Husband and wife, Johnny and Samantha Sallows, joined friends Lindsay Kelly and Gillian McCombe to perform for shoppers in Buchanan Street, yesterday.
Johnny, 26, from North Aryshire, said: "Myself and my wife were both devastated by what had happened.
"We thought why not get together, as musicians, it's for a good cause. There are families out there that could be doing with a lot of support, so it would be good to just do a good thing for them.
"There are a few people who I knew who used to go to the Clutha.
"I was speechless when I heard the news, shocked that something like that could just happen out of nowhere.
"I feel really sorry for the victims, those who are hospitalised and also their families."
Gillian, 27, from Paisley, said: "Everybody in Glasgow comes together in a crisis.
"You have to help out where you can."