The Reflex Prism: Bridging Modern Digital Video with Classic Analogue Displays

The Reflex Prism is a specialized digital-to-analog video converter designed and produced by MiSTer Addons. Its core purpose is to enable modern digital video sources, particularly those outputting via HDMI, to connect seamlessly and without lag to high-quality analog displays, such as professional video monitors (PVMs), consumer CRTs, and PC CRT monitors.

This device is primarily aimed at retro gaming enthusiasts and users of FPGA-based platforms who seek to experience modern or emulated content with the visual authenticity and minimal latency of a cathode ray tube (CRT) display.

Core Technology and Features

The Reflex Prism is engineered for accuracy and performance, focusing on a pure, unadulterated signal conversion:

• Lag-Free 1:1 Conversion: The device operates with lag-free, 1:1 digital video to analog conversion. This means it performs no resolution upscaling, downscaling, or automatic aspect ratio changes, ensuring the output exactly matches the digital input resolution and timing.
• Maximum Resolution: It supports video resolutions up to 1920×1200, allowing it to interface with superior CRTs or PC monitors that can handle higher resolutions.
• Output Formats: The Prism offers simultaneous conversion to multiple key analog video formats, including:
  • RGB (Red Green Blue)
  • YPbPr (Component Video)
  • S-Video
  • Composite video is present on one of the ports but is not officially supported due to potential signal degradation (dot crawl).
• Audio Output: It includes a buffered stereo audio output via an independent 3.5mm jack and the Mini-Din 10 port.

Connectivity and Output Ports

The converter features a standard HDMI input and a USB-C power input. Its primary analog outputs are split across two ports to cater to different display needs:

1. HD15 (VGA) Port:
   • Configurable via a switch to output either RGBHV (for PC CRTs) or YPbPr (Component video).
   • This port is designed for higher-resolution analog signals, supporting inputs from 480p up to 1200p. It is the port used for connecting to high-resolution monitors and PC CRTs.
2. Mini-Din 10 Port:
   • This port, which shares the connector style of the Sega Saturn’s video port, is dedicated to lower-resolution analog signals, specifically 240p/480i (~15kHz horizontal scan rate).
   • It is typically supported by specialized retro devices like the MiSTer FPGA, Raspberry Pi, and GCVideo but is generally incompatible with most modern consoles and PCs, which default to a minimum of 480p/31kHz output.
   • The Mini-Din 10 port can output RGB and S-video simultaneously.

Use Cases and Compatibility

While developed by MiSTer Addons, the Reflex Prism’s application extends beyond the MiSTer FPGA platform. It acts as a Digital-to-Analog Converter (DAC) for any compatible HDMI source:

• MiSTer FPGA: It provides a crucial solution for MiSTer users with a dual-RAM setup, which typically sacrifices the native analog output. The Prism restores the ability to output analog video for demanding cores like the Atari Jaguar and Saturn. Configuration requires specific MiSTer settings like direct_video=1 and vga_mode=rgb.
• Modern Consoles: Examples of tested devices include the Nintendo Switch, PlayStation 5, and Xbox Series X, allowing users to play new games with an “old school feel” on a high-quality CRT display.
• Other Digital Sources: It has also been shown to work with devices like the Steam Deck, Mac Mini, and HDMI-modded consoles such as the Wii and Dreamcast.

Reception

The Reflex Prism has received high praise from respected figures within the retro gaming community. Independent tester Kuro Houou, known for their expertise in video processing and display technology, spoke highly of the device, declaring it to be “one of the best DACs I have come across for retro gaming,” and noting its comprehensive support for formats from composite up to RGB.

You purchase/pre-order a Reflex Prism by clicking here.