ARpiCADE 4.2, QSound Audio, and Volume - How?

[petkorazzi]

I recently acquired a RaspberryJAMMA adapter and a Pi 4; currently running ARpiCADE 4.2. I have one single MAME ROM loaded to my SD card as a test bed (Espgaluda) and my monitor is in vertical orientation. The game runs and plays fine.

However, I'm having audio issues. My cabinet is a Capcom Impress which was designed to work with Capcom's CPS2 system - including the QSound amplifier/system. This has two RCA connectors for stereo sound that would plug into the CPS2 A-board, with volume adjusted on the A-board output itself (the amplifier runs full-tilt in this mode with no adjustment). Additionally it can run mono sound from the JAMMA connector, where the amp does have a volume adjustment pot.

Using the "normal" audio setup of the RaspberryJAMMA (3.5mm cable running from the DAC output to the 3.5mm input jack of the RaspberryJAMMA) and running the QSound system in mono mode, the audio works fine. And by "fine," I mean kinda distorted and crappy because it's mono JAMMA audio, but "functional." However, when I attempt to run the QSound system in stereo mode (using a stereo-3.5mm-to-dual-female-RCA adapter) there's a lot of background interference-y noise when there's no game/audio running, and then OMG BLOWS MY FUCKING HEAD OFF LOUD whenever sound is played (because the QSound amp isn't adjustable in stereo mode).

So I need to adjust the volume of the RPi output. I press F4 from attract-mode and go to the system volume adjustment option, hit enter, and...nothing. Black screen. I can exit this screen by hitting ESC, but there's nothing shown on the screen. I've tried various inputs (down keyboard arrow, down P1 joystick input, etc.) in an attempt to adjust the volume, but nothing seems to happen. I've tried using the RPi 3.5mm audio output and there's no audio output there at all - and it also does not appear to be adjusted by the system volume adjustment option.

So that's where I'm at right now. I need a reliable way to make output volume adjustments from whatever stereo source is best (probably the DAC) so that I can run my cab using QSound in stereo mode.

Any ideas? What (likely blatantly obvious) thing am I missing?

[dee2eR]

I'll have a look into why the Linux volume control doesn't show up on 4.2 (didn't realise it was broken until now... can confirm the bug on my end though so I'll figure it out.). It should the way you would adjust the overall system volume in software.

Luckily it works from the command line (I just checked). To do so exit the service menu with F4, then type

alsamixer

when you're finished type

sudo reboot

to reboot the system and get back to the menu.

A hardware solution I would consider in this situation is this: https://www.ebay.com/itm/FOSTEX-Volume- ... SwtUdgFBeU (there's probably similar things that are cheaper, but I have one of these and am happy with its quality, don't think I paid so much though...) I'm sure you could DIY a simlar solution very cheaply. Having a knob to adjust the volume while a game is running is certainly more convenient than doing it on the command line.

[petkorazzi]

That totally worked; thank you for the assistance. The idea to use a passive in-line volume adjustment is a good one as well.

Unfortunately I'm having other issues now (TONS of noise that's now louder than the game audio) but I think that's more an issue with ground loop or something hardware-related.

Thanks again!