I think I remember them actually saying something about an update breaking old dupes...

@Russian Glados
Then they must've changed something that broke old dupes. I might update this... There's a better way in which the cube itself is the Stream Radio instead of having one welded inside of it... Though I don't know if you can pick up Stream Radios with use/interact.

I have the 3d stream radio installed

It may be that old dupes use an old save format for 3D Stream Radio that no longer works.

@Russian Glados
Do you have 3D Stream Radio installed?

It just stands there and no music is doming from it

@POTATOS
What happens when you attempt to spawn the dupe?

I have portal 2

@WheatleyAntyStaśkowy69GejMing
It should appear under the "subscribed" category in the duplicator menu. Mouse over it and click "load." It may take a second to load.

how to spawn it?

I believe you need to ether install a content pack found on the internet, or mount the game Portal 2 to Garry's Mod.

To mount Portal 2 you must own a copy of it on Steam and it must be installed to your computer. Then you go to Garry's Mod and click on the little game controller icon located in the pause/title menu and click on Portal 2.

You can download the game content files by clicking this link [sites.google.com]. Note these are not the full games but only contain models and textures and formatted for Garry's Mod. To install these unzip the contents of the compressed zipped files into this folder in your Steam app application folder "steamapps/common/GarrysMod/garrysmod/addons". (Maybe you should look up a tutorial if you are confused.)

how to get music from portal 2