Let’s talk about TVL count

So, fellow retro gamer perfectionist, you’ve decided to jump on the pro monitor bandwagon that all of your fellow mates have been talking about for years. Whether it’s Fudoh’s thread on Shmups, the neo-geo.com CRT Fetish Thread, those “My Life in Gaming” guys on YouTube, or Matt from videogameperfection, the demand for Pro CRTs for retro gamers is now higher than ever.

Most commonly, people are going after Sony PVM and BVM monitors, since they are the most common. (They were, after all, the gold standard production monitor back in the day.) For simplicity’s sake, I’ll only talk about Sony monitors in this post, but you can apply the same logic to other brands as well. But even when you restrict your search to Sony, there are still many different models to pick from, with different attributes.

Sony CRTs are marketed under the “Trinitron” name. Trinitron is their brand name for their special aperture-grill CRTs. All Sony direct-view color CRTs are Trinitrons, whether consumer TV, professional monitor, PC monitor, or broadcast-grade. The only time you would encounter a Sony CRT that wasn’t a Trinitron, would be a monochrome CRT, or a rear or front projection CRT system.

Sony purchased aperture grill technology from Paramount Pictures and made the “Chromatron” in 1964, and finally the Trinitron in 1968. Sony would continue to be the only manufacturer of aperture grill CRTs until the patent expired in 1996. (Mitsubishi marketed “Diamondtron” CRTs as a direct competitor in the late 90’s and early 2000’s.)

But back to Sony’s professional monitor lineup. For their PVM (Professional) line, they offered models branded Trinitron, as well as “HR Trinitron” (High-Resolution). The difference between the two is that the HR tube has a higher TVL (Television Line) count.

The earlier 90’s models offered a TVL count of 600 for HR tubes and 450 for standard tubes. These include 13 and 19 inch models such as the PVM-1354Q (HR), the PVM-1954Q (HR) and the PVM-1350 (non-HR). The later generation, the PVM-20M2U, PVM-14M2U, PVM-20M4U and PVM-14M4U had a TVL count of 800 for HR and 600 for standard.

For Sony’s BVM lineup, only HR Trinitron tubes are offered, since BVMs are designed for extremely accurate critical evaluation of video signals and color correction. These are master grade, and is reflected in the price point. TVL count is a lot easier for BVMs. It is represented by a letter code in the model name. E=1000 lines, F=900 lines and G=800 lines. This letter code system starts with the BVM-20F1U series offered in the mid-90s up until the last BVM-A series. Older BVMs, such as the BVM-1911 use an 800 line CRT.

So what are TV lines anyway? A shameless copy and paste from Wikipedia says this:

TVL is defined as the maximum number of alternating light and dark vertical lines that can be resolved per picture height. A resolution of 400 TVL means that 200 distinct dark vertical lines and 200 distinct white vertical lines can be counted over a horizontal span equal to the height of the picture. For example, on 4 by 3 inches (10.2 cm × 7.6 cm) monitor with 400 TVL, 200 vertical dark lines can be counted over 3 inches (7.6 cm) width on monitor (Note that the 3 inches (7.6 cm) of monitor height is used rather than the 4 inches (10 cm) of whole monitor width).

TVL is an inherent quality of a camera or monitor and should not be confused with the horizontal scanning lines of broadcast television systems, which e.g. for a PAL system are 625 lines, and for the NTSC system 525 lines.

page1-562px-TVL.pdf

Note that part that I bolded up above. When measuring TVL count, you count the vertical lines in a horizontal distance equal to the height of the tube. This is why the PVM-20S1WU, the only widescreen PVM has a TVL count of 300, despite its fullscreen counterpart, the PVM-20M2U having a TVL count of 600.

So what’s the point of having a higher TVL count, and consequently a higher CRT resolution? In consumer TV land, back when everyone was still watching their TV programming on CRTs, TVL count is low. A typical 19″ color TV tube from the 80’s and 90’s will have a TVL count of about 300 to 350, and even that is being generous. But that’s by design. You see, consumer’s hate flicker. And the standard NTSC 480i flickers by nature due to the interlaced picture. With such a low TVL count, the alternating scanlines overlap each other and blur together, so you don’t notice any flickering.

On the other hand, broadcast engineers need to be able to accurately monitor and evaluate those individual interlaced scanlines. They need to be able to view them without them overlapping each other. To do that with zero overlap, you need a TVL count of about 800 or higher. Of course this makes the flickering nature of interlaced video extremely apparent. That’s why HR tubes are not market towards consumers.

HR trinitron
The HR Trinitron logo. The HR logo itself expresses the high TVL count that HR tubes offer.

TL;DR: the higher the TVL count, the sharper your scanlines are going to be.

So the important question here, is how sharp do you want your scanlines to be when you play your retro games? Do you like the scanline effect at all? Some people hate it. If you’re one of those people, you might be better off buying a consumer TV that has component inputs, or modding a consumer TV for RGB input.

If you hate scanlines but still have to have a pro monitor, I would go after an N-series PVM, such as the PVM-20N6U. The N series is the “budget” PVM. It has a lower TVL count of 500 and is internally closer to a consumer TV. Beware though: the N6U has RGB, but no component. Watch out for the N5U, which only has composite or S-video.

You could also go after an old CGA computer monitor, such as a Commodore 1084, Amiga monitor, or an Apple IIGS monitor. These use consumer tubes and have low enough TVL counts so that you won’t notice any scanlines. Of course they all have different connectors on their RGB inputs, so you’ll have to make some custom cables.

In my experience, I prefer a TVL count of about 600 for 240p games. I enjoy having visible scanlines, but not when the black space between the scanlines is greater than the scanlines themselves. 800 TVL HR tubes have about a 50/50 scanline to black space ratio. The 900 and 1000 TVL tubes on the BVMs have even more black space.

So end the end, it comes down to what you prefer to look at. If you are still shopping around for a pro monitor and are not sure if you like the scanline effect or not, try playing some emulators with simulated scanline effects turned on. If you love it, then go for that HR tube. If you don’t like it, don’t go for an HR tube.

3 thoughts on “Let’s talk about TVL count

  1. Hey. Not sure if you’re still around here, but if you are..

    Can you explain to my thick skull, why how many vertical lines are ln the screen affects how you see the scanlines?? Aren’t the scanlines horizontal?

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    • The scanlines are horizontal, but counting horizontal lines to measure “TV lines” doesn’t make sense. You would always have the same 480 or 525 lines or whatever regardless of how sharp those scanlines are. Counting theoretical visible vertical lines just gives you an easy way to estimate the “resolution” of the picture tube. Remember, this isn’t a digital pixel count we’re talking about here, so resolution refers to how much detail can be perceived in the tube’s image. We measure this resolution in “TV lines”.

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  2. Awesome info on this blog. I just read this post and learned a lot. I think I prefer something around 800 TVL with the scanlines as close to 1:1 as possible.

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