Yeah but this is Fete de la Musique where I believe everyone play for free, admission is free and the bands can be a very mixed bag. Maybe a few pros, mostly semi-pros and amateurs plus a couple of "never been on a stage before". If anyone gets a soundcheck it's most likely only the first band. 15 minutes changeover with no backline, no soundcheck, a large part of the crew will most likely be volunteers with very little experience and therefore more likely to get in your way then to provide any useful help... although this will probably differ somewhat between venues. With stuff happening all over the city there probably won't be a 100% professional crew at every stage. It will almost certainly be a bit chaotic at best or severely behind schedule at worst.
At least this is MY experience after playing Fete de la Musique in several European countries over the years, although never in Germany or in a city the size of Berlin... so it COULD be different there I guess, although I think the concept is more or less the same everywhere.
Don't get me wrong, it's fun, charming and a great day for music. Just don't expect the professionalism or the crew you get on bigger, commercial festivals.
My advice to the OP: Have fun and don't waste energy worrying about things that are out of your control. 15 minutes is pretty tight under the circumstances but no-one is gonna blame you if you need a couple of minutes extra as long as you do your best, treat everone with respect and play a great gig.
I would still plan to succeed. Then if you don't make the transition in time, you know you did your best, and someone else dropped the ball.
Also since a 15 to 20 minutes transition is pretty normal for festival gigs, it's good practice. IMHO you should always try to come across as professionally as possible. You never know who is watching and what sort of doors it can open up. If the band successfully does the quick change and also puts on a good show, they may get approached by other event organizers.


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