Sunday, April 13, 2008

Sequencing

Often, a band will get in to MIDI and synthesizers so that they can extend the sonic range of the band without adding another member. For example, you might have a song that would sound really good with an orchestra background. But, you don't want to have a 90-pc. orchestra waiting off-stage so that you can do that one song some justice. Synthesizers can help you get some of those extra sounds to round out your performance. Using a sequencer can also help you automate some of your other moves (like changing patches on your guitar rig so that you're not tied down to your pedalboard).

When we talked before about MIDI, we said that note information is going across the wire. Note that timing information is not.[1] So, if you just dump all the note information into the synthesizer then the synth will play all the notes as fast as it can. This is usually not what you want. A sequencer will keep track of note information and timing information so that you can record a performance and then play it back later. The sequencer, when playing a piece, will send all the text messages at the right time. So, think of the sequencer doing this:
"Dude #1: Play a C#"
(to self: one mississippi, two mississippi)
"Dude #1: OK, stop the C# and play a D. Dude #2 play an F#"
(to self: one mississippi)
"Dude #2: Stop the F# and then play an F#"
(to self: one mississippi, two mississippi)
"Dude #1: Stop playing all your notes and then switch to your Piano sound"
....
There's a couple ways to create a sequence. If you don't have any MIDI controllers, you need a sequencing program like Rosegarden, Cakewalk, Cubase, etc. Using the programs it's possible to enter in the notes by hand. (I'll probably explain the typical methods later.) The other (better) way is to record your performance with this sort of setup:

You plug the MIDI OUT of your keyboard (controller) into the MIDI IN of the sequencer. You also need to set up the Keyboard so that the notes you press only go to MIDI OUT (and they don't make any noise). Then, you connect the MIDI OUT of the sequencer into the MIDI IN on the keyboard. If your keyboard is also a synthesizer, configure it to "listen" to the incoming data. Make sure these are happening on the same channels. If you have any more synths, plug them up using the MIDI THRU ports.

The sequencer needs to be configured to echo incoming notes. But what this setup will do is allow the sequencer to record what you're doing as the messages are being sent to the synthesizers. The sequencers are able to record note info, the status of your pitch wheel, and knob/mod-wheel tweaks you make, and "patch" changes (when you change the synth voice).

After you've recorded it, the sequencer has note data — not audio. So you can fix mistakes, change keys, change tempo, etc. You can also insert stuff. For example, if you put a Line 6 Pod into your synth chain, you can send messages to the Pod that will change the patch you are on, change the volume, turn on/off the wah, set the delay time, etc. (This allows your guitar player the freedom of jumping off amplifiers instead of standing at his pedal board.)

USING IT LIVE

Sequencers are pencil-necked, inflexible, perfect people to play with. If a sequencer was a human, you'd call him a jerk because he doesn't listen to the band. If you're playing with a sequencer, it's his way or the highway. (One notable exception is Ableton's Live.) If you play with a sequence (even from Live) on stage, you will need to make sure that the band is fully synchronized on the tempo. The most common way to do this is with a click. This like a metronome that only the band hears while performing. Usually, at least the drummer will have the click, but anyone else who is going to be playing with the sequence will need to hear the click. The band will also need have the song progressions memorized. (Intro → Verse → Chorus → Verse → Chorus → Bridge → Chorus → Chorus → Outro).

If the band gets off the sequence, there is no recovery.[2] You either have to stop the sequence or grasp to get back on track. Here's a few ways to get the click:
  • Dedicate a synth (like the sequencer's built-in drum machine) to giving the click. The audio output of that synth will either go straight to the drummer's headphones, or into the mixing console the controls the stage monitors.
  • If you're using a high-end keyboard with extra outputs (e.g. Left, Right, 1, and 2), you can often route the click to one of the auxiliary outputs). Or if you are using a softsynth and a break-out box with several outs, you can use one of those outs for your click.
  • If your keyboard has stereo outputs and is able to do more than one sound at once (multi-timbral), you can dedicate the Left output to your real music, and then use the Right output for your click sounds.
  • If you guys are musician gawdz, you can watch a blinking lights on the sequencer's console for the tempo.
Someone will have to be dedicated to starting and stopping the sequences. If you have a keyboard player or a DJ... that's his job. Otherwise this usually falls to the drummer. However, the drummer usually has too many things going on already... so a guitar player with a MIDI foot controller might be a better option.

USING IT LIVE (Take 2)

What we've talked about so far is a MIDI setup that is inflexible and pre-recorded. You also have to lug around synths and set them up. You have to make sure that they're all talking to each other. All set up so that the synths will make freaky sounds while you're playing cool leads on the guitar. Why are we doing all this again?

You might consider recording (audio) all this stuff. Put the synth sounds on the Left. Put your click on the Right. Load it into an MP3 player (or iPod if you live an iLife in an iBand) and plug the output into separate inputs of the PA/Monitors. It's the same thing, right? And it weighs a lot less. If you have some loopers, you can possible load them into that for real-time rearrangement.

You might be thinking, "But... but... my synths are all sound awesome in stereo. If I put all the audio on the Left... then I lose my stereo. I just can't live with that!" The answer to this is simple: 99.9% of the places that you are going to play have a Mono mix for the PA. And if they do use a stereo mix... it's not for what you think it's for. Use all the stereo you want in the studio. On stage, you have to deal with mono. Even if you give the sound engineer a stereo signal, he's going to combine them into one, single, mono signal.[3]

ONE LAST WARNING (STUCK NOTES)

Remember how in MIDI there's a command for note on and a separate command for note off? What happens if you send the note off command... but the synthesizer was too busy to heed your instruction? What if the sequencer forgot to send it? What if the patch that you chose has an infinite delay loop that has become very odious sounding? Then, my friend, you have a stuck note. There's a special MIDI command for "EVERYBODY BE QUIET!!!" There's another one for "DUDE #4, WOULD YOU *PLEASE* BE QUIET." This is often called the "Panic" button or "All notes off." There's often one on the front of the synth. Otherwise you can send these messages (CC means Control Change):
  • For a single channel: CC#123 All Notes Off
  • For all channels: CC#125 (Omni Mode On/"Everyone be quiet and listen"), CC#124 (Omni Mode Off/"As you were...")
You usually don't need to know those 3 control codes... it's usually already set up in your sequencer. Know where it is before you get on stage.

SUMMARY

So, to wrap up, here's what you should take away from this one:
  • You can use a sequencer to automate your synthesizers.
  • You can use the sequencer to automate your other digital gear.
  • You must have a click set up if you're going to use a sequence.
  • Instead of a sequence, consider using a stereo recording with the audio on the Left and the click on the Right.
  • Know where the panic button is (all notes off).
Y'all have fun!

[1] - Actually, there are some special situations where timing information does go across the wire, but we won't get in to that.
[2] - Although, I've been working on something for Linux and the Jack audio server that allows for real-time tempo adjustment, beat skipping, etc.
[3] - Whether you like it or not, this is the convential wisdom for PA design. The idea is that the stereo mix is only effective for a person sitting in a single spot in your auditorium. That is to say, a stereo mix is not effective for 99.9% of the listeners. Plus, if you pan the guitar to the left, the folks on the right will not hear him. At all. Therefore almost all PA's in all bars, churches, and concerts are set up with a mono mix. Whether you like it or not. Agree or disagree. This is what you will find and complaints about having depth of sound will fall on deaf ears as they roll their eyes at you. And chances are that you are wrong. :-)

1 comment:

Anonymous said...

Thank you SO much for this series of posts, I've been trying to find a logical explanation of the basics of synthesizers for a long time. This has been immensely helpful.