Bluetooth Codecs: LDAC's 990kbps Is Rarely 990kbps

The number on the box is a ceiling, and you are usually not at it. Sony advertises LDAC at 990kbps, and its own developer site says the rate “automatically changes among 330kbps/660kbps/990kbps” depending on conditions. The bottom rung is 330kbps.

Now put that next to the figure Sony publishes for ordinary SBC in its own comparison: 328kbps.

So on a congested link, a “Hi-Res Audio Wireless” connection is carrying about the same data as the basic codec every Bluetooth device has supported for twenty years — and nothing on your phone says so.

Why it drops, and why that is the right design

This is not a defect. Sony calls it “best effort” mode, and describes it as controlling bitrate automatically “depending on the network condition, ensuring stable connection even in harsh environments.”

That is the correct trade. Bluetooth shares the crowded 2.4GHz band with Wi-Fi, microwaves and every other device in range, and a link that insisted on 990kbps would simply drop out. Falling back keeps the music playing.

The problem is not the behaviour. It is that the badge advertises the ceiling and the product never reports the floor.

What actually pushes you down a rung

All the ordinary things, none of which appear in a review:

• Your body. A phone in a back pocket puts a bag of saltwater between transmitter and receiver. This is the single most common cause.
• Distance and walls, in the usual way.
• A crowded band — a busy flat, an office, a train carriage.
• What else the phone is doing on Wi-Fi at the same time, since many phones share one radio.

Which is why the same headphones sound different on a quiet morning at home and on a packed commute, with no setting changed.

The check, on Android

Most Android phones will tell you, once you turn the developer menu on.

1. Settings → About phone, tap Build number seven times.
2. Settings → System → Developer options.
3. Find Bluetooth audio codec — it shows what is in use — and Bluetooth audio LDAC codec: Playback quality.

That last one is the interesting setting. It offers a preference for connection quality versus audio quality, and it is the lever that decides which rung “best effort” is allowed to pick. Set it to prioritise quality and watch whether the music starts stuttering on your commute; that is the trade being made on your behalf the rest of the time.

On iPhone there is no equivalent, and no LDAC either — Apple devices use AAC and SBC, and expose no codec picker. If the badge on the box was your reason to buy, on an iPhone it was never going to apply.

What matters more than the codec

Two things, both larger in effect and neither on the box.

The profile switch. The moment anything wants your microphone, Bluetooth leaves the high-quality audio profile entirely, and no codec saves you — why your headphones sound worse the second a call starts covers the mechanism.

The seal. On in-ear headphones a poor fit loses more bass than any codec choice will ever recover. Changing the tip size is free and beats every specification on this page.

What to actually do

• Do not pay a premium for a codec badge alone. You are buying a ceiling that conditions decide whether you reach.
• Check what you are actually connected with if you are on Android, using the steps above. It takes a minute and it settles the question for your phone, your headphones and your commute rather than in general.
• Move the phone before you blame the headphones. Out of the back pocket, into a front pocket or a bag on the same side. It is the cheapest possible upgrade.
• On iPhone, ignore LDAC and aptX entirely when comparing products. Neither is available to you, and paying for them is paying for nothing.
• Spend the money on fit and tuning instead. Both survive a crowded 2.4GHz band. A bitrate does not.