Tips for creating a playable synth patch part 2

Last time we talked about using Keyfollow for various synthesis function, this time we will look at using Velocity.

Velocity - Volume

Try hit a tone on any physical instrument with various strength and it will make a tone no matter how soft you hit it. This is the reason why i only have Velocity control Volume to a certain degree. Typical it will control 30-60% of the Volume but never 100%.

Velocity - Filter

Imagine the tone from a piano, when played soft its a kinda round smooth sound it produce. Play it hard and more brightness is added to the sound. The tricky part is to make that transition using Velocity, add too much Velocity to the filter and it will sound like the strings are about to break, add too little and it will sound muddy. Usually i find my self using a Velocity - Filter setting of max 25%.

Velocity - VCA-Decay

Imagine you hit a piano key soft and notice how long a decay it got, then hit i hard and notice the longer sustained note. To emulate this kind of behaviour we use Velocity - VCA-Decay. The correct setting for this depends on the instrument familie, drums need only a subtle change, pianos a bit more and guitars can go from a very short muted pluck sound to a very long sustained note. Velocity - VCA-Decay is often used along with a seperate Velocity - VCF-Decay to give the same feel to the filters, meaning the filter will open up as you play harder.

Velocity - Waveform

A classic Velocity - Waveform setting is when using Velocity to control the Pulse Width on a Square waveform. When emulating a jazz guitar sound i will often use Velocity to control the Pulse Width from a 40% position to a 30% position. This gives the waveform a little life on its own when playing at various strenght. Doing the same with Sync can also add a spark of life to the tone of a sound.

If you are working with Additive or Wavetable you can have the Velocity control the waveform in a more drastic way. Imagine a wavetable of nine pipes on a organ, have Velocity control the transition between those nine pipes going from 1 pipe to two pipes to three pipes etc. This will give you a very dynamic organ patch suited for soft to hard playing style.

This was some of the most obvious uses of Velocity within a synth.

/Michael

Tips for creating a playable synth patch part 1

Whats the big difference between playing a sample and a synthesized sound ?

Its the expression of the sound.

A sample is static whereas a synththesized sound can be much more.

To help us making a playable sound we have the following:

1. Velocity (Mapped to Volume,Filter and Waveform)
2. Aftertouch (Mapped to Vibrato)
3. Modwheel (Mapped to anything interesting)
4. Keyfollow (Volume compensation, Filter balance, Modulation (LFO) and Envelope spread)
5. (LFO) Modulation of the waveform (PWM, Wavetable, FM, Additive etc..)

Keyfollow example:

Pulse Width Modulation

A PWM waveform modulated by LFO will usually sound nice at the key we used to set the speed of LFO but if we play a much higher key it wont have the same modulation effect and if we play a very low key the effect will be way to much. This is where keyfollow comes in. We have to control the amount of LFO signal sent to the waveform by using keyfollow. In this case the keyfollow must be set to a positive amount around 50%+.

This should produce an overall nice modulation to the entire keyboard range.

Volume Balance

Next thing to consider using keyfollow is for Volume. High notes will alway be percieved at a higher volume than lower notes since high pitch sound travel faster thru air than lower pitch sounds. In this cast we have to use keyfollow with a negative setting thus making the lower notes play louder than the high notes. This is done by having keyfollow control the Volume with a 50%- setting.

This should produce an overall Volume balance to the entire keyboard range.

Filter Balance

Next thing to do with Keyfollow is balance filter offset for the entire keyboard range. Do we want it to play with a more open filter when playing high notes or do we wish to have the same strength of filter apply to the entire keyboard range. Remember IF you choose to have more open filter with high notes then the percieved Volume will be higher on high notes aswell so you need to adjust the Keyfollow->Volume balance.

Waveform Balance

The finishing touch using keyfollow goes to the Pulse Width waveform offset. When playing very high notes we all have a hard time hearing if its a Saw, Square or Sine waveform we hear. This is much more obvious when we play low key notes. To compensate for this loss of definition we have to strengthen the high keys towards a more Square'ish sound. In this case we use keyfollow to alter Pulse Width a small bit making high notes play with a wider Pulse Width and low notes play with a more narrow Pulse Width. Usually you would have to make the low notes be the offset and then have keyfollow increase the width as you play higher notes.

This concludes the typical use of Keyfollow.

/Michael