LG Plasma Panel tweaks for better blacks. - Page 12

That quote is describing the effect of the number of panel subpixels on brightness. Absolutely nothing to do with source resolution.

They are saying that more panel subpixels means more "time" is required to send data to all of them and thus less time is available to emit light. Since PDPs control brightness via "time" (i.e.- PWM), if there is less time to emit light then the panel is less bright.

In other words they are saying a 480p PDP display is brighter than a 1080p PDP display. Source is irrelevant.

This quote is really interesting. For one thing, it sounds like the number of sub fields is equal to the number of bits in the pixel data (in this case 8). I did not know this. In fact, I really don't know much about how the panels actually operate and also an still learning.

The second thing that jumps out is the effect of refresh rate. They state that for 8-bit data it takes about 12 ms to service the 8 sub fields and since there is 16.7 ms allocated per frame (at 60 HZ) there is left 4ms for the discharge sustaining interval except for the reset interval. Now if we refresh at 72Hz for a 24p movie the time per frame drops from 16.7ms to 13.9ms (1/72). This would leave only 1.9 ms for the discharge sustaining interval. What deleterious effect might this have on the image? Is this related to the reason why 24p feeds have a higher MLL?

Firstly, it is describing a very old PDP system. At the most I would just use it as a reference for basic learning.

Secondly, to answer your questions, in your example the panel brightness would be reduced because the total sustain period has dropped from 4ms to 1.9ms. In reality, a 72Hz capable panel would have either a dual scan system or like modern panels have single scan with faster addressing (e.g. - much less than 12ms).

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Now, THAT's interesting! Since having a couple of S10-plasmas (S1 in the USA) in 2009 I always thought of Panasonic to be superior with the pwm noise in the grey shades near black.

Besides beeing finer, the noise appeared as neutral grey to me.

So Panasonic got worse regarding this issue in the year 2011 versus the year 2009?

P.S.: I tuned Vs a little notch down and have the feeling, that the clumpy pwm noise near black is less obvious than before ("Marley is dead"-chapter in "A Christmas Carol" for example).

Also on the same time, I have the feeling, that I can see details in that secene more easily, but this is probably just, that my pupils keep a little bit wider than beforce, cause reducing the Vs lowers the light emission of the cells.

My set has a sweet spot regarding the VZB. Turning it anymore than that clockwise changes nothing for the PQ on my set.

The more I keep it counterclockwise, the more headroom I have for Set_UP though.

Hmmm, on my german PK350 there is one (only one) right combination ob

a) Gamma

b) Brightness

c) R, G, B of IRE5

On that sweet spot (again ), which is Gamma High, Brightness 54 and IRE5 at +5 -1 -2...

a) Black bars are always black

b) No black crush in the image itself

c) all different shades of grey from 17 up to 25 are perfectly distingushable from each other.



P.S.: Just found out, how bad line bleeding is n Panasonic GT30 and VT30! LG had the problem last year, but the PZ-models, like PZ250, PZ550 and PZ950 seem to not have any light bleed.

Screen filters aside, in a dark room a tuned and calibrated PZ250 should be a more than worthy opponent to a calibrated VT30.

It's 96hz (4 * 24) for germany.

The best MLL I have in 60hz, secondbest in 24p and 50hz (our broadcast over here) comes in third.

Nope.

Videolevel (16-235) is used on almost all sources! You must set your blu-ray-player for example to "RGB Standard".

0-255 is only PC Level.

Important: If you set "Blacklevel from Low to High" and back again, you have to change the HDMI1 to 2 or from 2 to 1, otherwise the whole greyscale of the TV is confused!


EDIT: 16-235 versus 0-255 has nothing to do with black level (MLL)! It's only the range from black to white. The correct shade for black is normally 16 and for PCs it is "0" (zero). White is 235 for videolevel and 255 for PC level

236 up to 255 is also used in video level thogh. It is the range from white (235) up to whiter than white.

Never use 0-255 (High) on Blu-ray!

I wrote about a week ago, that you will get with the VZB POT more color punch plus the mll will lower too a little bit, well that is true (((but))) your whites will start to look like a beige color,I have to let this know,I notice this alot on the movie sin city,,so I turn the VZB to its original position also I did the same with the VSC,both the VSC and VZB are now in there original position,,,,I recommend to stay away of those to POTS and just follow the safe tweak.


MODEL:LG 60 PK550

I wonder, why noone over there in the D550-thread bothers, to open his set. Maybe it's possible with the Samsungs also.

In the Samsung service manual there is nothing written of pots, but who knows?

Just a suggestion to all...

If someone is posting some feedback on a good or bad result of a pots tweak, please write the type/model of set. That would help us all in IMHO.

On the PZ950, the VZB only turned a hair clockwise then maxed out. Don't know if just my PZ?

I was already able to turn Set_Up full throttle clockwise with no negatives before the VZB tweak with the Vy and VA according to your instructions with the blu-ray. Still haven't touched VS. what would the VS do exactly and which way turn?

I'm also interested in that. I touched it and it just caused vertical lines appearing all around, it has a narrow range where you can adjust it.

I don't know very well what Set_dn does (and which way move it towards), it didn't help with MLL, but pixel missfires appeared.

And Turrican4D, do you keep adjusting VA full counterclockwise? Does it have some contribution to MLL? I think it just gives more room to Set_up, but I didn't notice much difference from being full left or full right.

Thanks

The VZB pot does nothing but worsen the picture. If turned clockwise it will accentuate IR, if turned counterclockwise it will introduce pixelmissfires and a dull looking picture. I would leave it where it is.

I can only speculate based on the patent and waveform plots I have. As I said, unless we obtain the entire waveform for one frame period we can only speculate.

The Vzb and Vsc look like bias voltages applied to ensure addressing discharge prevent discharge between the Z and Y electrodes. If you look at the waveform plots I posted earlier this shows this clearly as the Vzb is slightly biased from the Vz and the Vsc is slightly biased from GND to augment the Scan voltage pulses.

If you adjust either Vzb or Vsc you risk an address failure which would create a black pixels or bright sparkles.

Additionally the Vzb seems to be used also in the Set-down period which means adjustment of this could lead to loss of pixel control (on or off).

Edit: I looked it up and changed the reasoning

Ya'll are sime brave souls....

Sometimes things may be better left alone.

Waiting to get my PZ950. I wull tweak it bwst I can through settings and live with tge rest....

One light pulse of the PWM is created during the sustain period of one subfield. The width of that pulse is determined by the number of sustain discharges during that period.

The best part about this tweak, is that no one has bricked their tv in doing it (knock on wood).

I did the tweak on my 50PK550 (North American model, Mar 2010 build) this morning with stunning results (so far).

Following the tips in this thread, I adjusted only VY and Set_Up. Factory presets were 4 and 1 o'clock respectively; I started by turning these to 2 and 7 o'clock (i.e. Set_Up maxed out). Wow! Massive instant improvement! Turned TV off and allowed to cool 45 mins. TV back on, again v deep black level ... BUT suddenly saw too many misfiring pixels (unacceptably noisy-looking picture).

I decided to proceed as follows: sit at my preferred view distance (lately 63") and then throttle back VY and Set_Up, not necessarily til absolutely no pixels misfired, but only until I judged the results to be tolerable in actual viewing. (I figured I was willing to trade off a certain amount of picture noise for better black level -- exactly how much noise, to be discovered by experiment.)

I did all tests in 72Hz mode since on my set the MLL is visibly better than it is in 60Hz. I know in theory it should be the other way round but I'm not the first to report this on the 50" model of the PK550. To get the colour bar patterns, played on PS3, converted to 1080p24 I used an outboard video processor (DVDO Edge); I also tried some HD cable movies and of course Blu-rays.

Eventually I settled into VY 3 o'clock and Set_Up 5 o'clock. If I look very very hard (from 63" away) at the blue and red on the colour bar pattern I can still sometimes barely see the occasional misfiring pixel. BFD; black levels are now insanely good, and besides, I can't see the misfiring at all during a movie. With my bias light on (GE 20W Daylite flourescent strip 6500K) black appears almost as black as the bezel. I don't have a light meter so I can't say what the MLL is exactly. Suffice it to say it's pretty freakin' black. If I wanted to I could probably watch this set in the dark. (I couldn't before the tweak; MLL was way too high for that.)

I watched half of Sin City Blu-ray and was utterly floooooored by the new improved contrast. Other PQ-demanding films which instantly went from blah to wow: Dracula (Coppola), The Spirit, dark scenes in Pirates/Caribbean #1. Can't wait to try more.

I'd like to say a huge thank you to the contributors to this thread. What an awesome tweak. I will post back if I run into any issues in future.

PS: 50PK550 owners: As you remove the back cover watch out for the mini screws around the component video inputs; they're easy to overlook. Ditto for the lone screw near the HDMI ins and the one by the power socket.