[JonFo]

I just upgraded from a DLP projector to a Sony G70 CRT. Man, what an improvement, but that’s another story…


However, one of the downsides of CRT ownership (as ya’ll know) is having to perform convergence (registration in Sony parlance) when you first install it.

The most difficult and time consuming (after focus ) alignments is getting the green gun geometry perfect. Usually it involves lots of measuring at the screen. A real PITA in my book…


Since I kept my DLP projector in its ceiling mount location and the CRT is floor mounted, I had a cool idea for how to leverage one to help setup the other.


So, here’s a tip for those of you with CRT FPTV’s and access to a LCD or DLP projector:


Use the AVIA test patterns on the DLP proj. to deliver the crosshatch with dots image at 30 IRE onto the screen. Make sure it’s well aligned (i.e. centered), and with correct keystone.

Then go through a serviceman mode Green gun geometry alignment on your CRT, lining up with the projected gray hatch patterns already on the screen.

The geometrically perfect DLP image lets you easily see bows and skews that measurements might not easily detect. And more importantly, linearity errors are also very easy to spot and correct.


Presto! Perfect green geometry to work from for the R and B guns.


Setting 16:9 ‘picture size’ vertical squeeze is also easy: just switch to the 1.78 letterbox hatch on the system driving the DLP and resize the image on the CRT to fit.


I now have an amazing, perfectly aligned image from my G70.


Try it; you’ll like the results.

 

[Alan Gouger]

Not a bad marketing idea.


Avia should package one with every disc


God idea though, clever.

 

[jamoka]

Yet another excellent use of a digital projector.

 

[PF]

Yes, and if the projector has screen door effect, as an LCD projector would, its usefulness is even greater -- there's that many more on-screen grid lines to align against.

 

[Curt Palme]

We never miss an opportunity to bash digital, do we?


Curt

 

[Mark Glover]

Hmm, I didnt know that was another name for my CRT Projector Calibration Device

 

[PF]

You realize fellas, that the audio analogue (pun intended) of all this is vinyl vs. CD.


So, the question is, who has a turntable and a CRT projector? I only pose this in the interests of ultimate, metaphysical consistency, of course.

 

[jamoka]

Are you saying we should use a CD player to calibrate our turntables? I don't get it.

 

[Specboy]

I think PF means analogy, but I don't agree with him.

 

[PF]

Specboy,


No, I meant analogue.


jamoka,


CDs are digital technology. So is LCD, DLP, D-ILA, i.e., digital projection. CRTs, like vinyl records are an analog (or analogue) older technology. Discrete bits vs. continuousness, if you know what I mean. There is some intermingling of the technologies now -- the best turntables, for example, have their motor speeds governed digitally via computer chips, a particularly useful, apt application of digital processing.


Actually, like you, I was trying to think of a way to use a CD to calibrate a turntable. Perhaps greater minds than ours will come up with a clever method.

 

[Specboy]

If you mean analogue, then your post doesn't make any grammatical sense.

 

[PF]

Specboy,


It's a pun. Audiophiles refer to vinyl records and their associated playing equipment as "analogue." Just as CD is referred to by audiophiles as "digital."


Here in the U.S., analogue, a noun, is also defined in Webster's dictionary (analogue is the first spelling; analog is the second) as, "Something that is analogous or similar to something else."


CRTs, like turntables, are analogue (or analog) systems, electromechanically speaking. CDs, like LCD/DLP/D-ILAs, are digital systems.


Do you get the pun now?

 

[jamoka]

So, you're saying you can put a CD onto a turntable and somehow convert the turntable into a digital device? I still don't get it.

 

[Iceman]

PF,


There is a big distinction between "digital" projectors and other digital systems such as CD. The output from a CD-player is just as continuos as from your analog turntable. The reconstruction or anti-aliasing filter in a CD-player takes care of turning the discrete signal into a continuos ditto. This is not to say that the CD technology is flawless, though.


For myself, digital audio and CRT is the way to go (at least today).

 

[PF]

Iceman,


Of course the output stage is analog for CD playback, because that's what you're preamp stage requires -- voltage to pass along the reproduction chain. Unless, of course, it's a Meridian CD unit directly feeding one of it's digital speakers, in which case it's all ones and zeros from the laser all the way to the speakers. Phillips had an interesting speaker system that was similar many years ago, by the way, that was really ahead of its time.


The important point, though, is that CD playback is a digital system -- no varying voltage that represents the music's original acoustic pressure, just ones and zeros. The output stage of the CD player converts everything back to electrical pulses so that your speakers can take that magnified voltage (in corresponding amounts to the current the speakers require) and turn those electrical pulses back into acoustic pressure waves that correspond as much as possible -- with good speakers -- to those hitting the mike in the recording studio.


With a vinyl record on a turntable, the reproduction chain remains completely analog -- literally a mechanical device, the arm, reconstructing electrical pulses by moving in a groove. Reconstructing very similar electrical pulses from the analog output of your DVD player is what a CRT does, too -- nary a computer chip is to be found except in the peripheral support functions of the projector (menu system, convergence memories, etc.).


The analogy isn't perfect of course, and the digital DVD player as a source is where the analogy falls apart. So, in some ways the CRT is more akin to your speakers than your analogue turntable.


But the point I was really trying to make originally via my pun, is that the debate is precisely the same. The digital/CRT projector tussles that go on here are the same as those that go on in high end audio circles between vinyl diehards and CD fans. There, an inferior but more convenient media platform has almost completely displaced an infinitely superior sounding, but technologically archaic one. Vinyl record fans wonder, just as CRT fans do when viewing what passes for the home theater experience among digital projection fans, why proponents of the new technology can't see that the emperor has no clothes. They sit in their seats squirming and bored by the distinctly digital "flat sound" they're hearing, just as we do at the distinctly digital-looking flat images digital projectors produce. They know that turntables are inconvenient, complex and subject to imperfect ticks and pops...and they don't care because the sound is so rewarding. Just as we sit in our dark caves, content to put up with the inconvenient size, weight, complexity, and less-than-ideal brightness of CRT projectors...because the image we get in return is so compelling.


Anyway, apologies to all for the lengthy digression.

 

[Chuchuf]

Ahhhh, I see now that Jon has now "Seen The Light"!!

Great idea though.

Ya'll ought to hear Johns theatre. It is truly very impressive.

Later,

 

[Iceman]

PF,


Your analogy between turntables, CRT and digital technology is indeed tempting, but is in many ways not correct. There is way to much ground to cover on this vast subject, especially since we are clearly off topic here, so I will just limit myself to this:

The line structure in the vertical direction of a CRT is not continuos, but more or less discrete (depending on the degree of overlapping), making CRT technology at least half "digital" in its nature.


There is absolutely nothing wrong with digital technology, it just comes down to engineering whether its full potential is realized or not.

 

[Specboy]

PF, My original comment was nit picky really but you original said "the audio analogue ( pun intended ) is cd vs lp". My point was that you probably meant " the audio analogy ( pun intended ) is cd vs lp" would make more sense. I wasn't talking about analog vs analogue.


As for the rest of it, I'll say that most people I know when they sit down and look at projectors in appropriate environment can look at the different technologies used for projection and easily pick the crt's as the most lifelike. As for audio I believe most would not be able to pick the which is sonically superior with the same distinction and that is why I think the analogy doesn't fit.