HDFury Nano GX / Gamma adjustment on HDMI to VGA DACs

[kitty666cats]

https://www.hdfury.com/product/hdmidvi- ... a-gamma-x/



^ are people aware of this link here? It's been up for ages; could be neat if we all pooled money and someone was willing to produce these... I don't personally own one - but I do own a X-Vue Gamma Boost (also released as the HDFury GammaX) as well as a X-Vue Box1020 (RGB to component transcoder, also with RGB passthrough / can adjust the gamma on either output). I'll often chain said devices after a HDMI to VGA for use on my CRT presentation monitor, and the results can be really great depending on your source material.

The Nano GX obviously has had its praise sung in the JunkerHQ OSSC Wiki... but the article on DACs in said wiki doesn't really elaborate on how the gamma adjustment circuit is awesome for making your image vibrant again after applying artificial scanlines. The circuit is also particularly nice to use if you are connecting, say, your PS4 to a CRT monitor & playing a VERY dark game, like something from the ___ Souls series.

Here is a link that should *hopefully* work to show what I am talking about:
https://discord.com/channels/5552187551 ... 8558662656

(you'll probably need a Discord account to view this... can upload elsewhere if anyone is actually interested, lol)

[thchardcore]

I have an X-vue and I love it. I can't imagine my setup without it to be honest. It makes such a huge difference in making sure the details are present in darker games.

[nissling]

Pathetic. That's all I have to say.

[kitty666cats]

^ “Look at how much I know about ~colorspaces~, you pathetic simpletons!”
It’s like… what, if people aren’t sitting down and perpetually calibrating their CRT, they’re doing it wrong? These circuits are quite useful if you’re not just cranking them all the way up at all times. You can also switch the sync polarity to negative if need be (at least on mine, unsure about Nano GX)

[nissling]

It’s like… what, if people aren’t sitting down and perpetually calibrating their CRT, they’re doing it wrong?

In this case I'd say yes, absolutely. Although you don't need to calibrate most displays very often if it's just for consumer usage.

If your display is so bad that you need to compensate EOTF to even get proper clipping at black then you should just trash it or at least get it serviced as it is seriously defective. And if you're willing to spend 3,000 USD like the listing linked in OP without learning even the basics of calibration then you sure know how to waste your money.

Based on the pictures in the comparison I'd say this is all wrong. Partly because the levels are completely off but also because of how much the shadow details are lifted in the after shots. Especially in the last comparison you see some serious lacking bit depth and posterization. Doing proper calibration will solve everything and is a much more solid solution. I feel like most people on this forum make calibration seem far more difficult than it really is and instead opt to inferior alternatives that in reality just takes time and costs more money than necessary. That makes me feel it's all pathetic.

[kitty666cats]

How about the use-case of maintaining a vibrant image after applying artificial scanlines? Would something like this not be more idea than be than just cranking up a monitor’s contrast or gain?

Furthermore, the devices are moreso geared towards CRT projectors, which are an even bigger pain in the ass to calibrate than most CRTs. When I use mine they are with a 34” presentation monitor, which I am most assuredly not going to be moving around all the time.

Anyhoo - another thing for folks to take into account is that this DAC is on the higher-end of things as far as HDMI to VGAs go (my link in the OP doesn’t mention this, but 1920x1440p @ 60Hz will work; would be interesting seeing someone chain with a RT5X on a higher-end PC CRT)

[kitty666cats]

Also the $3,000 is essentially the rights to produce your own lol, not just for one unit

[nissling]

If you can achieve the kind of image with an external device you can most likely do the same by using the internal controls, again unless the display is incorrectly engineered or defective. And in the case of CRTs there can be multiple factors involved which affect how the EOTF will appear and they should always be used in a dark enviroment. But this whole thing that shadow detail get lost is something I am not familiar with unless the black level is set incorrectly or the display is in need of servicing. Of course there will be some blooming if there are bright objects on screen and thus cause the low ANSI contrast to become more obvious but it shouldn't be anywhere near the same issue as described. And I've worked with several CRT projectors but have never seen one where the EOTF curve have been so off that external hardware must be used.

As for the scanline effect then sure, I stand corrected. That can be a case where a slight change to the EOTF curve could make a more pleasing image but you're not using such filters on a CRT right? On LCDs and OLEDs it's imho a better idea to opt for a brighter light output in such a scenario but that's a personal preference from my limited testings. I'm not questioning the DAC whatsoever. I've had a few HD Fury devices and have not seen any issues with them as far as the image capabilities go.

[thchardcore]

My issue is certain games being incorrectly ported (GC MGS, DC Resident Evil 2/3, etc.) Where the gamma correction cures this without making me throw my setup off for everything else.

[kitty666cats]

As for the scanline effect then sure, I stand corrected. That can be a case where a slight change to the EOTF curve could make a more pleasing image but you're not using such filters on a CRT right?

Can be fun on PC CRTs every now ‘n again - “simulated high-TVL broadcast monitor” effect, heh. I apologize for coming off as saucy and defensive earlier, BTW. I just would like to see more HDMI to VGAs with extra features beyond the simple conversion being produced, it’s a nice concept. For example:

https://www.ebay.com/itm/High-quality-H ... 4695802867

[Shelcoof]

I have the Nano GX

The gamma boos helps with CRTs when using scanlines or even with old dim CRTs.

The boost does not affect the image as much but does just enough to brighten it to have a natural look.
It's not overly bright to the point where the image is degraded.

I too use it exclusively when using Scanlines on my CRT if my CRT does not already have a boost function built in

[kitty666cats]

I have the Nano GX

The gamma boos helps with CRTs when using scanlines or even with old dim CRTs.

The boost does not affect the image as much but does just enough to brighten it to have a natural look.
It's not overly bright to the point where the image is degraded.

I too use it exclusively when using Scanlines on my CRT if my CRT does not already have a boost function built in

I assume you’re referring to Super Bright Mode that some Mitsubishi/NEC DiamondTron monitors have, right? Or are there other PC CRTs out there with a similar feature that I am unaware of?

[Shelcoof]

I assume you’re referring to Super Bright Mode that some Mitsubishi/NEC DiamondTron monitors have, right? Or are there other PC CRTs out there with a similar feature that I am unaware of?

Yup plenty of other Monitors have tbis feature with a different name.

Philips
LG
Samsung

All have some sort of brightness feature or color feature for different applications

The best in terms of brightness is my Compaq which is bright enough

If you want the specific models I can look em up for you

[rodimus]

I finally got the GammaX, but I couldn't get it to work. I put external power, 5v 500ma, the light comes on, but no signal to the monitor. I've tried Dreamcast, Mister and Xbox360 through a hdmi/vga DAC. I also tried with another monitor and nothing, no signal. What could be happening?

[kitty666cats]

I finally got the GammaX, but I couldn't get it to work. I put external power, 5v 500ma, the light comes on, but no signal to the monitor. I've tried Dreamcast, Mister and Xbox360 through a hdmi/vga DAC. I also tried with another monitor and nothing, no signal. What could be happening?

Have you tried the switch on the GammaX that inverts the sync signal? Also, what kind of monitor is it going to?

[rodimus]

I have tried a Viewsonic Crt PC monitor and a Sharp LCD TV with VGA input. And yes, I have changed the polarity, and moved the 5v and pass switch. I don't know what else to do, and I'm a bit depressed because it didn't cost me cheap. Now I'm considering the possibility that it's faulty, and maybe I'll open it up to see if a friend can repair it. I don't know.

[kitty666cats]

I have tried a Viewsonic Crt PC monitor and a Sharp LCD TV with VGA input. And yes, I have changed the polarity, and moved the 5v and pass switch. I don't know what else to do, and I'm a bit depressed because it didn't cost me cheap. Now I'm considering the possibility that it's faulty, and maybe I'll open it up to see if a friend can repair it. I don't know.

Are you connecting the GammaX directly to the displays or do you have another cable between the GammaX output & the displays? Sometimes it needs another cable in between.

[rodimus]

I just tried the short extension cable it comes with and from there I put the cable that goes to the monitor. Still the same, no signal. Maybe I'm just unlucky.

[kitty666cats]

That’s a shame, sounds like it could indeed be a faulty unit. Hopefully your friend can fix it! I’d try using the extension cable and trying the sync inverter one more time…

[fernan1234]

A way cheaper way to do this gain/brightness boost thing for VGA monitors, etc. is to use an Extron interface that has a knob or switch for the exact same thing (originally meant to compensate for long cable runs).

[rodimus]

You're not far off kitty666cats. I replaced the cable I had connected between the GammaX and the Display, with the small cable that came with the GammaX in the packaging and it worked. Apparently the GammaX operates with a pin that traditional cables don't consider. Finally. Thanks a lot guys.