I spent way too long this weekend figuring out how to do Prologic II in the car, and during the process I managed to collect some info on how to eliminate the need for a head unit in the car.
Thought this info might be useful for people, so here ya go!
The first way to eliminate the head unit is fairly obvious. Download crap to your phone, turn on Bluetooth, and stream it to your stock head unit.
There are a couple of downsides to this option. First, Bluetooth is compressed. Second, your stuck with your stock amps. The speakers are fairly simple to replace of course.
I've told this story a hundred times, but here goes again:
I'm a big fan of keeping my stock stereo. I ripped out the stock system in an Accord I purchased fourteen years back, and the system I installed was so byzantine and ugly, it rendered the car un-sellable. I literally gave the car away.
Due to that, every system I've done since then is 100% separate from the stock system.
If you want to go that route, you can use an Android or iPhone, which connects to your processors, which connect to your amps.
Up until recently, I have personally used an RCA cable to connect to my processors. Bluetooth has come a long way though; I personally cannot tell the difference between the Bluetooth connection in my car and the RCA connection. If I'm not mistaken, my Bluetooth is compressed, which yields a bitrate of 352 kbps. ( Audio quality of bluetooth aptX - News and Articles - SoundExpert )
One thing that sucks about this setup is that it's compressed. Even worse, I listen to a lot of compressed recordings. So we're actually compressing it TWICE. (You have an MP3 that's compressed, the mp3 software on your phone uncompresses the mp3 data to an audio stream. Then the audio stream is fed to a bluetooth app on the phone, which REcompresses the audio, sends it out over the air, where's it's picked up by the Bluetooth receiver and decoded back into an audio stream.)
The obvious solution would be to keep the stream in MP3 format, and transmit that over the air. I'm not knowledgeable enough about Bluetooth to say why this isn't done. But I'm certain that it's NOT done, as APTX and MP3 are two entirely different codes.
TLDR : It's kind of amazing that Bluetooth sounds as good as it does, because there's a whole lotta compression going on.
Due to that, the obvious solution is to run lossless.
Apple's Airplay can do lossless. This is because it doesn't transmit over Bluetooth, it transmits over WiFi. 802.11N WiFi has a bandwidth of 600Mbps.
BTW, this is complete overkill for lossless stereo; this is enough bandwidth for something like 500 uncompressed audio streams. A compact disc requires 1.4Mbit/s! (https://cs.marlboro.edu/term/fall04/acoustics/bandwidth.txt)
I'm not a huge fan of the Airplay solution for a couple of reasons. First, it means you have to use an iPad or an iPhone for a source. Second, you have to hack up an Airplay unit to get it to work in a car. ( http://www.diymobileaudio.com/forum...nical-advanced-car-audio-discussion/162760-airport-express-w-optical-out-3.html )
If you're already an Apple user, the Airplay option looks decent, and costs less than $200. So, this is a cheaper option than a nice head unit, it doesn't require you to chop up your car, and it gives you the convenience of having all your music on your phone.
But if you're an Android guy like me, keep reading...
First, get yourself a phone or tablet that does Bluetooth 4.0. I'm using a "ZTE ZMAX" which is available at every WalMart for $180.
Second, get yourself a Bluetooth receiver than can do APTX lossless. There are dozens on eBay and Amazon for around $50. Here's one : http://www.amazon.com/AGPtEK®-Wirel...GHO/ref=sr_1_6?ie=UTF8&qid=1439230717&sr=8-6&keywords=agptek+bluetooth+receiver
By going this route, we can avoid a series of compression steps. For instance, you can put FLAC files on your Android (uncompressed), broadcast them over Bluetooth using APTX Uncompressed, which is received by the Bluetooth decoder and sent to your DAC via an optical connection.
By going this route you're eliminating a series of digital to analog conversions, and more importantly, you're eliminating the MP3 compression and the APTX compression.
On a side note, I was skeptical about Bluetooth for a long-ass time. I was an early adopter of Bluetooth and it sounded like ass. There was no treble, no bass, and it sounded worse than Skype. As I understand it, the reason that Bluetooth became so good is because the bandwidth was ramped up dramatically. Basically BT wasn't designed for audio, it was designed for peripherals, like wireless mice. "Bluetooth 4.0 promises speeds similar to Bluetooth 3.0 of up to 25Mbps. Both Bluetooth 4.0 and Wi-Fi Direct use the 802.11 networking standard to reach their maximum speeds. " http://www.pcworld.com/article/208778/Wi_Fi_Direct_vs_Bluetooth_4_0_A_Battle_for_Supremacy.html
Unless I'm missing something, this gets you very close to the ideal of having a digital connection from source to DAC. We are transmitting a digital uncompressed stream. The only difference is that we're doing it over the air instead of over a piece of glass.
Thought this info might be useful for people, so here ya go!
The first way to eliminate the head unit is fairly obvious. Download crap to your phone, turn on Bluetooth, and stream it to your stock head unit.
There are a couple of downsides to this option. First, Bluetooth is compressed. Second, your stuck with your stock amps. The speakers are fairly simple to replace of course.
I've told this story a hundred times, but here goes again:
I'm a big fan of keeping my stock stereo. I ripped out the stock system in an Accord I purchased fourteen years back, and the system I installed was so byzantine and ugly, it rendered the car un-sellable. I literally gave the car away.
Due to that, every system I've done since then is 100% separate from the stock system.
If you want to go that route, you can use an Android or iPhone, which connects to your processors, which connect to your amps.
Up until recently, I have personally used an RCA cable to connect to my processors. Bluetooth has come a long way though; I personally cannot tell the difference between the Bluetooth connection in my car and the RCA connection. If I'm not mistaken, my Bluetooth is compressed, which yields a bitrate of 352 kbps. ( Audio quality of bluetooth aptX - News and Articles - SoundExpert )
One thing that sucks about this setup is that it's compressed. Even worse, I listen to a lot of compressed recordings. So we're actually compressing it TWICE. (You have an MP3 that's compressed, the mp3 software on your phone uncompresses the mp3 data to an audio stream. Then the audio stream is fed to a bluetooth app on the phone, which REcompresses the audio, sends it out over the air, where's it's picked up by the Bluetooth receiver and decoded back into an audio stream.)
The obvious solution would be to keep the stream in MP3 format, and transmit that over the air. I'm not knowledgeable enough about Bluetooth to say why this isn't done. But I'm certain that it's NOT done, as APTX and MP3 are two entirely different codes.
TLDR : It's kind of amazing that Bluetooth sounds as good as it does, because there's a whole lotta compression going on.
Due to that, the obvious solution is to run lossless.
Apple's Airplay can do lossless. This is because it doesn't transmit over Bluetooth, it transmits over WiFi. 802.11N WiFi has a bandwidth of 600Mbps.
BTW, this is complete overkill for lossless stereo; this is enough bandwidth for something like 500 uncompressed audio streams. A compact disc requires 1.4Mbit/s! (https://cs.marlboro.edu/term/fall04/acoustics/bandwidth.txt)
I'm not a huge fan of the Airplay solution for a couple of reasons. First, it means you have to use an iPad or an iPhone for a source. Second, you have to hack up an Airplay unit to get it to work in a car. ( http://www.diymobileaudio.com/forum...nical-advanced-car-audio-discussion/162760-airport-express-w-optical-out-3.html )
If you're already an Apple user, the Airplay option looks decent, and costs less than $200. So, this is a cheaper option than a nice head unit, it doesn't require you to chop up your car, and it gives you the convenience of having all your music on your phone.
But if you're an Android guy like me, keep reading...
First, get yourself a phone or tablet that does Bluetooth 4.0. I'm using a "ZTE ZMAX" which is available at every WalMart for $180.
Second, get yourself a Bluetooth receiver than can do APTX lossless. There are dozens on eBay and Amazon for around $50. Here's one : http://www.amazon.com/AGPtEK®-Wirel...GHO/ref=sr_1_6?ie=UTF8&qid=1439230717&sr=8-6&keywords=agptek+bluetooth+receiver
By going this route, we can avoid a series of compression steps. For instance, you can put FLAC files on your Android (uncompressed), broadcast them over Bluetooth using APTX Uncompressed, which is received by the Bluetooth decoder and sent to your DAC via an optical connection.
By going this route you're eliminating a series of digital to analog conversions, and more importantly, you're eliminating the MP3 compression and the APTX compression.
On a side note, I was skeptical about Bluetooth for a long-ass time. I was an early adopter of Bluetooth and it sounded like ass. There was no treble, no bass, and it sounded worse than Skype. As I understand it, the reason that Bluetooth became so good is because the bandwidth was ramped up dramatically. Basically BT wasn't designed for audio, it was designed for peripherals, like wireless mice. "Bluetooth 4.0 promises speeds similar to Bluetooth 3.0 of up to 25Mbps. Both Bluetooth 4.0 and Wi-Fi Direct use the 802.11 networking standard to reach their maximum speeds. " http://www.pcworld.com/article/208778/Wi_Fi_Direct_vs_Bluetooth_4_0_A_Battle_for_Supremacy.html
Unless I'm missing something, this gets you very close to the ideal of having a digital connection from source to DAC. We are transmitting a digital uncompressed stream. The only difference is that we're doing it over the air instead of over a piece of glass.
And Sandisk now makes a 200GB microSDXC card! :surprised: Main music player app is the Android USB Audio Player Pro by eXtream Software Development.
