Marquee Modifications and Performance Enhancement 3 - Page 16 - AVS Forum
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post #451 of 465 Old 08-22-2004, 01:36 PM
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Hi Mike, Bill,

Quote:
Originally posted by mp20748
[B The main board (UMB) idea sounds like a good idea. I'll like to know how that turns out. [/b]
Hmm, you DO know that Mark has his Marquee apart :D
Removal of the UMB is only a few screws away :D

Bill wrote:
>Yes, but how will we know? There's really no easy way to AB.

Doing a "eye A/B" is impossible here since by the time you have
put everything back together again, your brain will never remember
what you saw before.

In Mark's case Mike (or Mark) could do a scope check on the rails and
the filament rails before and after, tho.

Greets,
Reinhard

Gimme a hot soldering iron. I got work to do ;o}
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post #452 of 465 Old 08-22-2004, 02:44 PM
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Quote:
Originally posted by bblue
Yes, but how will we know? There's really no easy way to AB.

--Bill
Bill,
It seems like you need to setup two projectors in your shop. One reference projector mounted just above the one you are working on for mods.

Glen Carter
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post #453 of 465 Old 08-22-2004, 05:16 PM
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Quote:
Bill,
It seems like you need to setup two projectors in your shop. One reference projector mounted just above the one you are working on for mods.
Oh I can just see it now. I can't seem to get out of my own way modifying just *one* projector all the time -- let alone two or three.

--Bill
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post #454 of 465 Old 08-22-2004, 10:02 PM
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Well actually MP has one of my 9500LCs but it is in the house with the mold. The other which is the one I use in my house still is pretty much together except for the pulled neck boards and the 2 pulled tubes. Certainly a lot of hanging wires. The tubes go to VDC tomorrow, 3 day air. I hope to have them back the first week in September. Then I hope to get MP to put them in ASAP. Ett es ze beginning of the NFL season azns Sundays my rear end wants to be in my HT watching those games in HD.

Vic. A one year old Greater Swiss Mountain Dog weighs in at about 100lbs. They can grow to about 150 lbs but this one will probably top out at about 125. They take 3 years to reach full maturity unlike me who at 59 is still in my puberty. We already have a small dog, our 16 1/2 year old broken coat Jack Russell Terrier, Fritz. The Greater Swiss came with the name Buddy and the breeder asked us not to change it.


As to me going AWOL, I will bring a stupid bulb projector home from my store if MP can't do a tube install and set up quickly. I'll hide it where the lenses that MP took out were and tell my guests that it is a CRT with a MP VIM mod so the contrast can be turned up to 95 with no blooming.

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post #455 of 465 Old 08-22-2004, 11:32 PM
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Quote:
Originally posted by bblue
Oh I can just see it now. I can't seem to get out of my own way modifying just *one* projector all the time -- let alone two or three.

--Bill
It was just a thought for your A/B comparisons.

I wish it were easier to get accurate, representative digital photos of the projected images for comparative purposes. I just haven't had any luck.

Glen Carter
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post #456 of 465 Old 08-23-2004, 04:52 AM
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Quote:
Originally posted by bblue
Yes, but how will we know? There's really no easy way to AB.

--Bill
There's only one way to know for sure and that is to use a spectrum analyzer.

Even with the A/B method, there's really no way of knowing if you've lowered the noise for the usable video bandwidth. The goal is to crush it at the useable frequency window, as there will be some level of noise above and beyond. By doing the UMB as well, there's a better chance of widening the window for easier end results.

The noise from the control board is very high, while the noise from the power supply is mid range, and the noise from the sweeps (vertical/horizontal/HVPS) circuits is the lowest. This is what is on the rails, and a scope will not show all of what's on the rails.

I like Reinhards method, because it would be the best method to lower the noise in all three areas without a spectrum analyzer. Once the work is done (pre decoupling) on the UMB, then it makes for better results from the secondary decoupling at the boards input (my method). This would be the absolute best way to go to lower the noise in the projector -- that is, if the goal is to lower the noise in the projector as a whole.

My newest (test) VIM/neck baords are able to produce a sharp and non blooming image all the way out to a contrast setting of 95. this means that the video circuits are not seeing any of the noise that is generated inside of the projector. But I must say, I'm doing more than adding caps.

Maybe the "pre decoupling" method could make for a cleaner signal bed. And this would lower the tweaks factor, by not having to contantly change caps in other areas of the projector (shifting noise windows) to a particular source of range of video signals.

As I said before, the video image test of your favorate source, should be the end result, not the test result.

It's all about the performance... Got Marquee!

 

High Performance Marquee Video chain modifications.  Now available!

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post #457 of 465 Old 08-24-2004, 07:00 AM
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Mark, I guess the "little guy" isn't so little at this point anymore, then. I'm sure he's getting a great home, though, either way. I hope he's settled in fairly well by now - it always takes a few days.

Guys, just a bit of an update. I've now modded my VIM to some extent. I added 1 47uf oscon, 1 0.01uf polyester and 1 150pf mica cap (in addition to the original 0.1s) to each voltage rail of the first 3 amps and the multipliers on my 03 board (removed the stock 1ufs here), and added 1 22uf tant as well as the smaller caps on the second set of amps due to space contraints. I have also subbed in 0.47uf stacked film caps like the type Bill is using for the input caps.
Since my projector still isn't really set up well, I gave this modded VIM and my set of neck boards (G2 resistors swapped for metal oxide, coupling resistors for signal path swapped out for metal film, 2x 1uf Z5Us swapped for X7R, blue 22uf caps subbed for 100uf caps, some additional capacitance added to the +-5volt rails near the amp, although not as much right now as on the VIM) to Paul Bellemare (GN2) for testing on his 8000.
Although it was somewhat of a quick test, Paul watched a bit of HD, and also used his computer (9700, not MPd) for a bit of veiwing.
He was not too inpressed with the changes so far, although he noted that the scanlines were maybe a bit more distinct, and there was a small bit of added detail to the background in some of the HD he viewed.

Therefore, as it stands, the changes are reportedly somewhat negligible, and probably orginate primarily from the input cap changes, and the resistor changes. The extra decoupling on the VIM does not appear to significantly help out the image when using the stock clc449s, as Mike and Bill both alluded to earlier.
My plan is to swap out the clc449s for the EL5166s that we talked about earlier. These are specced at roughly the same values for feedback as the clc449s are using on the board, and have a MUCH higher slew rate, and (maybe) has a higher bandwidth. I say maybe because the specced gain of 2 bandwidth on these ( http://www.intersil.com/data/fn/fn7365.pdf ) is not clarified for what output voltage value is being output. The clc449s have a typical value of 500Mhz bandwidth at gain of 2, large signal output. The 5166s give only that they have an 800mhz bandwidth at gain of 2. As stated, they still have a VERY high slew rate, so maybe the difference between large and small signal is much smaller due to the possibility of a much steeper slope for the edge of a square wave. I don't know, but I will see if they make a reasonable direct substitute in the next few days.
Thanks guys,
Vic


EDIT: I just took another look at the datasheet, and found a graph on page 6 of the 5166 datasheet regarding large signal, gain of 2 bandwidth. At gain of 2, 3v p-p input (therefore 6 volt p-p output), the amp has a very respectable 350mhz -3db bandwidth. Therefore, at a full 6 volt output, the bandwidth is a little under 50% of the smaller signal bandwidth. This is pretty good, as the CLC449s have a typical 500Mhz at less than 2 volt output (maybe input, but this would still only give a 4volt output). Note that the min according to the clc449 datasheet at 25 celcius is at 380mhz for this statistic.
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post #458 of 465 Old 08-24-2004, 07:24 AM
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post #459 of 465 Old 08-24-2004, 10:50 AM
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Guys, I realized that my mathematical anylysis of the amp noise was incorrect - I was thinking stats.
Either way, the datasheet for the clc449 specs a maximum voltage noise of 2.9nv/root hz, therefore the 1.7 value of the 5166 is 58% percent, for a total decrease thoughout the system of 40% without taking into account any artifacts that are produced throughout the signal path by the added noise. Also, the oscillation the clc449s are prone to should hopefully not be present in the signal as well.
Vic
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post #460 of 465 Old 08-24-2004, 11:18 AM
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Vic,
I would caution you in making and trying to evaluate all these changes without first establishing some viewing baseline to compare. Subjective evaluations based on an arbitrary setup condition, or first time viewers' opinions are of little value.

Is there any way you can get it well setup and running with good sources to where you can at least come closer to 'before' and 'after' evaluation?

HD source (at least) would be required.

--Bill
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post #461 of 465 Old 08-24-2004, 11:40 AM
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Bill, I agree with you on that - I was trying to get a general feel for the performace differences so far. I figured that perhaps the changes might have been a little more extreme so far than they proved to be (due to the large number of mods I've done so far)- generally I was wanting to know if the changes were very easily discernable even to general veiwers (Paul has had a marquee for at least a year, I believe, so he is pretty aware of how the stock machine looks with his sources -he also saw KBKs modded marquee a number of times - that said, I agree that it was not an ideal test- I hope to do better with that later). I will try and get the machine setup well soon. I am also waiting for the moment on a new version MP-1 and I am trying to find a 5700ultra locally (which is proving to be a challenge), so everything, including the aforementioned green tube is in a state of relative flux with my setup right now. When everything is together, I will definately be using HD sources, running from the computer, which should give a good baseline for comparison. I just hope that once everything is together, its not 2 weeks past the start of school (which is the 14th for me, but I do need some prep time for it).
Thanks for the feedback, though - as always, it is appreciated Bill.
Vic
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post #462 of 465 Old 08-25-2004, 12:43 PM
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Since the P14 voltages were being discussed, I decided to play with one of my tools. I did some data logging on the P14 voltages at 1 second intervals. The graphs show the results of one test.

 

p14 voltages.pdf 62.7421875k . file

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post #463 of 465 Old 08-26-2004, 08:23 AM
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Glen, excellent grphical representation. Thanks for that!

Guys, I took another look at the application notes on the chip ferrite beads at digikey (http://dkc3.digikey.com/PDF/C042/0752.pdf). The last entry states that they can be used to prevent oscillation in high frequency amps. This makes a whole lot of sense to me - how are you expecting a high frequency, inherently slightly finicky device to operate reliably at the high frequencies its specced for when the rail's input voltage is constantly shifting levels (however minutely)?

On another note, I finished installing EL5166s into all positions on my VIM and neck boards yesterday. So far I have only tried 1024*768 resolution, and dvd playback, but they don't seem to be causing any noticable problems so far (looking at the tube faces). I'm going to hand them off to Paul today for him to give them a quick test with some high definition content, to do a bit of performance and stability testing. Hopefully they make a noticeable improvment. If they don't I'm going to try and replace the buildout resistors with 80ohm, 3A ferrites, similar to what is used in the THS datasheet and give them another test (this is going to happen anyways, though). Currently, I'm only using 0.01uf and 150pf caps across the stock 0.1s on the various amps on the VIM. I still have the oscons, etc on the multipliers.

Vic
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post #464 of 465 Old 10-08-2004, 06:28 AM
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bump

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post #465 of 465 Old 11-18-2004, 05:04 PM
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Hey Vic, has this thread died or are you just taking a break. How did the tests with the 5166's go, any improvement.

Walter
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