Prior to seeking out and acquiring a CRT, it is imperative to consider your own situation and use case for one. The average CRT user today would likely be a gamer, who is primarily interested in retro gaming. Many analog video game consoles or media players have different methods and cables for video inputs, and it would be wise to research and understand your individual needs, which will in turn support what type of CRT you may want/need.
CRT Technology Differences
Aperture Grille is a technology created and patented by Sony for use in CRTs. Extremely thin wires were placed behind the glass and in front of the screen to differentiate colors of phosphors by separating them into strips. The primary advantage of the Aperture Grille, aside from its unique appearance, is a much finer dot pitch, which improves overall image clarity on the display. Almost all CRTs that use an Aperture Grille were manufactured by Sony, aside from PC CRTs made by brands such as Mitsubishi, Viewsonic, Dell, and HP after the patent expired, just a few years prior to the industry shifting to modern display technologies.
Shadow (Slot) Mask
Shadow Mask is the other form of CRT technology used to separate and display colors. Slot Mask, a form of Shadow Mask, was utilized by nearly all other CRT manufacturers throughout the industries lifetime. On a CRT that uses a shadow mask, the phosphors are aligned in a triangular (triad) shape. This provides a different appearance than an Aperture Grille up close, but from a standard viewing distance will not show much difference.
Shadow (Dot) Mask
Dot Mask is the other form of Shadow Mask used in CRTs. While identical to Slot Masks in the way they are implemented, Dot Masks are predominantly found in newer CRT PC Monitors, allowing for a generally improved dot pitch to support the higher resolutions that these monitors usually displayed.
CRT Input Formats
RF Video (Coaxial)
The earliest form of consumer grade video inputs, RF uses a coaxial connector to send all of the image information to a CRT to be displayed on the screen. Usually resulting in the lowest quality, using RF for video input should be avoided, unless necessary with specific consoles such as the original Nintendo Entertainment System (although consoles like the NES can be modified to use better video input formats, such as RGB).
Composite Video (RCA)
The most common video input format is composite video, which is transmitted via the yellow cable shown in the image above (the red and white are used for audio transmission). Composite video sends all the video information down one line, similarly to RF, but usually results in improved video quality over RF. Almost all analog media was designed to be able to output Composite video, and finding Composite cables, or a CRT compatible with composite video should be extremely easy.
S-Video, also known as Y/C, splits the Luminance (Y) and Chroma (C) signals that Composite video sends, resulting in vastly greater picture quality. Devices that are compatible with S-Video, and CRTs capable of taking S-Video are often harder to come by than those that use Composite video, but it was still a widely used video format in most of the world. For many looking to use a CRT display, S-Video is greatly preferable to Composite and should be the minimum to seek out when looking for a CRT.
Component Video (YpBpR)
Component Video, also known as YpBpR, splits the video and sync signals into three lines, which carries the signal of their respective color as shown by the cables in the image above. Green and video sync are carried on the Yp cable, blue is carried on the Bp cable, and red is carried on the R cable. As a result of splitting the video signal up even further than how S-Video did for Composite video, the picture quality is immensely improved compared to any of the previously mentioned formats. Component video was a standard used in North America and can be found on many CRT televisions produced from the year 2000 and onward. This would be my input format recommendation to those looking for the best picture quality out of their CRT.
RGBHV (VGA) & RGBs (SCART)
RGB video is the highest quality of video input format, with the red, green, blue, and sync signals all being sent separately. There are a variety of RGB connectors, with the most common being VGA, which sends respective signals across 15 pins, and EuroSCART, which sends respective signals across 21 pins. Many CRT PC monitors utilize VGA, while CRT television sets produced in Europe may sometimes utilize SCART. If you are based in North America, it may be easy to avoid RGB entirely, and focus on seeking a Component/S-Video CRT and cables for use with your analog media devices and retro game consoles.
Not a video format, but rather a connector type (similar in appearance to RF) for any of the previously mentioned video formats, such as Composite, S-Video, Component, or RGB. BNC connectors deserve a mention as they are often found on professional grade CRTs, and require specialized BNC cables to be able to send video signals to the display.
Different CRT Types
CRT Televisions (Standard Definition)
The most common form of CRT that was produced, Standard Definition (SD) TV sets can take a variety of input formats (depending on region) and are capable of outputting video at SD resolutions, such as 240p and 480i. A high-end SD CRT TV is usually what most retro gamers or analog media enthusiasts are searching for.
CRT Televisions (High Definition)
Rarer and often disregarded, HD CRT TV sets were developed and manufactured over the last few years of CRT production. Most of these sets are only capable of outputting video signals that are High Definition, usually 480p, 720p, or 1080i. The difficulties found in displaying SD video content on modern displays are usually found with HD CRTs as well, although they do still serve various niche purposes.
PVMs/BVMs (High-Resolution SD/HD)
Professional Grade CRTs, usually referred to as PVMs or BVMs, are CRT displays that were designed for use by businesses and sold at very high costs when CRTs were still being manufactured. These CRTs usually have the highest end input options, can be both SD and/or HD, and have much higher TVL count (AKA CRT picture quality) than consumer grade television sets. Finding these can often be difficult or expensive given their rarity, and should often be disregarded by those seeking a cheaper/easier CRT experience.
CRT Monitors (PC Displays)
CRT Monitors, also known as PC CRTs, are higher resolution monitors that are usually incapable of displaying SD video content. With that being said, many PC CRTs were much higher quality than SD television sets produced at the same time, and as such can display beautiful, bright images, while also being easy to find and cheap. With proper conversion technology, PC CRTs can be used to display both SD and HD content and produce thick scanlines that many retro enthusiasts are seeking from a CRT display.