First time playing keys in a band, guitarist asked me to transpose down one tone, this threw me off for playing the chords I learned and reduced me to a lot of one finger playing. I read many articles about not playing too much and even tying your left hand to your back. another was listen to the band and be sure to follow along with head. I need some advice on what to do next in preparation for our next set learning session then a small jam. I know my chords and they just didn't match, whats with that?
The advice to get a digital piano that transposes easily given in other answers is excellent; when I played keys in a cover band once upon a time that's what I did. Learn the pieces in whatever key is convenient for you, and then change the setting on the keyboard before the song. Practice changing the keyboard settings. That's part of your instrument, and you don't want to be opening the manual in the middle of a set.
That said, it is also very handy to be able to transpose on the fly on an acoustic piano. My advice to you is to take a common chord progression -- twelve bar blues and the "Heart and Soul" progression of
I vi IV V are good ones to start with -- and simply sit down and learn how to play them in all twelve keys. It will take some time.
While doing so, do not be thinking C - Am - F - G. Be thinking "I'm playing I - vi - IV - V in C". With enough practice it becomes more natural to think of progressions in terms of the relationships between the chords and not the specific chords of a particular key.
I admire your desire to want to be a part of a band and your willingness to try to improve your skills so you can make a valuable contribution.
As far as transposing - you can spend many hours practicing and learning to transpose from any key to any other key. But then you won't have time to practice with or play in the band (or anything else in life). So in order to get you to a point where you can play with the band in every key they play in - and transpose on the fly if needed - you may want to consider a keyboard or digital piano that has a transposition feature. Most do, but on some you have to read the owner's manual to know how to do it. It may not have a transpose button or a menu screen.
A piano is a very versatile instrument and is an excellent choice to accompany a singer if only one instrument is available. With two hands and ten fingers, you can cover a lot of the pieces of most popular songs on piano or keyboard. So a piano or keyboard works very well to provide solo accompaniment.
But a piano or keyboard in a band is another matter. In a band, each instrument has it's own place and must blend together with the other instruments in a congruent manner that results in a nice sounding whole. For example if playing piano as a solo instrument, you could play the bass line with your left hand. But if you are playing piano in a band that has a bass player to play the bass line, you would not want to play the bass line with your left hand.
A great deal of rock and roll music was written by or for bands, that only have a guitar or two, a bass and a drum kit. So many of the songs made famous by many "guitar bands" don't really have a keyboard part. On songs that don't really need anything more than guitars and drums, you could either sit out, or turn down the volume and play some fills or the melody, or play the chords with the rhythm guitar, but don't be so loud that you drown out the guitar. In fact, you want to be very subtle on those songs (if you play anything).
If the song has an actual piano part, then learn that part as best as you can for that song. Many cover bands use keys (such as a synthesiser) to play whatever part the band does not have anyone to play. So if the song has a sax line, the keyboardist covers it. If the song needs brass, the keys can cover it.
So if your band plays a song that has a place for a flute solo, learn the flute solo for that song and sit out the rest of the song. I know many bands that elect not to have a keyboardist at all because most of the keyboardist they have tried, don't seem to know when to stay in the background - and they feel like they have to be heard and featured in every song. They don't!
So the key (no pun intended) to being successful as a keyboardist in a band, is to know when and what to play, and more importantly - know when NOT to play. Your role in most songs is likely to be fill and embellish - not to carry the entire song. As long as you can add something that makes the band sound better on at least a few songs they play - you will be a valuable member of the band. Don't be afraid to sit out when the keys don't really have much to add.
And keep it fun!
I note you have the tag "digital-piano". Does your digital piano have a transposition setting? Almost all of them do. That makes it easy, as long as you don't have "absolute pitch" and get confused when you play a C and hear a B.
For acoustic piano players, transposition is a difficult but valuable skill. Almost everyone who accompanies singers will be asked to do it. There are a few tricks; for instance if you are reading a song in D and are asked to play it in D-flat, imagine that the key signature is five flats instead of two sharps. But to really be able to transpose, you have to practice a lot.
Never trade-off music quality with unsufficient technique. Until you feel really comfortable with manual transpose always use digital transpose.
Also when on your own, keep practicing for manual transpose all the time. You never know when you will really need it and have no other choice and time to prepare (some day you may have to do it on the stage on the fly, it really happens).
Make the band aware of your instrument's limitations.
For the purpose of this post I'm going to assume that your keyboard does not have a setting to enable it to transpose. This advice obviously applies to other instruments, particularly those that are only designed to play in one key, such as the tin whistle, bagpipes, and harmonica.
Transposing 1 tone on the guitar is very easy, unless playing near the nut. All you have to is move your fingering by 2 frets, all the actual shapes remain the same. If the guitarist doesn't play keyboard, he may not realise that transposition is more difficult for you.
Find out why the guitarist wants to transpose down. If it is to help the singer, that is a valid reason (but transposing by a fourth may also be possibility in this case.) If it is purely for his convenience, that may either be valid or completely selfish, it's difficult to say without knowing the exact situation.
That said, a keyboard player will be required to play in any key, so you need to learn to do that (As a guitarist, I'd like to completely redesign the keyboard in a layout that's easier to transpose, but the existing design is so entrenched an alternative would not catch on.)
Agree on the key before rehearsal
As much as possible, when practising a song alone, you should already know what key the band will be playing in. When new songs are proposed, the band should get together for a brainstorming session, and it should be decided what key the song should be in (this means bringing instruments along for a quick jam to check the singer's range, etc.) You'll waste a lot of time if you practice alone in the wrong key.
Yes, I know of a case where guest musician fell out with a band because he practised the song in the original key and the band didn't tell him they'd transposed it. He found this out at the rehearsal. It probably had more to do with the particular personalities involved than the actual situation, but it should have been clarified beforehand.
As a relatively inexperienced pianist/keyboard-ist in a band myself I had this same issue.
Digital transposition was key at first, and still is to a great extent. I found my stage piano (Kawai MP7) had both an overall transposition setting, and a transposition setting per-setup, which allowed me to save the transposition along with the setups I used to play each song. (it also allowed me to re-transpose the setup back to the original key to play with a recording!).
The first thing is to ask the question when you agree to learn the song. That said, it could still change if the band find it more difficult than they expected to play in that key.
The other thing that was touched upon above is knowing why they want to change the key. It'll either be the singer or the guitar (or perhaps brass/woodwind instruments if you have them). A song is much easier to play on guitar (in standard tuning) in E than Eb (but conversely could be much harder on piano). I have found (in my limited experience) that your band is likely to play in a limited number of keys, so work on those first!
I'm not sure what type of music your band plays, but I found blues music very helpful in understanding the relationship between chords, and am working on being able to improvise and play in any key. My band plays a fair bit of blues-based music, but blues is in the DNA of a lot of modern music, so is more helpful than it may first appear.
What keys can you play in? You need to expand your horizons by extending your known technique to adjacent keys --- like keys, and unrelated keys.
Do you know scales? If so, do you know "scales of chords"? That is, in C Major, your scale of chords is C, Dm, Em, F, G, Am, Bdim, C. Learn those, and then learn their 1st and 2nd inversions.
Then learn the same thing in other keys: F and G, and especially for a guitar band, D, E, A, B, etc.
Keep in mind that most of these chords occur in many different keys. For example, in G Major, 4 of the 7 chords are the same as those in C Major. So learning all the chords for, say, the 7 Major keys I've posted is simply a matter of learning 22 chords and their inversions, most of which are just transpositions of their neighbors.
This is, more or less, the basis of the Nashville Number System, which is exactly what those "studio cats" of old (and modern times) use to transpose things "on the fly" when the talent comes in with a head cold that day...
Playing in different keys: Guitar is an instrument where it's usually quite easy to transpose. Just move your hand up/down the fretboard one fret .. job done, unless there are open string chords. Keyboard isn't so easy. a transposition of 1 semitone means different fingering, etc. Songs are usually transposed to suit the vocalist, who may need things higher/lower to suit their range. So find a way of transposing easily, be it using a transpose button or just learning all the chords.
Play less (disable left hand): Yes. Please do this. But I'm biased as I'm a guitarist, haha. The bass player already has the bass domain, so don't play all over their area. This is especially true of bass because that's all they have (bless 'em).
Actually this is about physics & manner really. There's a phenomenon which you may/may not have come across yet (if you're new to playing witha a band) where one sound can mask another. That is: If you have, say, a vocalist delivering some lines, and have a rock guitar twanging away, the two are in a similar frequency range in the spectrum: upper middle (depending on vocalist). It's a real skill to mix them so that the guitar isn't bleeding all over the vocals, because two sounds in the same spectum will compete. One will most likely 'win' and obliterate the other so that you can't hear it. You don't want to enter into this battle with the bassist: they'll win (ever heard a bass amp turned up full .. ), and then everyone will be deaf.
That's what the "tie your left hand up" thing is about. Don't make a large, full sound that mioght sound lovely when no-one else is playing, but mushes everything when everyone's doing their part. That applies to every instrument but keyboard is such a braod range, the possibility for playing in all spaces is there. As Rockin Cowboy excellently points out, leave space for everything to do its job.
So where's the space for the keyboard? That's the thing, it's such a varied instrument that it'll probably be different for each song. Sometimes a keyboard-oriented piece demands you're the main carrier of the song, sometimes it's just a riff here and there.
Listen to the band & follow: Yes! This isn't just keyboards - it applies to everyone. There are two ways to hear when playing:
1) Listen to yourself, just like you do when you're practicing at home. The band fit in around you.
2) Listen to the whole band and appreciate where you fit in.
Option 1) results usually in a musician being too loud and sometimes out of time.
Option 2) results in the band as a whole sounding better. This is a bit like listening to a CD : if something is wildly loud or can't be heard, you're going to notice, so you'll be able to amend your instrument so as to mix evenly. Obviously it's best if everyone listens this way.