Right now I'm very into making drone/ambient type loops and I need a piece of hardware (preferably battery-powered) that can give me clean, crossfade-type seamless loops. I just can't do it with the SP or microsampler because I get clicks at the start/end points. And resampling a fade in/out sample and trying to do it manually that way is a pain in the ass.

I wonder if there are loop pedals that can self-crossfade at the ends. I had a casio sampling keyboard that actually had a dedicated setting for this exact purpose.

I've searched far and wide on youtube for people using loop pedals with samples instead of guitars, but having no luck. Anybody know a piece of hardware that can loop without clicks?

I highly recommend you check out the BOSS RC-505.
I have one, best looper i've ever used
Not positive about the crossfading, but can do seamless/click-less loops and has great effects. Also it's more oriented to be hand operated (vs foot) which is nice for synths/samplers.

EDIT:
This track was mostly built on an RC-505 (Drums on a track, melody on one, horn-type samples on another,bass, etc)
http://blavatsky.bandcamp.com/track/gumshoe

Thanks man, that thing looks nice... 500 bucks though, phew.

I assume it can overdub as it loops? like if I wanted a smooth tone I could just turn up the volume on my ext source and back down again, crossfading manually? Also it looks like the 505 has a lot of storage but no card slot, hopefully I could save projects within the machine?

i have the boss rc-20 xl and had the rc-2 before. there are no clicks when looping drones or pads. sometimes you can hear the start point a tiny bit because the drone may sound different at the start point then at the end. sounds very musical not clicky or something.
but when you layer a 2nd drone on top you have to press the pedal exactly at the right time because the loop lenght is already set by the first drone you recorded. the recording doesn't stop automatically when the loop starts over. it goes into overdub mode. so when you hit it to early there will be a little gap in your second drone and when you hit it to late you record over the beginning again and the sound gets doubled for an instant. hope you get what i mean.

otherwise these 2 pedals are cool but not the cleanest sounding. the recording always sounds a little more compressed then what you put into it. not much though. but if you tweak around to get the perfect drone for half an hour and then loop it on the rc-20 you may loose a little detail which can mean a lot sometimes. it's not a pristine recording like the rc-505 will probably give you. but since you use a 4-track tape recorder i guess it will be okay soundwise.

i do a lot of loop recordings nowadays and i have 2 ehx multi-track loopers now and the rc-20xl collects dust. so maybe you save some money and get the rc-505 or something later. depends on what you want to do.
good luck with your looping adventure!

@squ!L, thanks for the detailed info, and I'd like to hear anything you've done with the pedals you mentioned.

@Blavatsky, I'm interested in the description of the 'transpose' feature on the rc505.. In the manual it makes it sound like you can chromatically change the pitch, but probably not "true" pitch?

I've wanted the Electro Harmonix 45000 looper pedal. But I kind of wish they were cheaper than $545. And there are no effects built in, so that's sort of a bummer. (Probably because EHX would just LOVE to sell you more effect pedals to use with it) So the Boss unit would win if I had a choice between the 2, with its flashing lights, and the way you can build tracks very quickly with the loops you make. Using a SP with a looper would be mad fun.

this is a track i made with a boss rc-2. i played synths and drum machine through fx pedals into the rc-2. then i put everything through another pedal. just a little noisy beat.
https://squil.bandcamp.com/track/ghost-magnet

The next one was made with the ehx 2880 looper. i used a monotron delay on different tracks and a drum machine. this one is more droney.
https://squil.bandcamp.com/track/supercell

My good friend and DJ Mr.Pickles just released a cassette tape using only the BOSS RC-20XL Loop pedal, you might be interested, he is giving away this for free, check this:

viewtopic.php?f=5&t=22934

i've been just getting into more ambient/drone stuff and i use a kaoss pad//kp3 for live looping. the effects are cheesy sometimes lol but the looper is pretty nice.

sometimes i do have troubles with the start and ends clicking but idk sometimes either i dont notice it or it doesnt pop up