Enter the username you want to appear in Mumble, and click 'OK'.
Click 'Yes' when asked about a certificate.
Even though you are already connected, click 'Server > Connect'.
Click 'Add New...', change the Label to 'Silverfel' (or leave it as is), and click 'OK', then 'Connect' or 'Cancel'.
Click 'Configure', 'Settings', 'User Interface', 'Stacked' for Layout, and 'OK'.
Click 'Configure', 'Audio Wizard', and follow these instructions:
Introduction: click 'Next'.
Device selecton: if needed, change the devices till you hear yourself talking thru your own speakers, then click 'Next'.
Device tuning: slide the button all the way left (10 ms). If the output is choppy/jittery, start sliding it right till it clears up. Click 'Next'.
Volume tuning: First go into your operating system's sound/microphone setup, and turn your Microphone all the way up, and Microphone Boost also if you have that option. (In Windows, you can find this by right-clicking the speaker icon in the bottom right of your screen, then click 'Recording Devices', 'Microphone', 'Properties', and 'Levels'.) Follow the rest of the instructions to get the slider set correctly, then click 'Next'.
Voice Activity Detection: select 'Push To Talk' and set your Mumble keybinding. Mac Users - check the end of this post for special Mac PTT setup instructions.
(Probably just use the same key that you're currently using for Ventrilo. Also, avoid using any modifier keys (Shift, Ctrl, or Alt) as part of your keybind, or you might get some strange in-game behavior when trying to talk and use your abilities at the same time.)
Quality & Notifications: select 'Balanced' and 'Disable Text-to-Speech'. (Or 'Use Text-To-Speech' if you prefer.)
Click 'Next' till you get to the end, and then 'Finish'.
That's it - you should be up and running with Mumble!
Generally speaking, you'll want to use "Push-to-Talk" (PTT), so your microphone only broadcasts while you're holding down the PTT key. No one will hear any background noise, breathing, coughing, setting your headset on your desk, etc.
However, "Voice Activity" detection instead of PTT is a nice and powerful feature, freeing you from having to press an extra key while Raiding or PvPing. If you choose to go this route:
Take the time to get the settings below set as tightly as possible. You want only your intended speech coming across, and nothing else, so as not to annoy the rest of the people in your group.
Be sure to liberally use the 'Mute' button when you don't need to broadcast (answering the phone, coughing fit, removing/putting on your headset, etc).
Back in Mumble, click 'Configure' and 'Audio Wizard' again, but this time instead of PTT select 'Raw Amplitude' and follow thru with the rest of the wizard. If 'Raw Amplitude' doesn't work well for you, try again with 'Signal-To-Noise ratio'. This might take some trial-and-error to find the settings that work best for you.
Mumble requires what Apple calls "assistive devices" to be enabled if you want to select a push-to-talk key that's something other than SHIFT, or MOUSE BUTTON 1, etc. I normally use the ~ button for PTT. So to allow Mumble to select a wider range of keys, you need to do the following:
Open System Preferences.
Click on Security & Privacy.
Click on Privacy.
Click on Accessibility.
Click the Padlock and enter an administrator password to allow changes.
Open a finder window.
Click on Applications in the Side Bar.
Find Mumble and manually drag it into the section that says "Allow the apps below to control your computer."
Make sure that's checked. Close the lock.
Restart mumble and configure the PTT to the key of your liking.
* edited May 16 to update links from version 1.2.5 to 1.2.6, and to update the url to bdh.gotmumble.com * edited May 17 to add special Mac PTT setup instructions * edited November 5 to update links from version 1.2.6 to 1.2.8