New HDMI Audio Out Board (RGB2HDMI)

[Darklord]

(this was mentioned elsewhere but I thought it worthy of it's own message thread)

So the new audio HDMI add-on board is out for the RGB2HDMI mod. It's a very small
board that is soldered onto the existing hat for the RGB2HDM mod and will still fit
into the 3D printed RGB2HDMI case, according to the release.

I ordered one from Retroshack here in the US, along with the audio cable. Price was
$30.00 before shipping.

This would seem to be pretty handy for ST owners using the RGB2HDMI mod with a
desktop LCD with speakers included. It seems a bit less useful for my STacy, since
the replacement LCD panel I'm using there does not have any speakers.

So my question is, since it's still using the stock Yamaha sound chip from the ST line,
can we realistically see improved audio? At first glance, I would say not, but then,
what do I know?

Thanks all.

https://retrohackshack.com/product/rgbtohdmi/

[Darklord]

I think what I'm really wondering is if the audio signal from the HDMI audio out board would
be "cleaner" than the audio mod I'm currently using.

STacy Audio Mod01.JPG (236.11 KiB) Viewed 179 times

[alexh]

So the new audio HDMI add-on board is out for the RGB2HDMI mod. It's a very small
board that is soldered onto the existing hat for the RGB2HDM mod

I've ordered a custom version for my CDTV RGBtoHDMI v2. It's a tiny stereo audio ADC that samples the analogue audio and streams the digital sample data back into the RPi for insertion into the HDMI stream.

This would seem to be pretty handy for ST owners using the RGB2HDMI mod with a
desktop LCD with speakers included.

Definitely will be.

So my question is, since it's still using the stock Yamaha sound chip from the ST line,
can we realistically see improved audio? At first glance, I would say not, but then, what do I know?

It is intended to connect to the stereo analogue audio out (which for STe/MegaSTe/TT is a mix of YM and DMA). I don't know if the motherboard has any analogue filters you can bypass? i.e. take the audio from a different point on the motherboard? That is the only way you're going to improve audio quality.

I think what I'm really wondering is if the audio signal from the HDMI audio out board would
be "cleaner" than the audio mod I'm currently using.

I don't think so. It is Digital->Analogue->Digital->Analogue whereas your solution is Digital->Analogue

[Darklord]

Ah, okay then. I was hoping that it might produce a cleaner signal, resulting
in better sound when I fed it into one of the modern "smart" boom boxes that
simulate stereo sound from a mono signal. That's what I'm using with my
current setup - an LG Xboom P7.

I used it at VCF Midwest 2025 and it produced good sound (IMHO).

Here's that speaker:

https://www.lg.com/us/speakers/lg-p7-portable-speaker

Here's what it sounded like at VCF Midwest 2025:



And playing some MOD's: