| Okay, attempt no. 2 at writing a help reply.
Transcription is an excellent tool for learning and developing your basslines and musicianship. It can help you find nuances in artist's playing that you may not have picked up on from simply reading or just playing by ear. It can also help you develop your own bass lines, picking up significant ideas that work well You may also find that you start hearing mistakes in music that you thought was flawless, and even when a musician is coping a feel from a peer (or even plagiarising, a fairly big case this week has found a certain 80s classic to have done just that, Men at Work, Land Down Under anybody?).
Like with everything, there are a number of different ways of going about transcription. It all depends on how you are going to use it. For instance, if I'm trying to learn a bass line, I would probably pick out what chords are being played, for some harmonic direction, and then pick out just what the bass player is doing. I might then listen in on the other instruments to see if there are particular phrases that are in unison, or where the bass is punctuating things etc. That being just in bass clef; there's no need to over complicate things.
If I'm trying to learn/study a for example, a sax solo. I would again find out exactly what the underlying chords are, and then write in what the soloist is playing. Sometimes with solos (and basslines of course) you can find that the player is playing around with the time/pocket so that beats are pushed/pulled/stretched out etc. and sometimes this can be hard to notate, you can indicate this with annotations or articulations to help you understand it. I might listen to the other instruments, but only the solo would go into my transcription.
If I'm playing a piece with a band, I might transcribe the entire piece, so write out what each instrument is playing. You can do this in two ways, the first being a lead sheet to keep things simple, or a full transcription with each instrument fully notated. For the lead sheet I would write a treble and bass clef, and write in the melody, bassline, and chords, and then usually anything that is significant that would need to be played or worked with. For a full transcription I would take a stave for each instrument and write in what is being played by each one. You can then see where phrases line up, or where players are moving away from the harmony etc.
Sometimes it can be difficult to figure out the chords. I personally have difficulties where the root note isn't tonic, or where there are 6ths involved in the chords. The best way I find to get them right is to experiment, put the section on repeat and play some ideas over the top. Once you've isolated notes that you know are present, you can then deduce what other notes will work or would be suitable to fill the gaps.
There are a number of different notation programs. I use Finale for most of my work, there is another program called Sibelius (sic) which does essentially the same thing. These two programs allow you to create scores, using MIDI play back to listen to what you are inputting. Some sequencers (such as Logic and Cubase, and others) also contain score writing elements allowing you to input into a score and then hear the notes back on synthesisers or midi etc.
You can of course transcribe by hand, but like you already mentioned it is easier to make mistakes and if you have software that you can use to input a note and hear it back instantly (and most importantly, in tune!) this can help quicken things up substantially, and stop you from missing mistakes. Like with writing an essay though, I would advocate proof reading! It's never good to finish a chart, hand it out to a band, and then find you've made a handful of mistakes.
I hope that has helped, and not made you even more confused. I managed to get through the entire post without it all deleting itself this time.
Good luck, and most importantly have fun while you doing it!
Dan
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