when i see videos of people using the 303, their drums, sequences, and everything are just perfect, how do you make the sample truncate so perfectly?

you don't even gotta truncate, thats deleting everything that you have unmarked, just mark the samples and shit properly, run em through effects if you want to beef em up or smooth em out or whatever, start playin around with what you gotta sequence, and then sequence it up as best you can and adjust the mark points afterwards to tighten it up if you got to, you'll be flowin on the box in no time, just gotta stay on it for a little, keep makin beats and you'll get the hang of makin it sound good

http://www.roland.com/products/en/_support/om.cfm?PRODUCT=SP-303 here´s the manual it knows surprisingly much about the sampler

You have to just get good with that mark button.

Most gear you buy takes alot of trial and error. You stay up late, learning each function, how to push it to it's limits, and before you know it, it'd be like riding a bike. But if you get stuck, you should just ask around here.

As long all your samples have the same BPM as the sequence, then your beats will be tight. I would trim a sample to death until it matched the bpm so the samples could loop in harmony with another and infinitely.

I make my samples with computer and load off SM card.

Could you give a bit more detail on how to achieve setting your samples to the BPM of the sequence?

I notice that I cant't really adjust the BPM of a sample once its recorded onto a pad.

(All I can do is make it twice as fast or slow when I turn the FX knob??)

The key is to mark your samples precisely on the down beat and grab a small 2 or 4 bar loop. At that point you can stretch it to just about all but the most extreme bpm. People don't like the timestrecth, but after you add some crispy drums off vinyl and other embellishments the sound stretch artifacts blend nice brah. The 303 is weird and slow to learn but it'll never stop being useful and challenging.

It often helps a lot for me to compress the sum of the drums slightly (maybe with that vinyl function) and give em a short reverb.. it can be the glue for your drums.. when the drums fit, the beat will fit as long as you match bpm times

wrong knob, brah. there's a time knob and a bpm knob. bpm will double or half the bpm. time knob will do a time stretch or compress. do you have the manual? this is a pretty basic function, i don't really see how you could have missed it in there...
also, if you set the pad's bpm to 'ptn' it should change its bpm automatically to match the pattern bpm (when you change the pattern bpm)

wanna elaborate on how you compress the drums as one? if it can be done in the box i would like to know!

yo u got a beat that used the timestretch? i wanna hear that shit cuz i never fucked wit it for its sound. . .im usin a 404 but im pretty sure their simialar enough

I usually do it later on in the mix, but you can add one effect to many pads. I'm not sure if its the same like compressing the sum, but for my ears it does really well.