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When I plug my Mac into a DisplayPort monitor that has loudspeakers, the Mac's volume controls become disabled.

Is Apple assuming that if I have external speakers I am so much better using their own volume control that I have to be forced to do it? That is annoying because the monitor's volume controls are buried in terrible menus accessed by terrible buttons on the back of the monitor.

Also, if I am inside an app where I can select the audio device and I select the Mac's internal speakers, the volume controls are STILL disabled. Is there no way to control the volume of an app when an external speaker is connected even if the app is not using the external speaker?????

Some additional info: It's a Macbook Pro 13" 2018 version. Using a Thunderbolt to Displayport cable, plugging in to a Dell monitor with speakers. In another location I use the same cable to plug in to Dell monitors with Displayport but without built in speakers in the monitors. At that location the volume controls remain active and they control the internal speaker in the laptop as they should.

  • Usually, this happens when you are using digital audio(the thunderbolt cable instead of a 3.5 mm jack), so unless you want to lose audio quality, the Mac can't control the volume. Try using a regular 3.5 mm cable to the monitor and/or disable the speakers on the display(there must be an option for that somewhere) – abc Sep 17 '18 at 17:09
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It's because Apple computers don't support CEC (Consumer Electronics Control).

Basically, macOS doesn't allow you to control end devices attached via HDMI or DisplayPort. Changing the volume would be considered "controlling the device"

  • I can accept this (even if I don't like it) as the answer to why I cannot control the Dell monitor's speakers from the Mac volume control. But this doesn't explain why I cannot control the volume of the MacBook's internal speakers while the external monitor is plugged in! I can unplug the monitor, change the volume of the internal speakers, and plug the monitor back in. That works but is ridiculous. – jay613 Sep 17 '18 at 17:40
  • Is sound coming from the internal speakers? What does it say in Sys Prefs -> Sound? – Allan Sep 17 '18 at 17:45
  • Yes, sound does come from the internal speakers. Some apps allow you to select the audio device. The internal speakers and the external monitor appear as choices. If I select the internal speakers for an app, the sound does come out that way. It comes out at the volume that was set before I plugged in the external monitor. I don't have access to the relevant monitor right now, I will update this comment later, when I do, with what I see in System Preferences. – jay613 Sep 17 '18 at 18:04
  • This answer is correct. Thank you. You simply cannot control volume of a DP monitor from a Mac. You can still direct an app to use internal speakers, but because the Mac has disabled ALL volume control, you can't control volume of the internal speakers either. You can disconnect the monitor, turn the internal speakers up or down, reconnect the monitor and then use the internal speakers. It's pathetic. – jay613 Sep 28 '18 at 13:48
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And there is an app for that,

build in to your OS X.

In the utility folder >> Audio MIDI

try it, you will like it !

It will allow you to have simultaneous output to multiple devices.

I could not test it for your set up so let me know if it worked.

enter image description here

  • My monitor is not a MIDI device. But I will look at this utility and will look for similar things within System Preferences and update in a comment later with what I see. – jay613 Sep 17 '18 at 18:09
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    That has nothing to do with MIDI, it is just setting up multiple audio output. – Ruskes Sep 18 '18 at 3:58
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    I finally looked at this utility, and it looks nice but unfortunately doesn't change anything. Inside the utility the Master Volume for the internal speakers is disabled when the laptop is plugged in to a DP display. Just to emphasize, I understand now that a Mac cannot control the volume of a DP display, what's frustrating is that the INTERNAL speaker controls are also locked out when an external DP display is plugged in. Anyway -- thank you. – jay613 Sep 28 '18 at 13:46
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    I was able to get this working using USC-C by playing around with Soundflower and creating a Multi-Output Device. I'm not quite sure how exactly I got it to work but switching between the different options seem to do something. I have my output in sound preferences set to Soundflower (2ch). I will post an answer if I get chance. I'm using an LG monitor with MacBook closed. – Mindthetic Nov 9 '18 at 17:43
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I found two commercial apps which support this:

Both apps have a free trial. I've tried SoundSource and it works for me. I have not had the opportunity to try SoundControl.

  • These apps seem nice. Hopefully Apple will include this functionality in a macos release. Thanks. – jay613 Jun 2 at 21:51
  • Incidentally, the title plus the accepted answer from Allan refer to DP or HDMI monitors, but I’ve found that the problem with the volume keys not working even applies to newer USB-C connected monitors. (But SoundSource works in that scenario too.) – Scott Dudley Jun 2 at 21:59

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