hazeyjane7

macrumors newbie
Original poster
Oct 2, 2020
8
1
Hi, i'm trying to find a dock solution for connecting the 30 inch Cinema Display to the 16 inch Macbook pro with ONE CABLE. I want to use a dock so i'll have some available USB-A ports on my desk. I found the "Targus USB-C Travel Dock", and i can get the Apple Mini DisplayPort to Dual-Link DVI adapter. Will this solution work?

The Targus dock can be switched with other similar ones like:
Delock: Link
OWC: Link

display wiring diagram.png
 

joevt

macrumors 68040
Jun 21, 2012
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The Travel Dock might work.

Is 60W enough for your 16 inch MacBook Pro?

Does the Apple Mini DisplayPort to Dual-Link DVI adapter work with only two lanes of DisplayPort 1.2? If not, then you need a USB-C dock that only has USB 2.0 instead of USB 3.x. Actually, the Travel Dock has multiple display outputs which means it has an MST hub which means it can convert two lanes of DisplayPort to four lanes.

macOS doesn't support MST for multiple displays, but should be able to use a single display connected to the MST hub.

But wait, the description doesn't say it supports more than one display at a time, so maybe it has an automatic switch instead of a MST hub?

Cable Matters has some small inexpensive USB-C docks. Some with USB 3.0 and some with USB 2.0. So if two lanes of DisplayPort with USB 3.x doesn't work, then you can try four lanes of DisplayPort with USB 2.0.
 

hazeyjane7

macrumors newbie
Original poster
Oct 2, 2020
8
1
The Travel Dock might work.

Is 60W enough for your 16 inch MacBook Pro?

Does the Apple Mini DisplayPort to Dual-Link DVI adapter work with only two lanes of DisplayPort 1.2? If not, then you need a USB-C dock that only has USB 2.0 instead of USB 3.x. Actually, the Travel Dock has multiple display outputs which means it has an MST hub which means it can convert two lanes of DisplayPort to four lanes.

macOS doesn't support MST for multiple displays, but should be able to use a single display connected to the MST hub.

But wait, the description doesn't say it supports more than one display at a time, so maybe it has an automatic switch instead of a MST hub?

Cable Matters has some small inexpensive USB-C docks. Some with USB 3.0 and some with USB 2.0. So if two lanes of DisplayPort with USB 3.x doesn't work, then you can try four lanes of DisplayPort with USB 2.0.
60W is not enough for charging my MacBook, but i don't mind plugging the charger. A dock with 80W+ pass through power can be nice, but i mainly want the display to be plugged with one cable only.

I don't know about the DisplayPort lanes requirements of the Apple adapter, why do you think a dock with USB 2.0 instead of USB 3.0 might be needed? Also, is there any reason i should prefer a powered USB C dock?

Also i'll state that i don't need to use multiple displays. Only the Apple Cinema.
 
Last edited:

joevt

macrumors 68040
Jun 21, 2012
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2560x1600 requires four lanes of HBR or two lanes of HBR2 (different link rates for DisplayPort).

A USB-C hub can provide four lanes of DisplayPort if it does not use two of the lanes (one for transmit and one for receive) for SuperSpeed USB (USB 3.x). The USB 2.0 High Speed lines in a USB-C cable are separate from the Super Speed lines that are used by DisplayPort and USB 3.x so they are always available.

If a USB-C hub does support USB 3.x then it only has two lanes for DisplayPort, therefore the Apple adapter must support HBR2 to achieve 2560x1600.

If a USB-C hub only supports USB 2.0, then it means all four Super Speed lines are available for DisplayPort and the Apple adapter only needs to support HBR link rate to achieve 2560x1600.

I think you can connect the Apple adapter and then use the AGDCDiagnose command (google it) to determine what the max DisplayPort link rate it supports.

A powered USB-C dock would allow charging of the MacBook Pro or it could at least slow the draining of the battery. I think an unpowered USB-C dock should have enough power to power the Apple adapter.
 

hazeyjane7

macrumors newbie
Original poster
Oct 2, 2020
8
1
2560x1600 requires four lanes of HBR or two lanes of HBR2 (different link rates for DisplayPort).

A USB-C hub can provide four lanes of DisplayPort if it does not use two of the lanes (one for transmit and one for receive) for SuperSpeed USB (USB 3.x). The USB 2.0 High Speed lines in a USB-C cable are separate from the Super Speed lines that are used by DisplayPort and USB 3.x so they are always available.

If a USB-C hub does support USB 3.x then it only has two lanes for DisplayPort, therefore the Apple adapter must support HBR2 to achieve 2560x1600.

If a USB-C hub only supports USB 2.0, then it means all four Super Speed lines are available for DisplayPort and the Apple adapter only needs to support HBR link rate to achieve 2560x1600.

I think you can connect the Apple adapter and then use the AGDCDiagnose command (google it) to determine what the max DisplayPort link rate it supports.

A powered USB-C dock would allow charging of the MacBook Pro or it could at least slow the draining of the battery. I think an unpowered USB-C dock should have enough power to power the Apple adapter.
I see. So the two options that will definitely work are:
  • A dock that is using USB 2.x.
  • Or if the Apple adapter supports HBR2 - any dock will work (USB 2.x or 3.x). I doubt the Apple adapter supports HBR2, it's too easy. Maybe an alternate adapter will. I'll try to figure it out. Thanks!
I wonder if the usb port on the apple Adaptor is for power? or for the usb ports on the rear of the Cinema display? or both?
 

joevt

macrumors 68040
Jun 21, 2012
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I see. So the two options that will definitely work are:
  • A dock that is using USB 2.x.
  • Or if the Apple adapter supports HBR2 - any dock will work (USB 2.x or 3.x). I doubt the Apple adapter supports HBR2, it's too easy. Maybe an alternate adapter will. I'll try to figure it out. Thanks!
I wonder if the usb port on the apple Adaptor is for power? or for the usb ports on the rear of the Cinema display? or both?
The USB plug from the Apple adapter is for power because the DisplayPort port doesn't have enough power to do the conversion from DisplayPort to Dual Link DVI. You must connect the USB cable of the Cinema display to use the USB 2.0 ports of the Cinema display and also for brightness control.

I have a DisplayPort to Dual Link DVI adapter from StarTech I could check but it's not the Apple one and I don't have a two lane DisplayPort source.
 

hazeyjane7

macrumors newbie
Original poster
Oct 2, 2020
8
1
The USB plug from the Apple adapter is for power because the DisplayPort port doesn't have enough power to do the conversion from DisplayPort to Dual Link DVI. You must connect the USB cable of the Cinema display to use the USB 2.0 ports of the Cinema display and also for brightness control.

I have a DisplayPort to Dual Link DVI adapter from StarTech I could check but it's not the Apple one and I don't have a two lane DisplayPort source.
Alright. I didn't get the adapter yet and i don't mind getting the StarTech one or anything else. Maybe you could run AGDCDiagnose, and then we'll know if it supports HBR2 ? If so, the dock doesn't matter, right?
 
Last edited:

joevt

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Jun 21, 2012
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Alright. I didn't get the adapter yet and i don't mind getting the StarTech one or anything else. Maybe you could run AGDCDiagnose, and then we'll know if it supports HBR2 ? If so, the dock doesn't matter, right?
The StarTech has a max link rate of HBR. One strange thing is that it wouldn't work with two different USB-C to DisplayPort adapters I have (white Moshi and Cable Matters DisplayPort 1.4) connected to a Thunderbolt 3 port of my Mac mini 2018, or a OWC Thunderbolt 3 Dock, or a HP Thunderbolt Dock G2. It would detect and get the DisplayPort info but it wouldn't setup the display - it remained black. The Mini DisplayPort port of the OWC Thunderbolt 3 Dock also didn't work.

It did work after I connected it to a DisplayPort port of a HP Thunderbolt Dock G2 (which has a built in DisplayPort 1.4 MST hub so the connection is HBR2 to the Mac mini). The USB-C adapters worked when connected to the USB-C port (with DisplayPort alt mode) port of the HP Thunderbolt Dock G2 (which is also connected to the built in DisplayPort 1.4 MST hub). Of course, the Thunderbolt port of the dock is not connected to the internal MST hub.

All my connections were four lanes because I don't have a two lane source to test. I don't have any USB-C hubs with non-MST DisplayPort output.

Does this mean my Mac mini 2018 won't do HBR? That would be weird.

I tried connecting the Apple 30" Cinema Display to the HDMI 2.0 port of the Mac mini 2018 (must add 1280x800 timing with SwitchResX because that is the max for single link connection for this display). The DisplayPort rate is HBR2 for the DisplayPort to HDMI 2.0 converter even for low res timings.

I used low res timings on my 4K display (640x480 and 2560x1440) but the connection link rate still remained at HBR2 from the Thunderbolt 3 port.

I guess I need a real DisplayPort 1440p display to test HBR link rate. Oh wait - my 4K display has a DisplayPort 1.1 mode. In that case, my 4K display does switch to HBR link rate (for 4K30, and 1440p60).

Ok, so HBR link rate can work from my Mac mini 2018 Thunderbolt 3 ports. I just don't understand why the StarTech adapter is not working directly. Maybe you should go with the Apple adapter?
 

hazeyjane7

macrumors newbie
Original poster
Oct 2, 2020
8
1
The StarTech has a max link rate of HBR. One strange thing is that it wouldn't work with two different USB-C to DisplayPort adapters I have (white Moshi and Cable Matters DisplayPort 1.4) connected to a Thunderbolt 3 port of my Mac mini 2018, or a OWC Thunderbolt 3 Dock, or a HP Thunderbolt Dock G2. It would detect and get the DisplayPort info but it wouldn't setup the display - it remained black. The Mini DisplayPort port of the OWC Thunderbolt 3 Dock also didn't work.

It did work after I connected it to a DisplayPort port of a HP Thunderbolt Dock G2 (which has a built in DisplayPort 1.4 MST hub so the connection is HBR2 to the Mac mini). The USB-C adapters worked when connected to the USB-C port (with DisplayPort alt mode) port of the HP Thunderbolt Dock G2 (which is also connected to the built in DisplayPort 1.4 MST hub). Of course, the Thunderbolt port of the dock is not connected to the internal MST hub.

All my connections were four lanes because I don't have a two lane source to test. I don't have any USB-C hubs with non-MST DisplayPort output.

Does this mean my Mac mini 2018 won't do HBR? That would be weird.

I tried connecting the Apple 30" Cinema Display to the HDMI 2.0 port of the Mac mini 2018 (must add 1280x800 timing with SwitchResX because that is the max for single link connection for this display). The DisplayPort rate is HBR2 for the DisplayPort to HDMI 2.0 converter even for low res timings.

I used low res timings on my 4K display (640x480 and 2560x1440) but the connection link rate still remained at HBR2 from the Thunderbolt 3 port.

I guess I need a real DisplayPort 1440p display to test HBR link rate. Oh wait - my 4K display has a DisplayPort 1.1 mode. In that case, my 4K display does switch to HBR link rate (for 4K30, and 1440p60).

Ok, so HBR link rate can work from my Mac mini 2018 Thunderbolt 3 ports. I just don't understand why the StarTech adapter is not working directly. Maybe you should go with the Apple adapter?
Look what i found:

Though i wonder if the USB-A port is for data or power only..
🤔 🤔 🤔
 

joevt

macrumors 68040
Jun 21, 2012
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Hi, Did you wind up getting this to work?

I'm investigating for how to use my 30" ACD with a new M1 MacBook Air/Pro, should I get one. Thanks.
A USB-C to Dual Link DVI adapter would probably be best. Club-3d has one. But be aware that there are two variants - one that supports HDCP but doesn't work with the Apple 30" Cinema Display and that doesn't support HDCP and works with the Apple 30" Cinema Display (and is more expensive because...)

Alternatively, you could try a HDMI 1.4 to DisplayPort adapter connected to a DisplayPort to Dual Link adapter if you don't want to use one of the Thunderbolt ports. However, this will likely have problems caused by chaining multiple adapters together.
 

Tozovac

macrumors 68020
Jun 12, 2014
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A USB-C to Dual Link DVI adapter would probably be best. Club-3d has one. But be aware that there are two variants - one that supports HDCP but doesn't work with the Apple 30" Cinema Display and that doesn't support HDCP and works with the Apple 30" Cinema Display (and is more expensive because...)
Thank you. Ordered it last night.
 

hazeyjane7

macrumors newbie
Original poster
Oct 2, 2020
8
1
Thank you. Ordered it last night.
I also think this is the best option. Didn't buy anything myself yet. Remember that you won't be able to use the USB 2.0 ports in the rear of the Cinema display. Ideally i would connect the Club-3d to a dock and the dock will also charge the MacBook and add some USB-A ports.
 

Tozovac

macrumors 68020
Jun 12, 2014
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I also think this is the best option. Didn't buy anything myself yet. Remember that you won't be able to use the USB 2.0 ports in the rear of the Cinema display. Ideally i would connect the Club-3d to a dock and the dock will also charge the MacBook and add some USB-A ports.
Gotcha. Wouldn't it be possible to plug in the USB-A cord coming from the ACD as part of the octopus/squid set of cables into a dock, and then have access to the ACD ports?
 

joevt

macrumors 68040
Jun 21, 2012
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Gotcha. Wouldn't it be possible to plug in the USB-A cord coming from the ACD as part of the octopus/squid set of cables into a dock, and then have access to the ACD ports?
Yes. I think the point is that an adapter or dock is required to connect USB-A since the MacBook Pro only has USB-C ports. Once it's connected, the USB-A ports of the Cinema Display will work. For the FireWire ports, you need a Thunderbolt to FireWire adapter or a Thunderbolt dock with a FireWire port - I wouldn't bother with FireWire since you probably don't have any FireWire devices, or you would use FireWire 800 directly from the adapter or dock (the Cinema Display only supports FireWire 400 speed).
 

hazeyjane7

macrumors newbie
Original poster
Oct 2, 2020
8
1
Gotcha. Wouldn't it be possible to plug in the USB-A cord coming from the ACD as part of the octopus/squid set of cables into a dock, and then have access to the ACD ports?
Sure. But if you already have a dock, you'd probably prefer the USB 3.0 speed of the dock's ports rather then the USB 2.0 of the ACD.
 
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