How to set up 3 displays to one HDMI output - AVS Forum
HDMI Q&A - The One Connector World > How to set up 3 displays to one HDMI output
justwright4's Avatar justwright4 09:12 PM 01-20-2014

I just purchased a new computer that we use windows media center to record tv, watch movies, and use for some light emailing/internet surfing. It only has one HDMI output so I always have to switch out the cords when changing between our tv, projector, and monitor.  We will never use these displays at the same time- I just want to be able to switch between them without always unplugging the HDMI cords.  I have read a lot on HDMI switches and splitters but am confused on which one I need.  Can someone please help point me in the right direction?


Thank you!

alk3997's Avatar alk3997 10:51 PM 01-20-2014
You want a distribution amp (drive all displays at the same time). It's also known as a splitter. A switch allows you to switch between inputs.

Mechanical switches are not usually used with HDMI for a number of reasons.

Check the forum archives for opinions and recommendations on distribution amps/splitters.
AV_Integrated's Avatar AV_Integrated 10:06 PM 01-24-2014
While some mechanical/passive switches can be reversed into a passive 3-way output splitter, it is typically better to get an active splitter to run to multiple devices.

Something like this is well reviewed and is only 40 bucks:

The passive style:

That model actually looks identical to what Monoprice has...

I would get the one for 40 bucks which is really designed to do what you want.
alk3997's Avatar alk3997 07:26 AM 01-25-2014
The passive style:

That's not a passive switch. The LEDs on top show that some power is being used by the switch. The power is coming from the HDMI cable and we know that method of powering the switch is not the most reliable.

I still am trying to work out how the EDID is managed when this device is used as a distribution amp (splitter). There would be three EDIDs coming back at the same time. So, somehow the switch is either choosing one EDID or there is circuitry inside to combine the EDIDs. I suppose the switch when in splitter mode could simply select the EDID of whichever button is selected in front, even though the button selection doesn't make sense in splitter mode.

I hadn't even though about HDCP until just now. That switch has to exchange keys between the single source and the three displays for it to work in splitter mode. I don't believe that can be done unless there is active circuitry.
Joe Fernand's Avatar Joe Fernand 09:31 AM 01-26-2014
Andy - the 'Passive' Switch' used in reverse would only Output to the selected Output Port, it won’t drive all three at the same time.

justwright4 - you are into tricky territory here!

‘switch out the cords’ - is not advisable as you can cause mechanical and electrical problems with the kit/cables and if you do stick with that option ensure you always have all devices powered Off at the wall whenever you are making any physical changes.

HDMI has been designed so that all 'connected' devices are involved in background Handshakes to cover Capabilities (EDID) and Copy Protection (HDCP)- when you see an Output ' Selector' you can be sure there is a good chance you are going to run into problems unless you again power everything (Inc. the PC) down before you make a change on the Output Selector, and even then there is no guarantee things will work as required unless the Selector device properly passes the EDID and HDCP handshakes from Source <>Display.

Have you considered adding a second Graphics card to the PC – that way you could have one card optimised for the PC Monitor and a second card via a 1x2 HDMI Distribution Amp Optimised for the TV/Projector.

Keeping the PC Monitor permanently connected to the PC is likely to make your system far more stable than a 3-way Distribution Amp feeding the Monitor, TV and Projector and means you can set the optimum resolution/refresh for the Monitor (which is often different to the optimum settings for your TV/Projector).

alk3997's Avatar alk3997 09:10 AM 01-27-2014
Originally Posted by Joe Fernand View Post

Andy - the 'Passive' Switch' used in reverse would only Output to the selected Output Port, it won’t drive all three at the same time.


Joe, but if the Passive Switch used in splitter mode only drives one output, that wouldn't make it a splitter. In fact that would be just one source driving one display, in which case wouldn't that box be serving no useful purpose?
justwright4's Avatar justwright4 09:16 AM 01-27-2014
Thanks for the responses! I wish I had asked these questions before running all the wires in our basement-lesson learned for next time. I haven't looked at a second graphics card yet, but that might be the best option. I currently have one hdmi and one VGA output on the PC, but I ran HDMI to each of the displays. Any thoughts on VGA to HDMI converters? I understand the audio probably wouldn't work, but that's ok because all my audio is output through a receiver.

Also, I haven't purchased the PC monitor yet, but would it make any difference if I used a small tv instead of an actual monitor?

alk3997's Avatar alk3997 09:30 AM 01-27-2014
VGA to HDMI is certainly permitted by the adopters' agreements and you can find some converters out there. You have to be careful on quality though, particularly for a computer application. You may also have to convert from VGA to component to HDMI, depending upon cost. Again, worry about quality of the final image since it's tough to use computer output where the words are "dancing".

A computer monitor is really a small TV with HDMI. So, I'd say no difference. The type of panel used is more important (such as IPS vs TN). Remember, too, with the exception of some very expensive OLED monitors, everything advertised as LED is actually an LCD monitor with an LED backlight.
budwich's Avatar budwich 09:58 AM 01-27-2014
Justwright4... IF as you stated in your original post that you will only use one display at a time, a "reverse" manual 3X1 (even a 4X1) switch will certainly fill the job as it will allow you to select any display without pulling / plugging any cabling each time. I have used one for a few years. The main issue now is that there appears to be few of them around and they have gone up in price. You have to make sure that they are indeed "manual"... basically only push buttons, no display leds, no auto anything, no remote, no powering, etc, kind of looking like the old analog component RCA switchers with hdmi connectors instead of rca plugs. Mine originally came off ebay and was only $15 plus $10 shipping. A quick scan of ebay appears to show only a few and they are $40 olus.
justwright4's Avatar justwright4 10:22 AM 01-27-2014
Yes, I will only use one display at a time. Is this similar to the manual switch you are referring to:

Joe Fernand's Avatar Joe Fernand 10:47 AM 01-27-2014
Hello all

I think budwhich and I are on the same page smile.gif

You take a fully mechanical 3x1 HDMI ‘selector’ and now wire a Source to the Output side and your three Displays to the Input side and fingers crossed you can select which Display is connected to the Source (you now have a 1x3 selector).

As bud points out it can be trial and error finding a suitable Switch as even some of the low cost ‘mechanical’ (3x1) units are directional and require you to ‘hack’ them using a soldering iron to use them in reverse (1x3).

You could still have the problem (for some folk) of potentially having to reboot the PC every time you want to ‘hop’ to a different Display as the HDCP and EDID would potentially get in a pickle if you try and Hot Swap between Displays.

alk3997's Avatar alk3997 10:52 AM 01-27-2014
Joe, yes I was thinking that he was after a splitter rather than a selector. My bad...
budwich's Avatar budwich 11:38 AM 01-27-2014
Originally Posted by justwright4 View Post

Yes, I will only use one display at a time. Is this similar to the manual switch you are referring to:


Yep... that appears to be a likely candidate. As Joe mentioned, some units have diodes inside that need removal. There are internet posts elsewhere indicating how to handle this easily. My unit didn't have this "feature"... Odds are low that this will be an issue.

This "idea" was given to me by this forum a while back so I can't claim any originality... :-)
justwright4's Avatar justwright4 08:46 AM 01-28-2014
So it sounds like I can get a powered splitter (distribution amp) and this will send the same signal to all three displays at the same time. I will then just turn on the one display that I want to use. I assume that with this option the resolution will be that of the lowest display.

The other option is to get a manual 3x1 switch and a) hope it doesn't have the "directional" feature and works in reverse or b) I would have to "hack" the diodes to make it work in reverse? Would this manual switch allow for different resolutions between displays since the signal will only be going to the display that is selected? Or would it still only allow for the lowest resolution of the 3 displays?

Are there any other advantages/ disadvantages between these two scenarios?
budwich's Avatar budwich 10:07 AM 01-28-2014
Probably not quite that "simple" as a lot of units are placed in "standby" so when they are off, they are still on in terms of HDMI signalling so the "lowest common denominator resolution" will likely come into play unless you totally power down unused displays (ie. power bar, switch, or cord pull). However, lowest resolution might not be an issue as it may be the same across all displays as in "what resolution a displays accepts" versus its "native resolution"... thus all may accept the same "highest resolution" (ie. 1080p) but are able to scale to a lower given "native resolution" which may not be "pushed" back thru the hdmi signalling. My 720p projector doesn't affect my 2 1080p TV since it "appears" to indicate to the sources that it can handle a 1080p signal and scale it down.
AV_Integrated's Avatar AV_Integrated 10:59 AM 01-29-2014
At the end of all of this, unless you can give us the full EDID table for all the gear you have installed, it's just next to impossible to give you a good answer.

I would simply recommend that you get a ACTIVE HDMI splitter from Monoprice with good reviews, hook it up, and see what you get. It's the most stable and reliable solution out there and is a reasonable price with a good return policy.
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