DT990 Pro (250Ω)

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published: Feb-28-2015, updated: Aug-3-2021

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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.

descriptors2

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Beyerdynamic DT990 Pro-250Ω

DT990 Pro 250

The DT990 Pro in 250Ω impedance is a well known headphone in the headphone community.
It is a rugged headphone intended to be used from amplifiers with a higher output voltage.
This one has black velours pads which measure closely the same as the grey DT990 pads.
These headphones are very comfortable and have a decent clamping force  which is higher than the edition version.
The cups swivel in all directions and the sliding mechanism works problem free and has proven itself in this classic design.
It can be taken apart pretty easily and components can be replaced easily and support for obtaining spare parts is excellent.

The Beyerdynamic series DT770-DT880-DT990 exists in many different versions that have been released through their many, many years of existence.

These headphones are pretty lightweight, quite comfortable with soft padded headbands which are easily replaced as well as the velour pads The pads are a bit ‘squeaky’ when rubbing against (reading) glasses.

The cable for the Pro version is partly curled and sturdy. Not ideal when using it on the go but it is not intended for this anyway. The coiled cable is better suited for studio work.
Unfortunately the cable is non replaceable but is quite low in microphonics. It terminates in a 3.5mm TRS jack with a screw-on 6.3mm adapter.
Cable swappers need to modify the headphone when they want to change or shorten the cable or make it suitable to be driven by a balanced amplifier.

A soft caring bag is supplied as well.

specifications:

Type: Over ear, open
Usage: Home
Driver type: dynamic
Pads: replaceable, velour
Inner Pad dimensions: depth = 20mm, ø 58mm
Collapsible: No
Headphone connector: none, fixed (non replaceable) cable.
Cable entry: single sided (left)
Cable: 3m terminated in 3.5mm TRS with screw-on 6.3mm adapter.
Driver size: ø 45mm
Nom. power rating: 0.1W (100mW)
Max. voltage: 5V
Max. current: 20mA
Max. S.P.L.: 115dB
Impedance: 250 Ω
Efficiency: 96dB/1mW (102dB/1V)
Weight: 320 g. (with cable)
Colour options: Black
Clamping force: low (3.5N)
Accessories: Ø3.5mm to Ø6.3mm gold-plated connector, travel bag

Sound description:

The DT990 has a U-shaped character with a boomy and not well extended bass. Bass isn’t really ‘tight’.
The mids are warm and clarity is lacking compared to the DT880 versions. Those that find the DT880 a bit too clinical may well like the DT990 better.
The mids being relatively ‘sucked out’ which gives it a ‘musical’ and ‘forgiving’ nature on popular music and other not so well recorded studio material. Recordings that sounds ‘midrangy’ on flatter headphones and lack bass and treble will sound guite ‘full’ on these headphones.
Music that is recorded pretty well sounds overly bassy/fat and sharp/shrill/piercing though.
Jazz, classical as well as vocal or ‘hifi’ lovers may find this headphone too euphonic, as it lacks ‘realism’ but is ‘pleasant’ on most pop music.
The DT990 also lacks sub-bass but is more or less ‘masked’ by the overblown bass/lower mids.
Depending on music genre and taste, these headphones may be a good choice as they are relatively cheap and ‘forgiving’ and have a ‘fun’ sonic signature.
The treble is elevated but not poor quality/grainy. With popular music the elevated bass and treble could well be a blessing if one doesn’t mind the fierce treble. It works fine with classical music where the elevated treble gives the impression of a highly detailed sound.
With well made recordings the bass and treble are a fair bit too much.

measurements:

Below the frequency response of the DT990Pro (Left, Right):

FR 20-20k

This plot represents pretty well how it sounds. It is U-shaped and has lots of ‘warmth’ and is bassy. It also has a lot of treble energy up top. No deep dips and, aside from the peak at 13kHZ, no sharp peaks either.

comparison

Below the differences between the (old) DT990 – 600Ω and the current DT990Pro -250Ω version.
Both with slightly used but still fresh pads (left channel only).
The newer DT990 Pro obviously has almost 4dB more bass and appears to have even more ‘sucked out’ mids.
The older DT990 is more realistic and less ‘warm’ sounding, but still sounds somewhat ‘sucked out’.
The treble on both headphones is a bit too much and gives the headphone a (false) sense of ‘hyper detail’.
The highs, even though a bit piercing at times, sounds ‘smooth’. The DT990Pro is slightly ‘better’ in the treble but these differences are marginal.DT990 vs 990-600

Below the DT990-250 vs the Amiron HomeDT990 vs Amiron home
The Amiron extends slightly deeper in the lows but also is a bit muddier in the mids. Upper mids (clarity) also is a bit lower. Both have elevated treble but peak at different frequencies.

Another comparison between the DT990-250 and the DT880 Black EditionDT990 vs DT880 BE
The DT880 Black Edition has less bass extension and sounds muddier in the bass. Both have elevated treble.
The DT990 is the better sounding one.

Below the DT880 (the regular version) vs the DT990DT990 vs DT880
The DT880 has a lot less bass and is the more neutral one albeit a bit ‘thin’ sounding. The elevated treble makes the DT880 sound relatively sharper as well.

Below the closed version, the DT770 Pro vs the DT990DT990 vs DT770

The DT770 has better bass extension but bass quality isn’t the best one. A bit dis-attached from the rest of the music. Mids are good bit also here the elevated treble.

The DT990 has a more expensive Tesla driver brother with replaceable cable, metal enclosure and  comes with 2 different pads.
The A(nalytical) pads turn the DT1990 a DT880 alternative. Using the DT1990-B(alanced) pads it is an improved DT990.DT990 vs DT1990-B
The DT1990 has better bass extension, less of a midbass hump so a bit clearer sounding but has an annoying treble peak (which is fixable)

Below the DT990 versus the Flagship T1 mkII

DT990 vs T1 mk2
Similar bass extension, more ‘warmth’. There appears to be less clarity because of the recessed 1.5kHz to 4kHz area but this is not really as deep as it looks. The T1 driver is angled (for better imaging) and because it is angled the 1.5kHz – 4kHz area is elevated due to the shape of the pinnae. Of course there is the obligatory treble peak in the T1 as well only a little higher up in frequency.

Phase response

Below the phase response of the DT990 (Left, Right)phase DT990
Gentle sloping phase is not audible. Above 4kHz the phase changing within a narrow frequency band is more problematic and shows there are resonances in that area. Pad-bounce (65Hz) is minimal.

output resistance / damping-factor

As this is a dynamic headphone the frequency response can be amplifier output resistance dependent when certain higher output resistance amplifiers are used.
Instead of showing impedance plots, which are hard to ‘read’ when it comes to assessing the tonal balance change in the real world, the DT990 is measured via a
2 different resistance outputs (0.2Ω and 120Ω). On a higher output resistance amplifier the output level will be lower of course due to voltage division. To compensate for this the amplifier is cranked up to the same level (3.4dB for 120Ω at 1kHz in this case). This way the plots are overlaid and it is easier to see how the tonal balance changes. Output resistances between the mentioned resistance values will result in tonal changes between those traces.dt990 250- 120 ohm

The tonal balance hardly changes when the DT990 is connected to a higher output resistance amplifier. The resonance frequency is around 120Hz resulting in a just very slightly warmer sound.

Below the distortion measurements of the DT990 (Left channel).dist DT990 L
The plot above shows the level differences between the signal (upper trace around 90dB SPL) and the harmonics. Most people prefer to see percentages instead of level differences so below the exact same plot except ‘normalised’ to the actual signal and level differences given in percentages.

dist DT990 L percentDistortion levels in the lowest frequencies are mainly 2nd harmonic above 100Hz distortion drops below 0.5% which is good for a driver of this size.
The actual 2nd harmonic distortion above 1kHz may well be lower than 0.15% . A shortcoming of my measurement rig.

Below the CSD (waterfall) plot of the DT990 . (Left and Right are overlaid)CSD DT990

Below 2kHz damping is not that great. The resonance at 13kHz is high but fortunately short lived.

Below the Group Delay plot for the DT990 (Left, Right)GD DT990

Ignore the wiggle at 50Hz (is interference). There is some  pad bounce  at 75Hz, otherwise no surprises here. At 450Hz there is a resonance. It is also seen in the frequency response plot.

A different plot is the spectrum plot. This basically is a CSD (Waterfall) plot but viewed from above where the level differences are colour coded instead of being in the vertical axis. Also the frequency range of the spectrum plot is wider (from 100Hz instead of 500Hz). The time span is also bigger in the spectrum plots and expired time is shown from below to top where in the CSD the time is shown from rear to front.

Below the spectrum plot of the DT990 (Right channel)spectr. DT990
No alarming issues here either. Some lingering around 450Hz (also seen in the plots above)

Step response

Below the step response plot which, when the sound is balanced and well extended should show a rise to around 0dB, (indicating fast driver response) and should be slightly sloping downwards indicating bass extension. (Left, Right)step DT990-250

The lack of deep bass extension is visible as the horizontal trace drops  after 1.5ms. The fast rise and lower level of the mids are indicative for the peaky treble.

reducing the treble

The usage of felt in front of the driver can often help with removing sibilance and sharp treble. 3 mm thick wool-felt is most effective in the 4kHz to 13kHz area. For this headphone this is also the case. A 3mm felt disc, that replaces the foam driver protection, lowers the treble in the sibilance area (5kHz – 10kHz) by a good 5dB. It also seems to apply some extra damping for the lows as the bass extends slightly lower and the peak around 150Hz is lowered by 1dB. Below stock (left driver) and with 3mm wool-felt in front of the driver.
The headphone still sounds bassy and detailed but is less ‘shrill’ and will possibly be less fatiguing.

dt990 3mm felt

passive filter

A more ‘targeted’ lowering of the treble peak can be done using a passive filter. Below the schematic for the DT990-250 (not suited for other impedances)

One can also use (parametric) EQ or use the Kameleon.

Of course this headphone can be corrected with the Kameleon amplifier quite a bit further.
Below the difference between the stock DT990Pro-250Ω and via the Kameleon amplifier.DT990 kameleon

Bass extension is formidable and below 10Hz, the bass hump has been removed which ‘tightens’ the bass.
I gave it a bit of extra ‘bass’ because the headphone is open and DT990 owners do prefer ‘strong’ bass. The elevated treble peak has also been lowered.
As both the bass and treble peaks have been removed the midrange isn’t recessed any more. Treble extension, clarity are excellent.
Below the frequency response (L and R) of the DT990Pro-250Ω on the kameleon.DT990 Kameleon FR

conclusion

The DT990-Pro 250 is a sturdy workhorse often found in studios (along with the closed DT770).
It is very comfortable, highly affordable with available parts like the headband padding and pads.
The long curled cable is handy in studios where one does not want to stand on or trip over long cables.
The clamping force for the pro versions is kind of high.
Those looking for better looks, less clamping force are better off with the Edition versions or the Manufaktur (you can choose a color scheme). Those wanting to connect one to portable gear should buy the 32Ω version instead.
The DT990-250 and certainly the 600Ω version require a decent amplifier.

It is not a neutral headphone and no thunderous bass either but it has a warm and detailed sound. The treble peak does not seem to bother everyone. Those that do should address this via EQ or a filter or reducing treble with toilet paper or felt.

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