Thread: N810 Sound Output Fidelity
View Single Post
Capt'n Corrupt's Avatar
Capt'n Corrupt is offline Capt'n Corrupt
2007-12-01 , 19:27
Posts: 3,524 | Thanked: 2,958 times | Joined on Oct 2007 @ Delta Quadrant
#13
Originally Posted by bexley View Post
Check www.headphone.com for an excellent and well-priced portable headphone amp, the HeadRoom Total AirHead ($99).
When you provided that link, it was like the earth cracked beneath me, and a whole new world opened up before me. I had no idea that such devices existed, and the tantalizingly complex relationships that bind the various concepts of audio together, are just too mysterious to leave uncharted. I simply need to know more. It reminds me of the joy I felt when introduced to my first programming language. There was a world, so vast and mysterious, that I just couldn't leave it alone!

Needless to say, thanks for the recommend! I'm looking forward to buying a good amp (likely portable) and high quality cans/buds. I simply can't consider purchasing sound products based on wattage spec and marketing hyperbole anymore! That's a good thing!

Moving on....

One thing of interest that I pulled from the TI OMAP page that may give us some insight on what N810 facilities can be used

The audio portion of the TSC2301 contains microphone input with built-in pre-amp and microphone bias circuit, an auxiliary stereo analog input, a stereo line-level output, a differential mono line-level output, and a stereo headphone amplifier output. The digital audio data is transferred through a standard I2S interface. A fully programmable PLL for generating audio clocks from a wide variety of system clocks is also included.
Notice that the TSC2301 has "stereo line-level output." Could this be line-out functionality? If so, I wonder if this capability needs to be hardwired as a distinct port on the device that uses the OMAP, *or* if it is somehow a mode that can be turned on via some programmable interface. Certainly the picture of the 2420 suggest that there is only one out-port and one in-port on the device. Line out capability and headphone capability may suggest that the same port is used for amp and no-amp. In the interest of limiting pre-amp as much as possible for external amplification via the headphone jack, this would be interesting to explore. Certainly for portable Binaurals, but also for a quick-and-dirty 3.5mm connection to a HIFI stereo.


Originally Posted by bexley View Post
Ah, I thought of a solution that is actually getting me excited! I think the N810 would be able to drive the cousin of the AirHead called the BitHead, which is basically an outboard DAC (soundcard) too: that would clean up the audio quality greatly since the N810 would be supplying a perfect digital signal to the amp--as good as plugging an optical cable into your amp.
Me too! I know that the linux ALSA sound framework is a complex beast with many capabilities. If only I had an N810, I could run a couple of tests.

Originally Posted by bexley View Post
The only question is if the USB device would work, but I think the probability is high. Has anyone tested tested a USB soundcard with OS2008 and/or the N810 yet? If it doesn't work already, it should be feasible since it's a very simple and standard device. The Bithead takes batteries, so it shouldn't have any issues with a lack of USB power either.
I'm 99% sure that something like this will work. As far as I can tell, the potential problems are:

1) The format for the data. In the case of the BitHead device, it seems to require proprietary drivers to control the USB output. Is it streaming straight wav data, or some other format only recognized by its closed device? This would have to be investigated.

2) The amount of data. I'm assuming that any connectivity would have to be implemented a user-level application (not a driver built into the linux kernel). If the data requires conversion, this could potentially be computationally expensive. If it's beyond the requirements of the N810, choppy sound could be the result. Somehow, I doubt that this will be a hindrance.

Can anyone else shed a little insight?



}:^)~
YARR!

Capt'n Corrupt