[goodsound]

Does anyone know for sure what exactly is the internal DAC of the ipad ? especially the ipad 2.
Also, does the ipad have a true "line out" even if via a dock like the ipods ?
And then finally how does the sound quality (on a decent pair of headphones ofcourse) of the ipad compare to the ipod models - nano, classic ipod, and ipod touch.
 
Just trying to get a feel of how good or bad the sound quality of the stock ipad is.
Thanks!
 

 

[yuriv]

I don't know the exact model of the chip but it's probably the same as the one in the iPhone 4. I had a chance to listen to an iPad 2 and also take some measurements. The headphone out will work well as a line out. It's undistorted, has low noise, and has a uniform frequency response. Here are some of my findings for the headphone out with no load:

1. The output is 0.99V rms at maximum volume.
2. Noise and distortion figures are low--THD+N and IMD are about the same as the iPhone 4 and the original iPad, and much lower than the Sandisk Sansa Clip, Clip+, and Fuze.
3. Square waves and impulses on the iPad 2 have the same shape as on the original iPad and the iPhone 4. It uses a minimum-phase type filter. The ringing takes much longer to decay than on the Clip+ or the old iPod Video, but it doesn't exhibit pre-ringing.

 
The headphone amp is pretty good too. With a 16-ohm load, this is what I found:

1. You have up to 570-580 mV rms for a 1 kHz tone before the THD+N goes above 1%.
2. THD+N and IMD are much lower at typical listening levels with portable 'phones. The amount of distortion and stereo crosstalk is similar to measurements for the original iPad and the iPhone 4, and much lower than the figures for the Clip+.
3. The headphone amp has low output impedance. I get around 0.9 ohms, the same as the iPhone 4 and lower than the ~1.4 ohms for the original iPad. The Clip+ is still a stiffer voltage source. I think some popular portable headphones might be designed for a player with higher source impedance (like the old iPods). Some of those cans might not sound as good on an iPad. I have my suspects. Fortunately, there is a quick fix for that.

 
I listened to an iPad 2 for some time and I couldn't hear any obvious noise or distortion on my headphones and IEMs. Hooking up the headphone out to a line in sounds clean too--at least on my Speakers. It's at least as good as some of the USB DACs that some folks attach to it. What's funny is that some of those even perform worse.
 
I wish I had a chance to install the EQu and Equalizer apps to see if the extra speed improves usability and stability. 

 

[mcmurray]

Bump.

Great read yuriv, thanks.

 

[elfary]

Quote:

I don't know the exact model of the chip but it's probably the same as the one in the iPhone 4. I had a chance to listen to an iPad 2 and also take some measurements. The headphone out will work well as a line out. It's undistorted, has low noise, and has a uniform frequency response. Here are some of my findings for the headphone out with no load:

1. The output is 0.99V rms at maximum volume.
2. Noise and distortion figures are low--THD+N and IMD are about the same as the iPhone 4 and the original iPad, and much lower than the Sandisk Sansa Clip, Clip+, and Fuze.
3. Square waves and impulses on the iPad 2 have the same shape as on the original iPad and the iPhone 4. It uses a minimum-phase type filter. The ringing takes much longer to decay than on the Clip+ or the old iPod Video, but it doesn't exhibit pre-ringing.

 
The headphone amp is pretty good too. With a 16-ohm load, this is what I found:

1. You have up to 570-580 mV rms for a 1 kHz tone before the THD+N goes above 1%.
2. THD+N and IMD are much lower at typical listening levels with portable 'phones. The amount of distortion and stereo crosstalk is similar to measurements for the original iPad and the iPhone 4, and much lower than the figures for the Clip+.
3. The headphone amp has low output impedance. I get around 0.9 ohms, the same as the iPhone 4 and lower than the ~1.4 ohms for the original iPad. The Clip+ is still a stiffer voltage source. I think some popular portable headphones might be designed for a player with higher source impedance (like the old iPods). Some of those cans might not sound as good on an iPad. I have my suspects. Fortunately, there is a quick fix for that.

 
I listened to an iPad 2 for some time and I couldn't hear any obvious noise or distortion on my headphones and IEMs. Hooking up the headphone out to a line in sounds clean too--at least on my Speakers. It's at least as good as some of the USB DACs that some folks attach to it. What's funny is that some of those even perform worse.
 
I wish I had a chance to install the EQu and Equalizer apps to see if the extra speed improves usability and stability. 

Do you mean that some IEMs frequency response might be tuned with the interaction with a few ohms Z in mind ? So that pairing them with a really low Z amp might end up with a not so enjoyable frequency response ?
 

 

[yuriv]

[size=x-small]Yes. Many portable headphones and earphones are designed for the iPod, and you can see "for iPod" on the packaging. Early Nanos and models that use a hard drive have around 5 ohms output impedance, maybe a little more. See, for example, Stereophile's 2003 measurements for the 3rd-generation model. Portable headphones designed for these iPods might sound different (better?) on an iPad.[/size]
 
[size=x-small]Also, lots of folks here seem to enjoy sticking 75 ohm resistors in series with an ER4P. I'm not one of them, as I think it colors the sound too much. [/size][size=x-small]You can increase an iPad's source impedance with a simple passive in-line volume control. Channel balance issues aside, you can use one to emulate the behavior of a player with higher output impedance. [/size]
 
[size=x-small]Here's my experience with a pair of IEM's that I think sounds better with a higher-impedance source: http://www.head-fi.org/forum/thread/562331/need-a-graph-of-soundmagic-pl50-and-also-a-decent-mic#post_7609802[/size]

 

[elfary]

That's very interesting Yuriv. Thanks a lot.
 
It should be mandatory than manufacturers include impedance & frequency response graphs on their websites but reality is that not only they are not enforced to do so but they reject to give that info when requested.
 
Under these conditions it's hard to make informed decisions when choosing gear.
 
I've been for weeks trying to get an impedance curve of the Westone UM3x but there's no way to get it from Westone.Actually the good folks at Westone even refuse to give the minimum and maximum impedance. And they have been far more helpful than Shure staff which directly told me that it was classified information (Even when you find curves from the SE530 everywhere).
 
That status quo is what make really useful webs as goldenears, sonove or hifi.de