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8.1     Basics on how to use MIDI in a home studio:

MIDI is a very useful item in a serious home studio.  It offers the possibility to produce more complex recordings, simplify the recording process, and offer a pallette of sounds not usually available to you.  MIDI is generally sequenced or controlled by one specific device.  This can be a computer, a stand alone sequencer, or a sequencing keyboard.  I personally use my computer, running Cakewalk.  Many different components can be added to a MIDI system, making it very flexible.  A sequencer has the ability to record incomming MIDI messages, and store them for later editing or playback.  Here's an example of how a typical home studio MIDI setup might look:

1.  You have a computer, running some sequencing software, with some sort of a MIDI output.  Soundblaster compatible cards have the ability to control MIDI through the joystick port with a special adapter.  This is a Y-cord with a joystick adapter on one end, and a pair of  male 5-pin circular DIN connectors on the other end.   These circular DIN connectors are standard MIDI connectors.  One is labelled IN, the other is labelled OUT.

2. Next you need some MIDI equipment to connect to it.  For starters, you can have a keyboard to use as your main controller.  This is where you will perform.  Most keyboards will have 3 MIDI connectors,  IN, OUT and THRU.  Here's what they do:

You then make the following connections:  Keyboard's IN  to the computer's OUT.  Keyboards OUT to the computer's IN.  In this setup, playing the keyboard will send info so you may record it into the sequencer, and pressing play on the sequencer will force the keyboard to play back the MIDI sequences you've recorded.

3. I then connect any other devices to the MIDI THRU on the keyboard.   These outboard modules may be other keyboards, drum machines, drum modules, sound modules, samplers or MIDI controlled effects units.

Each additional piece of MIDI gear can be daisy chained from the output/thru of one device to the input of the next.  Unfortunately, each piece of gear has a slight delay from the time it recieves data to the time it mirrors the data on the thru port.  The effect of adding the MIDI delay of several pieces of gear in a chain may make the last few sound modules sound significantly late.  A way to avoid this is with a MIDI splitter or MIDI thru box.  They are generally have one MIDI input, and several thrus that all transmit the same data.  The units now run in parallel, and all recieve their data simultaneously.  

I own a 1x8 thru box... 1 input, eight outputs.  (but it may also be used as two seperate 1x4 splitters).  I connect the thru box to the output of the computer sequencer, and each output of the thru box goes to my other devices...  the synth, drum module, drum machine and fx boxes.

8.2    MIDI channels

You now have to determine which channel you want each device to respond to.  MIDI has 16 channels available.  Each channel like a track on a tape... and each channel would usually be set up to be a unique instrument.  Some devices will only respond to one channel at a time, while others will respond to any or all channels simultaneously.  For example: many drum modules use only one channel at a time, and as a standard, drums are usually set on channel 10 (although you should be able to change this from the default setting).   Many polyphonic keyboards and modules, on the other hand, can accept MIDI from several different channels simultaneously, directing each channel to do a different instrument.    

8.3     A Multiple Device Setup

Let's make an example song to clarify the MIDI system a little.  We are still using the aforementioned computer-based MIDI sequencer, a keyboard, and now we'll add a drum module and a keyboard module.  You'll begin to notice the more gear you add, the more complex the "mess" becomes.  You'll have to repatch your rig quite a bit, and you'll often have to combat some type of channel conflict between devices... a typical MIDI sequence: 

First, we want to record a drum track, and we'll use the standard for drums: channel 10.  We set the sequencer to record on channel 10, and set the drum module to receive on 10.  We then set our keyboard to transmit on 10.  You then need to look on the sequencer and turn on the Software Thru or MIDI echo.  What this does is forces the computers MIDI out to act as a thru.  We'll then connect our gear in a simple, logical order:

Keyboard Out -> Computer In    

Computer Out (Thru) -> Drum Module

Now when you press a key on the keyboard, it sends info to the sequencer, and the info from the sequencer is sent back out to the drum module.  You can now record your drum tracks.

One of the beauties of MIDI is the way you can stack sounds on the same channel.   On the sequencer, you may first record on channel 10, and play simply the kick drum.  You can usually (verify this for your software) simply rewind, reselect the track, then stack the snare on top in a seperate pass.  You can also put on the cymbals after that... making the recording fairly easy to do.    You're basically overdubbing each drum sound, but storing it all on one track.  

Now we'll add piano.  For that, we'll use the main keyboard.  You'd leave the gear hooked up in the same way, but now you have to select some different MIDI channels.  Let's use channel 1 this time... set the keyboard to transmit on channel 1, then select a new track on the sequencer, and select for it to receive data on channel 1.  Now if you record on the sequencer, it will play the drum tracks on channel 10 while awaiting input on channel 1.  You simple play out your piano piece along with the drum line you've already created.

When you go to playback your song, you'll notice there's a problem.  The output of the sequencer is not connected to the input of the keyboard... so we need to rewire.  Well, you'll still need the Keyboard Out connected to the Computer In, because we still plan to record more tracks.  Somehow, we need to get the data coming out of the computer to go into the drum module AND the keyboard at the same time... If you have a MIDI thru box, this is a perfect spot.  If you don't have a splitter, you can just connect the Thru of the drum module to the In on the Keyboard.  Let me note that the chain could also feasibly be:  

Computer Out -> Keyboard In

Keyboard Thru -> Drum Module In

Ok, we're all rewired so now you press play, and the sequencer sends data out on channels 1 and 10.  The keyboard plays the piano part on channel 1, and the drum module plays your drum track on channel 10. But guess what?  Your keyboard probably receives MIDI on ALL channels... so it's also playing the channel 10 data with it's own built in drum sounds... so it's doubling the drum parts that the drum machine is playing.  What you need to do is make it so the keyboard ignores channel 10 data, or maybe assign an empty patch to that channel.  You're going to need to check your manual to find out how to do this on your synth.  This a typical type of MIDI conflict, where two devices are responding to the same channel.

Now that we're satisfied with the piano and drum tracks, we can add a third track.  This time, we'll add a synth pad for a nice quiet background sound.  The best synth pad for this song is on the synth module, so you have to hook it into the MIDI chain somewhere.  You can simply hook it to any available Thru port on any device.  The ideal situation would again be using a MIDI thru box or MIDI splittler... then your sequencer could send messages to the keyboard, drum module and synth module in parallel.  A daisy chain with 4 devices is still not very large, but a very minimal delay may be audible in the last unit.... parallel is always better.  

After the synth module is wired, we'll record on MIDI channel 5 this time.  Set the synth module and sequencer to receive on channel 5, and set the keyboard to transmit on channel 5.  Again, you'll need to turn off the keyboard's built in sounds for channel 5, otherwise you'll always have two sounds playing simultaneously (which we don't want in this instance).  After you fix this conflict, you're set to record, right?  Nope!! Your synth module is also multi-timbral, and responds to all MIDI channels at the same time.  Now that you've added it to the MIDI loop with the other channel assignments, you'll need to make sure it ignores the data on channels 1 & 10.  After that's fixed, you're ready to record the new track.  You may keep building this until you've exhausted all 16 available tracks.

Resolving these little MIDI conflicts becomes second nature very quickly.  I whiz through menus and change channel assignments on gear with ease, and usually prevent all MIDI channel conflict before it even happens now.  It's daunting at first, but it's all quite logical once you get a grasp of it.

8.4    Other MIDI data

Up until now, we've only discussed MIDI channels.  When your MIDI equipment is "talking" to each other it doesn't reference notes in letters like we do (A, C#, E, etc); References are made to a note number instead.  Basically MIDI references notes on a range from 0 to 127.   With 12 notes per octave, that gives you an impressive range of over 10 octaves.  Using numbers instead of letters makes the "math" of transposing, etc easier... what's C# shifted up 8 half steps?  Who knows!! (Without some careful thought).  On the otherhand, transposing note number 36 up 17 steps is pretty easy... 36+17=53.  I think this system makes things easier to visualize (at least for me).

Up to this point, we've only used MIDI to control the notes being played (note number) and the channel it's played on.  We've only taken advantage of a portion of MIDI's maximum potential.  Using the various other control surfaces on your keyboard like a ribbon controller, pitch bender, data slider or mod wheel will also send MIDI data that can be recorded on your sequencer.   These types of events are called controllers, and they basically alter one parameter of the current instrument's sound.  Each parameter has it's own controller number, and here's a few common ones: (remember these are standards, but some manufacturers use different configurations)

There are usually two of these controllers hardwired into your synth: Modulation and Pitch Bend.  Pitch bend obviously alters the pitch of the note, the mod wheel often adds a vibrato effect.  Synths also commonly have data sliders and ribbon controllers that can be set to alter volume, panning or effects levels amongst other things.  It is usually very open ended, allowing you to control any parameter you desire.

I have a particular synth module that allows you to use a controller to alter the resonance or filter cutoff for an onboard resonance filter (Controller 13, in this case)... a very nice feature which allows me to get that nice "waaaah" sounding filter sweep (perfect in techno).  Again, you'll need the manuals for your gear to see what controllers are recognized, and also how to configure your control surfaces to transmit the controller number that you desire.  

Another parameter you'll be interested in is the velocity of the note.  Like most MIDI data, it's a number in the range of 0 to 127, and it corresponds to how hard you pressed the key on the keyboard.  The harder you push, the higher the velocity, the louder the note.

8.5     Sysex

Wouldn't it be nice if you could turn off all of your MIDI gear, then restart it in exactly the same condition?  Nobody would want to have to reset each MIDI devices sounds and receive and transmit channels each time they turn their gear on.   That's why Sysex or System Exclusive was created.  Sysex is a way for your sequencer to record all of your current settings for each piece of gear.  Basically each MIDI device can transmit all of it's current settings out of the MIDI Out port, and the sequencer saves the data in a special file.  When you play the file, the data is sent to the outboard gear and initialized to the proper settings.  System Excluive files typically store information like the current Bank and Patch of the device on each channel.  The bank and patch are the way to address the current sound that you have selected.  For example, the bank and patch would describe the particular organ sound I have playing on my keyboard.  It makes sure that after reloading the sysex file that the same organ sound will be selected, and all the parameters will be set the same.

8.6    Tape Sync

Finally, a sequencer can also stripe a tape track with FSK time codes.  You record the syncroniser tone generated by a sequencer onto a track of your tape deck.  Every time you play the tape, the sequencer can lock to this time code, and play along exactly in time with the tape.  Now it's possible to stripe a tape on track 8, and synchronize all of your MIDI gear together to your tape deck's transport functions.  You can then generate some sequenced drums to follow your song, these drums can simply be temporary, like a click track.  You can now perform your entire "live" performance with guitars, vocals, bass, etc.  You can even use real drums, as long as the drummer stays in time with the click track.  It's now possible to add any keyboard or synth sounds to your recording.  The best part, is that the MIDI can all be recorded during mixing, so you can fill ALL of your tape tracks, and still add more music!  

Most computer sequencers also have a virtual, automated mixer.  This is a graphic representation of a real mixer, allowing you to change volume, panning, and then modulate a few parameters. If you set the mixer to record, it will memorize all of your fader movements, so that all of your actions can be duplicated during playback.  Modulation is just gradually changing the value of one of your synthesizer's parameters.  It can be used to change pitch, or to change a wet/dry mix on a MIDI effects units, or to adjust a digital reverb's depth. 

There are also standalone hardware sequencers like the Alesis MMT-8.  These are usually a little more limited than a computer sequencer, but very functional still.  Many hardware sequencers also have an tape sync function to lock to your multitrack.

This is about as detailed as I'd really like to get. I only use a modest MIDI setup, and I'm by no means an expert. "The Billboard Guide to Home Recording" by Ray Baragary (Billboard, ISBN 0-8230-7531-1) is a great general purpose recording book, but has a sizeable amount of MIDI info at the end. His explanations are very thorough, and pretty easy to follow. It's a great place to start if you're interested in MIDI, but are confused by it. It also has a ton of good recording tips, too.

8.7      Using a Sequencer with a Drum Machine

Drum machines add a curious twist to the setup.  Drum machines have an onboard sequencer, and can record their own patterns and songs.   In the previous examples, we've always had the drum parts programmed into the computer's sequencer program, but the isn't necessary with a drum machine.  

You simply program your drum tracks on the drum machine in pattern form, and then create a song with strings of these patterns.  A typical pattern is somewhere between 1 and 4 measures long.  I tend to use longer pattern lengths for more realism.  With a pattern 4 measures long you can vary the drum hits a little throughout each measure which sounds much more interesting than repeating a measure 4 times.

8.8    Drum Machine Tips

For drum machine tracks, use all of the outputs your machine has. I'm familiar mostly with the Alesis SR-16, which has 2 main outputs and 2 auxiliary outputs. I also use a Roland R-5 which has 2 main outs and 4 auxiliary outputs.  I'll occasionally place the cymbals on one output, toms on a second output, then isolate the snare and bass drum on their own outputs. This allows more creative control because you can use different EQ settings and effects for each different sound. I use this technique if the sound of the snare and bass drum are crucial. Using the outputs in this manner limits the amount of stereo panning you can use on cymbals and toms, so usually I'll just segregate the drums and cymbals into two separate stereo outputs. Then you have a cymbal output in stereo, and a drum output in stereo

Even though the drums are separated onto four channels in the mixer, you can still mix them and record only onto two tracks. The purpose of isolating them is more for EQ reasons and for adding effects than anything. Two tracks is vital for a realistic drum sound. I usually pan drums similar to how they'd be set up in a real drum kit. Snare and bass drum in the center, with toms rotating from slightly left to slightly right and floor toms mid to far right. I use the high hats in the middle left, and fiddle with the placement of other cymbals throughout the kit. You should avoid panning things hard left and right, as the seem to sound weird. Compression is not really necessary, because a drum machine's samples have a very limited dynamic range. Using effects, on the other hand, can be very effective. Cymbals sound nice with a mild chorus, flanger or phase shifter, but the regeneration has to be kept low to avoid problems. Toms sound real nice with reverb, and you can make a gated snare with your noise gate.

When recording from a drum machine, you should avoid a "sterile" drum pattern sound.  Rather than making one patter 4 measures long, and repeating it 4 times, you should make one patter 16 measures long with each measure slightly varied.  This will sound noticably better.  Many grum machines also have some sort of "groove quantizing".  This adds a very slight change to the volume and timing of the notes to make it sound much more realistic.  You owe it to yourself to find out how it works on your drum machine!!!  

If you want a killer bass drum sound, try this:  Send your bass drum to it's own output.  Connect the bass' output  on the drum machine to a power amp or PA system.  Pump the PA up loud in another room, and mic it.  This will give you a huge, loud signal that you can then mic to get a great sound with some added "life".  Also try adding a little distortion to fatten up the sound.  This distortion will sound different between the PA and drum machine than it will between the mic and the recorder, so try both methods.   These same methods also work for other drum sounds, especially snare.

Another trick is to run the drum machine snare thru a small speaker cab about a foot under a real snare and then mic the top. Mix it in with the drum machine snare. Be sure to check phase. 

Also, if you have a dedicated percussion sampler, sample the same instrument 5 or 6 times, assign them to different MIDI notes and have them alternate to simulate the inconsistent hits of a human drummer.  

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