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What's the real reason that laptop batteries are made not-accessible?

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NiHaoMike:

--- Quote from: SilverSolder on December 11, 2021, 03:49:15 pm ---If you look at the article in the link, it appears to be the "It-girls" that find the wires satisfyingly bohemian!  :D

--- End quote ---
Thinking about that some more, I guess it would make sense for IT girls to want something that "just works" when they're used to working on stuff that keeps refusing to work.

--- Quote from: dunkemhigh on December 11, 2021, 04:10:34 pm ---Don't know if I think that is good or bad - on the one hand, as you say, you always have charged earphones, but on the other phone battery life can be an issue without some external thing draining it on the sly.

--- End quote ---
Turn that around, make the case bigger and have it double as an external battery for the phone.

SilverSolder:

--- Quote from: magic on December 11, 2021, 04:37:24 pm ---There is a public datasheet of this DAC :o
https://www.esstech.com/products-overview/digital-to-analog-converters/low-power-dacs-and-socs-to-headphone-socs/

Built-in headphone amplifier, voltnuts wouldn't approve. No specs at loading less than 300Ω.
No explanation of Quad DAC technology, but it's "acclaimed" :)

--- End quote ---


Interesting, thanks for linking!  - looks like the chip has its own built-in charge pump to generate the positive and negative supplies for the output amplifiers, I was wondering how they would do that...

The data sheet does say -106dB THD+N, 300mV RMS into 32 ohms.  Seems respectable enough?  Definitely comparable to my stand-alone FLAC player...




PlainName:

--- Quote ---make the case bigger and have it double as an external battery for the phone
--- End quote ---

I think it's already been tried.

magic:

--- Quote from: SilverSolder on December 11, 2021, 05:11:42 pm ---Interesting, thanks for linking!  - looks like the chip has its own built-in charge pump to generate the positive and negative supplies for the output amplifiers, I was wondering how they would do that...

The data sheet does say -106dB THD+N, 300mV RMS into 32 ohms.  Seems respectable enough?  Definitely comparable to my stand-alone FLAC player...

--- End quote ---
LOL, I went straight to "analog characteristics" and completely missed the specs on the first page.
Yes, that's within the usually accepted "good enough for audio" limits, but hardly state of the art performance and you don't need friggin' 32 bits for that.
This output level is some 110+ dB SPL with typical IEMs, but less efficient headphones might require more.

I have seen the charge pump trick before. I think they do it because:
- it doubles the output swing without differential drive, which is impossible with 3-terminal headphones
- the charge pump runs at high frequency so it gets away with smaller (and crappier) capacitors than those required for AC coupling the load

SilverSolder:

--- Quote from: magic on December 11, 2021, 05:35:53 pm ---
--- Quote from: SilverSolder on December 11, 2021, 05:11:42 pm ---Interesting, thanks for linking!  - looks like the chip has its own built-in charge pump to generate the positive and negative supplies for the output amplifiers, I was wondering how they would do that...

The data sheet does say -106dB THD+N, 300mV RMS into 32 ohms.  Seems respectable enough?  Definitely comparable to my stand-alone FLAC player...

--- End quote ---
LOL, I went straight to "analog characteristics" and completely missed the specs on the first page.
Yes, that's within the usually accepted "good enough for audio" limits, but hardly state of the art performance and you don't need friggin' 32 bits for that.
This output level is some 110+ dB SPL with typical IEMs, but less efficient headphones might require more.

I have seen the charge pump trick before. I think they do it because:
- it doubles the output swing without differential drive, which is impossible with 3-terminal headphones
- the charge pump runs at high frequency so it gets away with smaller (and crappier) capacitors than those required for AC coupling the load

--- End quote ---

Yes, audio specs are often of the "if somethin's worth doing, it's worth OVERdoing" type!   


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