OT: wired or bluetooth sound quality

  • Thread starter Thread starter pheasant16
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pheasant16

I still remember the old days of sending an FM signal to car radio and
sound quality was not good. (ugly cheap transmitter dongle)

Wife has android smartphone and Toyota's stock radio has either
bluetooth or aux jack option unless you have iPhone; then USB is in the mix.

What I've read so far seems to conflict, so would like everyone's
personal 2 cents here. (Figure conflicting advice in a newsgroup is
usually much more passionately defended) :)

Thanks

Mark
 
I still remember the old days of sending an FM signal to car radio and
sound quality was not good. (ugly cheap transmitter dongle)

Wife has android smartphone and Toyota's stock radio has either
bluetooth or aux jack option unless you have iPhone; then USB is in the mix.
Click to expand...

My wife's Lexus talks bluetooth to her Iphone (4 I think) and voice
quality is fine.
 
pheasant16 said:
I still remember the old days of sending an FM signal to car radio and
sound quality was not good. (ugly cheap transmitter dongle)

Wife has android smartphone and Toyota's stock radio has either
bluetooth or aux jack option unless you have iPhone; then USB is in the
mix.

What I've read so far seems to conflict, so would like everyone's
personal 2 cents here. (Figure conflicting advice in a newsgroup is
usually much more passionately defended) :)

Thanks

Mark
Click to expand...

I don't use Bluetooth, but that won't stop me.

Bluetooth has "profiles", and each profile covers a protocol
for doing things. The basic audio profile, is relatively
low bandwidth, and as a result of that, is good for voice
quality. If you wanted CD quality, presumably that would
raise the bandwidth.

You'd need to understand Bluetooth profiles quite well, to
determine whether the Bluetooth would make a suitable path
for playing through the car radio. It might well sound like crap.

http://en.wikipedia.org/wiki/Bluetooth_profile

"A2DP

A2DP is designed to transfer a uni-directional 2-channel stereo
audio stream, like music from an MP3 player, to a headset or car
radio. This profile relies on AVDTP and GAVDP. It includes
mandatory support for the low-complexity SBC codec (not to be
confused with Bluetooth's voice-signal codecs such as CVSDM),
and supports optionally: MPEG-1, MPEG-2, MPEG-4, AAC, and ATRAC,
and is extensible to support manufacturer-defined codecs, such
as apt-X. Some Bluetooth stacks enforce the SCMS-T digital
rights management (DRM) scheme. In these cases, it is impossible
to connect certain A2DP headphones for high quality audio."

The DRM prevents high-quality audio copies.

See how complicated that is ? How can you predict an outcome ?
You need a Geek to English dictionary, to make any sense of
that paragraph.

I understand there are some Bluetooth amplifying device, that use
apt-X, and it might be a higher fidelity path. Don't expect the
car radio to do that.

By comparison, using an audio plug and jack, is so much simpler...
Because otherwise, you might never get the degree of
detail needed to understand the Bluetooth quality possible.

To "neuter" the audio jack, they can "clip" the least significant
bits off the audio samples, and run just the upper eight bits
through the DAC. As a means to mess up the sound (on purpose).
Evil abounds.

If they wanted to, modern Bluetooth has enough bandwidth,
they could make a kick-ass high quality connection. But for
DRM reasons, they might not do that, to prevent digitally
perfect copying. Always expect them to insert quality-destroying
features (like lossy compression), to make digital copies of
inferior quality.

*******

Here, someone actually does head-to-head comparisons of
the various options, with a surprising result.

http://www.whatsbestforum.com/showthread.php?5709-Bluetooth-and-APT-X-a-listening-impression

Good luck,

Paul
 
Paul said:
I don't use Bluetooth, but that won't stop me.

Bluetooth has "profiles", and each profile covers a protocol
for doing things. The basic audio profile, is relatively
low bandwidth, and as a result of that, is good for voice
quality. If you wanted CD quality, presumably that would
raise the bandwidth.

You'd need to understand Bluetooth profiles quite well, to
determine whether the Bluetooth would make a suitable path
for playing through the car radio. It might well sound like crap.

http://en.wikipedia.org/wiki/Bluetooth_profile

"A2DP

A2DP is designed to transfer a uni-directional 2-channel stereo
audio stream, like music from an MP3 player, to a headset or car
radio. This profile relies on AVDTP and GAVDP. It includes
mandatory support for the low-complexity SBC codec (not to be
confused with Bluetooth's voice-signal codecs such as CVSDM),
and supports optionally: MPEG-1, MPEG-2, MPEG-4, AAC, and ATRAC,
and is extensible to support manufacturer-defined codecs, such
as apt-X. Some Bluetooth stacks enforce the SCMS-T digital
rights management (DRM) scheme. In these cases, it is impossible
to connect certain A2DP headphones for high quality audio."

The DRM prevents high-quality audio copies.

See how complicated that is ? How can you predict an outcome ?
You need a Geek to English dictionary, to make any sense of
that paragraph.

I understand there are some Bluetooth amplifying device, that use
apt-X, and it might be a higher fidelity path. Don't expect the
car radio to do that.

By comparison, using an audio plug and jack, is so much simpler...
Because otherwise, you might never get the degree of
detail needed to understand the Bluetooth quality possible.

To "neuter" the audio jack, they can "clip" the least significant
bits off the audio samples, and run just the upper eight bits
through the DAC. As a means to mess up the sound (on purpose).
Evil abounds.

If they wanted to, modern Bluetooth has enough bandwidth,
they could make a kick-ass high quality connection. But for
DRM reasons, they might not do that, to prevent digitally
perfect copying. Always expect them to insert quality-destroying
features (like lossy compression), to make digital copies of
inferior quality.

*******

Here, someone actually does head-to-head comparisons of
the various options, with a surprising result.

http://www.whatsbestforum.com/showthread.php?5709-Bluetooth-and-APT-X-a-listening-impression


Good luck,

Paul
Click to expand...

Guess it'll be a matter of testing and deciding what she likes best. Her
phone is Samsung; the article doesn't give good to either method.

Thanks for your help. :)
 
pheasant16 said:
Guess it'll be a matter of testing and deciding what she likes best. Her
phone is Samsung; the article doesn't give good to either method.

Thanks for your help. :)
Click to expand...

There is an example of a car kit here, that supports both A2DP profile
and apt-X coding.

You could try plugging that analog cable, into the car stereo analog input.
Note the advertising blurb, does not inspire confidence in what you're getting.

http://www.amazon.com/Kinivo-BTC450-Bluetooth-Hands-Free-Input/dp/B009NLTW60

The user manual is pretty thin. And the manual doesn't mention apt-X at all.

http://downloads.kinivo.com/product/manual/BTC450 User Manual.pdf

But their web page for the product, offers more promise. The big blob, plugs
into the lighter socket, to get power for the Bluetooth receiver.

http://www.kinivo.com/Kinivo-BTC450-Bluetooth-Hands-Free-Input/dp/B009NLTW60

"Seamlessly stream music from any Bluetooth (A2DP) capable device;
supports aptX for CD quality audio

Built-in microphone and easy to use music controls

Provides audio through your 3.5mm input in Car Stereo when
playing music and answering phone calls

Key Features
- Supports aptX for high quality audio
Note: The car kit requires a 3.5 mm input jack in the car stereo

Device compatibility
- All iPhones, iPads and iPod Touch
- Android smartphones - HTC, All Droids, Samsung
- Blackberry smartphones
- All Bluetooth (A2DP/HFP/HSP) capable devices"

It's too bad the manual doesn't line up with that description.

*******

I found a list of apt-X products here, which is how I located that one.
It seems this company invented apt-X and it isn't part of the Bluetooth
standard. And like all things Bluetooth, good luck getting it working
via apt-X (which might give a better result).

http://www.csr.com/technology-solutions/av/audio-products-powered-by-csr-aptx/bluetooth-receiver

Some more info on apt-X. It's a codec, rather than a profile as such.
That means it's a sub-part of a profile (an option that can be used).
A profile can have multiple coding options, and I don't know how
the two devices decide what to use.

http://www.csr.com/products/60/aptx

"Key Features

* Compression ratio: 4:1
* Audio Format: 16-bit, 44.1kHz (CD-Quality)
* Data Rates: 352kbps
* Frequency Response: 10Hz to 22kHz
* Algorithmic Delay: <1.89ms @ Fs 48KHz
* Dynamic Range: 16-bit: >92dB
* THD+N: -68.8dB"

When incorporated in Bluetooth A2DP Stereo products, aptX audio coding
delivers full 'wired' audio quality"

HTH,
Paul
 
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