Docks with multiple HDMI/Display ports

twisted-pixel

macrumors 6502a
Original poster
Sep 13, 2009
835
41
San Jose, CA
Hi All,

I have an early 2015 Macbook pro. One of the things I liked about it was the fact that it has multiple ports in the machine itself

2 USB
2 mini display
1 HDMI
1 Card reader

I currently have two mini-display to HDMI dongles and run two external monitors, giving me 3 in total (these are simply standard 21" monitors)

I was thinking of upgrading to a new MB pro, but I am struggling to find a single docking solution that gives me multiple HDMI ports that would allow me to keep my existing set up of two external monitors. I was hoping that I could simply plug everything into the dock and then only have one thing to plug into the MB.

I read somewhere that this was, in part at least, due to the fact that each USB-C port would only support a single external monitor, meaning that I would still need to plug in at least two dongles if I wanted my 3 monitor set up as I have now.

is that correct? what are other people using? (apart from very expensive apple monitors that is)
 

theluggage

macrumors 601
Jul 29, 2011
4,034
2,717
is that correct?
TLDNR:

https://www.caldigit.com/thunderbolt-3/mini-dock-HDMI-DisplayPort/
...but I haven't personally used it.
OK, so there are broadly two kinds of hub/dock for a current MacBook Pro:

"USB-C hubs/docks" - the cheaper ones - act as a USB 3 hub and can support HDMI or DIsplayPort displays via "USB-C DisplayPort Alt Mode". In this mode, the Mac can only run one display per port because (unless its changed in Mojave) Mac OS doesn't support "DisplayPort MST hubs* or daisychaining" (see http://www.caldigit.com/KB/index.asp?KBID=221&viewlocale=1). Also, these hubs can't support the full bandwidth of DisplayPort 1.2 and run USB 3 devices at the same time - although you're probably OK with standard-def displays this would be a problem if you wanted to upgrade to 4k.

"Thunderbolt 3 hubs/docks and dual-display adapters" - superficially appear to do the same job, but connect to the computer via Thunderbolt and provide far more bandwidth for the USB devices and displays connected to them, and can potentially support two displays. Usually, these have either a DisplayPort or HDMI output and you can connect a second display to their Thunderbolt 'out' socket via a USB-C-to-HDMI or DP cable. HOWEVER: beware - some models (especially the earlier ones) still rely on "MST hub*" mode and won't do dual displays on a Mac. Newer ones extract both of the two available DisplayPort streams from the Thunderbolt signal and should do what you want. The TB3 Mini Dock from Caldigit looks like what you need - fewer ports but dual displays without needing a second dongle.

* Note this is not the same thing as "MST tiled" mode as used by some 4k displays which is supported by MacOS.
 
  • Like
Reactions: twisted-pixel

twisted-pixel

macrumors 6502a
Original poster
Sep 13, 2009
835
41
San Jose, CA
thank you folks.

unbelievable that with all the docks out there, I can't find anything has more than 1 video output when you add things like power pass through etc.
 

iAussie

macrumors member
Dec 14, 2006
48
1
each USB-C port would only support a single external monitor
The MacBook Pro's USB-C ports also support Thunderbolt 3, which can output to multiple monitors from a single port on your MBP. The Thunderbolt 3 devices already suggested by others in this thread (Caldigit MiniDock and OWC Dual Display adaptor) will do exactly that, but you'll also need to connect your MBP charger to another port on your MBP, so it would be a 2-cable docking solution.

thank you folks.

unbelievable that with all the docks out there, I can't find anything has more than 1 video output when you add things like power pass through etc.
Do you want power pass-through (wall power socket -> MBP charger -> multiport hub -> MBP) or a dock that can charge your MBP (wall power socket -> dock power supply -> dock -> MBP)? These are 2 different things.

If you want power pass-through, these are typically USB-C "travel" hubs and will only support a single external display. You can always connect your 2nd external display to another USB-C port on your MBP, but now you're back to a 2-cable docking solution.

If you want a dock that can charge your MBP, a Thunderbolt 3 dock such as the CalDigit TS3+ or OWC Thunderbolt 3 dock will charge your MBP and allow you to connect up to 2 external monitors (you might need some adaptors to suit your existing monitors) and connect other USB devices etc, all with a single cable to your MBP.
 

IdentityCrisis

Suspended
Sep 9, 2018
685
340

twisted-pixel

macrumors 6502a
Original poster
Sep 13, 2009
835
41
San Jose, CA
sadly this

https://www.caldigit.com/thunderbolt-3/mini-dock-HDMI-DisplayPort/

didn't work. Monitors plugged into the dock, dock plugged into the MB....nothing.

I'm not sure if it's a problem with the dock or the machine though.

The two monitors work (they used to work just fine with my old MB) but I wonder if it's to do with their auto-detection of input. I used to have an occasional problem on my old MB that the MB would ping the monitors and by the time they had switched from VGA to HDMI input, the MB had decided there was nothing at the end and turn the display off. Sadly, the monitors do not have a way to default them to HDMI only.

so, I just spent £130 on a dock and two adaptors for nothing looks like.
 

iAussie

macrumors member
Dec 14, 2006
48
1
I'm not sure if it's a problem with the dock or the machine though.
What computer are you using? Sounds like you've upgraded from your 2015 MacBook Pro?


so, I just spent £130 on a dock and two adaptors for nothing looks like.
What are the 2 adaptors you’re using?


wonder if it's to do with their auto-detection of input.
On your Mac, try going to System Preferences > Displays > Detect Displays (press and hold the Option key to make this button appear in the place of the Gather Windows button, then click Detect Displays if your Mac doesn’t recognise a display you’ve just connected)
 

IdentityCrisis

Suspended
Sep 9, 2018
685
340
sadly this

https://www.caldigit.com/thunderbolt-3/mini-dock-HDMI-DisplayPort/

didn't work. Monitors plugged into the dock, dock plugged into the MB....nothing.

I'm not sure if it's a problem with the dock or the machine though.

The two monitors work (they used to work just fine with my old MB) but I wonder if it's to do with their auto-detection of input. I used to have an occasional problem on my old MB that the MB would ping the monitors and by the time they had switched from VGA to HDMI input, the MB had decided there was nothing at the end and turn the display off. Sadly, the monitors do not have a way to default them to HDMI only.

so, I just spent £130 on a dock and two adaptors for nothing looks like.
No idea on that dock but the ts3 dock works for everyone just fine that has gotten it. I’d talk to their support as it’s really good to see what they can tell you. My guess it’s either a config or monitor issue.