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USB headphone AMP with Android Phones, possible ???
Nov 20, 2011 at 7:48 AM Post #16 of 81
There seems to be some misconception towards what an amp can do. An amp can do a lot more than simply amplify a signal. An amp, depending on it's output impedance, will increase the damping factor on the headphones, basically increasing the grip the amp has on the driver, meaning that the driver would trace out the input signal more accurately. Also, if using a true line out, then the amplifiers slew rate will come into play. This changes according to the model of the opamp. This is the time it takes for an amp to change it's output from it's highest +ve voltage to it's lowest -ve voltage. This maintains the quality of the signal that the headphone is reproducing, meaning that the sound will be less blurred. Think of it as the transient response of an amplifier. There is more to it so if anyone wants, they can read the case study I wrote on solid-state amplification for my Higher Technological Studies:
http://www.mediafire.com/?9skkqw21rwcn6mb
 
Nov 20, 2011 at 8:37 AM Post #17 of 81


Quote:
j0nny said:
There seems to be some misconception towards what an amp can do. An amp can do a lot more than simply amplify a signal. An amp, depending on it's output impedance, will increase the damping factor on the headphones, basically increasing the grip the amp has on the driver, meaning that the driver would trace out the input signal more accurately. Also, if using a true line out, then the amplifiers slew rate will come into play. This changes according to the model of the opamp. This is the time it takes for an amp to change it's output from it's highest +ve voltage to it's lowest -ve voltage. This maintains the quality of the signal that the headphone is reproducing, meaning that the sound will be less blurred. Think of it as the transient response of an amplifier. There is more to it so if anyone wants, they can read the case study I wrote on solid-state amplification for my Higher Technological Studies:
http://www.mediafire.com/?9skkqw21rwcn6mb
Click to expand...


In short, u mean put an amp on headphone out will improve the power and also the SQ. If u put an amp on the true line out, the SQ improvement will be even more pronounced???
 
 
Nov 22, 2011 at 12:21 AM Post #20 of 81
Wanted: real life example of Android phone + USB DAC success?
 
So can anyone provide a link to an example of where an android phone has been successfully used with a USB dac?  i.e. along the lines of: android phone > usb cable carries digital stream (not analogue) > USB dac > amp > headphones.
 
I understand that "in theory" it should be possible (provided there is appropriate support from internal hardware/USB port wiring and Android ROM - stock or custom) - but try as I might googling has failed to pull up a real live example of success.  
 
 
Perhaps its a failure of my searching - and I'd be delighted to be proved wrong!  
 
(I ask as a Galaxy S owner who has an eye on the latest gen android offerings - Galaxy Note, Galaxy Nexus etc - but aware of their audio chip shortcomings which I'd love to have the option of bypassing via USB dac if at all possible. )
 
Nov 22, 2011 at 4:21 AM Post #21 of 81
Here's your proof, dude uses his Fiio E7: 
 
http://forum.xda-developers.com/showpost.php?p=16229673&postcount=587
 
Buried in this thread is another person who succesfully used his Beresford Caiman DAC on an Android tablet using USB Host. It's pretty easy to get working, all you need is an Android device with CyanogenMod7 support and USB HOST enabled. You need a powered hub for it to work though. 
 
http://forum.xda-developers.com/showthread.php?t=1105497&page=69
 
The reason you're not finding many hits is probably because it's such a niche application. Not many people out there are trying this. You have to be both an audiophile AND an Android geek. :wink: Like me! 
 
Nov 22, 2011 at 5:06 AM Post #22 of 81
Cheers for that. Encouraging indeed. Though from my v brief dipping into those threads just now is they look a little nook centric, but if it is wider than that hardware-wise as you say then excellent I may have to give the cryanogen mod a go on my galaxy s.

One quick question... powered hub... would this include a battery powered portable dac? (I have one ) Actually I think i can guess what you are going to say.. no, a powered hub needs to be interposed between the phone and the dac so the latter doesn't try to draw power from the former?

Just one more: so can you get battery powered compact USB hub with sufficient juice to work in such a setup... does such a gadget exist?

Sent from my GT-I9000 using Tapatalk
 
Nov 22, 2011 at 5:53 AM Post #23 of 81
That particular thread is about the Nook Color, because that's the tablet I use. The same rules apply to EVERY CyanogenMod7 supported device though. :) Check this website out for compatability.
 
Regarding the powered hub, the guy in my example used an UNpowered hub and it worked. I think you just have to experiment with this. No power on the hub does mean higher battery drain ofcourse. The Fiio E7 has it's own battery so that's why I see it working over something like a USB powered DAC. 
 
 
Dec 11, 2011 at 6:48 PM Post #24 of 81
If an unpowered hub works, does that mean a straight usb cable might work as well? Of course I can't find such a cable, but it should be possible...
I have a Galaxy as well, and the amp in it is atrocious, especially on the low end. I'd love to be able to use my fiio e7 in dac mode.
 
Dec 12, 2011 at 7:49 AM Post #25 of 81


Quote:
steel_3d said:
If an unpowered hub works, does that mean a straight usb cable might work as well? Of course I can't find such a cable, but it should be possible...
I have a Galaxy as well, and the amp in it is atrocious, especially on the low end. I'd love to be able to use my fiio e7 in dac mode.
Click to expand...



Just TRY it and let me know. :) And the cables are easy to find. All you need is a microUSB-male to USB-female OTG cable. 
 
Dec 13, 2011 at 5:05 AM Post #26 of 81
So for the n00b like me, does this seem like the correct steps?
 
  • I flash the Cyanogen Nightly build 135 or newer to my Desire.
  • Buy a nice short cable and connect up an Amp/Dac unit (Pico DAC/Amp, D-Zero, D6, etc)
  • Enjoy high quality audio bypassing the phones internal amp
 
So if I am understanding it correctly, I need to make sure that the phone is in "Host Mode" and the vBus is off?  Or is this only for the Nook?
 
Cheers,
St Veronus
 
Dec 13, 2011 at 5:09 AM Post #27 of 81


Quote:
stveronus said:
So for the n00b like me, does this seem like the correct steps?
 
  • I flash the Cyanogen Nightly build 135 or newer to my Desire.
  • Buy a nice short cable and connect up an Amp/Dac unit (Pico DAC/Amp, D-Zero, D6, etc)
  • Enjoy high quality audio bypassing the phones internal amp
 
So if I am understanding it correctly, I need to make sure that the phone is in "Host Mode" and the vBus is off?  Or is this only for the Nook?
 
Cheers,
St Veronus
Click to expand...


Host Mode, vBus off... Yep. Make sure the cable is OTG like this one. You need USB female on the other end to be able to connect your DAC's usb cable. If your DAC isn't battery powered you'll need an AC powered hub as well. You need an Android app like Poweramp too. Any app that supports USB HOST. 
 
 
Dec 13, 2011 at 7:19 AM Post #28 of 81
So the cable I linked won't work?  It has to be "OTG" and female ended?  That means a male to male adapter into the portable Amps (battery powered).  I would want to "stack" the phone and Amp, so the less connectors and cables the better.  I guess buying both cables and the adapter isn't too expensive to "test".  I will look up what makes an "OTG" cable special.
 
I currently use Meridian as it was at the time only player that supported flac files.  Is PowerAmp better, or have you used both?
 
Thanks for your help on this.
 
Dec 13, 2011 at 10:20 AM Post #29 of 81
I've only tried Poweramp after reading it worked with USB Host. You could try other apps too and see if they work as well. 
 
I don't quite get your cable dilemma but you'll figure it out. The cables are cheap and you can easily find the ones that work best for you. Good luck! Keep us posted. :) 
 
Dec 13, 2011 at 9:53 PM Post #30 of 81
I'm glad I finally ran across this thread. The news that a DAC works fine through PowerAMP is great also. However, I do have a question. Is only the music directed to the DAC? If so, what happens when a notification come in and the notification volume is not off?
 
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