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PSB M4U 1 Review (headphone)

amirm

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#1
This is a review and detailed measurements of the PSB M4U-1 headphone. It is on kind loan from a member. It is currently discontinued and seems to have come out back in 2012, costing US $230.

Time has not been kind to the specific sample I received which suffered from significant wear:

PSB M4U 1 Review headphone.jpg


Anything that can wear out in it, has. It looks better in these pictures than in person:
PSB M4U 1 Review Dimensions.jpg


The included cable has four pins and includes a microphone.

Overall comfort is good.

Note: The measurements you are about to see are preformed using standardized GRAS 45CA headphone measurement fixture. Headphone measurements require more interpretation than speaker tests and have more of a requirement for subjective testing as a result. In addition, comparison of measurements between different people performing it using different configurations requires fair bit of skill. So don't look for matching results. Focus on high level picture. Listening tests are performed using RME ADI-2 DAC and its headphone output.

Mounting the headphone on my test fixture was challenging, resulting in quite a lot of variation between channels and overall response. I optimized this as best as I could but like there are some error in low frequencies.

PSB M4U 1 Measurements
Let's start with frequency response of M4U-1 and comparison to our preference target to figure out tonality of the headphone:
PSB M4U 1 Measurements headphone frequency response.png


I looked for measurements from others and only found a couple which showed much elevated bass than what I got. We will have to verify who is right with listening tests. Taken as is, bass is obviously deficient as critical range between 1 and 5 kHz which has a strong influence on spatial qualities and presentation of female vocals.

PSB M4U 1 Measurements headphone relative frequency response.png


I expect the sound to be rather dull and uninteresting but also not annoying due to highs being controlled.

Distortion was remarkably low:
PSB M4U 1 Measurements headphone distortion percentage.png


High-end headphones with tons of distortion should take note!

PSB M4U 1 Measurements headphone distortion THD.png


The low distortion should give us freedom to boost the holes in frequency response without fear negative consequences on that front.

Group delay shows messiness below 1 kHz which we also saw in frequency response:
PSB M4U 1 Measurements headphone group delay.png


As always, massive spikes in high frequencies indicates reflections inside the cup and not a sign of frequency response errors. So don't be tempted to narrowband correction.

Impedance is flat but also low so current delivery matters:
PSB M4U 1 Measurements Impedance headphone.png


Then again, this is one efficient headphone:
most efficient headphone 2021 review.png


So you should be able to use it on just about any source.

PBS M4U1 Headphone Listening Tests
The M4U1 sounds exactly like it measures. Nothing annoying but not too exciting either. I pulled out the parametric EQ in my Roon player and dialed in some sub-bass EQ and that fit like a glove. Added a quick filter for 1 to 5 kHz and job was basically done:

PSB M4U 1 Parametric EQ Equalization.png


I had my son here so had him listen and he voted thumbs up on both fronts and the fact that the sound was not boomy or bass heavy post EQ.

I wanted to do more listening but alas, Roon folks just broke Tidal integration causing me to have a fraction of my test clips available for testing. :(

Based on what I did hear, with EQ, the sound was quite good. The boost between 1 and 5 kHz opened the soundstage and detail/instrument layering. The boost in bass was good although not quite substantial. It could stand accepting more based on taste.

Conclusions
The M4U1 has clear response errors that fortunately are correctable using EQ due to very low distortion. Good results can be had as a result. The problem is that the headphone itself seems to age poorly so not sure about getting a used one. Anyway, you have the data to make a decision.

Since the PSB M4U 1 is a discontinued item without performance that jumps out at you, I can't recommend it.

------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

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sweetchaos

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#2
To import this PEQ profile into 'Equalizer APO', use:
Preamp: -8.5 dB
Filter 1: ON LS Fc 40 Hz Gain 5.0 dB Q 1.0
Filter 2: ON LS Fc 80 Hz Gain 3.0 dB Q 1.0
Filter 3: ON PK Fc 2100 Hz Gain 5.0 dB Q 2.0
To import into your favorite PEQ app, enter it manually.
Otherwise, see my PEQ guide.
..................................................................................................................
For those who don't have PEQ-capable app, and want to use GEQs instead.
Preamp: -7.1db
32 6.7
64 0.9
125 -0.5
250 -0.7
500 -0.5
1000 -1.2
2000 3.9
4000 -0.8
8000 -0.8
16000 -1.1
Preamp: -10.1db
20 3.7
25 5.2
32 4.5
40 3.2
50 2.2
63 1.4
80 0.7
100 0.1
125 -0.2
160 -0.5
200 -0.5
250 -0.5
315 -0.6
400 -0.5
500 -0.5
630 -0.5
800 -0.5
1000 -0.4
1250 -0.2
1600 0.7
2000 4.0
2500 2.1
3150 -0.0
4000 -0.3
5000 -0.5
6300 -0.6
8000 -0.7
10000 -0.8
12500 -1.0
16000 -1.3
20000 -1.4
If you want to import into "Wavelet" (Android App):
GraphicEQ: 20 -0.2; 21 -0.2; 22 -0.2; 23 -0.2; 24 -0.2; 26 -0.2; 27 -0.2; 29 -0.3; 30 -0.5; 32 -0.7; 34 -1.0; 36 -1.3; 38 -1.5; 40 -1.8; 43 -2.2; 45 -2.4; 48 -2.7; 50 -2.9; 53 -3.2; 56 -3.5; 59 -3.8; 63 -4.1; 66 -4.3; 70 -4.6; 74 -4.8; 78 -5.0; 83 -5.2; 87 -5.4; 92 -5.6; 97 -5.8; 103 -6.0; 109 -6.1; 115 -6.2; 121 -6.3; 128 -6.4; 136 -6.5; 143 -6.6; 151 -6.7; 160 -6.7; 169 -6.8; 178 -6.8; 188 -6.8; 199 -6.9; 210 -6.9; 222 -6.9; 235 -6.9; 248 -6.9; 262 -6.9; 277 -6.9; 292 -7.0; 309 -7.0; 326 -7.0; 345 -7.0; 364 -7.0; 385 -7.0; 406 -7.0; 429 -7.0; 453 -6.9; 479 -6.9; 506 -6.9; 534 -6.9; 565 -6.9; 596 -6.9; 630 -6.9; 665 -6.9; 703 -6.8; 743 -6.8; 784 -6.8; 829 -6.8; 875 -6.7; 924 -6.7; 977 -6.6; 1032 -6.5; 1090 -6.4; 1151 -6.3; 1216 -6.2; 1284 -6.0; 1357 -5.8; 1433 -5.6; 1514 -5.2; 1599 -4.8; 1689 -4.2; 1784 -3.6; 1885 -2.9; 1991 -2.3; 2103 -2.0; 2221 -2.3; 2347 -2.9; 2479 -3.6; 2618 -4.2; 2766 -4.8; 2921 -5.2; 3086 -5.6; 3260 -5.8; 3443 -6.1; 3637 -6.2; 3842 -6.4; 4058 -6.5; 4287 -6.5; 4528 -6.6; 4783 -6.7; 5052 -6.7; 5337 -6.8; 5637 -6.8; 5955 -6.8; 6290 -6.9; 6644 -6.9; 7018 -6.9; 7414 -6.9; 7831 -6.9; 8272 -6.9; 8738 -7.0; 9230 -7.0; 9749 -7.0; 10298 -7.0; 10878 -7.0; 11490 -7.0; 12137 -7.0; 12821 -7.0; 13543 -7.0; 14305 -7.0; 15110 -7.0; 15961 -7.0; 16860 -7.0; 17809 -7.0; 18812 -7.0; 19871 -7.0
Otherwise, see my GEQ guide.
 
Last edited:

Tks

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#3
Best THD I've ever seen. Unbelievable. From a dynamic driver to boot, just wow.

No excuse for anyone out there. Sennheiser especially now that I think about it.
 

Grotti

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#6
IIRC, the version with NC sounded way better in active mode. But we also had many customers complaining about the build quality.
 

Maiky76

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#7
This is a review and detailed measurements of the PSB M4U-1 headphone. It is on kind loan from a member. It is currently discontinued and seems to have come out back in 2012, costing US $230.

Time has not been kind to the specific sample I received which suffered from significant wear:

View attachment 118449

Anything that can wear out in it, has. It looks better in these pictures than in person:
View attachment 118450

The included cable has four pins and includes a microphone.

Overall comfort is good.

Note: The measurements you are about to see are preformed using standardized GRAS 45CA headphone measurement fixture. Headphone measurements require more interpretation than speaker tests and have more of a requirement for subjective testing as a result. In addition, comparison of measurements between different people performing it using different configurations requires fair bit of skill. So don't look for matching results. Focus on high level picture. Listening tests are performed using RME ADI-2 DAC and its headphone output.

Mounting the headphone on my test fixture was challenging, resulting in quite a lot of variation between channels and overall response. I optimized this as best as I could but like there are some error in low frequencies.

PSB M4U 1 Measurements
Let's start with frequency response of M4U-1 and comparison to our preference target to figure out tonality of the headphone:
View attachment 118451

I looked for measurements from others and only found a couple which showed much elevated bass than what I got. We will have to verify who is right with listening tests. Taken as is, bass is obviously deficient as critical range between 1 and 5 kHz which has a strong influence on spatial qualities and presentation of female vocals.

View attachment 118452

I expect the sound to be rather dull and uninteresting but also not annoying due to highs being controlled.

Distortion was remarkably low:
View attachment 118453

High-end headphones with tons of distortion should take note!

View attachment 118454

The low distortion should give us freedom to boost the holes in frequency response without fear negative consequences on that front.

Group delay shows messiness below 1 kHz which we also saw in frequency response:
View attachment 118455

As always, massive spikes in high frequencies indicates reflections inside the cup and not a sign of frequency response errors. So don't be tempted to narrowband correction.

Impedance is flat but also low so current delivery matters:
View attachment 118456

Then again, this is one efficient headphone:
View attachment 118457

So you should be able to use it on just about any source.

PBS M4U1 Headphone Listening Tests
The M4U1 sounds exactly like it measures. Nothing annoying but not too exciting either. I pulled out the parametric EQ in my Roon player and dialed in some sub-bass EQ and that fit like a glove. Added a quick filter for 1 to 5 kHz and job was basically done:

View attachment 118459

I had my son here so had him listen and he voted thumbs up on both fronts and the fact that the sound was not boomy or bass heavy post EQ.

I wanted to do more listening but alas, Roon folks just broke Tidal integration causing me to have a fraction of my test clips available for testing. :(

Based on what I did hear, with EQ, the sound was quite good. The boost between 1 and 5 kHz opened the soundstage and detail/instrument layering. The boost in bass was good although not quite substantial. It could stand accepting more based on taste.

Conclusions
The M4U1 has clear response errors that fortunately are correctable using EQ due to very low distortion. Good results can be had as a result. The problem is that the headphone itself seems to age poorly so not sure about getting a used one. Anyway, you have the data to make a decision.

Since the PSB M4U 1 is a discontinued item without performance that jumps out at you, I can't recommend it.

------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Thanks for the review


Here are some thoughts about the EQ.

Notes about the EQ design:
  • The average L/R is used to calculate the score.
  • The resolution is 12 points per octave interpolated from the raw data (provided by @amirm)
  • A Genetic Algorithm is used to optimize the EQ.
  • The EQ Score is designed to MAXIMIZE the Score WHILE fitting the Harman target curve with a fixed complexity.
    This will avoid weird results if one only optimizes for the Score.
    It will probably flatten the Error regression doing so, the tonal balance should be more neutral.
  • The EQs are starting point and may require tuning (certainly at LF).
  • The range above 10kHz is usually not EQed unless smooth enough to do so.
  • I am using PEQ (PK) as from my experience the definition is more consistent across different DSP/platform implementations than shelves.
  • With some HP/amp combo the boosts and preamp gain need to be carefully considered to avoid issues
Good L/R match.

I have generated one EQ, the APO config files are attached.
Score no EQ: 74.4 better than many most probably thanks to the trough at HF being just above 10kHz (outside of the range used for the score)
Score Armirm: 86.9 nice improvements
Score with EQ: 101.1

Code:
PSB M4U APO EQ Score 96000Hz
March162021-135553

Preamp: -7.1 dB

Filter 1: ON PK Fc 37.6 Hz Gain 7.47 dB Q 0.46
Filter 2: ON PK Fc 193.5 Hz Gain -5.26 dB Q 0.72
Filter 3: ON PK Fc 2239 Hz Gain 5.17 dB Q 1.26
Filter 4: ON PK Fc 8495 Hz Gain -1.74 dB Q 4.94
PSB M4U APO Dashboard.png
 

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sweetchaos

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#8
Amir vs Jaakkopasanen (measured by InnerFidelity):
ezgif.com-gif-maker.gif

PEQ profile by Amir (from my post #2 above):
Preamp: -8.5 dB
Filter 1: ON LS Fc 40 Hz Gain 5.0 dB Q 1.0
Filter 2: ON LS Fc 80 Hz Gain 3.0 dB Q 1.0
Filter 3: ON PK Fc 2100 Hz Gain 5.0 dB Q 2.0

PEQ profile by Jaakkopasanen (measured by InnerFidelity):
Preamp: -6.6 dB
Filter 1: ON PK Fc 64 Hz Gain 3.4 dB Q 2.53
Filter 2: ON PK Fc 529 Hz Gain 3.7 dB Q 1.53
Filter 3: ON PK Fc 3773 Hz Gain -2.2 dB Q 2.37
Filter 4: ON PK Fc 9427 Hz Gain -3.8 dB Q 0.87
Filter 5: ON PK Fc 17901 Hz Gain 6.7 dB Q 0.30
Filter 6: ON PK Fc 155 Hz Gain -5.0 dB Q 0.79
Filter 7: ON PK Fc 166 Hz Gain 2.9 dB Q 0.38
Filter 8: ON PK Fc 1887 Hz Gain 2.5 dB Q 1.72
Filter 9: ON PK Fc 1913 Hz Gain -1.5 dB Q 0.59
Filter 10: ON PK Fc 3948 Hz Gain 0.6 dB Q 2.99

Oratory1990 didn't measure.
 

hyperplanar

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#9
Interesting to see that bass roll-off measured in this pair, my brother had a pair way back in 2013 or so and I definitely remember being the bass being much fuller than what was measured here... Wonder if this pair being worn out (pads maybe?) has something to do with it.

The headband broke maybe a year and a half later, so it definitely didn't strike me as being built well.
 
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#10
ff measured in this pair, my brother had a pair way back in 2013 or so and I definitely remember being the bass being much fuller than what was measured here... Wonder if this pair being worn out (pads maybe?) has something to do with it.

The headband broke maybe a year and a half later, so it definitely didn't strike me as being built well.
Maybe that peak between 100 and 300Hz makes it sound like that for you.
 

hyperplanar

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#11
Maybe that peak between 100 and 300Hz makes it sound like that for you.
Definitely not, that would make male voices sound boomy/chesty, I don't perceive a boost in that region as increased bass. If anything I hate it when that area is boosted. I listen to a lot of music with significant subbass content and don't remember the bass being rolled off like the graph shows.
 

don'ttrustauthority

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#13
My question is, if these measurements mean so much and these are audibly better headphones, why do these headphones not sell well even among the ASR data-driven readers?
 

Helicopter

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#14
To import this PEQ profile into 'Equalizer APO', use:


To import into your favorite PEQ app, enter it manually.
Otherwise, see my PEQ guide.
..................................................................................................................
For those who don't have PEQ-capable app, and want to use GEQs instead.
Preamp: -7.1db
32 6.7
64 0.9
125 -0.5
250 -0.7
500 -0.5
1000 -1.2
2000 3.9
4000 -0.8
8000 -0.8
16000 -1.1
Preamp: -10.1db
20 3.7
25 5.2
32 4.5
40 3.2
50 2.2
63 1.4
80 0.7
100 0.1
125 -0.2
160 -0.5
200 -0.5
250 -0.5
315 -0.6
400 -0.5
500 -0.5
630 -0.5
800 -0.5
1000 -0.4
1250 -0.2
1600 0.7
2000 4.0
2500 2.1
3150 -0.0
4000 -0.3
5000 -0.5
6300 -0.6
8000 -0.7
10000 -0.8
12500 -1.0
16000 -1.3
20000 -1.4
If you want to import into "Wavelet" (Android App):
GraphicEQ: 20 -0.2; 21 -0.2; 22 -0.2; 23 -0.2; 24 -0.2; 26 -0.2; 27 -0.2; 29 -0.3; 30 -0.5; 32 -0.7; 34 -1.0; 36 -1.3; 38 -1.5; 40 -1.8; 43 -2.2; 45 -2.4; 48 -2.7; 50 -2.9; 53 -3.2; 56 -3.5; 59 -3.8; 63 -4.1; 66 -4.3; 70 -4.6; 74 -4.8; 78 -5.0; 83 -5.2; 87 -5.4; 92 -5.6; 97 -5.8; 103 -6.0; 109 -6.1; 115 -6.2; 121 -6.3; 128 -6.4; 136 -6.5; 143 -6.6; 151 -6.7; 160 -6.7; 169 -6.8; 178 -6.8; 188 -6.8; 199 -6.9; 210 -6.9; 222 -6.9; 235 -6.9; 248 -6.9; 262 -6.9; 277 -6.9; 292 -7.0; 309 -7.0; 326 -7.0; 345 -7.0; 364 -7.0; 385 -7.0; 406 -7.0; 429 -7.0; 453 -6.9; 479 -6.9; 506 -6.9; 534 -6.9; 565 -6.9; 596 -6.9; 630 -6.9; 665 -6.9; 703 -6.8; 743 -6.8; 784 -6.8; 829 -6.8; 875 -6.7; 924 -6.7; 977 -6.6; 1032 -6.5; 1090 -6.4; 1151 -6.3; 1216 -6.2; 1284 -6.0; 1357 -5.8; 1433 -5.6; 1514 -5.2; 1599 -4.8; 1689 -4.2; 1784 -3.6; 1885 -2.9; 1991 -2.3; 2103 -2.0; 2221 -2.3; 2347 -2.9; 2479 -3.6; 2618 -4.2; 2766 -4.8; 2921 -5.2; 3086 -5.6; 3260 -5.8; 3443 -6.1; 3637 -6.2; 3842 -6.4; 4058 -6.5; 4287 -6.5; 4528 -6.6; 4783 -6.7; 5052 -6.7; 5337 -6.8; 5637 -6.8; 5955 -6.8; 6290 -6.9; 6644 -6.9; 7018 -6.9; 7414 -6.9; 7831 -6.9; 8272 -6.9; 8738 -7.0; 9230 -7.0; 9749 -7.0; 10298 -7.0; 10878 -7.0; 11490 -7.0; 12137 -7.0; 12821 -7.0; 13543 -7.0; 14305 -7.0; 15110 -7.0; 15961 -7.0; 16860 -7.0; 17809 -7.0; 18812 -7.0; 19871 -7.0
Otherwise, see my GEQ guide.
I am so tempted to get my old Sansui 10-band out and see how its analog graphic EQ compares to the software EQ (PEACE APO) I am using. Obviously it won't be as good, but the controls are nice and I wonder if it still sounds close.

3-band tone control settings (maybe based on Schiit Loki Mini+ bands) might be useful to some as well.

Thanks for all your contributions.
 

don'ttrustauthority

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#15
I am so tempted to get my old Sansui 10-band out and see how its analog graphic EQ compares to the software EQ (PEACE APO) I am using. Obviously it won't be as good, but the controls are nice and I wonder if it still sounds close.

3-band tone control settings (maybe based on Schiit Loki Mini+ bands) might be useful to some as well.

Thanks for all your contributions.
Can you set it up flat and have someone do a/b? Since it's obviously not as good, lets have a friendly wager to see if you can tell which signal is which out of ten tries.
 

Helicopter

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#16
My question is, if these measurements mean so much and these are audibly better headphones, why do these headphones not sell well even among the ASR data-driven readers?
Headphone measurement is the most crude of the measurements here, so we still need to rely on listening impressions to get a reasonable picture of what is going on; i.e., to evaluate performance. The measurements only get you 85% of the way there, based on Sean Olive's research and controlled listening tests. That leaves another 15% to listening. Speakers are a little better. Amps are substantially better. DACs, we don't really need listening tests.
 
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Bugal1998

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#17
PSB M4U1s were my travel headphone for several years and the first "nice" headphone I ever purchased. They were comfortable, but I don't recall ever hearing great bass out of them. The build quality, materials, and design were junk... No other way to put it. They literally fell apart.

Getting OEM replacement pads has proven impossible. Took four months to get replacement screws for the headband.

Many better options available...
 

Helicopter

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#19
PSB M4U1s were my travel headphone for several years and the first "nice" headphone I ever purchased. They were comfortable, but I don't recall ever hearing great bass out of them. The build quality, materials, and design were junk... No other way to put it. They literally fell apart.

Getting OEM replacement pads has proven impossible. Took four months to get replacement screws for the headband.

Many better options available...
These days, we should demand excellent build quality or excellent performance by this price point, as by $9, the Sony headphones already have very good performance.
 

Robbo99999

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#20
My question is, if these measurements mean so much and these are audibly better headphones, why do these headphones not sell well even among the ASR data-driven readers?
These headphones in this review didn't measure particularly well though, apart from distortion, and perhaps you could say also that the frequency response isn't too funky so it can be EQ'd fairly easily. But also, ASR has only been measuring headphones for less than a year so there's not assertions re "selling well amongst ASR readers"....and there's also not any data re sales, and also this is a discontinued headphone......there's quite a few problems with your statements. I mean that's fine and all, but you're not seeing the wood for the trees.
Can you set it up flat and have someone do a/b? Since it's obviously not as good, lets have a friendly wager to see if you can tell which signal is which out of ten tries.
This one also doesn't really make much sense. (I don't know if your username says anything about the clarity of your thought process.) It doesn't really matter, but they are a couple of pretty strange posts from you.
 

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