I just had a look in the BR manual.
In "MP3 Mode" you can:
Record - The inputs to the recorder are still operational, and you can record direct to stereo MP3 or WAV, this is probably the fastest way to get the song you want onto the box. Get a line out from your source (your cd, dvd, or record player - even from your PC's soundcard, record direct off the internet, eg youtube or spotify, etc...)
Timestretch - Speed up or slow down playback of an MP3 or WAV. The default is 100% (normal speed). You just change this percentage. It implies you can get it up to 200%, and I assume down to, er, 0% :lol:
It has a warning that sound deteriorates at anything other than 100% - but, we already knew that, I guess they had to cover their @rses :D
Centre Cancel - You can take the middle out of the stereo image. This removes anything that's "in the middle", usually the lead vocal or the "solo". It also lets you move the cancelling position, you can adjust it left or right in the stereo image.
Again it warns you that it might not do exactly what you expect, depending on how the original recording was mixed.
(Note that you can do centre cancelling in PC software studios, by inverting the phase of one of the stereo channels - if your software has this facility)
Repeat Sections - You can set a Start (A) and an End (B) and then set the song to loop over this section repeatedly.
You can do this when you use it as a multitracker as well - I'm about to use it a lot this weekend to practice a keyboard part that I need on my project. The A - B functionality is also used in the multitracker to allow you to do "drop-in" overdubs to repair mistakes in your playing.
Play along - because the recorder's inputs are still active during playback, you can plug in and play along :D
The only thing I'm not sure about is whether the onboard guitar effects will be available (ie the amp modelling) when you're running in MP3 mode - I seriously doubt it, I would be stunned and amazed, and VERY impressed, if they've managed that as well :D
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I would whole-heartedly recommend this beastie. It's a "real" multi-tracker, with the addition of very usable drum patterns and some very usable effects for guitar, vocals, and mixing/mastering (the reverb's not superb, but hey! :D).
I think it does what you want you can use it simply or delve into more deeply into it. It introduces you to multi-tracking with a set of tools that enable you to produce superb results...
If you do get hooked on recording, and go the PC route later, you still might use it - I've come across people who bought it as a notebook and have ended up using it as their recording device, then they export all the tracks as WAV (it's a 4 track, each with 8 virtual tracks = 32 tracks), then load them into their PC set up for mixing.
The ONLY drawbacks to the unit as far as I'm concerned (this is in multitrack mode) are:
1) The effects do not include a "pitch-shifter" - they've got nearly everything else. Lots of people mock up demos by playing a guide "bass" part on a guitar and then pitch-shifting it down. It's not ideal, but it gets the job done fast if you're songwriting or travelling. If it had a pitch shift, then this little box and just one guitar, and you're all set wherever you are :D
2) There is no midi interface.
But neither of these are particularly getting in my way.