CRT lag

Introduction and history

Technical setup

Spoiler: Photo of scope

Spoiler: Two photos

Expectations and lag classes

Measurement results

CRT type|Brand / model|Photo of CRT|Lagless?|Min. amount of lag|Max. amount of lag|Scope screenshot|notes

PC monitor|Sony GDM-F520| Yes |1 µs|30 µs|

Broadcast monitor| Sony PVM20M7MDE| Yes (480p only, lags on 480i)|1 µs|50 µs|

Flat late-era CRT TV|Panasonic TX-29E40D/M| No, heavy lag |25 ms|25 ms|

Late-era CRT TV|Samsung CW-28C75V| No, medium lag |8.3 ms|8.3 ms|

16:9 CRT TV|Sony KV-28WX1D| Yes |? µs|330 µs|

4:3 CRT TV|Sony KV-X2101D| Yes |? µs|340 µs|

Small 4:3 CRT TV|Toshiba 14N21DB| Yes |~10 µs|144 µs|

4:3 CRT TV|Daewoo| Yes |~50 µs|364 µs|

CRT type|Brand / model|Photo of CRT|Lagless?|Min. amount of lag|Max. amount of lag|Scope screenshot|notesPC monitor|Sony GDM-F520||1 µs|30 µs|Broadcast monitor| Sony PVM20M7MDE|(480p only, lags on 480i)|1 µs|50 µs||Lags 8 ms when fed 480i from frame rate doubling, no lag on 480p though, where no doubling happensFlat late-era CRT TV|Panasonic TX-29E40D/M||25 ms|25 ms||Seems to do frame rate doublingLate-era CRT TV|Samsung CW-28C75V||8.3 ms|8.3 ms||Seems to do frame rate doubling16:9 CRT TV|Sony KV-28WX1D||? µs|330 µs||Seems like 5 lines of overscan4:3 CRT TV|Sony KV-X2101D||? µs|340 µs||Seems like 5 lines of overscanSmall 4:3 CRT TV|Toshiba 14N21DB||~10 µs|144 µs||Seems like 15 lines of overscan4:3 CRT TV|Daewoo||~50 µs|364 µs||Seems like 6 lines of overscan

Interpretation

Conclusion

Recommendation

A simple VGA CRT setup consists of

The converter's output will always output a black screen for 1-2 seconds after ending a match on a bright stage, which can be fixed by replacing a capacitor. There are no mid-match problems even without the capacitor changed, so it doesn't interfere with tournament play strictly. If the blacking out bothers you and you don't want to solder in a different cap yourself, you can also contact me, I plan to sell VGA-005 boxes with the cap exchanged together with my controller orders.

Alternatively, you could go for the cheap Wii VGA cables on AliExpress, which do not have the blanking problem, however their picture quality is worse and less sharp, so I don't think that's worth the trade.

Comparison pictures will soon be in the OP of this thread!

Possible upgrades

Over the years, there have been quite a few reports of CRTs that do in fact lag. One somewhat prominent example was Armada's Genesis 1 pools set against WhatIsFear in 2009 . The first match was played on a CRT TV that, according to @Armada , lagged. TOs and other players were consulted, but whether they confirmed the impression of lag or not is controversial.According to @ajp_anton , a technical guru, yet expected to, as a fellow Swede, to be biased in Armada's favor, reported here on Smashboards that everyone agreed that the TV lagged.On the other hand, @WhatIsFear told me in a Twitter direct message conversation that all TOs said that the TV was fine and did not lag at all.Regardless of how the TOs really reacted, this anecdote tells us that CRT lag is a problem that should be seriously evaluated and addressed and needs a standardized way to be dealt with.As a follow-up to StabbyMcKniferson 's recent post in this very thread, I used a similar set of tools to measure the delay between video signal and photon output.Devices used:1. Rigol DS1054Z oscilloscope (4-channel, ~400€)2. Vishay BPW34 Silicon Photodiode (since sold out, cheapest other offer here . The photodiode was connected with its + pin to 5V (from Wii USB through a breadboard power adapter) and with its − pin to scope probe (through breadboard).Reference signal was a complete black-to-white scene change, which is very easy to set the oscilloscope to trigger for, since during the black scene, the video levels always stay below the point they immediately reach as soon as the first bright pixel is sent.This is done by using a Melee iso with debug menu access and(as camera control is deleted from 20XX, making it impossible to pan the camera properly). DBMODE is set to develop, stage to STORY (Yoshi's), environment visibility is set to black (with four presses of R+↓ on D-pad) and interface visibility is set to pure black (with one press of X+↓). The camera is shifted to the very top (with → on D-pad and C-stick ↑).At this point, pressing X+↓ another time will immediately cause a scene change from pure black to pure white.In my scope screenshots here, I used input 3 for the video input and trigger. Input 1 is the photodiode connected to 5V.For the VGA CRT PC monitor tests, I used a Gamecube with a VGA DAC cable that was run through an Extron MVX 88 matrix switch ( previously proven to be lagless (<10 nanoseconds) and synced (<5 ns) . One VGA output was connected to a Sony GDM-F520 (reference class graphical CRT monitor) and a different output was connected with a VGA-5BNC cable to the scope (green signal was used).For all CRT TV tests, I used a Wii's composite video cable that was connected to CRT and scope with a simple passive splitter.The photodiode was put inside a small breadboard connected to the main breadboard with jumper wires. The small breadboard was put in front of the CRT at its northwest corner.Doing so notably did not compensate for the overscan problem StabbyMcKniferson explained in his post here before. On the two CRT TVs that had a few lines delay, expected to stem from overscan, I also ran a second test, where I positioned the photodiode at the vertical middle of its left side, where I also showed a light gray platform (to be used as the first vertical bright color information to be picked up by the photodiode) that was toggled on with X+↓ too.Due to the imperfect positioning of the photodiode and possible overscan, it's expected that there will be some error range in when the photodiode first reads full white level. This delay is expected to be in the range of up to 100µs (three 480p lines).In the table below, "min. amount of lag" will be the lowest amount of time after scope trigger after which there is a notable brightness increase in the photodiode levels. "Max. amount of lag" is the time it takes until the photodiode levels have reached 100%.I expect the "true lag" to usually be much closer to the former than the latter, but with my current set of equipment and process, I can only prove that the true lag is not more than the "max. amount of lag" in the table.Every amount up to 1 ms (1000 µs) is negligible and should be classified as "lagless". In fact, in CRTs, delays in that order of magnitude are most likely only due to overscan and inaccuracies of my process.For some of the TVs, I re-did the test using a black-to-white scene change that only occurs at about the vertical middle of the screen, so that I can compare video signal levels to photon output without overscan interfering. For these, I added the respective screenshots and changed the max. amount of lag to the respective delay.Delays from 2 ms to 5 ms should be fine for playing, but I think the terms "nearly lagless" or "low lag" are better to use for these.Every amount of lag that exceeds 5 ms should not be considered free of lag. 5-10 ms should be classified as "medium lag" / "it lags a bit", and everything above 10 ms as "heavy lag" and downright unplayable.Most of the CRTs I tested have under a millisecond delay (1/16th of a frame) to display the first line of new frame video information, and that is only due to overscan delay. For the tests I did with mid-frame black-to-white scene change, the delay was much lower and easily below 100 µs.The only CRTs that did lag are late-era ones that seem to have laggy post-processing; frame rate doubling, to be precise. I theorized before that this feature necessarily introduces a minimal amount of lag of 8.3 ms, which was confirmed by the Samsung CRT lagging exactly that amount (and the Panasonic even more).The explanation for this is that to double the frame rate, the CRT needs to wait for half a full frame until it starts shooting its buffered data, so that it receives new video information just by the time it "runs out" of buffer lines.Effectively, only the first line of the Samsung CRT has 8.3 ms of lag. In the middle of the vertical screen, I expect it to only be delayed by 4.15 ms, and at the bottom the delay would be less than 1 ms.Very strange is why the Panasonic CRT TV adds an entire additional frame to the necessary 8.3 ms frame-doubling delay. I suppose it's possible that it also does different post-processing like comb filtering during that frame.This test series proved that there are CRT TVs that do lag. So far, all of these have been late-era SD TVs, but I suppose it's not impossible for older TVs from the eighties and early nineties to lag too.HD / ED TVs (those with YPbPr inputs that accept 480p) are, from reports I've read so far, expected to be even likelier to lag from post-processing, with the exception of PVMs and other reference monitors.VGA monitors (intended to be used with PCs) are completely free of lag and can always be configured with the OSD controls to have no overscan too.I highly recommend that, if you are in need of a screen to play Melee on, you go for a VGA CRT monitor. By doing so, you completely avoid the risk of buying a useless laggy CRT.If that is not an option to you (for example because they are unavailable or above 50$ in your area, or because of the need to get extra speakers), at least avoid CRT TVs that are flat or look like they are rather new (1998 or later), since their chances of having severe lag seem to be much higher.1.(~25$)2.(~5$) (don't forget to enable Native Control in Nintendont! And perhaps "Unlock Read Speed", which decreases read times, but should only be used when you have the music off since it causes the in-game music to cut out about every third match)3., see my post below (~20$ together).4.(0-10$ for low to mid-end / 15-50$ for high-end)5.for better picture quality and compatibility with distribution amplifiers and capture cards (no need for the Mayflash converter when going with this option)6.(for example 109xi or 164xi; only needed when using the Mayflash VGA005) (~20-40$) (to make the VGA cables output compatible with dist amps and capture cards) (slightly worse picture quality than #5, but still pretty good)7.(50-150$) (helpful if you use a multitude of consoles / other VGA output devices and VGA monitors)8.(30-50$) (useful if your CRT has low brightness / contrast and you want to improve that without opening the CRT and subjecting yourself to dangerous high voltage) (examples: Kramer VP-103, Extron PA 250)