As in just to break up the sound reflection, or to spare your neighbours?
If it's the first a load of speaker fabric from AliExpress stretched over DIY pine frame would be a good option. You could do them to match your interior without being too reddit audiophile, and the timber will come in handy for other stuff.
One of the less gash attempts Google images throws up
Proper curtains are another idea, being both useful and reducing reflection.
Quite like that, though given the amount of DIY I've already got on the list it'll be few months until I get round to it! Might have to just stick a few bits of foam around the room for the time being.
As in just to break up the sound reflection, or to spare your neighbours?
If it's the first a load of speaker fabric from AliExpress stretched over DIY pine frame would be a good option. You could do them to match your interior without being too reddit audiophile, and the timber will come in handy for other stuff.
One of the less gash attempts Google images throws up
Proper curtains are another idea, being both useful and reducing reflection.