7Hertz Timeless IEM Review

[Curupira]

What would cause the distortion to rise so precipitously above 1kHz?

Most probably a resonance due to the driver, as a lot of the earlier planar iems share a very similar implementation and driver (the old s12 was literally a "flee-floating" driver in a CNC shell, with no tuning filters or materials whatsoever).

Are there multiple drivers in this IEM,

There aren't, just the 14mm planar driver and the passive tuning material.

It is basically a sheet of mylar with copper traces in it so if not designed well, will have various modes.

Interestingly, this planar driver generation was the first one to break the ice with usable FR profiles. There were a lot of planar iems before 7Hz's, with either inhouse built-in drivers or obscure solutions that performed as you might expect. It was only 7Hz made their debut with the Timeless that the surge commenced, with planar iems adopting a harmanesque FR.

Personally I suspect they share suppliers and driver manufacturers, as the Letshuoer S12, which is almost a dead ringer to the Timeless in FR, launched almost simultaneously with it (and didn't have any tuning material).

 

[Klonatans]

7Hz is actually the brand and Timeless the model name. It was the first of its kind that paved the way for many more affordable planar IEMs in the market.
The dip at 3,5 kHz looks beneficial in my book to tame excessive upper midrange energy, but otherwise the frequence response looks rather wonky, especially the massive bump above 10 kHz.

 

[lewdish]

3% distortion isnt terrible, its slightly above avg, still for most folks is underneath what they can hear. I do think that relatively speaking the timeless is now somewhat aged, and 7HZ has since moved on from this model to other ones despite there being an abundance of these on the market. The timeless was the first planar IEM that kicked off the Planar market in the IEM space (there were older ones but they werent very good until Timeless appeared). Theres many improved models on the market now.

 

[sealman]

So for 160.00 to 200.00 more dollars than the Truthear GATE you get roughly the same compliance as a 17.00 IEM with a crap ton more distortion?
No thanks.
Way too many IEMS out there for less than 100.00 to pay for this crap.

 

[Madlop26]

I bought the 7 Hz timeless after the Famous Crinacle face reaction in Youtube, I have always enjoyed the sound but was evidently different that the Red and the Monarch that i also own, most likely due to the emphasis in 1K to 3K range, but still quite enjoyable, But the Timeless stands out on how easy to get a good seal, and the comfort, but that may be not the case for everybody.

 

[Jimster480]

Funnily enough these are not as impressive as the $17 set that you you posted on the same day. What a stark comparison between two products at vastly different price ranges.

 

[Miley_B]

These planar IEMs appear to have a more extended HF than most but still roll off sharply before 20kHz.
The manufacturer claims extension to 40kHz so is the specification a wild fabrication or is there a limitation to the measurement system?

 

[amirm]

The manufacturer claims extension to 40kHz so is the specification a wild fabrication or is there a limitation to the measurement system?

The measurement system is not accurate above 10 kHz let alone 40 kHz. But sure, if you just want to know it is producing sound, I could measure well above there.

 

[Miley_B]

Thanks for the swift reply.
Personally I’m only really interested in 20Hz - 20kHz and unsurprisingly my own hearing doesn’t get close to this range. Just find it odd that all of these IEMs claim to extend past 20k but in our measurements they all fall short. I’m aware and appreciate that all fixtures have accuracy limitations at high frequencies.

I’d also like to add a thanks for measuring the harmonics, impedance, GD etc. of all these units. They’re important factors in the final result and this information is hard or impossible to find elsewhere.

 

[mc.god]

Manufacturer advertized FR often going near bats earing threshold is nothing more than marketing claim, I never put attention to it.

 

[Maiky76]

This is a review, listening tests, EQ and detailed measurements of 7Hertz (Hz) Timeless planar driver IEM. It was kindly sent to me by a member and is on sale right now for US $176 (normal $220).
View attachment 439561
As you see, the same is unique as is the construction made out of machined aluminum. I thought this would be an issue but wearing them was very comfortable for me. I performed my testing using the tips you see. Two boxes are provided, one for a different shape than the other. IEMs are stored in a solid, metal box that is not pocket friendly but would stand driving your car over!

If you are not familiar with my headphone measurements, I highly recommend to watch my tutorial on it:

[And subscribe to the channel ]
Timeless 7 Hertz IEM Measurements
As usual, we start with our IEM frequency response measurements using GRAS 45CA as a fixture:
View attachment 439563
At high level, this is very good compliance with our target. There are small variations especially the pulled down area around 3.5 kHz which we have to evaluate using listening tests.

Relative difference to our target as a result, only shows small variations:
View attachment 439564

What was shockingly disappointing was the distortion in lower to mid treble:
View attachment 439565

We have nearly 3% distortion at 1.8 kHz!
View attachment 439566
The planar panel must be resonating at those frequencies.

Group delay is not revealing of much as IEMs don't suffer from internal reflections like headphones do:
View attachment 439567

Typical of planar transducers, impedance is on the low side:
View attachment 439568
I rescaled the vertical axis to show the variations that we observe in frequency response and distortion, showing this is some kind of acoustic event.

Sensitivity is worse than average:
View attachment 439569

Timeless 7Hz IEM Listening Tests and Equalization
I am migrating my Roon server to another platform so temporarily don't have access to my usual test tracks. Using what I had, I found out of box tonality to be very good. I did try to two corrections though:
View attachment 439570
Band 2 opens the sound up a bit -- as it usually does in headphones and IEMs. Spatial qualities went from good to very good. Band 1 took a way a bit of boominess especially before I reduced its negative gain. In balance, I found the two filters to benefit most of the tracks I threw at it. But on one of my bass and treble heavy tracks, I found the sound to become brighter than I liked. I would say then that the deviations are within degrees of error in the research target.

With or without EQ, sub-bass performance was excellent owing to nice boost in low frequency response.

Conclusions
The tonality of 7 Hertz IEM lands slightly outside of our target. Per listening test remarks, we simply don't have accurate enough target to say this is bad or good. The high level picture of good amount of bass response is certainly good. Overall then, I have no complaints about the tonality. The issue is that of distortion. Sometimes I feel that I am the only one running distortion tests and identifying clear engineering issues that could have been resolved had there been any focus on it. Yes, the distortion response doesn't immediately tell you what audible issues you may have. But it does tell you that all else being equal, you want an IEM/headhphone that doesn't have copious amount of distortion, especially where our hearing is most sensitive.

Putting it all together, I will recommend the Timeless 7Hz IEM for its tonality, comfort and unique look. Distortion keeps me from highly recommending 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/

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 constraints) 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.
• 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

Good L/R match.

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

Score no EQ: 78.7%
Score Amirm: 82.4%
Score with EQ: 96.6%

Timeless 7Hertz Harman Full EQ
March292025-215437

Preamp: -5.00 dB

Filter 1: ON PK Fc 178.1 Hz Gain -3.39 dB Q 0.87
Filter 2: ON PK Fc 503.9 Hz Gain 0.91 dB Q 1.76
Filter 3: ON PK Fc 1690.0 Hz Gain -4.26 dB Q 1.58
Filter 4: ON PK Fc 3417.6 Hz Gain 3.74 dB Q 2.26
Filter 5: ON PK Fc 6978.6 Hz Gain -3.05 dB Q 5.93
Filter 6: ON PK Fc 9193.4 Hz Gain 9.67 dB Q 3.43
Filter 7: ON PK Fc 14207.5 Hz Gain -15.48 dB Q 1.71

 

[Martin]

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 constraints) 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.
• 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

Good L/R match.

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

Score no EQ: 78.7%
Score Amirm: 82.4%
Score with EQ: 96.6%

Timeless 7Hertz Harman Full EQ
March292025-215437

Preamp: -5.00 dB

Filter 1: ON PK Fc 178.1 Hz Gain -3.39 dB Q 0.87
Filter 2: ON PK Fc 503.9 Hz Gain 0.91 dB Q 1.76
Filter 3: ON PK Fc 1690.0 Hz Gain -4.26 dB Q 1.58
Filter 4: ON PK Fc 3417.6 Hz Gain 3.74 dB Q 2.26
Filter 5: ON PK Fc 6978.6 Hz Gain -3.05 dB Q 5.93
Filter 6: ON PK Fc 9193.4 Hz Gain 9.67 dB Q 3.43
Filter 7: ON PK Fc 14207.5 Hz Gain -15.48 dB Q 1.71

View attachment 440113

Thanks for the personalized EQ. I just implemented it in my Neutron Audio Player. (Cool player and well worth the $8.99.)

And I realize I forgot to thank Amir for the measurement of my IEMs. Thank you @amirm!!!

Martin

 

[oratory1990]

The measurement system is not accurate above 10 kHz let alone 40 kHz. But sure, if you just want to know it is producing sound, I could measure well above there.

If you were to do this, I would actually recommend measuring this in a free-field scenario. With coupler measurements you will mostly see the coupler's own modes.

 

[Miley_B]

If you were to do this, I would actually recommend measuring this in a free-field scenario. With coupler measurements you will mostly see the coupler's own modes.

I’m not sure if this is a silly question but how would IEMs be measured in free field?
I would be interested in this as a technical exercise/example, maybe with the Timeless II if they are coming up for testing as they also claim to operate up to 40kHz! Call me skeptical if you wish, but 40kHz…..?

 

[oratory1990]

I’m not sure if this is a silly question but how would IEMs be measured in free field?

It becomes a question of what exactly one wants to measure.
If you want to see whether the transducer can produce sound, then ideally you'd want to remove the transducer from the earphone and measure *only* the transducer. In free-field you'll see how it performs with a constant load (all resonances would only be caused by the speaker, e.g. membrane modes).
You could also build a jig with a small volume and a known acoustic load, e.g. a jig that has a known, fixed resonance. You could then mentally subtract that resonance and see how the speaker performs in a small volume (where SPL would correlate to excursion, not to acceleration).

When asking "can this earphone produce 40 kHz in a human ear", then the acoustic load of the human ear becomes very relevant - at 10-40 kHz you'll see a bunch of resonance peaks caused by the physical shape of the ear canal. And since no two ear canals are alike, whatever you measure in an ear simulator will not necessarily correlate to what happens in your ear. We're talking differences of 10-20 dB above 10 kHz.
So if we only want to compare how earphones do at high frequencies, without caring too much about where exactly the ear canal adds peaks, then measuring the earphone ex-situ (e.g. in free-field conditions) is useful. That way we can see if the transducer itself (or any part of the front volume of the earphone) prevents it from producing much SPL above a certain frequency without being distracted by ear canal resonances (which will change a lot depending on how deep you insert the earphone into the ear simulator)

 

[Poiuyt23]

Was the distortion noticeable and / or bothersome in the listening test?

Edit: P.S. Thanks for yet another great review.

I found the fit really good and daily drove these for quite a while.
The high distortion was about the least surprising thing I found in this review, as I found it would distort just below uncomfortable listening levels. As these were my work headphones that wasn't a drawback for me.