Bluetooth audio is part of the Bluetooth specs.
As the bandwidth is limited the maximum bitrate is 576kbps for 2 channel audio.
Bit like a 256kbs MP3.
In general I use the WASAPI driver.
It bypasses the Win mixer.
All what is send using WASAPI must match the properties of the audio device.
Sending Redbook (16 bit/44.1 kHz) to the Bluetooth audio device failed.
Obvious Bluetooth audio only plays 48 kHz.
If you play Redbook over Bluetooth it must be resampled to 48 kHz and lossy compression must be applied.
No bit perfect playback here.
Small wonder Bluetooth has a bad reputation sound quality wise.
I bought a Sennheiser PXC 360 BT.
The BT stands for Bluetooth of course.
Why did I buy a Bluetooth headphone as it is such an audiophile disgrace?
Well the analog out of my Samsung Galaxy S II is a disgrace too.
The internet says Samsung switched from Wolfson to Yamaha.
Now I do think Yamaha has a good reputation in audio but I can’t escape the feeling Samsung was looking for the cheapest of the cheapest possible solution.
This sounds like 8 bits.
You can also connect the PXC by wire to the phone.
Believe it or not, over the Bluetooth the sound is better than wired!
Simply more transparent.
APT-X is a proprietary codec by CSR
Over Bluetooth it is a lossy protocol but said to improve sound quality compared with SBC, the mandatory BT audio codec.
The Sennheiser comes with support for both SBC and APT-X.
As APT-X is not part of the Bluetooth standard you need a dongle supporting this protocol to communicate with the Sennheiser over APT-X.
To compare it with standard Bluetooth audio codec (SBC) I made 2 zones in JRiver.
One using the build-in Bluetooth the other a dongle by Creative (BT-D1 USB transmitter).
Both zones use WASAPI – event style with a 250 ms hardware buffer.
Internal volume at 100%
JRivers DSP studio is used to resample from 44 > 48 kHz.
Rapid AB is a bit troublesome in this scenario.
You have to switch of the laptop Bluetooth, insert the dongle and wait for the devices to pair.
The paring is automatically but last a couple of seconds.
APT-X is a bit louder than SBC, don’t know why.
But as louder is better it makes the comparison more complex.
As a true reviewer I of course don’t use stuff like a SPL-meter, that is for the weak!
I don’t even own one.
So I turned the headphone volume a notch down.
Using this amateur way to match volume I still perceived a difference.
The APT-X simply supplies more details, is more transparent.
BTW: I have not found a way to verify what codec is actually used.
The USB descriptor dumper tells a lot about the dongle but not what is going on inside.
Next question: how do you get APT-X on your Android?
Last test, connect the PXC wired to the Benchmark DAC 1 and compare this with the APT-X.
This is no match.
That is not necessary due to APT-X.
By using the headphone wired you also bypass the DAC and headphone amp of the PXC.
Wired the sound is more detailed.
Very last test, compare the PXC with the Etymotic ER4P both wired to the DAC1.
Again a volume match problem as they do differ substantial in Impedance.
Again no match.
The Etymotic offers a superior performance.
The PXC simple is not able to resolve tiny details. It smears the sound. It is also a bit bass heavy.
Anyway I’m happy with the PXC.
Commuting by train, this headphone over the Bluetooth gives me a better sound than the analog crap out of the Galaxy into the Etymotic.
All testing has been done sighted.
It is up to you to provide the proverbial grain of salt.
As the bandwidth is limited the maximum bitrate is 576kbps for 2 channel audio.
Bit like a 256kbs MP3.
In general I use the WASAPI driver.
It bypasses the Win mixer.
All what is send using WASAPI must match the properties of the audio device.
Sending Redbook (16 bit/44.1 kHz) to the Bluetooth audio device failed.
Obvious Bluetooth audio only plays 48 kHz.
If you play Redbook over Bluetooth it must be resampled to 48 kHz and lossy compression must be applied.
No bit perfect playback here.
Small wonder Bluetooth has a bad reputation sound quality wise.
I bought a Sennheiser PXC 360 BT.
The BT stands for Bluetooth of course.
Why did I buy a Bluetooth headphone as it is such an audiophile disgrace?
Well the analog out of my Samsung Galaxy S II is a disgrace too.
The internet says Samsung switched from Wolfson to Yamaha.
Now I do think Yamaha has a good reputation in audio but I can’t escape the feeling Samsung was looking for the cheapest of the cheapest possible solution.
This sounds like 8 bits.
You can also connect the PXC by wire to the phone.
Believe it or not, over the Bluetooth the sound is better than wired!
Simply more transparent.
APT-X is a proprietary codec by CSR
Over Bluetooth it is a lossy protocol but said to improve sound quality compared with SBC, the mandatory BT audio codec.
The Sennheiser comes with support for both SBC and APT-X.
As APT-X is not part of the Bluetooth standard you need a dongle supporting this protocol to communicate with the Sennheiser over APT-X.
To compare it with standard Bluetooth audio codec (SBC) I made 2 zones in JRiver.
One using the build-in Bluetooth the other a dongle by Creative (BT-D1 USB transmitter).
Both zones use WASAPI – event style with a 250 ms hardware buffer.
Internal volume at 100%
JRivers DSP studio is used to resample from 44 > 48 kHz.
Rapid AB is a bit troublesome in this scenario.
You have to switch of the laptop Bluetooth, insert the dongle and wait for the devices to pair.
The paring is automatically but last a couple of seconds.
APT-X is a bit louder than SBC, don’t know why.
But as louder is better it makes the comparison more complex.
As a true reviewer I of course don’t use stuff like a SPL-meter, that is for the weak!
I don’t even own one.
So I turned the headphone volume a notch down.
Using this amateur way to match volume I still perceived a difference.
The APT-X simply supplies more details, is more transparent.
BTW: I have not found a way to verify what codec is actually used.
The USB descriptor dumper tells a lot about the dongle but not what is going on inside.
Next question: how do you get APT-X on your Android?
Last test, connect the PXC wired to the Benchmark DAC 1 and compare this with the APT-X.
This is no match.
That is not necessary due to APT-X.
By using the headphone wired you also bypass the DAC and headphone amp of the PXC.
Wired the sound is more detailed.
Very last test, compare the PXC with the Etymotic ER4P both wired to the DAC1.
Again a volume match problem as they do differ substantial in Impedance.
Again no match.
The Etymotic offers a superior performance.
The PXC simple is not able to resolve tiny details. It smears the sound. It is also a bit bass heavy.
Anyway I’m happy with the PXC.
Commuting by train, this headphone over the Bluetooth gives me a better sound than the analog crap out of the Galaxy into the Etymotic.
All testing has been done sighted.
It is up to you to provide the proverbial grain of salt.
. When I got one I will do the A/B comparsion again to hear what aptx really sounds like.
