Did not find anything about this in the forums - sorry to be long winded if=
it has already been raised...
"This post is more for the benefit of people searching for this information=
than regular readers, who (I assume) already know this. I conducted some e=
xperiments with this a few days ago for an article I was writing for CM, an=
d have since figured out some new things, so I thought I'd share them.
Q: Can I use a USB audio interface with an iPad? A: Yup. There are some cav=
eats, and they need to be paid attention to, but in general it Just Works.
Q: Caveats? You're gonna drop Latin in to this x? A: That's how I roll. Ser=
iously, though, as far as my experimentation shows, the following informati=
on is true: first, the interface has to be class-compliant. That means that=
it needs to work in an OS X computer without a driver install. Second, it =
has to be USB1.0-compatible. No USB2.0-only interfaces. And finally, it has=
to either use less than 200ma of power or be externally powered.
Q: Hold on, let me get my... what? A: A safe rule of thumb is that if it ha=
s mic pres (especially if it's able to provide phantom power) it's going to=
need a wall wart or something.
Q: Okay. Got it. What else do I need? A: Pop over to the nearest Apple stor=
e and get yourself a Camera Connection Kit. This otherwise useless =A325.32=
adaptor plugs in to the 30-pin docking port and gives you a USB port, oste=
nsibly for hooking up cameras that have only on-board memory. As a camera c=
onnection kit, it's kind of stupid, because you can buy SD cards now that h=
ave as much storage as even a maxed-out iPad, so I'm unclear as to its stat=
ed purpose and the usefulness thereof. But as an audio adapter, it works fi=
ne.
Q: Okay. Last question. Does every audio app just sound out the interface w=
hen it is plugged in? A: Nope.
Long answer: there are several ways to give a program sound in Cocoa Touch.=
These are, on the whole, the same ways as in OS X proper. You can use Open=
AL, but that's just a sample playback engine, really. There is also a syste=
m sound engine, or you can programically access the part of the OS concerne=
d with playing back MP3s/AAC/whatever if you'd like. The final method, and =
the one that gives you bit-level access to the outputs, is to talk to CoreA=
udio, just like in OS X.
This final method is poorly documented and hideously complex, and even big =
companies x it up occasionally. But this is, as far as I can ascertain, the=
only method by which the USB outputs are utilized.
So, long story short: any App that uses CoreAudio for its playback, and doe=
s a good job of using it, automatically shunts its inputs (if it has 'em) a=
nd outputs to the USB device. Applications that use OpenAL (games for the m=
ost part, but some audio programs like the ridiculous-bordering-on-stupid M=
agic Piano, and many sample playback apps of that ilk) send the audio to th=
e headphone jack or the onboard speakers only. Apps that use the system sou=
nd engine or access the iTunes library in some crafty way also can't access=
this method.
One exception to this rule is Korg's iElectribe. As I said, CoreAudio in Co=
coa Touch is incredibly complicated and poorly documented, and even big com=
panies mess it up. iElectribe is an example of that. iElectribe _must_ use =
CoreAudio; it wouldn't work any other way. However, when a USB audio device=
is plugged in, iElectribe crashes on start-up. This will no doubt bum some=
people out.
And last but not least: all that x I said about the iPad above? It also app=
lies to the iPhone. (And I assume the iPod Touch, although I've not verifie=
d this.) I will say, however, that I have OS4 in my iPhone, so I can't say =
for certain that it works with OS3.1. If someone has a CCK and an iPhone wi=
th OS3.1 and wants to verify this, that would be cool.
EDIT: I just tried it with my wife's iPhone, which is running 3.1, and it D=
OES NOT WORK. So if you were planning on going to get a Camera Connection K=
it just to use audio from your iPhone or iPod Touch, you need to wait until=
OS4 is released for this to work. It works fine with OS4, though, essentia=
lly the same as with the iPad."
this has mostly been tested by hifi buffs but i would assume the micport pr=
o would also be compliant...
Confirmed works
- Nuforce uDAC [Skylab, Headphoneaddict, uofmtiger, torcik]
- DacMagic [uofmtiger]
- Xitel Pro Hifi-Link [deadie]
- Predator [jc9394] (have to put the volume to 100%)
- iBasso D4 [Headphoneaddict]
- iBasso D1 [trickywombat]
- iBasso D3 [hypoicon]
- iBasso D10 [qusp - doesn't work; HeadphoneAddict, rhw - works (charging o=
ff)]
- Pico DAC [Headphoneaddict, warp08]
- Micro II usb/digital [kredmore]
- Headroom Total BitHead [qin]
- Headroom Desktop Portable amp w/DAC [muski]
- TTVJ Portable w/DAC [grawk]
- TTVJ Slim DAC/Amp [gopack87]
- Fiio E7 [Jack-Micca, feiao]
- C&C F1U USB DAC/Amp [phytonix]
- Meier Corda Symphony DAC/Amp [Noumenon]
- Little Dot Dac1 [uofmtiger]
- devilsound v2.1 dac [decur]
- Music Hall DAC 25.2 [Skylab]
- Vivid Technologies V1 USB DAC HD AMP [ccklone]
- Valab NOS USB DAC [ccklone]
- Aune USB DAC/AMP [ccklone]
- Sigtone h1 - without any trouble [rhw]
- USB monica NOS DAC - no problems [rhw]
- DACport (works after flash update) [HeadphoneAddict]
- HA Info NG Coax USB to SPDIF Converter [rhw]
Issues(?):
- Headphonia DAC cable [qc98, shigzeo - works; utdeep - works but seems "li=
feless"]
- PopPulse PCM 1796 DAC [rhw - first an error message, but after reconnecti=
on works fine]
Doesn't work
- MobilePre (legacy) [porieux]
- iQube V2 portable [Skylab]
- Yulong D100 home DAC [Skylab]
- PWD [jc9394]
- uDAC-2 [headphoneaddict]
- nuForce Icon Mobile [yukster]
- Hot Audio DAC-Extacy USB DAC [ccklone - dialog box;too much power]
- M2 Hiface USB stick [ccklone - not really a DAC, but didn't work feeding =
a "known good" DAC]
Further to this I know that several budget pro audio interfaces are compati=
ble but do not have a full list I can add...
griffin imic
edirol ua25
the rest have slipped my memory maybe we could compile a list here?
Personally my needs are for 2ch digital i/o and to this end i am going to t=
est the roland UA-1G as it is a simple low profile cheap interface with all=
ows me to hook preamps / conversion of my choice... Will settle for 2ch now=
until apps start supporting multichannel i/o....
As to the inevitable ergonomics issues that will be brought up cant argue w=
ith them but still think it is a kinda cool high resolution 2 track as a ba=
ckup / toy ;-)
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