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Discussion Starter · #1 ·
Hi,

I have Sharp zw99 projector and a computer monitor for my display units. Right now I am using common RGB A/B switcher to select between them. My questions are:

1. How much does the switcher degrade the picture quality? How do I find out?

2. Can I switch them during both units on? How is damage potential?


Xiaoyu,

 

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I can't answer your second question as far as your Sharp projector goes, but I would be very surprised if there is any harm in switching while the projector is running. Many forum members, including me, do exactly that. But then again, you're using a cheap A/B switch, which leads me to your first question:


I can tell you from personal experience that cheap mechanical A/B switches introduce significant and readily visible ringing (faint outlines around screen objects) and sparkles (where what should be solid, steady-state pixels appear to "sparkle" at random) into the picture. If you have a $3,000 projector, and especially if you're feeding high-quality DVD and HDTV signals into it, it's insane to pollute the bitstream with the interference caused by a $20.00 switch.


The three biggest problems with mechanical switches are the fact that they are mechanical (moving parts that eventually degrade and wear out), are often poorly shielded, and usually lack the bandwidth capacity needed to pass high-definition video signals unmolested. Solid-state electronic switchboxes by Altinex, Extron, et al do not suffer from any of these problems.


If you search the forum back around the March-April timeframe you will see a number of posts from me on this subject, grousing about the dismal picture quality caused by cheap boxes from QVS and Belkin and my gripes about how expensive the Altinex and Extron units are. Now that I actually own one, though (an Extron SW4 VGAxi, $443.75), I can see with my own eyes the quality picture that is possible with these devices. Quite frankly, there IS no visible deterioration of the video signal with my Extron 4-to-1 DB15 switcher. It's as if the video source was directly attached to my projector (an NEC VT540 LCD front projector with native XGA resolution).


But don't take my word for it... try displaying a simple Windows desktop on your Sharp projector through your A/B switch. Now go walk up to the projector screen and look closely at the text. See all the faint gray outlines around each pixel in each character? Notice how solid swaths of color seem to shimmer? That's your crappy A/B switch (not) hard at work. Of course, it could be that you also have a cheap VGA cable or two in the circuit--you can verify that by retesting with a known high-quality cable directly linking your computer to your projector. My money's on the switch, though.


Trust your friendly neighborhood Scooter. He's agonized through this whole process so you don't have to. Just save your shekels and buy a nice electronic switch so that you won't ever have to even think about switching again--one of the added benefits of electro-switches is that nearly all of them can be set to automatically detect and switch to the active video source, eliminating the need to ever touch the switchbox again. You'll forget that the switch is even there, because your picture will be perfect and you'll never have to worry about manually changing the video source.


My 4-to-1 switch connects my computer card, my compter HDTV card, my DISH 6000 receiver, and my RCA DTC-100 receiver to the projector and it all works as advertised. Life is beautiful--don't crap it up with a cheap switch!


Good luck.


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Scott Gammans
The Scooterplex Cinema 1


[This message has been edited by Scott Gammans (edited 06-02-2001).]
 

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I agree with Scott 100%. I am using the Altinex 1916SX switch for over a year with no issues whatsoever. They can be found on Ebay for a lot less than I paid. around a $100 used. Extrons will run you more but like Scott says you will have more inputs available.



Rick


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RJW
 

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Somewhat related. Is it better to go with a external video switch, and a good sound processor, or an intergrated unit?


SM
 

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Swampfox,


Ultimately, the answer is yes. An integrated unit will always risk electrical interference of some sort, where an outboard switcher simply will not have that as an issue.


But, if the integrated unit is designed properly, it may not be a real problem. The key issue is determining what the design compromises are (and there are always some) vs. what your needs/wants are.


Most recently, the current crop of mid-to-high end surround audio preamps have proper design in this area and I would not hesitate to use this type of equipment for both audio processing and a/v switching, making sure to verify the specs first.


In a few cases, I would even take a good old a/v receiver, assuming the design takes all of my criteria into account. Some of the latest Denon, Marantz, B&K, Onkyo (and others) units fall into this category.


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"better living thru modern expensive electronics"

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Discussion Starter · #6 ·
Hi Scott,


Thank you for taking time to answer my questions. I am going to check out the electronic switcher for my application.


Xiaoyu,
 

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On EBAY do a search on Altinex, They show up every so often. A good way to judge the used market is to check the prior auctions for the same topic.


Good luck


Rick




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RJW
 

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Discussion Starter · #8 ·
Quote:
Originally posted by wezar:
I agree with Scott 100%. I am using the Altinex 1916SX switch for over a year with no issues whatsoever. They can be found on Ebay for a lot less than I paid. around a $100 used. Extrons will run you more but like Scott says you will have more inputs available.



Rick


Hi Rick,


I found that Altinex DA 1917 SX is perfect solution for me. I have progressive dvd player and iScan Pro. This switcher has two VGA in for my two video sources and two VGA out for my projector and computer monitor. Which catagory can I find used switchers on the ebay? I may try it.


Xiaoyu,

 

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A mechanical switch is *not* bandwidth limited. The mechanical switch may not make good contact and cause ringing but when working correctly the switch should act as if a single piece of wire was run. The obvious test, bypass the switch. If it looks the same its not the switch. Electronic switches *are* bandwidth limited, making them have enough bandwidth to support HDTV is what makes them expensive.


I'm using a mechanical switch and have been happy with the results. Same as running the cable direct. I'm using BetterCables VGA cable. My cable run is short though, less than 10 feet.


ChrisO
 
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