How the vk-8 works, About the virtual tonewheel sound generator, How the organ sound are created – Roland VK-8 User Manual

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How the VK-8 Works

About the Virtual Tonewheel Sound Generator

A traditional tone wheel organ produces the sound by 91 toothed wheels called “tone wheels.” Each tone

wheel produces a different pitch. A motor is used to rotate these tone wheels past electromagnetic coils, and

as the teeth of each wheel pass by the corresponding electromagnetic coil, an audio signal is generated. The

combination of harmonic bars and the notes that are pressed then select the audio signals that are output,

producing the sound of the organ.

The virtual tonewheel sound generator of the VK-8 uses digital technology to precisely re-create the sound-

production mechanism of a tone wheel organ. The 91 toothed wheels are constantly “rotating” digitally, and

are able to produce sound at any time. The sound produced by these virtual tonewheels is determined by the

combination of harmonic bars and the state of the notes played on the keyboard—exactly as on traditional

tone wheel organs.

How the Organ Sound are Created

Tone Wheels

Tone wheels rotate constantly, and will therefore “speak” the instant you play a note. The virtual tonewheel

sound generator of the VK-8 is also producing sound constantly, allowing very rapid response when you play

a note. This rapid response is especially valuable when you use characteristic organ performance techniques

such as glissando.

The organ sound consists of a fundamental and eight harmonics, and these are mixed according to the

combination of the harmonic bars. You can use the harmonic bars to modify the tone even while you play,

allowing a high degree of expressive flexibility.

Percussion

Tone wheel percussion is used when you want to add an attack to the notes you play, making the sound more

crisp. Relative to the pitch of the note you play, you can specify either the second (SECOND) or third (THIRD)

partial as the pitch of the percussion sound, and you can decrease the percussion volume (SOFT) or lengthen

its decay (SLOW).

The percussion on tone wheel organs is of a type called “single-trigger,” meaning that percussion was not

applied to all the notes that were played, but only to the note that was pressed first. If you release the

currently-played key(s), percussion will sound for the next-played note. If you play legato (with notes

smoothly connected), percussion will be applied only to the first note, and not to subsequent notes. If you play

staccato, percussion will be applied to all notes. If you play rapidly when using percussion, the percussion

circuit may not keep up with your playing, causing the percussion sound to become softer. However, the VK-

wheel organ, the way in which percussion is applied is a very important element in enhancing the

expressiveness of the performance.

On tone wheel organs, the 1' harmonic bar was used to produce the percussion sound. This means that when

you add percussion, the sound of the 1' harmonic bar will no longer be heard. Also, percussion will be applied

only to the Upper Part.

On tone wheel organs, turning off percussion [SOFT] button would lower the volume of the organ, but the

VK-8 allows you to adjust it so the volume of the organ won’t change when percussion [SOFT] button is

Key Click

The first generations of traditional tone wheel organs produced a “blip” noise (separately from percussion)

when a note was pressed or released. Initially, this click noise was considered a problem, but blues and rock

musicians came to utilize it in their performances, and the key click became an indispensable part of the organ

sound in jazz as well.