Head-Fi.org › Forums › Equipment Forums › Sound Science › iPhone 5 sound quality
New Posts  All Forums:Forum Nav:

iPhone 5 sound quality - Page 7

post #91 of 239
Quote:
Originally Posted by Trenn View Post

 

Take a look at TI or Cirrus ADC data and you'll see A Weighting is always 3 dB better than unweighted. Yes, if your noise floor is hugely distorted that rule won't hold. If your signal of interest isn't 1 KHz that rule won't hold. But for flat noise with a 1 KHz test tone, it's 3 dB. 

 

See the section "Noise Floor" on the page below. The noise floor of an MP3 is substantially higher than a 24-bit file format. If this graph is true, then it'll readily be audible. 

 

http://www.quantasylum.com/content/Home/tabid/40/EntryId/23/Apple-iPod-Nano.aspx

 

For measuring which THD figures I can hear, it's pretty simple to just generate a 1 KHz tone, and then add in a 2, 3, 4, 5, KHz tone at an increased volume and note at which point you can hear the added tone. Try it and report back. It's really hard to hear 2nd and 3rd order distortion, and much much easier to hear 7th order.  

Thanks for the info.  

 

If you make a statement like "A-Weighting is always 3dB better than unweighted", I'll challenge you every time because the statement is incorrect.  The entire point of a weighting curve is to weight audible noise and de-emphasize less audible parts of the spectrum (even if A-weighting is a bad match for reality).

 

 If you state the specific conditions where your statement is true, like flat noise spectrum, then I won't challenge you.   You have to know by now that the bulk of the folks reading these forums are fairly fresh to audio, and would read a statement like that and take it to be true in all cases.  Such is how myth is born.

 

Where can I find Cirrus ADC data? I've checked the Cirrus site, they must be under some sort of non-disclosure agreement, the data they publish is sketchy, and doesn't even include the chip used in the iPod. 

 

You aren't measuring your ability to hear real THD though, you are measuring the audibility of a pure tone with various other harmonically related tones added, in essence, your'e confirming the masking curve.  Real THD does look that way on spectral analysis with a pure tone test signal but the true audibility of the distortion mechanism should be evaluated with program material. Various distortion mechanisms generate different harmonic distributions and levels, and the specific rate of distortion onset at different signal levels changes how audible distortion becomes very significantly.  An extreme example would be distortion when a system is driven into hard clipping vs the softer nonlinearity of a class A amplifier that is over-driven.  

 

Yeah, I don't need to try that and report back.  Been there, done that decades ago, when the test signals were analog sine generators and the analyzer was a Tek AA501, and a 5L4N spectrum analyzer.  I found very poor correlation between an artificially generated harmonic spectrum and the actual audibility of a distortion mechanism with program material.  I don't think years would change that.   A device with a certain amount of even-order harmonic distortion produces far less audible distortion than a device with the same amount of odd-order harmonic distortion.  Again, under program conditions only, even though an artificially generated harmonic spectrum like that may be audibly similar.  

post #92 of 239
Thread Starter 

Apple's chips always use their own part number and specs aren't published, but if you look at the line you'll see that they list their own identical version with their own part number. It isn't hard to figure out which one it is.

post #93 of 239
Quote:
Originally Posted by bigshot View Post

Use a line out dock, and it will be worthy of your reference system.

 

Not.

post #94 of 239
Thread Starter 

Yeah huh!

post #95 of 239

You talking of reference system but it has got no tubes, NO TUBES!!!!!!!!111

post #96 of 239
Quote:
Originally Posted by xnor View Post

You talking of reference system but it has got no tubes, NO TUBES!!!!!!!!111

 

What is so special about tubes that you can't achieve with solid state?  Sure, they sound pleasing but you can emulate that sound with solid state gear.

post #97 of 239

I was just kidding.

post #98 of 239
Quote:
Originally Posted by xnor View Post

I was just kidding.

 

I know.  Your signature gave that away. :)

 

Tubes do sound great though on guitar amps and produce a lush sound for recording purposes.

There are a lot of tube headphone amps that sound superb, too, but I still would take solid state over them any day.

post #99 of 239

Galaxy uses quality chipset for audio, cant say the same for apple 

post #100 of 239
Yeah my Galaxy S2 gets louder and sounds better than the other 3 Android devices I've owned including the Nexus 7. That said, I still don't think it gets as loud as my iPod photo did. Apple mobile devices really have pretty great built-in dacs/amps compared to most portable devices out there.
post #101 of 239
Thread Starter 

The DAC in the iPod is basically the same as in standalone CD players and DACs.

post #102 of 239
Quote:
Originally Posted by IPodPJ View Post

 

I know.  Your signature gave that away. :)

 

Tubes do sound great though on guitar amps and produce a lush sound for recording purposes.

 

Guitar amps are a special case: you may want distortion as part of the sound, and you'll choose and adjust the appropriate amp. But a hi fi amp is the opposite - it's job is to recreate what the musician create rather than trying to make the Monkees sound the Velvet Underground or vice versa.

post #103 of 239
Thread Starter 

I think the main appeal of tube amps is turning off the lights and watching the tubes glow. Audiophile Christmas lights.

post #104 of 239
Quote:
Originally Posted by jaddie View Post

Thanks for the info.  

 

If you make a statement like "A-Weighting is always 3dB better than unweighted", I'll challenge you every time because the statement is incorrect.  The entire point of a weighting curve is to weight audible noise and de-emphasize less audible parts of the spectrum (even if A-weighting is a bad match for reality).

 

 If you state the specific conditions where your statement is true, like flat noise spectrum, then I won't challenge you.   You have to know by now that the bulk of the folks reading these forums are fairly fresh to audio, and would read a statement like that and take it to be true in all cases.  Such is how myth is born.

 

Where can I find Cirrus ADC data? I've checked the Cirrus site, they must be under some sort of non-disclosure agreement, the data they publish is sketchy, and doesn't even include the chip used in the iPod. 

 

You aren't measuring your ability to hear real THD though, you are measuring the audibility of a pure tone with various other harmonically related tones added, in essence, your'e confirming the masking curve.  Real THD does look that way on spectral analysis with a pure tone test signal but the true audibility of the distortion mechanism should be evaluated with program material. Various distortion mechanisms generate different harmonic distributions and levels, and the specific rate of distortion onset at different signal levels changes how audible distortion becomes very significantly.  An extreme example would be distortion when a system is driven into hard clipping vs the softer nonlinearity of a class A amplifier that is over-driven.  

 

Yeah, I don't need to try that and report back.  Been there, done that decades ago, when the test signals were analog sine generators and the analyzer was a Tek AA501, and a 5L4N spectrum analyzer.  I found very poor correlation between an artificially generated harmonic spectrum and the actual audibility of a distortion mechanism with program material.  I don't think years would change that.   A device with a certain amount of even-order harmonic distortion produces far less audible distortion than a device with the same amount of odd-order harmonic distortion.  Again, under program conditions only, even though an artificially generated harmonic spectrum like that may be audibly similar.  

 

I count several unqualified statements in your post, Do you need to be challenged on those? Hopefully not because I understand generally where you are headed. Let's not get too pedantic otherwise each post grows to pages in size. :) 

 

Cirrus has a bunch of ADC specs here: http://www.cirrus.com/en/products/a-d_converters.html  If you click on the link you can download the pdf.

 

Agree on the audibility of distortion in program material. But I think it's very telling for someone who's never contemplated distortion before to hear it in its purest form. You obviously think so to as you've also done the same experiment. If someone is worried about 0.01% distortion, and yet can't hear 0.5% in a very contrived case, that's educational. I think everyone interested in audio should have a rough understanding of their abilities. 

post #105 of 239
Quote:
Originally Posted by bigshot View Post

I think the main appeal of tube amps is turning off the lights and watching the tubes glow. Audiophile Christmas lights.

 

It's a big appeal: I was so disappointed when I did my research and found out that they're not really worth buying. Seriously, I'm the person who sits on a train grinning at his Seiko diving watch (Seiko have the best lume of any watch maker) watching in awe every time it lights up as the train goes through shade. Plus there's that whole "This Island Earth" interferociter look that valves have got going...

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Sound Science
Head-Fi.org › Forums › Equipment Forums › Sound Science › iPhone 5 sound quality