On 14/01/2011 10:00 AM, scott wrote:
>> Making a DAC what "works" is probably quite trivial. Making one that can
>> isolate all the signal noise from the rest of the phone, handle sudden
>> transients while being powered only by a feeble half-flat battery, and
>> so on and so forth is probably much harder.
>
> But you're still only talking about 20 kHz signals, the rest of the
> phones deals with exactly those same issues for frequencies many orders
> of magnitudes higher.

I was under the impression that GSM broadcasts don't care particularly 
about 10% THD, and only need to generate constant-amplitude carrier 
waves. (Then again, I don't design GSM transmitters...)

> The audio DAC is probably one of the simplest
> parts in the phone for the designers to do.

The audio DAC (and the ADC, for that matter) is presumably an 
off-the-shelf component.

>> Then again, it's MP3, so it probably won't sound fantastic anyway.
>> Certainly most people are going to plug in those horrid £2 things from
>> the market, so the quality of the electronic signal is quite irrelevant.
>
> Exactly, they're not really expecting Mr Hi-Fi to connect up his 30 quid
> Nokia to a 20k hi-fi with a gold-plated half-inch-thick 2xphono to 3.5mm
> cable. At best they are expecting you to connect a 100 quid pair of
> headphones to it and listen on the train, and in that case I doubt most
> people would be able to tell the difference between having a phone or an
> mp3 player connected up.

You're talking to somebody who actually owns a £100 pair of headphones. 
;-) And they're not just for show. (They never leave the house, in fact.)

But yes, I'm never quite sure why these small portable devices pretend 
to be able to produce hi-fi sound when it's perfectly obvious that they 
cannot possibly do so.

>> Far more problematic than carrying the player is carrying the large £30
>> headphones I usually use it with.
>
> Invest in a smaller pair?

I could buy a smaller pair, but then what would be the point of listening?

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