[Dogway]

I'm searching Bluetooth transmitters for the PC to send aptX adaptive LPCM audio to my DAC (thinking Qudelix-5K here). For some reason description on transmitters is always vague or ambiguous.

 

[Monstieur]

Doesn't exist.

 

[Dogway]

Thanks!

 

[visanj]

Please don't use aptx adaptive. Aptx HD is way better codec than Adaptive. for starters, aptx adaptvie limits quality to 470 kbps ps and the quality varies depending on the signal strength and most of the times it falls to lowest quality of 270 kbps which is lower than normal aptx. LDAC is facing same problem now. LDAC supports upto 990 kbps but since its adaptive, most of the time it defaults to 330 kbps which is worse.

After using all the codecs, I can safely say that Aptx HD is way better codec than LDAC

 

[Toth21]

Please don't use aptx adaptive. Aptx HD is way better codec than Adaptive. for starters, aptx adaptvie limits quality to 470 kbps ps and the quality varies depending on the signal strength and most of the times it falls to lowest quality of 270 kbps which is lower than normal aptx. LDAC is facing same problem now. LDAC supports upto 990 kbps but since its adaptive, most of the time it defaults to 330 kbps which is worse.

After using all the codecs, I can safely say that Aptx HD is way better codec than LDAC

Do you have a link to a report on this? What was this tested on? This sounds weird, what would be the point if by default it usually only hits worse than Aptx quality?

 

[vmiguel]

I use Creative BT-W2, wich has SBC, normal aptx and aptx low latency.

 

[Monstieur]

Please don't use aptx adaptive. Aptx HD is way better codec than Adaptive. for starters, aptx adaptvie limits quality to 470 kbps ps and the quality varies depending on the signal strength and most of the times it falls to lowest quality of 270 kbps which is lower than normal aptx. LDAC is facing same problem now. LDAC supports upto 990 kbps but since its adaptive, most of the time it defaults to 330 kbps which is worse.

After using all the codecs, I can safely say that Aptx HD is way better codec than LDAC

Your device is defective. There's not much difference between aptX flavours - HD has 2 more bits in the low frequencies resulting in a marginal but audible difference in sound quality. All of them are measurably worse than "real" psychoacoustic codecs like AAC.

 

[Dogway]

You mean AAC sounds better than aptx HD?
I'll post here my notes in case someone finds it useful:

    Bluetooth sends LDAC HQ (990kbps at 24 bit/96 kHz) LDAC LQ (330 Kbps @ 24 Khz) (connection often fails though)
    Bluetooth sends SBC* encoded audio (328 kbps 48Khz) (but worse quality response than simple aptX -crushed treble-)
    aptX sends aptX LL  (352 kbps 16-bit/48Khz) (32ms)
    aptX HD sends aptX HD  (576 kbps 24-bit/48Khz) (1-32ms)
    aptX Adaptive sends aptX VBR  (279-420 kbps 24-bit/48Khz) (80ms)
    AAC (256 Kbps 16-bit/48Khz) (on paper worse than SBC, on real better)
    * through A2DP interface (can send MP3 without transcoding but in reality all devices reencode to SBC)

 

[Monstieur]

You mean AAC sounds better than aptx HD?
I'll post here my notes in case someone finds it useful:

    Bluetooth sends LDAC HQ (990kbps at 24 bit/96 kHz) LDAC LQ (330 Kbps @ 24 Khz) (connection often fails though)
    Bluetooth sends SBC* encoded audio (328 kbps 48Khz) (but worse quality response than simple aptX -crushed treble-)
    aptX sends aptX LL  (352 kbps 16-bit/48Khz) (32ms)
    aptX HD sends aptX HD  (576 kbps 24-bit/48Khz) (1-32ms)
    aptX Adaptive sends aptX VBR  (279-420 kbps 24-bit/48Khz) (80ms)
    AAC (256 Kbps 16-bit/48Khz) (on paper worse than SBC, on real better)
    * through A2DP interface (can send MP3 without transcoding but in reality all devices reencode to SBC)

Those numbers are mostly irrelevant. The algorithm used by the encoder and device-specific implementation have the highest impact on fidelity. The bitdepth such as 16-bit and 24-bit is only applicable to PCM signals and the concept is not applicable to psychoacoustic codecs like AAC and MP3. aptX uses adaptive PCM compression, so while bitdepth is still applicable, it's reduced at the output and the number is just a marketing gimmick.

SBC encodes with audible distortion and can be written off immediately. Someone conducted an analysis of SBC and found that most devices have a low quality implementation. In rare devices with a high quality implementation, it was not audibly distorted.

aptX (all flavours) are simple bit-discardation adaptive PCM encoders. They are low fidelity by design and are meant for low power hardware implementation. aptX HD is transparent to the ear but measurably inferior to psychoacoustic codecs.

AAC is measurably the highest fidelity codec and is transparent at 256 kb/s. The only AAC sources are Android, iOS, and macOS. The iOS and macOS AAC encoders are the highest quality ones and are transparent. The Android AAC encoders are low quality and may not be transparent.

MP3 is almost as good as AAC and is still audibly transparent. However there are no Bluetooth sources that use it so it's irrelevant.

LDAC is a marketing gimmick and has no reason to exist next to AAC. It's a psychoacoustic codec but is still inferior to AAC. The higher bitrates are irrelevant when AAC is transparent at 256 kb/s. It could be useful on PC as there is no AAC encoder on Windows (only SBC and aptX, both of which are audibly distorted), but there is no LDAC on PC either.

 

[Dogway]

While inferior a psycho acoustic or visual encoder (audio or video) mostly is so to counteract the lack of bitrate. Now an encoder that doesn't have a psychoacoustic algorithm of any kind like apTX is quite of a shock, but given that LDAC has one I doubt that it is inferior to AAC given the difference of bitrate. But I can't tell without an AB. In windows I encode with qaac.

 

[Monstieur]

While inferior a psycho acoustic or visual encoder (audio or video) mostly is so to counteract the lack of bitrate. Now an encoder that doesn't have a psychoacoustic algorithm of any kind like apTX is quite of a shock, but given that LDAC has one I doubt that it is inferior to AAC given the difference of bitrate. But I can't tell without an AB. In windows I encode with qaac.

With the additional constraint of real-time low power encoding, software psychoacoustic encoders are typically run in low quality mode for Bluetooth transmission. iOS devices for example have hardware AAC encoders that encode in in normal / high quality mode. In high quality mode, software encoders will outperform hardware encoders, but at the cost of high CPU usage and reduced battery life.

LDAC is not used as a storage format, but only for real-time transmission. Thus for Bluetooth it's a comparison between a low quality real-time software LDAC encoder and a normal / high quality hardware AAC encoder.

 

[meyerovb]

Those numbers are mostly irrelevant. The algorithm used by the encoder and device-specific implementation have the highest impact on fidelity. The bitdepth such as 16-bit and 24-bit is only applicable to PCM signals and the concept is not applicable to psychoacoustic codecs like AAC and MP3. aptX uses adaptive PCM compression, so while bitdepth is still applicable, it's reduced at the output and the number is just a marketing gimmick.

SBC encodes with audible distortion and can be written off immediately. Someone conducted an analysis of SBC and found that most devices have a low quality implementation. In rare devices with a high quality implementation, it was not audibly distorted.

aptX (all flavours) are simple bit-discardation adaptive PCM encoders. They are low fidelity by design and are meant for low power hardware implementation. aptX HD is transparent to the ear but measurably inferior to psychoacoustic codecs.

AAC is measurably the highest fidelity codec and is transparent at 256 kb/s. The only AAC sources are Android, iOS, and macOS. The iOS and macOS AAC encoders are the highest quality ones and are transparent. The Android AAC encoders are low quality and may not be transparent.

MP3 is almost as good as AAC and is still audibly transparent. However there are no Bluetooth sources that use it so it's irrelevant.

LDAC is a marketing gimmick and has no reason to exist next to AAC. It's a psychoacoustic codec but is still inferior to AAC. The higher bitrates are irrelevant when AAC is transparent at 256 kb/s. It could be useful on PC as there is no AAC encoder on Windows (only SBC and aptX, both of which are audibly distorted), but there is no LDAC on PC either.

I love how this bloated self righteous monologue doesn’t have a single mention of latency. The only reason I’m tapping my foot for a aptx adaptive transmitter is to watch tv with true wireless earbuds. Currently living with aptx LL but want to upgrade for the better sound quality adaptive will provide with the minimal latency.

 

[Monstieur]

I love how this bloated self righteous monologue doesn’t have a single mention of latency. The only reason I’m tapping my foot for a aptx adaptive transmitter is to watch tv with true wireless earbuds. Currently living with aptx LL but want to upgrade for the better sound quality adaptive will provide with the minimal latency.

Most sources with combined Wi-Fi + Bluetooth antennas will probably never support low latency due to interference. That's the reason there is no mobile phone with aptX Low Latency.

With a dedicated transmitter, it's yet to be seen if aptX Adaptive in low latency mode will have the same audible distortion as aptX Low latency. For non-interactive content, it's probably better to use a higher quality code with lip sync. Sources like Apple TV will auto-compensate for AAC latency.

 

[turbobb]

@meyerovb - well, I wouldn't go as far as what you said but to be fair @Monstieur has provided a fair bit of useful details (thx!), just that his assumptions on SQ priority is different than our use case. I too am very interested in aptX adaptive but not for SQ since I'm at a stage where convenience of TWS trumps pure SQ (and if I really wanted to indulge that, I do always have wired units to go back to).

I just got the SoundPEATS TrueAir 2 as it has aptX Adaptive; I do a bit of video editing and wanted alternatives to aptX LL since TWS featuring that have been quite rare. The TA2 are actually quite decent (priority here was long term comfort vs. SQ) but alas, I'm unable to test the codec as of now since there are no Tx that feature aptX Adaptive (yet). Will be keeping an eye on this thread in case anyone posts any they've found.

 

[Ggg99]

Well here goes my first post here. Thanks mods for giving me the go-ahead.

Hey turbobb, I'm also searching for a Tx that features aptX Adaptive and so far also not seeing one in my search.

Additionally, I'm on the hunt for a decent pair of TWS that support aptX Adaptive but also support an ambient pass-thru mode. Want them for TV viewing and also for biking safely so being able to toggle between isolation and hearing surroundings when biking is important for me. I thought this was another unicorn I was searching for but interestingly I see you mentioned that SoundPEATS TrueAir 2 has aptX Adaptive. If true, then these would be the unicorn I am searching for since by design they physically do not provide isolation and allow me to cycle, enjoy music and hear surrounding traffic.

I also own the SoundPEATS TrueAir 2. They are excellent for biking but not for TV with the Taotronics Tx unit I own which only supports aptX and aptX ll. https://www.amazon.ca/gp/product/B07NQ52J76/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

But I am questioning if the TrueAir2 do indeed have aptX Adaptive enabled...

Described as: SoundPEATS TrueAir2 Wireless Earbuds Bluetooth V5.2 Headphones with Qualcomm QCC3040

Qualcomm's site indicates QC3040 supports aptX but no mention of Adapive ... https://www.qualcomm.com/products/qcc3040
"Qualcomm® aptX™ audio playback support: Qualcomm® aptX™ "

Qualcomm's site does say that QCC304x,enables Qualcomm® aptX™ Adaptive - so possibly it is not used by SoundPEATS TrueAir2 but can be enabled
"Qualcomm TrueWireless Mirroring, featured on the QCC304x and QCC305x, enables Qualcomm® aptX™ Adaptive audio for the first time in earbuds"

Also in reviews posted on this site it is noted that aptX Adaptive appears to be lacking on the TrueAir2....

https://www.head-fi.org/showcase/so...lcomm-qcc3040.24797/reviews#item-review-24864
"The box is almost identical to the Sonic, which I reviewed here. It advertises the 25 hour battery and QCC3040 chipset. No mention of aptx-adaptive."

https://www.head-fi.org/showcase/soundpeats-sonic-tws.24787/reviews#item-review-24832
"The Sonic feature aptx-adaptive, and the BT5.2 Qualcomm QCC3040 chip is also present in the TA2. We only get aptX on the TA2, but the chip I would imagine could allow for software enhancements in the future."