General Forum

Re: Cut off levels on an avant

Beobuddy — Wed, 11 May 2011 04:49:36 GMT

Remember one important thing: B&O handles a different colourtemperature! So starting with this guide gives you a different picture.

The guide handles the official 6500K whereas B&O goes much higher. Around the (measured) 10K with a BV10-46 and 9300K at my BV9.

Re: Cut off levels on an avant

Beobuddy — Wed, 11 May 2011 04:46:17 GMT

Somewhere in this guide:

Brightness: The control used to adjust black level. Setting brightness too low will cause darker details to be lost into black (called 'black crush'). Setting brightness too high will cause the black to appear grey. Brightness affects all colours at the same time.
Contrast: The control used to adjust white level or peak light output. Setting contrast too low will result in a dim picture. Contrast set too high can cause lighter details to be lost into white (called 'white clipping') or blooming/smearing. Contrast affects all colours at the same time. Some manufacturers call it 'Picture'.
RGB LowEnd: The control used to adjust the amount of individual Red, Green, or Blue colour in the darker end of the black to white scale. Think of it as an individual brightness control for each colour. Manufacturers all use a different name for this control though 'Cut', 'Cutoff' and 'Bias' are the most common terms used. I will refer to this control as 'RGBLowEnd' in this guide to avoid any confusion.
RGB HighEnd: The control used to adjust the amount of individual Red, Green, or Blue colour in the lighter end of the black to white scale. Think of it as an individual contrast control for each colour. Manufacturers all use a different name for this control though 'Drive' and 'Gain' are the most common terms used. I will refer to this control as 'RGBHighEnd' in this guide just to avoid any confusion.

Re: Cut off levels on an avant

Beobuddy — Wed, 11 May 2011 04:40:56 GMT

To add: http://www.curtpalme.com/forum/viewtopic.php?t=10457

Here a guide how to calibrate if you're thinking of doing it yourself.

Buy yourself a Eye-One LT instead of the Spider3. I bought the Eye-One in a large (online) photoshop in The Haque.

Re: Cut off levels on an avant

tournedos — Wed, 11 May 2011 03:16:59 GMT

nbohemen:
Rcu Gcu en Bcu (cut off levels). What do they do?

Thought I'd answer the question for future reference.

The "cut-off" points for a CRT refer to the grid control voltage (and thus electron flow) where the phosphor dots cease to emit any light. This sometimes changes when the tube ages - material from the cathode evaporates and contaminates the grid surfaces, or some similar process.

As the red, green and blue circuits are mostly separate, what this setting effects in a colour CRT is more intuitively called "black balance" by camera control operators - quite simply put, whether black is black.

Aging components can also put this setting between R, G and B out of balance. This is obviously originally set at the factory and you can't just copy values between sets or use some "correct" values, they depend on the particular tube and the component tolerances in the set.

The adjustment should be set with a fully warmed TV, colour saturation set to 0, using a gray scale test image. If you see any tint in the darkest areas, adjust the cut-off levels to make it go away. This will not be easy at all if you don't know how the RGB colour system in television works.

If - and only if - you see any discolouration in the brightest areas AFTER setting the cut-off levels, should you use the respective drive level settings to arrive at correct white. It is very easy to make a mess here!

***

ALWAYS make notes of original settings before messing wth the service menus! Better yet, don't even go there unless you have the skills and the test equipment needed to set them correctly!

Re: Cut off levels on an avant

Beobuddy — Tue, 10 May 2011 16:18:39 GMT

Kokomo:

What do cant & isnt mean? They are not proper words!

I know, sorry, I meant can not and is not. My keyboard fails now and then.

@ Nico, how did you solve the problem?

Re: Cut off levels on an avant

nbohemen — Tue, 10 May 2011 14:32:25 GMT

I already solved it. Thanks

Re: Cut off levels on an avant

Kokomo — Tue, 10 May 2011 14:03:53 GMT

Beobuddy:

This is why we all are warned not to enter the service menu. These settings cant just be resetted to the originals.

Try to find someone who has an avant with probably the (most) same settings. It isnt the right way, but it probably will do.

The official way is to recalibrate the rcu figure with the help of a testpattern.

This is what I could find about the settings in the servicemanual.

Sorry for not helping you.

What do cant & isnt mean? They are not proper words!

Re: Cut off levels on an avant

nbohemen — Tue, 10 May 2011 13:42:50 GMT

I know you can't just set them back to the original.

Re: Cut off levels on an avant

Beobuddy — Tue, 10 May 2011 12:49:57 GMT

This is why we all are warned not to enter the service menu. These settings cant just be resetted to the originals.

Try to find someone who has an avant with probably the (most) same settings. It isnt the right way, but it probably will do.

The official way is to recalibrate the rcu figure with the help of a testpattern.

This is what I could find about the settings in the servicemanual.

Sorry for not helping you.

Cut off levels on an avant

nbohemen — Tue, 10 May 2011 11:58:48 GMT

In the section picture adjustments of my Avant, there is the possibility to alter the Rcu Gcu en Bcu (cut off levels). What do they do?