Truthear Zero Blue 2

A refinement on the classic with a Harman++ Tuning and lots of “technicalities”

Truthear’s collaborations with Crinacle have consistently aimed to deliver Harman-tuned excellence at budget-friendly prices. The Zero Blue 2 is the latest iteration of their dual dynamic driver (DD) IEM tries to outdo the previous Truthear Zero models, the original Zero and the Zero Red but did it “fly too close to the sun” with its treble tuning?

It has been hard to ignore the hype both positive and negative surrounding this IEM and with Crinacle own brand Crinear also announcing 3 other IEMs it seems like this IEM has been under extra scrutiny, this is especially true with the main suggestion to only use Foam eartips.

However, after using the Zero Blue for a few weeks now (both the pre-production unit and production unit) I can confirm that tip selection can be crucial but not for everyone needs to worry and there are some other alternatives to using foam ear tips which i will present later in the review.

While Foam tips deliver an excellent Harman tuning even for those sensitive to upper treble by helping to dampen down the treble, I think the inclusion of the 5 Ohm adapter to boost the bass beyond Harman and even Crinacle own preferences indicate to me that a Harman++ shaped tuning with extra sub-bass balanced with extra upper treble was one of the goals of this IEM, but these options make the Zero Blue 2, a versatile high quality IEM to add to your collection.

But before we get into the sound, let’s dive into the unboxing experience.

Unboxing and Build Quality

Truthear keeps things minimalist but functional. The Zero Blue 2 arrives in a compact box:

I do like it when an IEM has a frequency response on the back which shows both the normal FR and the bass boosted one you get with the 5Ohm adapter:

Sliding the box out of its sleeve you get an internal box: Opening up you get a brief manual: Removing it you finally get to see the Blue 2 and the carry case:

Taking everything out of the box this is what you get:

Inside, you’ll find:

• The IEMs

• A soft carrying pouch

• A very decent detachable cable - this cable is similar but better than the one in the Truthear Gate:

• A good selection of ear tips (foam and silicone)

• A 5Ω adapter

• 

The IEM Itself

The Zero Blue 2 retains the sleek, transparent shell aesthetic:

The build quality is solid, feeling durable without being too heavy.

Comfort and Fit

The smaller nozzle makes a massive difference in comfort.

While the original Zero Blue had nozzle fit issues for many, the Zero Blue 2 resolves this and should accommodate more ear shapes without discomfort:

They have also changed the angle of the nozzle compared to the original:

Here are some size comparisons with the Truthear Zero:

And you can see the difference in angle here:

This for me is even more crucial for nozzle size as I do find the original and the Zero Red move slightly in my ear when I used them out walking but after a few days with the Zero Blue 2 I find it stays very secure with an excellent fit.

Technical Advancements over the original

Like its predecessors, the Zero Blue 2 features dual dynamic drivers, but with significant internal modifications. The 7.8mm driver, responsible for mids and highs, now utilizes a larger magnet (25% increase) and an expanded dome area (50% increase). These changes enhance conversion efficiency, treble extension, and overall resolution.

The driver structure incorporates:

• LCP (Liquid Crystal Polymer) dome diaphragm for improved rigidity and transient response.

• Flexible polyurethane suspension to enhance smoothness in frequency transitions.

• Refined high-frequency conductive structure, leading to clearer, more transparent upper frequencies.

I am a sucker for diagrams of the internals of audio products:

These advancements were designed to make the Zero Blue 2’s treble significantly more refined while retaining the Harman tuning balance in the lower frequencies, but does it go too far?

This is why I cheekily mentioned it might have “too much ’technicalities’” but let’s get onto my subjective opinions and these might surprise you a little.

Sound Impressions

The Truthear Zero Blue 2 continues to nail the Harman IE 2019 tuning, offering a balanced sound signature that should appeal to a wide audience while this time adding that extra technical prowess in the treble but also with the optional 5Ω adapter for bass heads. So there are quite a lot of options for those who like to tweak sound without using EQ.

I only briefly used the adapter as normally for me, a Harman tuned IEM has a little too much bass but in this case, that added treble mostly balanced out nicely with very nice Harman “tuned” bass provided. I did play around with using both the silicon tips, foam tips and many other third party ear tips. It it wrong to say “silicon bad - foam good”, I would suggest find the ear tips that work for you as this IEM will respond differently to different eartips (as you will see in the measurements).

Overall impressions

Overall, I think the bass is exceptional better than the 2 previous Zero’s, the midrange is superb. And while I am more of a fan of a JM-1 like tuning, the specific treble peaks, that show up on the measurements, did not subjectively bother me at least. Treble is the area of massive subjective differences between how people hear things and I think this IEM with silicon tips might exaggerate this differences, it certainly does on the measurements rigs. As we get older that 15K / 16K upper treble can actually do with a boost in these regions as we move into our 40’s:

So for me, the Blue 2 sounded like it has we used to call “good technicalities”, that extra little “shimmer” on high-hats and a very detailed sound that many will appreciate. So, I would suggest giving the Zero Blue 2 a go, you might be surprised, especially if you are a fan of Harman tuning.

If there was one area of the treble that I personally would change, it is the 4-5K region, as I have come to appreciate a JM-1 tuning more over the past year but given even the most recent research shows
Harman and a JM-1 target are both perfectly acceptable ‘scientifically proven’ popular targets.

Here are some more details:

Bass

The dual DD configuration ensures a well-extended, clean bass response. Out of the box, bass is tight, punchy, and well-controlled, but those who prefer more warmth can use the included 5Ω adapter to increase low-end presence slightly.

Test Track: “Billie Eilish - bad guy”

• Impactful and clean bass, no muddiness
• Great sub-bass extension without overpowering the mids

Mids

The midrange is neutral and clear, benefiting from the Harman tuning. Vocals are well-placed and transparent, never too recessed or too forward.

Test Track: “Fleetwood Mac - Dreams”

• Vocals are natural and textured
• Acoustic instruments sound organic and lifelike

Treble

Treble is where the Zero Blue 2 differs the most from its predecessor. High frequencies are **more detailed and airy **, giving the IEMs a sense of greater technical precision. However, as I mentioned earlier if you are suspectable to treble sibilance the silicone tips might make treble overly sharp for you. While foam tips dampen things perfectly..

Test Track: “Daft Punk - Giorgio by Moroder”

• Cymbals and high hats are crisp and resolving
• With Silicone tips it was excessibe brightness

Soundstage & Imaging

The Zero Blue 2 has a spacious soundstage for an IEM in this price range. Imaging is precise, allowing instruments to be well-placed across the stereo field, this is one area where extra treble can help allowing the upper harmonics of certain instruments stand out given them depth.

Specifications and Measurements

Frequency Response

Note: The following measurements were taken with my KB501X soft ear Pinna and a 711 clone coupler. They are available on my measurement database here.

Let’s start with the FR and the channel matching using the Silicon tips:

I highlighted 2 areas on this initial FR, the extra bass ’tuck’ (1) and that 15K peak (2).

Now the difference with the Foam tips and the Silicon ones: You can see the Foam tips mostly low the extreme peak but also change other areas of the treble. Whether this will work better for you will be very subjective, my suggestion is to give it a go you might not hear that peak as a peak and the foam might introduce a peak that you can hear in a different area.

I noticed that smaller foam has less of a seal and therefore lowered a bass a little: And I tried slightly longer third party ‘red’ foam tips also:

For a bit of fun I also tried a triple flange (which typically works better for those with long ear canals) This again changed the treble considerable but didn’t have the same peak as the silicon eartips.

I had received a pre-production pair so it was also interesting to compare the differences between these and what was “changed” for the production version:

Silicon	Foam

So, the changes were basically in the 4K to 8K region (I may actually prefer the pre-production unit).

Finally, I measured the 5 Ohm and the 10 Ohm (from the Zero Red) to see the difference in Bass:

Comparisons

First lets compare with the KE4 and the Truthear Zero Red:

The Zero Red has less bass (1) (at least without the 10 Ohm Adapter), but the 5 Ohm adapter from the Blue 2 on the Zero Red might actually be a nice option, and you can see that lack of a mid-bass ’tuck’ with JM-1 tuned IEMs like the Kiwiears KE4 and finally i highlight that the even with the Foam tips there might be a little bit too much pinna gain (3).

Adding the Aful Explorer and the silicon tips : I highlight the different in mid-bass tuning (1) and especially the different in the pinna / presence region (2) and that 15K treble peak (3).

Finally comparing with some recent Harman tuned IEMs that I like:

Distortion Measurements

The Zero Blue 2 (like the Red) show incredible low distortion ( and much improved over the original Blue ):

Showing these distortion as a percentage you can again see the treble distortion but its is less than 0.5% so nothing to worry about:

An alternative ‘pairing’ option

So, one extra thing I thought might be useful is I did play with some EQ for the Zero Blue 2, and specifically I tried it out walking with FiiO UTWS5 (2025 edition) and I liked how this combination worked for
comfort and for those who want to keep using the silicon tips and tweak the sound using EQ:

Of course, there are many ways to EQ, but I liked how the Zero Blue 2 fit easily into the case and I believe because of the subtle changes in the angle of the Nozzle it worked really well in my ear unlike other IEMs with the UTWS5 as it is less flexible than a table when you need to get an accurate fit.

Rating

I have given the Truthear Zero Blue 2 a 4-star Pragmatic Rating. It offers a lot of improvements over the previous generation of Truthear Zero’s at effectively the same price (given inflation and tariff increases):

• Much better internal design, improving both the bass and treble especially
• A much smaller nozzle, improving fit over the oversized original
• A significantly upgraded cable
• An optional microphone cable
• A 5Ω adapter, which slightly increases bass presence for those who prefer a warmer tuning

While there might be some uncertainty for those who only like silicon tips and especially whether an “enhanced” Harman tuning is still the best or has that been replaced by JM-1 / “new-meta”. So, if you do not like foam tips, are affected by treble sibilance and in your 20’s, I would go for a different IEM.

Here is a breakdown of my opinions:

• Build Quality: ⭐⭐⭐⭐⭐ (Durable and a great cable so good improvements over the original)
• Comfort: ⭐⭐⭐⭐☆ (Smaller nozzle improves fit, but tip selection may be critical)
• Sound: ⭐⭐⭐⭐ (Balanced Harman tuning with great detail )
• Value: ⭐⭐⭐⭐⭐ ($65 is an outstanding price for this performance)

Conclusion

The Truthear Zero Blue 2 takes an already excellent budget IEM and makes meaningful improvements. The better cable, smaller nozzle, and added tuning flexibility make it a clear upgrade over the original Truthear, but you if you are fan of Harman tuned IEMS you might still prefer the Truthear Red tuning slightly over than the Truthear Blue 2, it is all in the “technicalities”.

But for just $65 (or $70 with a mic), this is a no-brainer recommendation for those seeking top-tier tuning at an affordable price and a great option to add to your collection.