similar subbass extension but a bit more bass. The most often heard complaint of the HD600/HD650 was that the upper mids are too ‘forward’ and elevated.
This has been ‘solved’ in the HD660S. The HD660S thus is a bit more ‘laid back’. Also the treble peak is not there, the treble is much better extended but overall lower in amplitude. The SRH-1840 thus is a bit clearer sounding but with a hair less quality.

Below the SRH-1840 versus the K-701
The K701 has the exact same bass/mids response as the SRH-1840. The K701, just like the DT880 and HD600 are often said to be a bit light in the bass. In bass levels there is no reason to upgarde to the SRH-1840. However the peak around 2kHz is giving the K701 a more ‘forward’ sound and combined with the following dip and peak make the K701 have a different clarity and stereo image. The treble peaks above 10kHz as well make the K701 more ‘splashy’ in the treble but also a bit ‘coarser’ and less smooth.
Overall I would give the nod to the SRH-1840 as it is not as bright and because of this seemingly having a bit more body/lows and is a bit more relaxing/less forward.

Below the SRH-1840 versus the X2HRIt is quite obvious the X2HR doesn’t have any rolled-off bass. In fact it is elevated.
The X2HR, just like the HD660S has a dip around 3kHz making it less ‘forward’ BUT because the X2HR has angled drivers the 3kHz dip is ‘filled in’ again making them have about equal ‘clarity’. Treble quality is about on par so is treble extension. depending on the the desired amount of bass (without resorting to EQ) the choice could be for either.
Of course when one looks at build quality and support for parts the Shure is a much safer bet.

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. With open headphones the effect usually isn’t nearly as profound. Below the effect of different levels of seal breach are shown.
Perfect seal, seal broken with thick armed glasses,  seal broken using a 6.3mm TRS plug. A perfect seal  is not needed. Using thinck armed glasses won’t audibly affect the Low Frequency response of this headphone. Breaking the seal a bit further also does not influence the sound signature.

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 9.0 dB 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.
This headphone does react slightly to a higher output resistance by increasing the bass levels slightly. The headphone thus will sound alomost audibly slightly ‘fuller’ on high output resistance amplifiers.
This headphone thus can be driven by most amplifiers and a higher output resistance has very little effect.

Below the distortion measurements of the SRH-1840. Below the Left channel.The plot above is in a dB scale, below the same measurement but in a percentage scale.There is quite a lot of 3rd and 5th harmonic distortion (indicating compression) below 200Hz. 4% in the lows is reaching audible levels. This is measured at 90dB (slightly over 1mW). Above 500Hz the distortion is reaching low levels. At 3.5kHz the 2nd harmonics reach 3% which is quite high.
This prompted me to dig a little further (as I did with the HE-35X)

It looks like the SRH1840 (and less so the SRH1540) are over damped which restricts airflow at higher SPL. Below some measurements to clarify.

First a linearity measurement for the Edition XX (ignore the 50, 100 and 200Hz spikes/dips = hum)What 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.
What 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.
Here we see some slight compression at 92dB (between 30 and 60Hz)

Below the response of the SRH1840 at 97, 90, 80 and 70dB SPL.And ofcoarse below the overlayed frequency responses.
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.
At low (background) listening levels there will be 3dB more bass than at higher (loud) listening levels. This is caused by non-linearities at larger excursions of the membrane. We hear it differently because of equal loudness contour effects which only just partly ‘compensates’ for the perceived loudness difference in the bass.
Anyway… this should not be there and can be seen as a design error.

This is also visible in the distortion plots shown below.At 70dB SPL the 3rd harmonic distortion is 4.7% (at 80Hz) . Note the little 2nd harmonic peak (at 4kHz) it is reaching 0.4%.

Below measured at 80dB SPL the 3rd harmonic distortion (80Hz) is 5%. The 2nd harmonic peak (4kHz) is reaching 1.2%. Notice the frequency where distortion drops increases

Below at 90dB SPL the 3rd harmonic distortion (80Hz) is still 4%. The 2nd harmonic peak (4kHz) is reaching 3.9%.

Below at 97dB SPL the 3rd harmonic distortion (80Hz) is still 3.1%. The 2nd harmonic peak (4kHz) is reaching 8.7%. There also seems be breakup? distortion at 8kHz at this SPL.

These are effects that I do not see that often when measuring headphones and seems to be a design issue.
Despite the high values the sound quality is still quite good but at higher SPL there is some ‘hardness’ to the sound.

Time domain measurements

Below the CSD of the SRH-1840 (Left and Right are superimposed) @ 90dB SPL.There are some very short lived and not sound degrading resonances visible at 4kHz and 8kHz and at 12kHz. The lower mids decay pretty fast. Till 5kHz this looks quite good.

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-1840 (Right channel)
Frequencies below 500Hz are well damped (a bit too much actually). There is some low amplitude resonance around 750Hz, 1.5kHz, 2.2kHz and 3kHz. The higher frequencies are well damped.

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)
The part that is supposed to be horizontal drops down fast. This shows the bass-light character of the headphone. The rising edge goes all the way up to 0dB and is downward sloping from there on which shows the impulse response is excellent. No overshoot and no undershoot.

Square-wave and impulse response

Below the 40Hz and 440Hz square-wave response as well as a 100μs DC impulse.
This is for the Right channel only.
The 40Hz square-wave shows there is roll-off in the lowest frequencies. Not very severe but audible.
The 440Hz squarewave is quite good. The fact that the horizontal part is is sloping downward slightly shows the mids are slightly on the ‘brighter’ side of neutral. The rising edge is fast with very little overshoot.
There is a very slight overshoot in the 100μs pulse but remarkably little post ringing and a good shape of the pulse itself. This means treble quality is high and there is enough resolution/detail. The higher frequencies are well damped.

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-1540 and SRH-940 pads would do with the sound when fitted on the SRH-1840.
When one wants the SRH-1840 to be turned into a warmer, bassier (and slightly ‘muddy’/’hollow-ish’ perhaps) sounding headphone it makes sense to slap some SRH-940 or SRH-1540 pads on there. A bit like a DT-1990 with Balanced pads but witout the treble peak.

treble peak

The small but audible (but not annoying) treble peak around 8kHz can be removed using a passive filter if one is bothered by it (not many will be). Below the effect of the filter.
The sound signature is not changed at all but there is a small ‘sharpish’ sparkle that isn’t supposed to be there which can be removed with the passive filter shown below.

summary

The Shure SRH-1840 is a quite neutral headphone with somewhat light but good quality bass.  No dynamic nor forward mids but clear and realistic mids with good clarity. There is no obvious shrillness or sibilance, but there is a hint of it.
Treble is at a good level and detailed. Maybe just a bit lacking in treble extension/air but this can easily EQ’ed in there. The same is true for the lows. These too are quite easy to EQ in.

The comfort is very good and one can wear this headphone for long periods.

Some of the measurements are a bit of a let down. It looks worse than how the SRH1840 sounds in reality. I don’t think it is a good alternative for the DT880, HD6** or DT1990 (with filter and analytical pads). Perhaps the Fidelio X2HR (with bass mod) is a better and cheaper alternative for the SRH1840.

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