Microphone not detected

Could you please provide a system model number?

These days Dell desktops have a "universal audio jack" on the front that combines multiple functions, including microphone, headphones, and multiple headset configurations with different pin assignments. Since your headset mic worked, I presume this is what you have. Recent models use the "MaxxAudioPro" app to allow you to specify what kind of device you've plugged in, so the system can operate accordingly. (I don't know your model, so I don't know whether your model supports this.) There are USB audio adapters like this one that provide additional audio devices (with separate drivers) that you can assign as you want, but I don't know what you used.

- Dave (not a Dell employee)

We also need to know the version of Windows.

Hello,

Thanks for the replies.

I have a Inspiron 3891, running Windows 11.

As I said the universal jack on the front of the tower works fine, but cuts out the speakers when plugging anything else in the socket.

I will buy the adapter suggested by NJDave.

As I said before I'm surprised that there is not the usual sockets at the back of the PC to allow connection of mic and speakers.

Thanks,

Rod

I think the main issue is with your setup.  Your computer seems to have the same standard input/output as every other desktop computers.  As mentioned in your original post, you are having trouble to get the integrated mic to work.  Yet, no mention of information for the device.

Without going further with asking you all the questions, I will tell you a basic setup for using webcam on desktop pc.

• To use external speakers, connecting the speakers audio cable to audio out jack on the back, top connector with light green color coded.  A pop up on your screen (from Waves) asking your input, select external speaker. 
• To use webcam, after proper setup atop of monitor or on tripod, plug the webcam USB cable to one of USB port in the back of the computer.  If using 4k webcam such as Logitech Brio, you must use USB 3.0 port.  Windows should automatically installing proper drivers, including mic and sensors.  Otherwise, follow webcam installation instruction from manufacturers (oftenly not needed).  For special features such as Windows Hello, you will need separate setup.  Once, the webcam is added, you can launch your app such as Team, Skype, Zoom and making adjustment to sound level, zoom level, etc.  All the sounds will playback on your external speakers.
• If you prefer to use private mode while others are around, you can plug in a headset to the universal input jack at the front of your computer.  Again, you will get a (one time) pop up and you need to select headset.  This should allow you to hear and speak with headset device.  
• If you were using headset and want to use separate speakers so that others can hear the third party, you can change the sound output from headset to speaker (Realtek audio).  A simple way is to click on the volume icon in desktop tray area, then click on select a sound output (icon on the right of volume level bar), you should find the speaker option, just select it and all audio will route to external speaker while you still can use your mic from the headset.

I hope this information can help to resolve your issue.

I know the topic is closed, but for what it's worth, now that we know the model:

Recent systems with Realtek audio (like mine) have been paired with MaxxAudioPro software, which seems to be joined to the Realtek driver at the hip. Yours (as mentioned) has the Cmedia CM6548 chip, which may just use a generic driver. I don't know how the 3891 would detect that the device inserted into the audio jack is a mic, and apparently it doesn't.

I took a quick peek at an Envy PC on HP's website, and it has 3 audio jacks on the rear including a separate mic jack. That's still 3 fewer than my previous HP PC had... but the elimination of all the jacks but one seems to be a Dell thing.

The Sabrent audio interface I posted was only an example; I've never actually tried it, but it's inexpensive and the reviews are good. I hope it works well for you.

@Rod Styles  Are you sure the mic>USB adapter is compatible with the type of plug on any of these mics? There are many different types of mic plugs...

Thanks for you help, I have ordered an adapter of the type you suggested. I am not sure if the previous type had 4 or 3 pick up points, but were supposed to be for microphones, and my mic has just 3 pick ups

Thanks again.