Re: [EE] DAC-to-headphone-level output amp

Hi there, Neil.

"AUX" level is usually -10dBV.  That level is fairly close to what 
headphones are happy with.

dwayne


At 03:58 PM 12/19/2024, Neil wrote:
>I'm designing a one-off device for myself that will generate audio 
>from a microcontroller and I want to send that audio to a small BLE 
>audio transmitter (something I picked up on Amazon).
>The BLE transmitter has a 3.5mm headphone plug and they specify it's 
>for "Aux" level devices, but works very well when plugged into my PC 
>or cellphone, so I take that to mean headphone level.
>FWIW, the audio signal is mono, but I want to drive both left and 
>right channels.
>
>Researching online gets me a whole lot of different answers -- 
>everything from line level being 10k ohms input impedance and 1V or 
>2V to 3V and headphone level is 8 to 600 ohms, with voltage level 
>from 0.3 to 0.8V (though I would've expected headphone level to be 
>higher since it's amplified).
>
>Can anyone shed some light on this please. I'm unsure what I'd be 
>designing for... should I just do an op-amp with a very low output 
>impedance and adjustable volume until it sounds decent? Or is there 
>a spec I should follow?
>Alternately, I'd be happy if there's some simple monolithic chip 
>that would do this for me (take a 0V-3.3V audio signal from a uC DAC 
>and convert it to headphone level audio).
>
>Cheers,
>-Neil.


-- 
Dwayne Reid   <[email protected]>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
780-489-3199 voice   780-487-6397 fax   888-489-3199 Toll Free
www.trinity-electronics.com
Custom Electronics Design and Manufacturing