Gunnar Turnquist's U-AMP Aims to Be a Universal, Open Source Audio Amp for the Retro Console Crowd
Designed to assist the "portablizing" community in getting high-quality audio from their creations, Gmanmodz's U-AMP is now available.
Gunnar "Gmanmodz" Turnquist has released a new open source "universal" audio amplifier, primarily — though not exclusively — designed as an improvement for classic games consoles receiving an upgrade to direct digital audio output.
"It’s now 2020, I don’t see myself using normal old analog audio in a portable ever again. I’ve got digital audio working for PS2, Wii, Dreamcast, and even almost N64," Turnquist writes. "Digital audio has the benefits of being able to bypass the digital-to-analog audio converter present on motherboards which takes out the middle man to reduce interference on the audio output. This also gives the best audio quality you can have in a portable and allows us to trim motherboards smaller in some cases.
"The portablizing community has needed a good audio solution for a very long time. The only audio amps commercially available are portable speakers, which is a bad hack. And the PAM8803, which doesn't have a headphone amplifier. Neither of these solutions is ideal."
The answer: Turnquist's U-AMP, a compact board designed as a universal amplifier — or as close as possible, supporting the digital audio from his previous modding efforts as well as an analog input. "The board is based around the LM49450 IC which I have used many times. The amp is controlled by a PICLF15324; the LF version of the same PIC I use in the WiiPMS.
"I added two jumpers on the PCB which set the audio configuration between the four input sources. The code will configure the LM49450 to operate in the correct console mode. It also handles volume control. I added the feature to be able to hold the volume plus/down and it will periodically increase, rather than tapping it fiercely. It also has a quick mute feature by pressing the plus and minus buttons at the same time to toggle mute."
Turnquist has released the PCB files and firmware source for the U-AMP on his GitHub repository; pre-assembled boards, meanwhile, are available to purchase from the BitBuilt website at $25 apiece.