Mitchell & Johnson JP1 DJ

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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.

sound descriptions mine

 post separation
Mitchell & Johnson JP1 DJ

The Mitchell & Johnson JP1 DJ is a semi-closed headphone intended for DJ usage.
The most remarkable aspect of this headphone is that it is a 2-way system with a dynamic driver for the lower frequencies and an electret driver for the higher frequencies (crossover at 4kHz acc. to the manufacturer).
The hybrid design finds its origin in the Sharkk ‘Bravo Hybrid Electrostatic Headphones’ kickstarter project. This is not the same headphone though as the dynamic driver is different but is related. This same headphone is also available (at lower price) as the Verisonix N500.
Verisonix also supplies this as OEM so the Mitchell& Johnson JP1 is actually a Verisonix N500 with a different name on the cups.
Another, much more expensive hybrid headphone is the ENIGMAcoustics Dharma D1000 but is different in design and quality.

The engineering of the JP1 seems O.K.
Steel parts, real leather (headband) and a nice looking Cherry wood is used for the cups.
It retails for around € 680.- ($ 600.- as well as £ 600.-) which is quite expensive for a headphone.

The pads are made of soft pleather (fake leather). The clamping force is medium, so not a tight squeeze on the head nor too loose.
The height adjustment capability is just 20mm which means it won’t fit properly on all heads. Also the sidewards adjustment range where cup tilt is possible is quite small. It ‘hangs’ a bit too low on my head so the top of my Pinnae somewhat hold it up instead of the headband itself.
The 17mm depth between driver baffle and uncompressed pad is a bit on the small size. This means that for a lot of people their ears will be touching the driver.
The soft pads with memory foam are just barely comfortable on my head amd do get hot and sweaty after some time.
The grey headband padding may not have been the best choice to add some color accents. My suspicion is that it will discolour unevenly over time.

folded

The 1.2m long headphone cable has a woven cloth finish and two nice looking thin 3.5mm TRS connectors (dual entry). The cable itself doesn’t care whether the connectors are inserted in the left or right cup. It is always connected the right way because the TRS sockets in the headphone itself determine what is left and right cup, not the cable.
The cable as well as the metal headband are microphonic which means you can hear mechanical contact sounds in the headphone when the cable rubs against clothes or the headband is handled/touched/adjusted etc.
It is not annoyingly loud though but can be heard.

The right cup can rotate 90 degrees forward and backward. DJ’s use such a feature when they only want one cup on one ear while not falling of the head. A DJ application feature pur sang.

DJ stand

The efficiency is very high. It thus plays pretty loud from a phone or small player. The low impedance and high efficiency most likely means it can’t handle a lot of power.
As the OEM manufacturer isn’t very forthcoming with specifications I had to measure some specs myself. As distortion became quite high above 50mW so I suspect this is its max. power rating. Not a problem when driving from portable equipment but something to whatch out for when connecting to higher power desktop amps.
However, this headphone is said to be a DJ headphone.
The power rating and efficiency (120dB/V), however, tell a completely different story. This is clearly intended to be driven from low output voltage devices like tablets, phones,  laptops as well as small Digital Audio Players.
Outputs from mixing consoles are usually designed to supply a lot more power which will quite likely destroy the driver(s) when for instance the headphone is lying on a desk and turned up too loud by accident.
Also most desktop amps can supply way more than 50mW into 32Ω so are potentially able to burn out the driver.
The maximum voltage is 1.3Vrms which is 3.7Vpp. This voltage swing shows where the driver is made for, namely devices fed from 3.6V or 5V batteries. Portable stuff and dongle type DAC’s thus.
At that maximum voltage the SPL is 123dB. As this is peak power this means that an album with a DR of 10 will be blasted in your ears at a whopping 110dB.

As mentioned before the ‘special’ thing about this headphone is it being a hybrid design where 2 different types of drivers are used. One dynamic range driver (lower frequencies) and an electret, filtered at 4kHz. acc. to this website.
An electret driver is basically an electrostatic driver but without the needed external high bias voltage.
The ‘bias’ voltage in an electret is ‘impregnated’ as a static charge in the mebrane itself, thereby eliminating the need for an external bias voltage.

There is nothing new or revolutionary about electret headphones. Most of these were full range like the well known Stax SR40. These tend to loose their ‘permanent’ bias charge over time though reducing the efficiency.
One of the few hybrids of old is the AKG K340 (1979).

The membrane is permanently pre-biased in the factory.
It still needs a higher plate voltage than the dynamic driver though. Many times the dynamic driver voltage. In this case this is done using small transformers within the enclosure. They can be small as they only need to handle high frequencies so small ferrite cores can be used.
Below the (angled) electret driver is seen as well as the high pass filter capacitor (10μF bipolar capacitor) and the small ferrite core transformer.

driver rearBelow the PCB with the transformer on it the rear side of the dynamic driver can be seen. The PCB mounted so close to the driver is asking for reflections though.

driver itselfBelow the business side of the dynamic driver and the electret. The folder claims the dynamic driver is 40mm but my measuring tape tops out at 32mm for the membrane itself. Its housing is indeed 40mm.

driver front
The specs say: 32Ω and those measuring the DC resistance will find a nice 33Ω which is the DC resistance of the voicecoil of the dynamic driver. There is a hidden ‘problem’ though. The electret is fed via a small transformer inside the cup which is coupled through a 10μF bipolar capacitor (high pass filter). The DC resistance of its primary winding is 2.7Ω. At 20kHz the impedance of the headphone measured almost which is extremely low. This means that when the output resistance of the source is a few Ω already the upper treble will be considerably lower.
Totally not suited for higher output resistance amps and sources. This headphone thus is quite amp picky/dependent.

The design of this headphones appears ‘closed’ which the product folder also suggests. In reality the headphone is partly open between the baffle and the cups. In between that gap the sleeve of the pads is present but this doe not seal that gap, it only makes the gap a bit smaller. Sound thus leaks in and out though that gap. The headphone thus doesn’t isolate well. Even the Denon D2000 isolates more…
For this reason I characterize the JP1 one as semi-closed headphone and not as closed/sealed.

The headphone comes in a nice box which includes a hard carrying case, a braided cable with 3 x a 3.5mm TRS jack plug,  a 6.3mm adapter and an airplane adapter.

specifications:

Type: Over ear, semi-closed
Usage: Home, portable, DJ
Driver type: dynamic + Electret
Pads: replaceable, pleather with memory foam
Collapsible: yes
Headphone connector: 3.5mm TRS connector
Cable entry: dual sided
Cable: 1.25m woven cloth, terminated in 3.5mm TRS jack plug
Driver size: 32mm membrane (manuf. states 40mm) + 40 x 30mm electret
Colour options: Cherry wood
Inner Pad dimensions: depth = 16mm, Width = 40mm, height = 60mm, oval shapedMax.
power rating: unknown (assumed 50mW)
Max. voltage: 1.3Vrms (3.7Vpp)
Max. current: 40mA
Max. S.P.L.: 123dB
Impedance: 33Ω but drops to 4Ω @ 20kHz
Efficiency: 106dB/1mW (121dB/1V)
Weight: 340g. (incl. cable)
Clamping force: medium
Accessories: Ø3.5mm to Ø6.3mm gold-plated adapter,  hardcase, airplane adapter

Subjective sound description:

This is a bassy and ‘dark’ sounding headphone.
The bass sounds punchy and full bodied yet not ‘fat’ or bloated’. The bass also does not ‘bleed’ into the mids. The mids have a ‘warmth’ to it but also sound a bit ‘hollow’ and lack clarity and detail.
The high amount of bass to lower mids mask the upper mids and treble.
Because of this the mids lack clarity and brilliance. The subdued, but pleasant and soft treble also adds to the ‘full’ and ‘dark’ sound signature.
The sound is not very ‘dynamic’ but a bit muffled and ‘congested’.
For poorly recorded pop music this tonal balance may work well but for the better quality recordings the sound is way too dark, muffled and lacking in details.

The overall tonal balance is VERY far away from ‘neutral’ in any case and very different from electrostatic headphones or the ‘better’ headphones.
Those that prefer the sound of say.. the Nighthawk or Meze 99 headphones may well like this headphone.

Measurements:

Below the frequency response of the JP1 (Left, Right)

FR MJ1

Channel matching is poor. I have re-measured it a few times with different positions and even with L-R swapped pads but the level differences are really there.
For the retail price of € 680.- I find this kind of imbalance differences  not acceptable.

Bass extension is quite good.  From 40Hz to 500Hz the response is almost ‘flat’.
From 500Hz (mids) to 3kHz (upper mids) the output drops about 15dB.
This is quite a lot and shows the bassy/full/overly warm character of the sound.
The 5dB to 10dB drop from 1.5kHz to 6kHz is responsible for the ‘laid back’ mids and the missing ‘clarity’ and ‘presence’.

Treble goes up to 18kHz and drops about -35dB opposite the bass and mids.
The electret takes over from there.  There is a soft signal to at least 30kHz but most likely also somewhat above there (can’t measure it and us humans can’t hear it).
The subdued treble means there is some ‘sparkle’ but subdued. Therefore the sound is lacking ‘air’ and finer nuances. The treble quality is not poor though. Not harsh, nor sibilant but soft just subdued. Flattering for poor quality recordings with sharp treble.

Getting a good seal is important when using this headphone.
The soft pleather memory foam earpads (cushions) help with getting a good seal.
However, bone/skin structural differences, fit and/or wearing glasses may affect bass response.
Below the Right channel is shown. Normal seal, wearing glasses with ‘thick’ arms, bottom part of the pad slightly lifted so loss of seal.

seal loss

As can be seen a good seal is important for the amount of bass.

As mentioned the tonal balance is on the bassy/warm/thick side. The more realistic headphones have a more horizontal frequency response. Of course some people really like this type of ‘tuning’ and find it more realistic/speaker-alike than ‘flat’ headphones which are found boring and lifeless.
Below a comparison with a similarly ‘tuned’ and often well liked headphone, the AudioQuest Nighthawk versus the JP1.
The plot is heavily ‘smoothed’ to get a better ‘feel’ of the tonal balance.

comparo NH

As can be seen the JP1 is even bassier and warmer than the Nighthawk. Also the upper treble level of the Nighthawk is higher. So for those that find the Nighthawk not bassy enough and feel it has too much treble the JP1 may well be a viable option.
Those looking for a more realistic tonal balance should look for something else.

On the box of the JP1 a plot is shown with the scales being ‘wrong’. I corrected the scales in this plot below. The fact that such a plot is published is rare though. Especially when they are almost accurate as well. Below the M&J JP1 plot (with the corrected frequency scale) and in red my measurement (Right channel) in the same scale and overlayed.
The plot is heavily smoothed which removes sharp peaks and dips. Above 400Hz the plots deviate substantially.

compar plots 2

output resistance / damping-factor

As this is a hybrid headphone the impedance won’t be flat and thus the frequency response will be amplifier output resistance dependent.
Instead of showing impedance plots, which are hard to interpret properly when it comes to assessing the effect in the real world, the JP1 is measured via a low resistance output (0.2Ω) and a high resistance output (120Ω).120 Ohm

On a high output resistance amplifier the output level will be about 15dB lower as well. To compensate for this loss and see tonal balance changes more clearly the amplifier is cranked up to the same level (at 1kHz). This way the plots are overlaid and it is easier to see how the tonal balance changes.
As can be seen the tonal balance does change considerably when connected to a higher output resistance amplifier. Above 700Hz this is caused by the transformer and high-pass filter of the electret. The increase around 50Hz is caused by the dynamic driver.
The JP1 is not really usable at all from higher output resistance amplifiers such as tube amps for instance unless you want even less clarity and treble (hard to imagine as it already has little of it).

Below the distortion measurements of the JP1 (Left channel).

Dist MJ1 L

The plot above shows the level differences (in dB) between the signal 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 MJ1 L percent

Distortion levels are quite high. Around 1% 2nd harmonic distortion in the 80Hz to 500Hz range is quite high. The 3rd harmonic around 700Hz peaks to an audible level of 0.5% which is quite high.
The actual 2nd harmonic distortion above 1kHz may well be lower than 0.5%. A shortcoming of my measurement rig.

Time domain

Below the CSD (waterfall) plot of the JP1. Left and Right are overlaid.

CSD MJ1

Above 3kHz the dynamic driver is well damped (a bit too much ?)
Mids are lingering longer than they should.

Below the spectrum plot of the JP1 (Left channel). 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.

SPECTR MJ1 L

The lingering below 1kHz is clearly visible. This headphone is not performing poorly in the time domain though.

Below the square-wave response at 40Hz, 440Hz and a 100μs pulse response.
The measured signal should match the applied signal as close as possible.
The slight time delay is actually caused by the speed of sound. It takes approx. 100μs for the sound to reach the microphone.

SQR.png

In the 40Hz plot the gradual bass roll-off below 50Hz is seen as the measured amplitude is sloping downwards compared to the applied signal . Bass extension is decent.

The 440Hz signal looks like a triangle wave showing the lack of ‘clarity’ as the rising and falling edges are not nearly as steep as the squarewave stimulus. The signal going above the stimulus is evidence of the bass to mid boost affecting the mids as well.

The measured 100μs pulse is not reaching the target level by a long shot. This is by far the worst treble level I measured till this day.

Below the step response of the JP1 (left channel)

step MJ1 L
This too shows the initial rise (attack) is severly lacking. The rising edge remains 13dB below the bass/mids. The positive side is there are no resonances visible. The driver appears to be over damped.

dynamic and electret drivers

For those interested in the plots of the individual electret driver and dynamic driver  the following plots may be of interest.
In an attempt to find out where the crossover point is from ‘woofer’ to ‘midrange/tweeter’ and how they may have created a 2 way system with a real crossover the 2 drivers were measured separately (at the exact same input signal level) and merged into one plot.
The JP1 folder suggests there is a crossover point where the best qualities of both worlds combine.
Bass and lower mids of the dynamic driver and the fine detailed sound of the Electrostatz (as they call it) for the treble.
speaker + electret

It appears that the dynamic driver is simply a full range driver with a somewhat lower output above 400Hz. There is no low pass filter for the bass/midrange driver.
The electret starts from 500Hz (connected via the high-pass filter) and runs all the way up to at least 30kHz.
Acc. to the manufacturer the crossover is at 4kHz. This certainly is merely advertising talk and far from the truth.
Unfortunately the dynamic driver still plays 10dB louder than the electret driver. Thus the dynamic driver is twice as loud above 500hz.
On top of that the electret also shows big dips and peaks. Even higher than those of the dynamic driver.
In essence it looks like the electret is more of a gimmick than a real contributor to the sound as the dynamic driver is always much louder.
Listening to the dynamic driver alone gives the same tonal balance as with the electret combined. Still.. with the electret playing as well there is slightly more ‘sparkle’ (for whatever one can talk about sparkle which it lacks big time)

Below a plot with dynamic driver, electret driver separately and when these 2 drivers are combined.

speaker + electret vs MJ1

Only around 1.5kHz as well as at 6kHz there is a bit more presence (red trace) as well as above 20kHz. This is what I think I hear as well (not the 20kHz + part of course).
Slightly more treble thus not only electret sound above 4kHz as promised by the manufacturer.
It looks like the very high efficiency full range dynamic driver is way too loud (120dB/V) for the electret (95dB/V) to let it make a big audible difference even though the dynamic driver already has a substantially lower output (105dB/V) above 2kHz.

This result is not what I expected when reading the few reviews and marketting talk.
Also I don’t believe this sample is not representative or faulty.

Conclusion

For € 680.- one should at least expect a high quality headphone, both build wise and sound wise.
This headphone seems  well constructed with nice materials and has a nice looks as well (at least to me). Comfort is decent (for my head). The pads do get warm and sweaty with longer listening sessions.

Those looking for a highly detailed hi-fi headphone with a neutral tonal balance with a small bass boost perhaps can skip this headphone.
Not suited for classical, Jazz or other well recorded material. Better suited for Pop music and rock music for instance.

This headphone is said to be aimed at the DJ’s. The tonal balance and cup swivel would support that.
It’s low power rating , however, as well as the small 3.5mm TRS connectors at the bottom side of the cups which may break when dropped on a console as well as the low impedance at higher frequencies makes this headphone not really suited for this kind of work. The HD25 or HDJ2000 or ATHM50X are better recommendations for DJ’s.

Before one suggests … ‘well perhaps this headphone wasn’t broken in yet’ I have to disappoint. This is a used headphone with quite some hours on it already.

The electret seems to be merely a gimmick. The exteremly low impedance at 20kHz, the poor measurements and not really hi-fi sound is not worth the MSRP.
Based on looks and build quality I would not pay over € 150.- for this headphone. And  most of that figure would be for the wood cups and looks. Soundwise I find € 50.- already too much. Others may well find it is worth $ 600.-

Microphony of the cable and headband also is something that is somewhat disappointing despite the looks and feel of the supplied cable.
One can easily say that the sound quality is not on par with the mechanical quality.
The small adjustment range of the cups, the comfort level, the sweaty pads also do not help this headphone either.
A cheaper and also well made alternative would be the AudioQuest Nighthawk or perhaps the Meze 99 classic, Sony MDR1A or even the Pro 82 with maximum bass setting.

So what’s the final verdict ?
Is it all bad or does it have some positives as well?

Those looking for a neutral headphone or electrostat sound should look elsewhere.
Not suited for desktop amps nor mixing consoles. Also not really suited for DJ’s either.

For portable usage some extra bass/lows usually doesn’t hurt, some bass lift is even desirable on the go. Also when one only plays the headphone at a very low levels the bass boost works well enough to make the overall sound ‘full bodied’.
Playing directly from a player with the bass dialed down -8dB and treble lifted +2dB the sound is more neutral.

Those looking for a warm bassy headphone with subdued treble that needs to be driven directly from a phone are in luck. For this application it isn’t half bad. Not great either but usable.
The sound signature is something one can get used to. At times, when playing softly in the evening there were some songs I almost enjoyed the ‘rendition’ of the JP1with.
Nighthawk fans can relate to this headphone. For them this may be a nice side grade / alternative but certainly not an upgrade.
One has to bare in mind that the isolation from outside noises is rather poor making them less useful when looking for isolation or when travelling in a plane, bus or car.

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