[jseth]

I have a Bose Model I Classic - I prefer to run striaght through that, but I have a T1 as well, mostly for the extra inputs in case I have friends sitting in... I have NEVER had any feedback trouble with the mic I use - a Shure Beta 58A - and I don't sing extra loud myself, so I have the volume up pretty good. I leave the system "hot" when I take a break, too; volume up and ready, never even a whimper from the vocal mic...

So, in addition to the other comments here, the FIRST thing to do is to follow Bose's "gain staging" process when setting up your mic channel. Just do it like they suggest (actually a great idea with any PA or mic/guitar, not just Bose's good idea)...

Singing "close-mic" is a good way to limit feedback, as is having the mic slightly angled upward. Some mic's are more prone to feedback than others; perhaps it's time to switch mics? You didn't say what type of microphone you are using, but I'm assuming it's a good one - why have a great sound system and a crappy mic, right?

Let us know if you solve the problem - I REALLY think the gain staging process is going to take care of it, though. Another thing, cut ALL fx on your vocal mic and try it that way. If you use a lot of "treatment" on your vocals, that can wreak havoc with the overall sound.

I do like the suggestion about working on your vocal technique - one thing's for sure, you have to BREATHE when you sing or you'll have nothing to project your notes.

Good luck - I hope this is helpful for you!