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

For a one off I would try direct drive the BLE from the DAC via a 10uF capacitor and work out where to go from there.


Cheers,
Martin.


On Friday, 20 December 2024 at 09:58, Neil <[email protected]> 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.
> 
> 
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> https://mailman.mit.edu/mailman/listinfo/piclist