Posted tagged ‘General MIDI’


March 19, 2012

TCM Mastering: Home Music Studio Tips and Information

Part 55 MIDI Continued

In last week’s TCM Mastering Home Music Studio series, we looked at the various pieces of gear (Sound Generator, Interface, Controller and Sequencer) that are needed for a MIDI setup, as well as looking at the various MIDI messages and modes.

This week, we continue our look at MIDI by considering General MIDI. We’ll also delve into sequencing, recording and editing MIDI data.

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General MIDI

General MIDI (level 1) is a protocol that was developed in 1991 which defined specific features of a MIDI instrument. It means that the sounds on one MIDI instrument are largely consistent with the sounds on another MIDI instrument. In conjunction with the use of Standard MIDI Files (SMF), this means that a sequence created in one programme can be replicated or played back in another – the result should be that both sequences sound the same.

Writing Music With Pencil & Paper And With Finale Software.

The process of composing music these days is quite different to how it was done 100 years ago. There are many musicians of course who still compose the ‘traditional’ way, using pencil and paper. But for those musicians who never had much of a formal musical training, modern technology and particularly MIDI, allows them to create music by playing their efforts directly into a sequencer or computer and then adjusting or fixing any errors, without touching a pencil or piece of paper.

The Popular Sibelius Scoring Software.

What’s more, music can be created and recorded by a musician in one part of the world, then worked on or completed by a musician in another, without either of them leaving their studios.

Musicians On Opposite Sides Of The World Can Contribute To The Same Project.

For example, let’s say there are two musicians – Courtney in New York and Kurt who lives in London. They both have home studio setups with General MIDI compatible synths and sound modules. Using GM, Courtney can take the SMF of a song created in her programme, send it over the internet to Kurt who then plays it back on his system. The result is that the playback heard in the UK will (or should) sound the same as the version created in the USA.

It’s important to mention different programmes and sequencers often use proprietary file formats which may not be compatible with each other. For the example above to work, the file needs to be saved in Standard MIDI File format, which is usually an available option in most good sequencing programmes today.

In addition, not all MIDI instruments follow the GM standards. So if  this feature is likely to be important to you, then make sure the synth or other MIDI instrument you’re considering is GM compatible, before you buy it.

4 Families Of GM Instruments Each Containing 8 Patches.

General MIDI Level 1 protocols consist of…..

A minimum of 24 polyphonic voices which respond to velocity and 128 instrument patches. The 128 patches are divided into 16 family types, with 8 instrument patches in each family. For example, family #1 consists of piano type sounds whilst family #4 is guitars.

All 16 MIDI channels are supported for receiving and sending. Each individual channel is capable of playing a variable number of voices (polyphony) and can play a different instrument (patch or timbre).

Sound Patches Can Contain Several Different Instruments Spread Over A Keyboard’s Width. Here We See The Standard GM Key Assignments For Drums & Percussion.

Key-based percussion defaults to MIDI Channel 10. With each Note number (key #) corresponding to a different drum sound. For example, Note 35 is Acoustic Bass Drum, whilst Note 60 (middle C) is High Bongo.

In addition, General MIDI 1 is capable of handling a multitude of performance and controller messages.

General MIDI Level 2 was introduced in 1999. It is compatible with GM 1 and consists of…..

Over 380 sounds, 32 note polyphony, added features and greater control for sound editing and musical performance. A GM 2 device can handle 16 channels, up to 16 simultaneous instruments (patches) and 2 simultaneous percussion kits (on channels 10 and 11). Several more control messages were implemented, including MIDI tuning. Also added to the GM 2 standard were various effects, for example reverb and chorus.

Pro Tools MIDI Editor.


A MIDI sequencer works on the same principle as a multitrack recorder in some ways (except you never record to tape). There are the same transport functions – Record, Start, Stop etc. Each instrument is assigned and recorded to a separate track.

To differentiate between the various tracks, a separate performance can be assigned to one of 16 MIDI channels. Meaning that 16 different MIDI sounds or instruments (if you have that many) can be played back simultaneously – providing you have the right equipment (MIDI interface etc.) with enough Ins and Outs and a computer or sequencer with the processing power that is capable of handling it all.

In this way, the audio outputs from each instrument (synth or sound module) can be connected directly into a mixing deck (often part of the software programme or DAW that contains the sequencer) without ever going to tape and therefore are first generation sounds, giving you the cleanest of signals.

The sequencer can record the incoming MIDI signal in Real Time (as you play it) or Step Time (one note at a time), this signal contains the performance information for that recording – the note pitches, durations and volumes. No audio is recorded. To play back the MIDI recording, a MIDI OUT signal is sent to the synth or sound module where a sound is then triggered.

BeatDesigner – MIDI Plug-In Step Sequencer For Drum Patterns.

The advantages of recording performance information are…..

  • It allows you to record a track using a piano then play back that track information using any instrument you desire.
  • If you’re not the greatest player in the world, it allows you to record each note of a sequence one note at a time.
  • On play back you can alter the musical key of the performance from the original.
  • You can also alter the placement, pitch, volume or length of a note in the sequencer.


Prior to recording you need to make sure that all of your instruments, sound modules and sequencer/computer are talking to each other or synchronised.

You will need to…..

  • Decide which device is going to send MIDI commands – be the ‘Master’ and which devices are to receive commands – ‘Slaves’.
  • Check the polyphony setup for your instruments.
  • Assign MIDI channels for each device. For example, drum machines are usually set to channel 10, because this is the default channel for General MIDI.

If you play the ‘Master’ device and hear nothing from the other devices in your system, check through your setup. In particular, check the MIDI channel assigns (and of course you will need to monitor the audio outputs from each instrument in your system). Your specific instrument manuals should be able to help you with these setups.

Prior To Recording, You May Find It Useful To Sketch Out Your Setup If You’re New To MIDI, Noting Channels & MIDI Ins/Outs/Thrus.

Before recording, make sure you have the correct sound patch going to the right track and adjust the levels of the various instruments assigned to the various MIDI channels.

Your sequencer will have a metronome. If you choose to use it, you need to set the tempo and time signature…..3/4, 4/4 etc. Tempo can always be altered after you’ve recorded. You may find it useful to record at 60 bpm (beats/minute) if your playing skills are basic, but want the track to play back at 120 bpm.

Just make sure you decide on the final tempo before you start recording any audio. MIDI can be sped up and slowed down without altering the pitch. Audio cannot, without using pitch change plug-ins or software like Elastic Time and Pitch (see links below).


As with digital audio you can cut, copy and paste MIDI recordings. You can also easily quantise and transpose MIDI too. In recent years, big steps in audio manipulation software enable you to treat audio files in similar ways to your MIDI files. Check out Quantising audio with Elastic Time and Transposing with Elastic Pitch.

Left: Unquantised MIDI. Right: Quantised MIDI.

Quantising a performance can fix poor timing or rhythm. Let’s say you recorded a MIDI kick and snare from a synth keyboard, but on hearing back your performance, you feel it’s not quite tight enough – some of the beats stray a little.

You could manually move each drum hit to the correct position, but that might take a long time, especially if your performance is really bad! Alternatively, by setting the right quantisation value in your sequencer, you could hit a button and all the hits would snap to the correct beat.

If you choose a quantisation value of 8, then all your notes or drum hits would snap to the nearest 8th note. Choose a value of 16 and all the notes would move to the nearest 16th note. Most good programmes often have the added ability to somewhat or partially quantise – allowing a human feel to remain in your recording and preventing a robotic quality to the music.

If you’re rhythm is really out, there’s the risk that quantising the track will move some beats further out than in. It tends to work best for tracks that are slightly out. So listen carefully to the result. If it makes some beats worse, you may have to move those specific beats manually.

Transposed Music Sequence From A Major To E Major.

Transposing allows you to simply change your MIDI tracks from the key of A major to the key of E major, for example.

You may want to try out several vocalists for a song. Each one may have a different vocal range and consequently require the song to be played in a different musical key. Using the sequencer’s transposing facility enables you to change key at the touch of a button, without having to re-record your tracks.

Logic’s Piano Roll Editor Window.

In most good software programmes, MIDI can be represented graphically in a few different ways. The Piano-Roll Window tends to be the most common window used when editing. The picture above shows the piano keys represented on the left. The horizontal bars represent the different MIDI notes recorded on a track. The length of the bars shows how long each note was played. By selecting a note you can alter its position, length, pitch etc. Additional features allow you to adjust volume, change MIDI channels and more.

Logic’s Score Page.

When using Step Time to record one note at a time, some sequencers provide a Score Page where your musical performance shows up in musical notation. If you can read music this may be a useful page to work on and edit your MIDI tracks. It allows you to make all the alterations we’ve discussed earlier e.g. move notes, alter pitch, volume etc.

Events List Showing MIDI Data.

Some programmes include an Events List Window. Those of you who are techies will probably appreciate this page. It presents all the MIDI data of your music. Everything from velocity, pitch bend, pan and more.

So by using a combination of window displays, you can alter every nuance of a MIDI performance, even if the original lacked expression and dynamics.

Next week we look at Mastering, the final stage in the technical process of music making.

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