Sony MDR-CD900ST Japan Headphone Review

[amirm]

This is a review, detailed measurements, listening tests and equalization of Sony MDR-CD900ST which was produced for Japan market. It is on kind loan from a member and costs US $138.

As you see, it quite resembles other headphones in the MDR series. It is a light headphone with very compact cups. The latter created a hellish situation trying to measure it. Bass response was hugely variable depending on smallest changes to the headband/position. After half hour of messing with it, I posted the best measurements I could get below.

Sony MDR-CD900ST Measurements
Here is our familiar headphone frequency response measurement:

We have both rolled off bass and treble holes. If your interest is only to evaluate vocals, I guess it could pass but otherwise, I don't know what the designers were thinking. Relative response shows the deep impairments:

As if to add a bit of insult to injury, bass distortion is high which makes our EQ decisions more challenging:

We also have resonances that peak up narrowly. They are even visible in Group Delay:

Impedance is medium meaning both voltage and current are important to drive it:

Sensitivity was quite high, likely due to shallow pads:

Sony MDR-CD900ST Listening Tests and EQ
I had seen the measurements before listening but that did not prepare me properly for how bad this headphone sounds. It sounds hugely muffled and with no bass, it was anything but a high-fi experience. I would rate it as one of the worst headphones I have listened to. I was afraid of fully EQing it so went modest:

Due to large amount of bass boost, I had to dial in about 9 dB of headroom on top of 3 dB that Roon builds in. With that, I could avoid clipping. The impact here is that you need a more powerful headphone amplifier and a quieter one than you would think from sensitivity numbers.

Once there, the sound was nice, giving my reference tracks the respect they owe. I could at times detect a bit of distortion but I can't directly say it was due to distortion of the headphone.

Conclusions
Clearly some special tuning is applied here for the local market. I find some Japanese pop music bright so maybe this headphone was designed to tame that. The lack of bass is mostly due to small cups not creating a good seal. Whatever the reason, as is performance is well below an threshold of fidelity that I go by. Fortunately just three filters lifted the headphone out of the gutter, producing profoundly better experience.

I can't recommend the Sony MDR-CD900ST headphone.

------------
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/

 

[amirm]

Reserved for @AdamG to kindly post the specs.

Manufacturer Specifications:

 

[sushi2020]

These very old headphones were first sold to corporate customers in 1989 and to consumers in 1995.

Here in Japan, they are still widely used for vocal monitoring.

 

[192kbps]

If there are such obvious leaks in 45CA, then for people, this headset has lost the need to wear it seriously.

 

[GXAlan]

These are very much like the Yamaha NS-10. They measure poorly yet are widely used even to this day in Asia for music production decisions. They are still in production!

【インタビュー】SONY”MDR-CD900STを創った男”投野耕治氏インタビュー！​

e☆イヤホンのはまちゃんです！2017年も、もう少しですね！今年のクリスマスの予定は決まっていますか？僕のクリスマスの予定は、バンドでレコーディングです！最高です！ 本日は！

e--earphone-blog.translate.goog

“The consumer MDR-CD900 was released in 1985 and production ended in 1990. MDR-CD900 has a folding mechanism and is a curl cord. Overseas, it is sold under the model number "MDR-V6" with slightly different specifications.

At the time, the monitor headphones used at the CBS/Sony studio in Shinanomachi had a fairly round sound, and although voices could be heard well, I felt it was lacking. After all, I learned that the voice has a very high priority in the studio, and that the timbre is what matters, so I started creating the sound of monitor headphones for the studio based on the MDR-CD900. During development, digital recording was also just beginning, and we wanted to find new sounds.

Three years after the MDR-CD900, we developed a new headphone called the MDR-CD900CBS (1988) for use only within CBS/Sony's Shinanomachi and Roppongi studios. The sound is different from the original MDR-CD900, but I think it's more advanced than the studio headphones of the time.

While we were creating the sound in the studio, we talked about how we were concerned about the sharpness of the low range, and while we were talking about it, we even poked holes in the headphones with a pencil to make fine adjustments.

After completion, the sound of the CBS/Sony Studio headphones gradually became popular with musicians, and the headphones were not only used at the CBS/Sony studios, but were also sold to other studios. At that time, you decided to name it MDR-CD900ST.

 

[GXAlan]

I don't know what the designers were thinking. Relative response shows the deep impairments:
View attachment 372649

Interestingly, the roll off as early as 1 kHz reminded me of this FR curve from the JBL 4312M II, also a Japanese-market only product. Coming from Harman (which measures everything they ship), it does look more similar than different.

 

[Robbo99999]

Ain't gonna be playing no subbass! (was it tested for bad seal, I've not looked at comments yet, EDIT: lol only 3 comments so far, and ok not mentioned yet)

 

[Curupira]

Another example to show that, maybe, mass adoption inside the studio world doesn't necessarily imply quality, but rather pack mentality.

 

[AdamG]

This may be one of the worst natural frequency Response for a headphone ever. Add in all that baked in distortion in exactly the frequency range where you need to add eq to fix the sound and you have nothing but a midrange headphone with massive amounts of distortion if you try to flatten the sweep. Sad to see SONY put their brand name on such a poor performing product. This is the perfect example of how measurements can predict actual performance.

Thanks for the review Boss.

 

[Maiky76]

@

This is a review, detailed measurements, listening tests and equalization of Sony MDR-CD900ST which was produced for Japan market. It is on kind loan from a member and costs US $138.
View attachment 372647
As you see, it quite resembles other headphones in the MDR series. It is a light headphone with very compact cups. The latter created a hellish situation trying to measure it. Bass response was hugely variable depending on smallest changes to the headband/position. After half hour of messing with it, I posted the best measurements I could get below.

Sony MDR-CD900ST Measurements
Here is our familiar headphone frequency response measurement:
View attachment 372648
We have both rolled off bass and treble holes. If your interest is only to evaluate vocals, I guess it could pass but otherwise, I don't know what the designers were thinking. Relative response shows the deep impairments:
View attachment 372649

As if to add a bit of insult to injury, bass distortion is high which makes our EQ decisions more challenging:
View attachment 372650
View attachment 372651

We also have resonances that peak up narrowly. They are even visible in Group Delay:
View attachment 372652

Impedance is medium meaning both voltage and current are important to drive it:
View attachment 372653

Sensitivity was quite high, likely due to shallow pads:
View attachment 372654

Sony MDR-CD900ST Listening Tests and EQ
I had seen the measurements before listening but that did not prepare me properly for how bad this headphone sounds. It sounds hugely muffled and with no bass, it was anything but a high-fi experience. I would rate it as one of the worst headphones I have listened to. I was afraid of fully EQing it so went modest:
View attachment 372655
Due to large amount of bass boost, I had to dial in about 9 dB of headroom on top of 3 dB that Roon builds in. With that, I could avoid clipping. The impact here is that you need a more powerful headphone amplifier and a quieter one than you would think from sensitivity numbers.

Once there, the sound was nice, giving my reference tracks the respect they owe. I could at times detect a bit of distortion but I can't directly say it was due to distortion of the headphone.

Conclusions
Clearly some special tuning is applied here for the local market. I find some Japanese pop music bright so maybe this headphone was designed to tame that. The lack of bass is mostly due to small cups not creating a good seal. Whatever the reason, as is performance is well below an threshold of fidelity that I go by. Fortunately just three filters lifted the headphone out of the gutter, producing profoundly better experience.

I can't recommend the Sony MDR-CD900ST headphone.

------------
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/

@amirm The EQ you designed is not displayed correctly, I could not calculate its score.

Here are some thoughts about the EQ.
Please report your findings, positive or negative!

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 (and other constrains) with a fixed complexity.
  This will avoid weird results if one only optimizes for the Score, start your journey here or there.
  There is a presentation by S. Olive here.
  It will probably flatten the Error regression doing so, the tonal balance should be therefore more neutral.
• The EQs are starting point and may require tuning (certainly at LF and maybe at HF).
• The range around and 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 (loss of Dynamic range) need to be carefully considered to avoid issues with, amongst other things, too low a Max SPL or damaging your device. You have beed warned.
• Not all units of the same product are made equal. The EQ is based on the measurements of a single unit. YMMV with regard to the very unit you are trying this EQ on.
• I sometimes use variations of the Harman curve for some reasons. See rational here and here
• NOTE: the score then calculated is not comparable to the scores derived from the default Harman target curve if not otherwise noted.

Average L/R match.

I have generated one EQ, the APO config file is attached.
I followed Amirm max boost at LF as the loss of sensitivity is already 12dB.

Score no EQ: 66.3
Score with EQ: 100.7

Sony MDR-CD900ST EQ Flat 96000Hz
June022024-222429

Preamp: -12 dB

Filter 1: ON PK Fc 34.3 Hz Gain 12.00 dB Q 0.43
Filter 2: ON PK Fc 143.3 Hz Gain -1.22 dB Q 1.47
Filter 3: ON PK Fc 1978.5 Hz Gain 8.51 dB Q 1.43
Filter 4: ON PK Fc 3865.2 Hz Gain -2.38 dB Q 2.01
Filter 5: ON PK Fc 6156.1 Hz Gain 10.72 dB Q 1.54

 

[teched58]

Reserved for @AdamG to kindly post the specs.

Manufacturer Specifications:
View attachment 372699

These specs are very similar to that of the widely used Sony MDR-7506, which was first introduced in 1992 and today remains a popular montoring headphone in audio, pro sound, film and television. (MDR-7506 specs here.) Sean Olive has said that the FR on the 7506 is close to the Harmon curve.

Personally, I like the 7506, and I don't find a noticeable lack of bass. Of course, my ear pads aren't degraded.

 

[martin900]

Another example to show that, maybe, mass adoption inside the studio world doesn't necessarily imply quality, but rather pack mentality.

It has nothing to do with quality or pack mentality. It's a tool for evaluating certain aspects of a recording. For the same reason studio's still use NS10M's and Auratones - they are 'purposedly broken' and nothing more than an evalution tool. This is also the case with the JBL 431x series - it's a control monitor.

 

[markanini]

It has nothing to do with quality or pack mentality. It's a tool for evaluating certain aspects of a recording. For the same reason studio's still use NS10M's and Auratones - they are 'purposedly broken' and nothing more than an evalution tool. This is also the case with the JBL 431x series - it's a control monitor.

Indeed, the purpose of headphones in a studio environment is better served by isolation and being easily driven loud. Not by hifi reproduction.

 

[GXAlan]

These specs are very similar to that of the widely used Sony MDR-7506, which was first introduced in 1992 and today remains a popular montoring headphone in audio, pro sound, film and television. (MDR-7506 specs here.) Sean Olive has said that the FR on the 7506 is close to the Harmon curve.

Personally, I like the 7506, and I don't find a noticeable lack of bass. Of course, my ear pads aren't degraded.

Yeah, my link mentions that in Japan, these are the successor to the the 7506 and were developed expressly for CBS Japan recording studios. Makes sense why it never came to the U.S.

 

[Vamp898]

Its already been so many years since they have been replaced by the MDR-M1ST, they should be left resting in peace

 

[dasdoing]

It is on kind loan from a member

- what is the address to ship it back?

- throw it in the trashcan

 

[VientoB]

Is this the model DMS has been raving about recently on his YouTube channel? He doesn’t use the stock pads with his, I believe he switched them for bigger Yaxi pads.

 

[amirm]

I looked it up and yes, he is talking about this headphone but with a larger, deeper pad.

 

[markanini]

The deviations from the target are similar to AKG K712 FWIW

I'm not sure this headphone should have been considered for content consumption in the first place. Clearly it can't be competitive with it's FR. DMS should not have talked about it other than a quirky curiosity.

 

[kelesh]

These specs are very similar to that of the widely used Sony MDR-7506, which was first introduced in 1992 and today remains a popular montoring headphone in audio, pro sound, film and television. (MDR-7506 specs here.) Sean Olive has said that the FR on the 7506 is close to the Harmon curve.

Personally, I like the 7506, and I don't find a noticeable lack of bass. Of course, my ear pads aren't degraded.

I'd bet the drivers inside are the same ones used in the 7506 and that they sound roughly the same.