However this did not mean musicians only performed the songs of the original American blues masters.
''We are open to interpretation but the people who come and play love the genre.''
And with no door charge, everyone does it for the love of a music style captured by greats like Muddy Waters and Howlin' Wolf.
''They only come because they love playing that sort of music and the audience is really appreciative. Younger people are coming - the standard of musicianship is very high,'' Porter said.
The shift to Jack Dusty's followed Drivers Bar owner Peter Taylor and wife Deb selling the venue, which Porter understood was being turned into a restaurant.
''We had a huge amount of support from regulars to keep the jam going, and had several offers of a new home from other venues in town.''
Porter said Jack Dusty's was a good location because it had more space for musos and fans, good parking, and access to a PA system provided by Andy Craw who managed the bar's live music programme.
The regular house band, Chill Factor, featured Porter (bass and vocals, Ken Green (keyboards/vocals), Simon Fenlon (drums), Tony Baucke (guitar), and many longtime regulars.
He said Chill Factor provided the backline setup (amps, drums, etc), the bar supplied the PA, so it was all set up for musicians to just drop in.
''Top local musicians regularly take part in the jam, sitting in with the house band, in their own line ups, or in various combinations - depending on who drops in. There's a tremendous amount of talent in the Bay.''
Porter said they were expecting a big turnout for the final jam at Drivers Bar on August 8. The switch to Jack Dusty's was September 12.
He was always careful that the jam was neither too loud or too quiet.
''We respect the customers.''
Another important element of the jam's success was to vary the mix and not allow one musician to go on and on.
