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GoDAP amplifies your mobile audio and provides optical output for iPhone 4

Most of the gadgets we're seeing here at CES 2011 this year aren't too big a surprise -- we set up meetings even before we walked into the convention center, and the surprise is in seeing the new gadgets we've only read about before. But the GoDAP was a surprise, found just by walking around the show floor and checking out the booths. It's made a Japanese company named VentureCraft, and it's a clip-on unit for the iPhone that not only works as a rechargeable battery, but also serves as a headphone amp, spiking up the output audio on your iPhone 3GS or 4.

The current model for the 3GS isn't quite as impressive as the new model -- it's just basically got a volume control (though the audio heard through headphones does sound really clear and loud). But the iPhone 4 model (of which we only saw a prototype on the show floor -- the real thing "will probably be thinner," according to VentureCraft, and should be ready to ship around April) is really interesting. It has digital audio output, and can send it through a optical cable in either 96k/24bit or 48k sampling rate (adjusted via a toggle). That means you can use the DAC port to kick out audio to a home theater system directly from the iPhone itself, and because the amp is running, it'll sound that much better. The frequency response is listed as 10 Hz to 120 kHz and suitable headphone impedance is listed as 16-100 ohms. The op-amp is a Texas Instruments/Burr-Brown running on each channel, which all adds up to some pristine digital audio output.

These are billed as battery chargers as well, but we suspect they may be more of a drain than a dedicated battery -- while you use the amp, you'll probably need to just keep it plugged in. The unit isn't cheap -- the 3GS version (without optical) runs $199 shipped from Japan, and the iPhone 4 version will probably be somewhere between $300-350. That is shipped, VentureCraft told us -- no extra charge, even though the unit is coming from Japan. But come April when this thing is ready, the right user might find it just what they need.

We've got a quick video from the booth on the next page.
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Most of the gadgets we're seeing here at CES 2011 this year aren't too big a surprise -- we set up meetings even before we walked into the...
 

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persistent

There is no digital output on the iPhone dock connector, so any digital output would have to be re-digitized from the analog output. Why bother?

January 08 2011 at 12:23 PM Report abuse rate up rate down Reply
Greg

"you can use the DAC port to kick out audio to a home theater system directly from the iPhone itself, and because the amp is running, it'll sound that much better"

What does this sentence mean? If you are using the digital output, you wouldn't need the amp to be "running."

"The op-amp is a Texas Instruments/Burr-Brown running on each channel, which all adds up to some pristine digital audio output."

Why would I need an opamp for digital output? Presumably the op-amp is being used as a headphone amp, which is fine, but it has nothing to do with the digital output.

Also, since they almost certainly haven't licensed the digital output stream from Apple, they're probably just taking the line output and running it through an ADC to make an optical stream. In other words, there's almost no point to this digital output nonsense.

January 07 2011 at 11:28 PM Report abuse rate up rate down Reply
1 reply to Greg's comment
Brian

I'm certainly not an authority on this, but I think you nailed it. I don't believe this product is anything more than a really expensive battery charger.

January 08 2011 at 12:01 PM Report abuse rate up rate down Reply
AppleZilla

The maximum that the iPhone can play is 48kHz, so 96kHz would be up-sampled accomplishing nothing. I have a Nuforce uDAC-2 that provides 24 bit 96kHz digital output from my Mac, because it is capable of playing those files. It only cost $130.

This device is really expensive for what you get. The Fiio e7 ($99) is a similar product to the GoDAP and provides similar functionality.

And of course, most of the music we all have is 16-bit 44.1khz.

January 07 2011 at 11:19 PM Report abuse rate up rate down Reply
1 reply to AppleZilla's comment
honkylips

That's the thing. The vast majority of audio on the internet (music and internet video) is mastered and compressed at 44.1kHz. Why upsample to 48kHz or 96kHz? This is not simple math, the conversion process between 44.1/88.2 and 48/96 is a complicated situation. Your audio quality takes a significant hit. I'm all for listening (and recording) at the highest quality available, but once something's been mastered and finalized at 44.1, that's only way it should be listened to.*

Now, a 24bit output (especially if you're touching the software volume slider in some video game) makes perfect sense to me. Does anyone know enough about iOS, is it even capable of 24bit output?


*unless you're using some super duper upsampling algorithm, which none of us are.

January 08 2011 at 1:49 AM Report abuse rate up rate down Reply
honkylips

I've wanted a product like this for soooo long, but.....

Why does the optical output stick to 48kHz or 96kHz outputs? Almost all music (and internet video) is encoded at 44kHz. What kind of sample rate conversion are they using? Why do any sample rate conversion, when they could easily just kick it out at the native sample rate?

January 07 2011 at 10:37 PM Report abuse rate up rate down Reply
1 reply to honkylips's comment
Brian

That's a good point. I'm not sure there would be an advantage in converting to a higher sampling rate. And regarding the product's usage, I don't quite understand why it's necessary, unless the amplifier to your speakers is just not enough.

January 07 2011 at 11:46 PM Report abuse rate up rate down Reply
Chris

Instead of 10 kHz to 120 kHz you mean 10 Hz to 120 kHz. Otherwise there would be absolutely no bass.

January 07 2011 at 10:16 PM Report abuse rate up rate down Reply
2 replies to Chris's comment
Victor Agreda, Jr.

Fixed. The typo was on their brochure, sorry about that. You're right. That would sound pretty crappy.

January 07 2011 at 10:23 PM Report abuse rate up rate down Reply
Bloobie

120kHz? Why so high, when the average human ear can only hear between 20Hz and 20kHz?

January 08 2011 at 10:36 PM Report abuse rate up rate down Reply
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