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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Pro AV Forum => Topic started by: Bob Cap on January 16, 2012, 06:08:52 pm

Title: VGA Cable run
Post by: Bob Cap on January 16, 2012, 06:08:52 pm
I have a show this weekend that just told me they want to run a laptop VGA output to a couple of video projectors.

It's a mac laptop with only a VGA output.

The projectors have VGA input and looping output.

The distance we need to go is about 60-70 feet to the first projector and then on to the next.

The customer wants us to provide long VGA cables to make this hookup.

Will this work?

I don't own a mac laptop to even try this out.

I always understood you could not go that type of distance.

Any suggestions?

Thanks

Bob Cap
Advanced Audio Inc.
Gilbert, MN
Title: Re: VGA Cable run
Post by: Brad Weber on January 16, 2012, 06:22:54 pm
I have a show this weekend that just told me they want to run a laptop VGA output to a couple of video projectors.

It's a mac laptop with only a VGA output.

The projectors have VGA input and looping output.

The distance we need to go is about 60-70 feet to the first projector and then on to the next.

The customer wants us to provide long VGA cables to make this hookup.

Will this work?

I don't own a mac laptop to even try this out.

I always understood you could not go that type of distance.

Any suggestions?
Maybe.  Seriously, the quality of the cable, the resolution and scan rate (and thus the bandwidth) of the signal, the quality of the connections and even the video out of the laptop and projector input can all affect the image.  And since you're looking at looping through the first projector, possibly the distance between the two projectors.  Of course, what is considered as an acceptable image is also a critical factor.  So it might work but about the only way to be sure would be to mock it up.
Title: Re: VGA Cable run
Post by: David Buckley on January 16, 2012, 07:49:34 pm
I've got a 15m VGA cable (about 45 feet) which works just fine at 1024 x 768, so that's more than half way there, so I'm tempted to say 60 feet should work.

Most projectors I've seen that have the extra 15D connector allow them to be configured as either an input or an output, so the electronics hacker in me says there isn't a relay and a genuine loop in there, the socket is electronically driven, so the extra leg is not directly fed from the input cable but via an active split.
Title: Re: VGA Cable run
Post by: Jonathan Kok on January 16, 2012, 08:35:10 pm
I have a show this weekend that just told me they want to run a laptop VGA output to a couple of video projectors.

It's a mac laptop with only a VGA output.

The projectors have VGA input and looping output.

The distance we need to go is about 60-70 feet to the first projector and then on to the next.

The customer wants us to provide long VGA cables to make this hookup.

Will this work?

I don't own a mac laptop to even try this out.

I always understood you could not go that type of distance.

Any suggestions?

Thanks

Bob Cap
Advanced Audio Inc.
Gilbert, MN
Can't speak for others, but my experience with macs has been that the strength of the VGA output lacks...well, strength.  I've had to throw a booster in there at distances of 100'.  Of course, it will depend on the cable.
Ask how long their cables are, and the gauge.  Just because the distance is 60-70', doesn't mean they'll provide you with 75' cables.  Could be 100', could be more.

Something like this (http://www.kramercanada.ca/products/model.asp?pid=589&sf=25) is a handy tool to keep on...hand...bleh.  I hate puns.
Title: Re: VGA Cable run
Post by: Brad Weber on January 16, 2012, 11:08:57 pm
Most projectors I've seen that have the extra 15D connector allow them to be configured as either an input or an output, so the electronics hacker in me says there isn't a relay and a genuine loop in there, the socket is electronically driven, so the extra leg is not directly fed from the input cable but via an active split.
I've send HD15 inputs and outputs that, when used with the appropriate cables and/or adapters, could be used with VGA, RGBHV, RGB, component, Y/C or composite video but I don't think I've ever seen an HD15 connection on a projector that could be configured as either an input or an output.  And I have seen some projectors where the HD15 output is a simple loop from the HD15 input.

On a different note, if the Owner is providing the cables have you verified a path that allows you to pull a preterminated HD15 cable and coordinated whether any of the cables need to be plenum rated?
Title: Re: VGA Cable run
Post by: Ray Cerwinski on January 17, 2012, 01:26:40 am
Just an FYI, the OP stated he was contacted to provide cabling to the client while giving the impression the client was to provide the projectors and laptop. It also seems this is a one-off event, removing an installation scenario from the mix.

In this case, I'd run the output from the laptop into a VGA distribution amplifier and then run two individual cables from the DA to each projector. As long as you are using a quality active (powered) DA, you should be fine. I would stay away from those lovely HD15 y-cables that pop up from time to time. K.I.S.S.

That said, I've never seen first-hand any projector that had any kind of loop out on an HD15 connector, let alone user configurable.
Title: Re: VGA Cable run
Post by: Brad Weber on January 17, 2012, 08:43:44 am
Just an FYI, the OP stated he was contacted to provide cabling to the client while giving the impression the client was to provide the projectors and laptop. It also seems this is a one-off event, removing an installation scenario from the mix.

In this case, I'd run the output from the laptop into a VGA distribution amplifier and then run two individual cables from the DA to each projector. As long as you are using a quality active (powered) DA, you should be fine. I would stay away from those lovely HD15 y-cables that pop up from time to time. K.I.S.S.

That said, I've never seen first-hand any projector that had any kind of loop out on an HD15 connector, let alone user configurable.
Ray, you are correct about the general situation, I misread the OP.  However, many projectors have a loop out for the HD15 input, although they vary in exactly what it is and can do.  It would probably make sense to confirm looping through the first projector is even a viable option for the projectors involved, if it is not then that would be all the more reason to look at a DA.  You might also want to confirm the native resolution of the projectors, assuming them to be 1024x768 and finding out they are instead 1920x1080 could make a difference in what may work and what you provide.
Title: Re: VGA Cable run
Post by: Gary Creely on January 17, 2012, 09:02:15 am
Maybe.  Seriously, the quality of the cable, the resolution and scan rate (and thus the bandwidth) of the signal, the quality of the connections and even the video out of the laptop and projector input can all affect the image.  And since you're looking at looping through the first projector, possibly the distance between the two projectors.  Of course, what is considered as an acceptable image is also a critical factor.  So it might work but about the only way to be sure would be to mock it up.

Couple thoughts here.

60 feet is not that long a run for VGA, however looping in and out of projectors is not the best route because they are often a passive loop and weaken the signal.

The VGA distro amp would be the way to handle this if you were trying to stay with VGA cables.

I would suggest a Kramer TP114 VGA to Cat5 distro and pt120 receivers. This would give you a 300' range and 4 outputs, for the cable just use regular cat5 cables.
Title: Re: VGA Cable run
Post by: Jonathan Kok on January 17, 2012, 10:05:01 am
I've send HD15 inputs and outputs that, when used with the appropriate cables and/or adapters, could be used with VGA, RGBHV, RGB, component, Y/C or composite video but I don't think I've ever seen an HD15 connection on a projector that could be configured as either an input or an output.  And I have seen some projectors where the HD15 output is a simple loop from the HD15 input.
Eiki LC-WB42NA
http://www.eiki.com/wb42na.htm

(first one that comes to mind...I'm sure there's more)
Title: Re: VGA Cable run
Post by: Brad Weber on January 17, 2012, 11:32:05 am
Eiki LC-WB42NA
http://www.eiki.com/wb42na.htm (http://www.eiki.com/wb42na.htm)

(first one that comes to mind...I'm sure there's more)
In my experience that is an unusual configuration and the manual is confusing on the functionality.  When describing the Computer In 2/Monitor Out terminal the manual states "This terminal can be used to output the incoming analog RGB signal and component signals from COMPUTER IN 1/COMPONENT IN terminal to the other monitor (p.17)."  But then Page 17 states "Analog RGB and component signals cannot be output from the COMPUTER IN 2/MONITOR OUT terminal when using the COMPUTER IN 2/MONITOR OUT terminal as output."  These seem to directly contradict one another and I have a feeling the latter may be a typo with the last "output" supposed to be "input".  Whether it functions as a second input or a loop though of Input 1 is selected as a 'Setting' menu option, however other comments like "When the cable is of the longer variety, it is advisable to use the COMPUTER IN 1 / COMPONENT IN and not the COMPUTER IN 2." suggest that it is potentially limited in its use as an input. 
Title: Re: VGA Cable run
Post by: Scott Carneval on January 17, 2012, 05:07:11 pm
First of all, how old is this Macbook that it has a VGA output?  I have one about a year old and one about 5 years old, the newer model is an Apple DisplayPort output that requires an adapter to do VGA, HDMI, or DVI.  The older one is DVI and again requires an adapter if you want to do HDMI or VGA.  I'm willing to bet your client has a relatively new model Macbook and will require an adapter of some sort.  You need to verify that they have the VGA adapter before you proceed any further. 

Next, I would not count on the loop thru of the projector because you're going to be running about 150' of cable by the time you get to the second projector, and if it isn't amplified that is at the extreme max of an RGBHV run.  Your best bet is to get a VGA DA (distribution amplifier) with multiple outputs and run a separate VGA line to each projector.  Since you're posing this question in the first place, I'd say it's pretty safe to assume you don't own the DA or cables.  Whoever you're purchasing or renting the cables from should be able to provide you with a DA for no more than $30-$40 a day. 

Someone mentioned a Cat-5 solution, and while that would do the job just fine, normal category cable is fragile and won't last long in the rental/production world.  Heavier duty cable is available, but it's not going to be as cost effective or readily available as normal VGA and a DA.
Title: Re: VGA Cable run
Post by: Jonathan Kok on January 17, 2012, 07:14:07 pm
In my experience that is an unusual configuration and the manual is confusing on the functionality.  When describing the Computer In 2/Monitor Out terminal the manual states "This terminal can be used to output the incoming analog RGB signal and component signals from COMPUTER IN 1/COMPONENT IN terminal to the other monitor (p.17)."  But then Page 17 states "Analog RGB and component signals cannot be output from the COMPUTER IN 2/MONITOR OUT terminal when using the COMPUTER IN 2/MONITOR OUT terminal as output."  These seem to directly contradict one another and I have a feeling the latter may be a typo with the last "output" supposed to be "input".  Whether it functions as a second input or a loop though of Input 1 is selected as a 'Setting' menu option, however other comments like "When the cable is of the longer variety, it is advisable to use the COMPUTER IN 1 / COMPONENT IN and not the COMPUTER IN 2." suggest that it is potentially limited in its use as an input.
Agreed on the typo.  Just pointing out an instance where such a beast exists.
What this allows, then, is basic Room Combining without the need for a splitter or matrix.  In theory, with the proper RS-232 control, you could attach Input Plate A in Room A to Projector A, then Input Plate B in Room B to Projector B, and tie the Computer2/MonitorOut jacks together.  Using the RS-232 control to reverse the configurations on the Computer2 Jack, you could control which way the signal flows.  Input Plate A-->ProjectorA-->Projector B, or Input Plate B-->ProjectorB-->ProjectorA.
Not that I've ever actually tried it...but the theory's sound.  Assuming you can control the config of the Computer2 jack over RS-232.

Back on topic...as others have mentioned, you're certainly better off splitting the VGA signal at the source, rather than trusting the monitor out.  No-one's saying it WON'T work...but if you're going in blind, may as well have the right tools to 'make it work' when things start going bad.
Title: Re: VGA Cable run
Post by: Bob Cap on January 17, 2012, 09:53:11 pm
Tomorrow I'm going to check out the VGA cable through jacks on the projectors. Being in Northern Minnesota does not give me a lot of local sources to find this type of gear...

My client says the output on the Mac is VGA...

I won't even see the laptop until soundcheck. Grrr.

Anybody work with the Nelson brothers doing "Ricky Nelson Remembered"? Do you know what they showed up with?

Just the normal everyday show...

Thanks

Bob

Title: Re: VGA Cable run
Post by: Bob Cap on January 18, 2012, 11:29:57 am
Project update!

They have a 3 year old 15" MacBook Pro. It has an Apple mini display port. He has adapters to standard VGA and/or DVI.

Any suggestions?
Thanks
Bob
Title: Re: VGA Cable run
Post by: Scott Carneval on January 18, 2012, 04:12:03 pm
Project update!

They have a 3 year old 15" MacBook Pro. It has an Apple mini display port. He has adapters to standard VGA and/or DVI.

Any suggestions?
Thanks
Bob

VGA distribution amp as mentioned above
Title: Re: VGA Cable run
Post by: Chuck Fudge on January 18, 2012, 04:28:15 pm
I have not had any problem going long distances using VGA/RGBHV cabling, as long as DA's are used in the correct places.  It was suggested to use a DA at the source, and then run seperate cables to each projector....great suggestion as long as you have enough cabling.   I have in the past used a DA at the source, cabling to first projector placing another DA at this point, short cable to projector and then continue your run to the next.

Rule of thumb is to not amplify a weak signal....amplify at or near the source.  Personally I wouldn't go more than 50' without having a DA on hand just in case.  Computer VGA output is never consistant between models, or manufacturers.   Its always handy to use a scaler/switcher at the source.  This gives you the ability to blackout if needed, scale to the projector, and amplifies the signal at the source.  I've gone 100' out of our extron presentation switchers to projectors using vga/rgbhv cable with no apparent issues.

good luck

ps...is there spell check?
Title: Re: VGA Cable run
Post by: Bob Cap on January 29, 2012, 01:21:06 pm
Hey guys,

I took your advice and ran a DA at the laptop. 50' VGA Cables to each projector.

Rock solid slides and video.

Thanks much.

Bob
Title: Re: VGA Cable run
Post by: Scott Carneval on January 29, 2012, 02:36:06 pm
Glad to hear it worked out for you!