At the very end of The Jam, so about 1982 / 83 from memory?? They stayed at the hotel I was working at and they had a ghetto blaster / brixton briefcase.
I was very very taken with this - and with the reggae tape that was constantly playing on it in the bar of the hotel that they'd taken over. At the end of the stay their roadie gave me the tape, plus a tip of about £60 (a month's wages for me back then). I went out and got me a big old Panasonic blaster, cassette player, big radio dial like the one above AND critically I took it apart and 'customised' it. Just like the Jam had done.
Took off one speaker cover and wrote on the cone (as above), painted it, covered it in stickers and snapped a few bits off. Really kicked it about before I took it out.
My mum went ballistic.
Battery life made me sad.