General Information




10.1mm high precision custom dynamic drivers

Dynamic transducers (tolerance +/- 1 db)

Active Noise Cancellation (ANC) Qualcomm® cVc™ Noise Cancellation

Axel Grell Noise Annoyance Reduction (NAR)

Transparency Mode

Max Sound Pressure Level 105 dB SPL 1 kHz in some countries

Frequency Range 4Hz - 22 kHz

Low-noise, match-paired microphones

SoundID app


In-ear headphones

Splash Proof (IPX4)

Weight: 7.3g each earbud

Aluminum charging case


Bluetooth 5.2 with Qualcomm 5141 chipset

Bluetooth range over 50 meters (164 feet)

Compatible with iOS and Android, as well as tablets and laptops.

Audio Codecs: SBC, AAC, Qualcomm® aptX™, Qualcomm® aptX™ adaptive, LHDC


Up to 34 hours of listening time with ANC ON (6 hours in earbuds and over 4 full charges in the charging case)

Up to 45 hours of listening time with ANC OFF (Over 8 hours in earbuds and over 4 full charges)

USB-C charge connector

Wireless charging compatible


Glass touch field for gesture commands on each earbud

Built in voice-assistant


Latest reviews


Reviewer at hxosplus
A new star is born
Pros: + Very musical and engaging
+ Good sub-bass extension
+ Excellent and expressive mids
+ Smooth yet extended treble
+ No loss in sound quality with ANC and NAR enabled
+ Stable connection
+ SoundID application by Sonarworks
+ Excellent call quality
+ Good battery life
+ Lightweight
+ Quality craftsmanship
Cons: - Bass is a touch boomy
- Mid-bass is way too emphasized and lacking in definition
- Dynamically shy
- Not very detailed
- Fit is ear shape dependant and some users will have a hard time into fitting them firmly
- Some extra tips should be welcomed
- It is not backwards compatible with aptX HD and not all phones support aptX adaptive.
The Grell TWS/1 was kindly provided by Drop + free of charge.
The TWS/1 is launching through an exclusive pre-order release on and it is selling for $199.99.
You can purchase it from this not affiliate link Drop.
Full specifications are available here.


Axel Grell is a legend among the Headfi community, I doubt if there is a single headfier who doesn't know of him.
The lead designer behind all the great Sennheiser headphones, from the HD580 precision to the venerable HD650 and the latest three flagships, the HD800 - 800S and 820.
In case you didn't already know, he resigned from Sennheiser to start his own brand, the Grell Audio.

About Grell Audio

For over three decades, Axel Grell has crafted headphones designed to produce world-class sound — at times, with little-to-no regard for price consideration. Throughout his mission to enhance the clarity and transparency in the headphone lines he produced, Grell garnered a devoted following among members of the audiophile community for his close attention to detail throughout all parts of the manufacturing process, pairing high-quality components with cutting-edge product designs — until the 1990s, when his uncompromising pursuit to design the most neutral headphones possible catapulted him to legendary status amongst those obsessed with high-end audio.

Axel Grell continues his quest to make the world sound better through his bold, new product designs. The new grell audio true wireless headphones are a direct response to a growing new generation of audiophiles in the digital era who are looking to experience the ultimate transparency and clarity that headphones can offer — in a smaller in-ear form factor. Unlike any of the designer’s earlier endeavors, however, grell audio seeks with its business model to lower the cost for the end-user, ushering in the future of high-res audio through a sales model tailored toward the spending habits of the digital age looking for opportunities to save money on high-end products without sacrificing quality for price.


Grell Audio TWS/1

The Grell Audio TWS/1 feature TWS technology with custom 10,1mm dynamic drivers transducers with a tolerance of +/- 1 dB.
They offer Active Noise Cancellation (ANC) plus the Axel Grell Noise Annoyance Reduction (NAR) technology.
They have 34 hour combined battery life with ANC ON.
Grell audio true wireless headphones boast minimalistic, industrial-style design, which contrasts the complexity and richness of the acoustic output, without sacrificing a comfortable fit.
It has an IPX4 rating so you can use it even on rainy days.


What is NAR?

When the environment is noisy the TWS/1 blocks it out passively in the high mid and high frequency range. For the low and low frequency range the ANC function can be activated. A very strong noise reduction in the low frequency range makes higher, more annoying, frequencies more audible. Therefore, the new grell Noise Annoyance Reduction (NAR) technology (patent pending) scans the noise spectrum and controls the ANC using a psycho- acoustic model for a minimum of annoyance.

SoundID application by Sonarworks

Unlock the full potential of your grell TWS/1 headphones with SoundID so you can rediscover your favorite music with unprecedented audio clarity, exactly the way the artist intended it to sound in studio, then further personalized to your unique hearing ability and listening preferences. SoundID represents a paradigm shift in audio quality, moving away from the traditional one-size-fits-all approach to personalizing sound throughout the journey from creators to the end listener. Your sound profile is as unique as your fingerprint—but even more advanced, thanks to smart algorithms and machine learning that evolve with you over time. The free profile can be set up in minutes with a simple app test to identify your SoundID and is automatically saved directly on your grell TWS/1 headphones. With SoundID’s Advanced Parametric EQ built-in, there are infinite ways to create your own custom preset or reset your frequency response curve to its flat state. Intuitive adjustments are tailored for even the most demanding audiophiles for an unmatched level of personalization, detail, and clarity.



The TWS/1 supports Bluetooth 5.2 through the Qualcomm 5141 chipset which is compatible with the Audio Codecs: SBC, AAC, Qualcomm® aptX™, Qualcomm® aptX™ adaptive, LHDC and has a working range over 50 meters.
It is compatible with iOS and Android, as well as tablets and laptops.

Battery life

With the case fully charged the TWS/1 can provide up to 34 hours of listening time with ANC ON (6 hours in earbuds and over 4 full charges in the charging case) and up to 45 hours of listening time with ANC OFF (Over 8 hours in earbuds and over 4 full charges)
The case is charged through the USB type C charge connector and it is wireless charging compatible.
Actual battery life is quite close to the one advertised by the manufacturer.
I was able to get about 6 hours of playing music and making calls with ANC and NAR mostly enabled while the case provided four full charges.


Charging case

The case body is made from brushed aluminum with a plastic bottom and it is lightweight with a premium black matte look.
Build quality is very good and at the front there are four LEDs that flash white and green to indicate the remaining battery life of the case and the earbuds that are magnetically attached into it.
The case is designed in such a way so it can accommodate the ear buds with the attached silicone ear fins that are used for better fit.


Build quality

The black matte earbuds shell is made from a combination of plastic and aluminum with an outer glass touch field for gesture commands.
Build quality is very good and they look beautiful with a contemporary design that is discrete and doesn't call for attention.
There are no physical buttons and all control actions are performed through the touchpad.


Fit and comfort

The TWS/1 are advertised as easy and firm to fit but I had some trouble in doing so.
The inner part of each earbud is quite bulky, the nozzle very shallow and the ear tips selection limited.
So fitting firmly was quite challenging for me and never managed to get a deep insertion of my liking, at least with the silicone ear tips.
The trick is to do some kind of a twisting move and while doing so one of the ear tips detached and ended up shoved into my ear canal.
Then I used the included silicone ear fins that helped a little with stability.
Thankfully there were included two pairs of memory foam ear tips that at last offered the long desired fit but I hate the idea of using them and have to buy a new pair every month.
You mileage may vary depending on your ear shape but they should definitely have included some double and triple flange ear tips.
On the plus side is that after you fit them, then they are so featherweight and feel super comfortable without causing any ear fatigue after a prolonged time of use.


User interface and functionality

Connecting with the TWS/1 is extremely simple as they will automatically enter pairing mode upon pulling them out of the case.
Connection signal is stable with a good working distance and I haven't experienced any disconnections at all.

Controlling the earbuds is done through gesture commands in both pieces.
You can perform all the usual actions like raise/lower the volume, play/pause, skip tracks, answer calls, activate voice assistant and enable/disable ANC and NAR or the voice transparency mode.

Learning curve is minimal and the touch area is quite sensitive and responsive but due to the small effective area people with thicker fingers will end up with a few accidental actions.
The gesture commands are fixed and cannot be further customized as you can do for example with the Sennheiser TWS earbuds.

Call quality

The TWS/1 employs an advanced microphone array and patent-pending Multilayer Turbulence Eliminator (MTE) which in practice results in a crystal clear communication both for the caller and the answerer.
A truly remarkable performance, nothing more to add here.


Stock sound quality

When someone buys TWS earbuds he is definitely prepared for sacrificing some sound quality in favor of functionality but with the TWS/1 this loss is minimal.
The sound quality (with aptX adaptive codec enabled) is very good with an engaging and highly musical presentation.
The target response is Harman type and the lows get a boost that is carried up to the mid-bass area and makes for a warm and enjoyable sound signature suitable for all kinds of music.
There is plenty of sub-bass energy with enough rumbling to please with contemporary music and despite the mid-bass emphasis the TWS/1 is equally competitive with classical and acoustic music although heavy bass lines get somewhat masked and sound clouded.
The bass is full bodied and tight, controlled and impactful but not reference firm or too fast and you can hear a certain amount of boominess / hollowness.
Clarity is good and the layering is satisfying only hampered by the aforementioned masking.
The mids feature, what else, an Axel Grell trademark tuning, that means they are very engaging, slightly upfront with full and rounded vocals that have excellent expression and the finest articulation.
There is plenty of harmonic wealth with a mostly natural timbre and all instruments sound organic and real, guitar solos are delicious and this is an earbud with some seriously rewarding vocals.
Treble is only slightly forward to add the necessary sparkle but everything is in tune, nothing sounds bright or harsh, voices are not shouty and this is an exemplary performance with plenty of energy while staying smooth and controlled.
Higher frequencies sound full and absent of the related thinness that is usually observed in TWS earbuds.
Decay is natural with cymbals and other percussion instruments sounding full bodied with good reverb without being rushed to fade out.
The TWS/1 is not the most detailed earphone but it is resolving enough to express all the needed information, after all it isn't meant for critical listening.
The soundstage is open and spacious with accurate positioning from the left to the right but the projection is mostly flat, layered in the horizontal axis, missing in depth and dimensionality.

TWS earbuds are often used for watching movies and playing games and from my testing I can report that I didn't experience any kind of lagging even under fast moving frame rates.


Sound quality with the SoundID application

The SoundID application has some pretty powerful algorithms and a DSP that offers a great amount of quality customization to the sound.
The listener can use the Parametric EQ and simply adjust the sound to his preferences or even better have the advanced SoundID tests to further personalize the adjustments.
I have used it with some excellent results and I enjoyed a much improved experience without hampering the technicalities of the ear buds.
This free to have application is a powerful tool and I would count it as the strongest selling point of the Grell TWS/1.


Active noise canceling and NAR

ANC and NAR are pretty much close in performance, doing a decent job in canceling the incoming noise without lowering the quality of the sound experience.
While I have certainly used more efficient active noise canceling solutions, the key difference here is that the implemented algorithms do not negatively affect the sound in any way.
I would even dare to go as far as to say that the sound is better with the ANC and NAR enabled!
The difference with NAR engaged is minimal but it does add some extra audible quality to the sound.
The NAR is activated after the ANC so the user can have the options of - none active - ANC active - ANC & NAR active.

At the end

I liked the TWS/1 and I can happily confirm that it is a successful premiere for the Grell brand.
The sound is very good with all kinds of music and that is with both ANC/NAR active or not, the tuning can be highly personalized with the SoundID application, battery life is great and build quality is top notch.
My only objection is related to the fit which may not be so firm for all users and the lack of some extra ear tips that could compensate for that.
The TWS/1 are excellent sounding earbuds with the Axel Grell legacy imbued into them but the road to glory is not paved with gold.
This is an oversaturated market with some tough and established competition but I am sure that the TWS/1 is going to find its way to the top.

Test playlist

Copyright - Laskis Petros 2021.
Last edited:
Hi @Admor , I didn't use it because my phone supports only LDAC and not LHDC.
What phone even supports lhdc?
I really don't know!



human bean
This is weird. I own a few pretty high tech items. I have the K9 Pro. Focal Clear. HD600. Gryphon. FIIO iem's. Bunch of wireless iem's, including Sony xm4.

Yet, for some reason, I am finding myself sticking in these Grells more and more.