Since it's on sale currently, This might help someone.

I have been using the OP Buds 4 for more than 8 months now.

What should you expect?

Before you read the whole review let me answer the most important question. is it worth it?

If you are already using a decent sub 5K TWS or a good wired IEM around the 2K range, do not expect a massive jump in pure sound quality with the OnePlus Buds 4. The upgrade is more about the complete package. Features like ANC, transparency mode, call quality and overall convenience are what this is all about.

Sound Quality

The tuning is mostly L shaped. Bass is deep, punchy, and has a lot of presence, sometimes too much. In fact, I ended up using EQ presets mainly to tone the bass down. Thankfully, the bass does not completely muddy vocals or instruments. The secondary driver helps with detail retrieval and gives the sound a wider presentation compared to most budget TWS.

Details are above average for a wireless earbud in this segment. Soundstage and separation are decent enough that movies and shows feel immersive. Default Balanced mode works especially well for movies since loud explosions do not become harsh or uncomfortable.

That said, if someone is expecting head shaking bass above everything else, there are cheaper options that do that better. The Buds 4 aim for a more balanced sound instead of becoming DJ in your head.

Missing LHDC support on some phones also affects the experience because AAC implementation on Android is inconsistent. On some devices AAC works fine, on others it can feel unstable or compressed. So research whether your device support LHDC or not. Most of the flagship and some mid range phones do.

Some of you might be tempted to buy a headphone instead since there are some good options in this price range. I personally found the Buds 4 much cleaner and more balanced. Most of the popular offerings from brands like JBL or Soundcore focus heavily on bass to the point where it overpowers everything else.

Personal EQs

Vocal Forward Sound: -3, -3, 2, 1, -3, -1

Wider Soundstage and Bass: 0, -2, 0, 1, 3, 2 (Sometimes reducing Basswave to -1 makes the sound cleaner)

ANC and Transparency

ANC performance is among the best in the segment, though still far from perfect. It easily cuts out engine noise, fans, AC hum, and even reduces traffic sounds to some extent.

Human voices are less consistent. Sometimes voices get reduced heavily, other times they pass through more than expected. I was able to clearly hear in -cabin announcements while plane engine noise was completely blocked.

Transparency mode is where the Buds 4 really stand out. It sounds very natural and does not have the robotic effect common in most sub 5K TWS. I would easily place it among the best transparency implementations in this price range.

The adaptive ANC mode is also implemented well. It automatically adjusts based on surroundings. In quieter places it feels more open and natural, while sudden loud sounds trigger stronger ANC. This is my default mode.

Call Quality

This is probably the strongest feature of the Buds 4. Call quality is excellent even in noisy environments like busy markets or public transport. Voices remain clear without sounding overly processed.

I have used them across different environments and never had complaints about mic quality.

Battery Life

Battery backup is average. With adaptive ANC and LHDC enabled, I usually charge them every other day or every two days. Turning off ANC and using AAC improves battery life, but overall battery performance is not class leading.

Build and Comfort

The case is larger than average and slippery, which took time getting used to. I dropped it multiple times during the first month, but both the case and buds survived without issues.

The earbuds themselves are compact with short stems, though they protrude slightly from the ears. Comfort is surprisingly good, even for my smaller ears.

Features

In ear detection works properly on both Android and Mac. Dual device connection is stable and well implemented. Touch controls are mostly reliable unless your hands are extremely dry (Static from your dry skin can cause double touches)

The find my earbuds feature works well enough indoors because the beep is loud. However, Features like 3D audio and Golden Sound feel more gimmicky to me than genuinely useful.

Comparisons

Versus Budget Wired IEMs

Compared to something like the BLON BL03, the Buds 4 sound smoother and more versatile across genres. BLONs can sound amazing on certain tracks but can become harsh or shrill on others.

The Buds 4 are simply easier to live with day to day.

Versus Headphones

Even compared to some entry level wireless headphones like the Sennheiser HD450BT, the Buds 4 hold up surprisingly well. The dual driver setup gives them better detail and separation than many bass focused wireless headphones. But headphone still wins in immersion.

Final Thoughts

The OnePlus Buds 4 offer a great balance between sound, ANC, transparency, mic quality, comfort, and features. They’re a safe recommendation for a complete wireless package under 5K. If sound quality is your priority, a wired setup is still better. But as everyday TWS, the Buds 4 excel.

OP Buds 4 are fairly well built

For stronger bass, you can get the Nord Buds 3 pro or even Enco Bud 2, Buds 4 are for balanced sound.