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7Hz x Crinacle Zero:2 IEM Review

Rate this IEM:

  • 1. Poor (headless panther)

    Votes: 4 1.2%
  • 2. Not terrible (postman panther)

    Votes: 10 2.9%
  • 3. Fine (happy panther)

    Votes: 35 10.2%
  • 4. Great (golfing panther)

    Votes: 295 85.8%

  • Total voters


Staff Member
CFO (Chief Fun Officer)
Feb 13, 2016
Seattle Area
This is a review, listening tests, EQ and detailed measurements of the 7Hz x Crinacle Zero:2 IEM. It was kindly donated to me by a member and costs US $24.99.
7Hz x Crinacle Zero 2 IEM Harman compliant review.jpg

The cable is soft and longer than typical which I like. They take fair amount of effort to push it but then they make a reassuring soft click. The tips look cheap and are quite soft. You may need aftermarket ones. I tested and listened using the default red ones you see in the review picture.

Compared to 7Hz Zero IEM that I reviewed recently, these supposed to have a bit more bass and less treble. Let's measure to find out if that is the case.

7Hz x Crinacle Zero:2 IEM Measurements
Let's start with our standard measurement on GRAS 45CA measurement fixture. I was pleased that they fit instantly and generated the predicted results:
7Hz x Crinacle Zero 2 IEM Frequency Response Harman Measurement.png

At high level, this is excellent compliance with our target leaving enough room for manufactures to tune and owners to decide based on their taste. Getting specific, ignoring sub-bass, we have a bit of lift between 100 and 300 Hz and some short fall from 4K to 8K. So overall I expect these to have a bit more bass and more closed in/less sparkle than the original Zero. Here is the relative response for EQ development:
7Hz x Crinacle Zero 2 IEM relative Frequency Response Harman Measurement.png

While the differential is not great, developing precise filters may be bit challenging due to their shape. Then again you may not need to modify the response anyway.

The distortion measurements made my jaw drop:
7Hz x Crinacle Zero 2 IEM Distortion relative Measurement.png

As you see, even 114 dBSPL generates negligible distortion by transducer standards. It was so low that I decided to zoom way in. You see noise on the blue 94 dBSPL indicating corruption due to measurement noise. So in reality performance is better than that (SINAD of nearly 80 dB). This is one clean sounding IEM.

Absolute levels also show the same:
7Hz x Crinacle Zero 2 IEM Distortion Measurement.png

Group delay shows no news which is what we like to see (and is typical of IEMs):
7Hz x Crinacle Zero 2 IEM Group Delay Measurement.png

Impedance is flat and low which is as expected:
7Hz x Crinacle Zero 2 IEM Impedance Measurement.png

Combined with average sensitivity, just about any source can drive it:
Most sensitive IEM Review.png

7Hz x Crinacle Zero:2 IEM Listening Tests and EQ
First impression was that familiar sound I hear from accurate transducers with two differences: the highs were a little recessed and at times I was hearing bass I didn't even know was there! I went after the former with EQ:
7Hz x Crinacle Zero 2 IEM equalization parametric EQ.png

The measured shortfall in treble is 5+ dB. I started there and while that brought fantastic amount of detail and great improvement in spatial qualities, after some listening, I realized it is too bright. I pulled it down to 3 dB. Listening to bass heavy tracks I started to be bothered a bit about the extra upper bass. I dialed in a filter for that which solved that but them made the sound bright. I took down the treble EQ to what you see and reduced the amount I had taken down the Bass. These values are basically 40% of what measurements indicated. AB tests of EQ and no EQ showed preference for EQ.

Then I sat back and listened. That deep, impressive sub-bass is there and is now so clean. The highs are to die for. I have no immediate comparison but I kept getting surprised by the clarity up high in tracks that I have listened to hundreds of times for review. As much as I have had the pleasure of listening to some really great headphones and IEMs, I continue to be startled by moment to moment level of fidelity as I continue to listen to them. I think this IEM will likely make you not like your regular speaker system unless it is of highest caliber! The sound is just so good.

Also amazing is the level of instrument separation/spatial qualities. So, so satisfying. I can't say enough good things.

You have to shake your head when you see and read about the performance of this $25 IEM. It displays a level of performance with a bit EQ that is world class. Feed it some well recorded music and you are there: the pinnacle of high fidelity sound. I don't care if you don't want to use an IEM. Get one of these (or the original Zero) and get calibrated on what good sound is.

As to whether to get the zero or zero:2, I would say that with the above EQ, Zero:2 sounds more to my liking than the original 7Hz Zero. That one though sounds more correct without EQ. Your opinion may vary.

I am happy to recommend the 7Hz x Crinacle Zero:2 IEM.

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/


  • 7Hz x Crinacle Zero 2 IEM Frequency Response.zip
    33.3 KB · Views: 545


Staff Member
CFO (Chief Fun Officer)
Feb 13, 2016
Seattle Area
Yeh, I think a package with better tips at $29 would be the ticket.

Here are the Technical Specifications:

Technical Specifications:​

Frequency response range. 10HZ-20KHz​

Impedance. 32 ohms​

Total Harmonic Distortion (THD). <1% at 1KHz​

Driver. 10mm dynamic driver​

Cable Interface. 3.5mm​

Plug Type. Detachable 0.78mm 2Pin​

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Major Contributor
Forum Donor
Feb 7, 2021
I've got these and new daily drivers replacing the Simgot EA500 which are nice, but these really are terrific. The tips are flappy when moving them, but easily swapped out. Gaming is nice also in Destiny 2.


Active Member
Forum Donor
Feb 25, 2021
just got mine today. I am trying them as I am writing. First IEM for me in a looooong time, more than 15 years since my last IEM. Very impressive indeed!

now need to go back and read Amir's review ....


Master Contributor
Forum Donor
Jan 1, 2019
São Paulo, Brazil
I am glad you like them. Well worth donating both. My Zero 2 should be arriving soon too.
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Jun 7, 2019
Just placed the order, it came out to $47.62 with VAT and shipping to my country (Hungary/EU), from Amazon.com. From Amazon.de it had cost even more. Est. Delivery is jan.17.

If someome knows a better place to order from, pls let me know :)


Senior Member
May 28, 2020
French, living in China
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.
    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 regards to the very unit you are trying this EQ on.
  • I sometimes use variations of the Harman curve for some reasons. See rational here: https://www.audiosciencereview.com/...pro-review-headphone.28244/page-5#post-989169
  • https://www.audiosciencereview.com/...pro-review-headphone.28244/page-6#post-992119
  • NOTE: the score then calculated is not comparable to the scores derived from the default Harman target curve if not otherwise noted.
  • 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.
  • 1. more bass = better seal
    2. More isolation from the outside world = better fit
    3. Comfort

Great L/R match.

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

Score no EQ: 77.0%
Score Amirm: 82.9%
Score with EQ: 95.8%

7Hz x Crinacle Zero 2  Harman Full EQ .png

Knowles Target, the scores are NOT comparable

7Hz x Crinacle Zero 2  Knowles EQ.png

THD with different plot



  • 7Hz x Crinacle Zero 2 Harman Full EQ .txt
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  • 7Hz x Crinacle Zero 2 Knowles EQ.txt
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