People tend to check in during these times:
Turn off your mobile. It was a great experience apart from the four señoras who sat at the front row. They've been poked to stop talking then their mobile phones went off which annoyed everyone!
Not a public concert hall as such, but the BBC Symphony Orchestra hosts free studio concerts here, to which you can readily find tickets.
Old-fashioned radio recording studio with its indisputable fascination
Historical BBC radio studios with the charms of old radio days
Some of the best engineers around
Security are rude.