28-Dec-2015, 13:40
And if you're comparing to bluetooth speakers, would be nice to know what A2DP codec the connection was using.
Phantoms are equipped with CSR bluetooth chips, which means they fully support aptX (CSR was the owner of aptX before selling to Qualcomm), the codec which provides almost-lossless 44/16 audio experience over bluetooth.
Apple mobile devices sadly do not implement it, so they're limited to lossy A2DP codec.
Some Android phones support aptX. Mac OS X starting with Lion support aptX well also. You can check on Mac OS X if it's using aptX by holding "option" key while clicking on the bluetooth icon in the top bar, and moving mouse pointer to Phantom. It will show the codec right there.
In any case, aptX is not true lossless 44/16 (although it comes near) - it divides the 22khz range (=44KHz Nyquist sampling rate) into 5.5KHz subbands (=11KHz sampling rate each), and codes each frequency subband using ADPCM which is well-suited for "smooth" signal with little variation. It then allocates more bits to lower subbands and less to higher, because generally there's much less variance in higher frequencies. Standard allocation is 8bits 0-5.5KHz, 4bits for 5.5KHz-11KHz, 2bits for 11-16.5KHz, 2bits for 16.5-22KHz, altogether 16bits, at 11KHz "sampling" rate (because each subband is 0-5.5KHz) = 352Kbit/s compared to 1.4Mbit/s PCM rate of 44/16 signal.
These are all bits of ADPCM coded data, so not comparable to PCM bits, as ADPCM losslessly takes much less space than PCM on average.
Bottom line - aptX is the closest you can get to PCM in bluetooth, and it's important to know if it was used while evaluation: most "bluetooth speakers" don't bother implementing aptX as they know that sound quality is limited by speaker itself.
Phantoms are equipped with CSR bluetooth chips, which means they fully support aptX (CSR was the owner of aptX before selling to Qualcomm), the codec which provides almost-lossless 44/16 audio experience over bluetooth.
Apple mobile devices sadly do not implement it, so they're limited to lossy A2DP codec.
Some Android phones support aptX. Mac OS X starting with Lion support aptX well also. You can check on Mac OS X if it's using aptX by holding "option" key while clicking on the bluetooth icon in the top bar, and moving mouse pointer to Phantom. It will show the codec right there.
In any case, aptX is not true lossless 44/16 (although it comes near) - it divides the 22khz range (=44KHz Nyquist sampling rate) into 5.5KHz subbands (=11KHz sampling rate each), and codes each frequency subband using ADPCM which is well-suited for "smooth" signal with little variation. It then allocates more bits to lower subbands and less to higher, because generally there's much less variance in higher frequencies. Standard allocation is 8bits 0-5.5KHz, 4bits for 5.5KHz-11KHz, 2bits for 11-16.5KHz, 2bits for 16.5-22KHz, altogether 16bits, at 11KHz "sampling" rate (because each subband is 0-5.5KHz) = 352Kbit/s compared to 1.4Mbit/s PCM rate of 44/16 signal.
These are all bits of ADPCM coded data, so not comparable to PCM bits, as ADPCM losslessly takes much less space than PCM on average.
Bottom line - aptX is the closest you can get to PCM in bluetooth, and it's important to know if it was used while evaluation: most "bluetooth speakers" don't bother implementing aptX as they know that sound quality is limited by speaker itself.
