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ZERO AUDIO Carbo Tenore ZH-DX200-CT Review (IEM)

Robbo99999

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I tried it once and it was tons of work and I didn't like the results at the end. I will have to give it another try sometime.
(It's easy & quick when you've used it a couple of times, and with manual filters that you create there's noone to blame but ourselves.)
 

Maiky76

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This is a review and detailed measurements of the Japanese ZERO AUDIO Carbo Tenore ZH-DX200-CT In-ear Monitor. It is on kind loan from a member and costs US $44 from Amazon including Prime shipping. It has been around for a while and seems to have quite a following from scan of online reviews and forum discussions.

"Carbo" apparently refers to carbon fiber look (or is it real) of the body of the IEM:

View attachment 140782

As you see there is not much strain relief on the wires and what there is, is already split. People complain that the wire is thin but it is actually thicker than the ones on my Panasonic IEMs.

Note: The measurements you are about to see are made using a standardized Gras 45C. Headphone measurements by definition are approximate and variable so don't be surprised if other measurements even if performed with the same fixtures as mine, differ in end results. Protocols vary such as headband pressure and averaging (which I don't do). As you will see, I confirm the approximate accuracy of the measurements using Equalization and listening tests. Ultimately headphone measurements are less exact than speakers mostly in bass and above a few kilohertz so keep that in mind as you read these tests. If you think you have an exact idea of a headphone performance, you are likely wrong!

Fitment on the fixture was a bit challenging at first with one channel having no bass at all. A slight adjustment all of a sudden snapped it into the picture. I used the medium silicone tip for measurements which from experience, fits best on my testing fixture.

Zero Audio Carbo Tenore ZH-DX200-CT Measurements
Let's start with our usual dashboard and special target for IEMs:

View attachment 140783

Ignoring the kink around 200 Hz which may be a fitment issue, response is remarkably close to target all the way to 3 kHz. Post that energy is too low so likely the headphone will sound dull and lack sparkle.

View attachment 140784

Distortion unfortunately is rather high in the 2 to 5 kHz where we actually need to boost the response:

View attachment 140785

View attachment 140786

Group delay is very clean:

View attachment 140787

Impedance is very low:
View attachment 140788

Surprisingly, you need fair amount of drive for these IEMs, worse than some headphones!

View attachment 140789


ZERO AUDIO ZH-DX200-CT Listening Tests and Equalization
I fit these on my ears and I was shocked how poor the sound was. Not only were there no highs as the measurements indicated, there were no lows either! What the heck? After playing around with EQ for a while and getting nowhere, I decided to adjust how they fit in my ears. Bam! The bass was there and the sound was transformed. I had forgotten that the middle sized tips are too small for my ears. They would only have proper response if I held them manually. Switching to large silicone tips was a revelation. This is why we measure folks. When listening tests are wrong, they put you on warning that you maybe evaluating them incorrectly!

The treble had to be fixed though so out came the EQ tool:

View attachment 140790

Fitting a filter by eye to the hole there is very challenging. I used two filters but likely an automatic system can generate better fitting. Still, just those two filters were enough to give the much needed excitement to these headphones including providing decent spatial effects. I could listen to them for hours if I did not have to stop to take a picture for this review.

Conclusions
The Carbo Tenore IEMs have excellent bass and mid-range response. While they lack high frequency energy, you may be OK with them and as such, use them without EQ. With EQ though, they become my type of headphone/IEM with excellent dynamics and overall response.

Happy to recommend the ZERO AUDIO ZH-DX200-CT Carbo Tenore IEMs especially with equalization.

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

Hi,
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 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 need to be carefully considered to avoid issues
  • Not all units of the same products are not made equal. The EQ is based on a single unit measured. YMMV with regards to your very unit f you try this EQ.
  • Occluding IE devices generally must have very good fitting/seal in the user's ear canal for best performance.
    please spend a few minutes to pick up the best ear tip... Be sure to perform this step otherwise the FR/Score/EQ presented here are just worthless.
  • Just select the tip based on:
    1. more bass = better seal
    2. More isolation from the outside world = better fit
    3. Comfort
Great L/R match.
The glitch around 200Hz is probably caused by the ear tip spring combined with the mass of the earbud.

I have generated one EQ, the APO config file is attached.

Score no EQ: 73.6
Score Armirm: 80.2
Score with EQ: 94.0

Code:
ZERO AUDIO ZH-DX200-CT Carbo Tenore APO EQ Flat@HF 96000Hz
July142021-120100

Preamp: -5.3 dB

Filter 1: ON PK Fc 222.32 Hz Gain -4.30 dB Q 0.87
Filter 2: ON PK Fc 623.18 Hz Gain 1.66 dB Q 0.86
Filter 3: ON PK Fc 1243.66 Hz Gain -1.81 dB Q 2.98
Filter 4: ON PK Fc 2373.08 Hz Gain -4.40 dB Q 2.19
Filter 5: ON PK Fc 4213.32 Hz Gain 5.72 dB Q 1.54
Filter 6: ON PK Fc 8049.07 Hz Gain 1.21 dB Q 3.60
Filter 7: ON PK Fc 15475.36 Hz Gain -5.91 dB Q 4.80

ZERO AUDIO ZH-DX200-CT Carbo Tenore Dashboard.png

For those thinking there more to be EQed to get a higher score:

Code:
ZERO AUDIO ZH-DX200-CT Carbo Tenore APO EQ OTT Flat@HF 96000Hz
July142021-171435

Preamp: -5.2 dB

Filter 1: ON PK Fc 172.26 Hz Gain 3.22 dB Q 4.87
Filter 2: ON PK Fc 208.37 Hz Gain -4.72 dB Q 0.87
Filter 3: ON PK Fc 660.98 Hz Gain 1.65 dB Q 0.86
Filter 4: ON PK Fc 1252.66 Hz Gain -1.93 dB Q 2.50
Filter 5: ON PK Fc 2380.38 Hz Gain -4.40 dB Q 2.19
Filter 6: ON PK Fc 4207.82 Hz Gain 5.72 dB Q 1.52
Filter 7: ON PK Fc 7955.81 Hz Gain 1.08 dB Q 4.91
Filter 8: ON PK Fc 11872.65 Hz Gain 3.28 dB Q 4.45
Filter 9: ON PK Fc 15623.65 Hz Gain -8.94 dB Q 4.97

Score 95.9(/100), I am not sure it will actually be better.
ZERO AUDIO ZH-DX200-CT Carbo Tenore OTT Dashboard.png
 

Attachments

  • ZERO AUDIO ZH-DX200-CT Carbo Tenore APO EQ Flat@HF 96000Hz.txt
    448 bytes · Views: 62
  • ZERO AUDIO ZH-DX200-CT Carbo Tenore APO EQ OTT Flat@HF 96000Hz.txt
    552 bytes · Views: 65
Last edited:

GWolfman

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Any noticeable distortion? Luckily less power is required for higher volume levels than headphones.
 

GeekyBastard

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Hi,
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 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 need to be carefully considered to avoid issues
  • Not all units of the same products are not made equal. The EQ is based on a single unit measured. YMMV with regards to your very unit f you try this EQ.
  • Occluding IE devices generally must have very good fitting/seal in the user's ear canal for best performance.
    please spend a few minutes to pick up the best ear tip... Be sure to perform this step otherwise the FR/Score/EQ presented here are just worthless.
  • Just select the tip based on:
    1. more bass = better seal
    2. More isolation from the outside world = better fit
    3. Comfort
Great L/R match.
The glitch around 200Hz is probably caused by the ear tip spring combined with the mass of the earbud.

I have generated one EQ, the APO config file is attached.

Score no EQ: 73.6
Score Armirm: 80.2
Score with EQ: 94.0

Code:
ZERO AUDIO ZH-DX200-CT Carbo Tenore APO EQ Flat@HF 96000Hz
July142021-120100

Preamp: -5.3 dB

Filter 1: ON PK Fc 222.32 Hz Gain -4.30 dB Q 0.87
Filter 2: ON PK Fc 623.18 Hz Gain 1.66 dB Q 0.86
Filter 3: ON PK Fc 1243.66 Hz Gain -1.81 dB Q 2.98
Filter 4: ON PK Fc 2373.08 Hz Gain -4.40 dB Q 2.19
Filter 5: ON PK Fc 4213.32 Hz Gain 5.72 dB Q 1.54
Filter 6: ON PK Fc 8049.07 Hz Gain 1.21 dB Q 3.60
Filter 7: ON PK Fc 15475.36 Hz Gain -5.91 dB Q 4.80

View attachment 140988
For those thinking there more to be EQed to get a higher score:

Code:
ZERO AUDIO ZH-DX200-CT Carbo Tenore APO EQ OTT Flat@HF 96000Hz
July142021-171435

Preamp: -5.2 dB

Filter 1: ON PK Fc 172.26 Hz Gain 3.22 dB Q 4.87
Filter 2: ON PK Fc 208.37 Hz Gain -4.72 dB Q 0.87
Filter 3: ON PK Fc 660.98 Hz Gain 1.65 dB Q 0.86
Filter 4: ON PK Fc 1252.66 Hz Gain -1.93 dB Q 2.50
Filter 5: ON PK Fc 2380.38 Hz Gain -4.40 dB Q 2.19
Filter 6: ON PK Fc 4207.82 Hz Gain 5.72 dB Q 1.52
Filter 7: ON PK Fc 7955.81 Hz Gain 1.08 dB Q 4.91
Filter 8: ON PK Fc 11872.65 Hz Gain 3.28 dB Q 4.45
Filter 9: ON PK Fc 15623.65 Hz Gain -8.94 dB Q 4.97

Score 95.9(/100), I am not sure it will actually be better.
View attachment 141025
Tried it with my DX200, love it so far, really nice & easy sound out of the box, even better after eq.
 

weasels

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These are my go-to recommendation for friends who want cheap in-ears and like hip-hop or EDM. I like them as well, although the cable can be microphonic when wearing them for a walk.

The tiny size should be emphasized - these are a great option for smaller ears or if you want to wear them while sleeping.
 

MCH

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hi, any recommended tips for the tenore? thanks!
 

MCH

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thanks a lot, i see those are available in amazon.de what model are you using? (website recommends "comfort 200" for the tenore but amazon.de shows me only "tsx-200", no clue if they are the same....)

edit: no worries, i see tsx and ts are two different lines of the same fit.
 

Lttlwing16

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Alas, the 90 degree 3.5mm connector on my Tenore's gave up the ghost, so I was wondering if anyone thinks it's feasible to re-terminate these or if it's just easier to buy a new pair?

Thanks!

David

EDIT: For those who need to re-terminate these: Red - RT Green - LT Copper - Ground
 
Last edited:
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