Audio only through HDMI?

[johnsone]

I work in a school that recently upgraded their classroom technology to only allow for HDMI inputs. We used to have a way for a teacher to plug in their phone to play music. Is there any way to go from a headphone jack to HDMI so the sound can come though the system speakers?

 

[americanaudiophile]

You could try using an AV to HDMI converter but you might need to also provide an composite video signal too.
Or you could use MHL if the phone supports it.
https/www.pcworld.com/article/253902/how_to_connect_your_hdtv_and_smartphone_with_mhl.html

 

[Solandri]

If you just want to convert 3.5mm analog audio to HDMI, a variety of adapters will work depending on your input cable. Be aware that some phones use a 2.5mm headphone jack, not 3.5mm.

https/www.amazon.com/Monitor-FOINNEX-Connecting-Laptop-HDTV-Male/dp/B071SHJ1S3
https/www.amazon.com/Neoteck-Composite-Converter-Blue-Ray-Projector-Upgraded/dp/B01JYCXP3S

For a more complete solution, you could buy a used AV receiver with HDMI out off of Craigslist (I see them for about $50-$90 on my local CL). That will give you a whole bunch of different audio inputs (and often analog video as well), along with 5.1/7.1 speaker capability and a AM/FM radio tuner.