Well it's definitely a red flag that your guitarist would barely acknowledge it with you or divulge the conversation to you. It may sound like high school, but damn if it ain't true: He is supposed to be on your team.
It should have been: "I don't know, let me talk to him about it and I will get back to you. By the way, can I have the contact info for the other bass players who would be using his amp so he can talk to them?"
You paid for your gear, probably worked hard to get that cash you had to fork over. Don't be shy about looking after it. If your places were swapped and you did it to him, you can be sure you'd hear about how guitar amps are this or that and some random guy playing it could turn out badly.
And you're right - it's bush league to ask someone you don't know to provide their amp for everyone to use. It's something that has to be offered by the owner. And appreciated by everyone else. Not some assumed load of B.S.!
This isn`t the first time my guitarist has done something like this. He already offered another band to use my rig without permission once and the whole situation just turned out ugly. I would go into more details, but you can find the thread about it elsewhere in Band Management
Here's what I would do. I would ask for a fee. For twelve hours, $400 sounds good to me.
I'd also ask for a deposit. Enough to cover the entire rig and a half.
I'd give them very specific instructions on how to treat my gear. They would be written and attached to the rig in a way that you couldn't even plug your bass in without having to see them.
I'd speak with everyone scheduled to use my rig, and tell them what they are and are not allowed to do.
I would not allow anyone to use my rig without speaking with me some time beforehand.
I'd check in periodically to make sure all the knobs are in acceptable positions. If they're not, money is coming out of that deposit and going into my pocket.
When it's all done, I would take it straight to a tech. He would make sure that it's in 100% great and perfect condition. And if it's not, the deposit pays to make it better. If it straight out doesn't work, the deposit is mine, all of it.
Then, once I've made sure I've got my rig at 100%, they get the deposit back.
And if they agree to all that, why not? There's nothing to lose as long as you protect yourself adequately. If it's a well run charity, they're going to do their best to protect their deposit and make sure that everyone treats your stuff real nice. And I just pocketed a nice $400 rental fee. That's worth a bit of trouble for me.
Seems like a bit too much for me, but I like the idea!
I'm sure the bass players of the other bands will have their own amps too and if they are serious would prefer to use their own.
This was my thought as well. On top of that, there was no mention of a backline for the guitars so I`m just curious what`s going on with them. I guess if every band was contributing something I could take it into consideration more, but if all the guitarists are using their own rig then I don`t see why we can`t do the same for the bassists.
