Re: Duo-Art Expression Coding
By Jim Heyworth
Hi Robert,
I saw your request for information about Duo-Art expression coding in the MMD and hope that I can clarify some of your ideas.
Basically you have it right, but not quite. I will annotate your comments in the hope that a better understanding may be reached.
> Here is what I think I know with several questions:
>
> There is an accompaniment expression unit and a theme unit.
Correct.
> The accompaniment unit controls the overall sound level of the whole
> keyboard,
Correct.
> the theme unit makes the 'themed' notes play one degree (what ever
> that is) louder than the accompaniment.
No. The "one degree louder" comment applies _only_ to setting up the machine or checking its operation and relates only to the "zero" or softest setting for both theme and accompaniment. That is, the softest setting of the theme is "one degree louder" than the softest setting of the accompaniment. The theme settings are otherwise independent of the accompaniment levels.
> The accompaniment level is coded using a series of 4 perforations on
> the left side of the roll. These perforations allow for 16 levels
> of expression.
>
> Q. Is this roughly correct?
Yes.
> Q. What does 'one degree' louder mean?
This has been the subject of a _lot_ of discussion and controversy. I interpret it to mean that the vacuum measured for the theme at "zero" intensity is the same as measured for the accompaniment set to intensity level "1". There are many who disagree, some suggesting it is halfway between and others simply adjusting by ear and test roll.
Outside of this, during actual operation of the piano, the theme vacuum level is controlled by four rows of expression holes on the right side of the tracker bar corresponding to the four rows on the left which control accompaniment vacuum. The theme level is independent of the accompaniment level, with the exception that it cannot be lower and have an effect on the music.
> Q. Is there only one set of accompaniment control, or is the
> player divided in half with accompaniment control for both
> bass and treble?
Unless the theme is triggered by a snakebite the accompaniment level applies to the whole keyboard. When a snakebite triggers the theme on the side of the piano affected (there are two rows of snakebites, one on each edge of the roll, the left for bass and the right for treble) that _half_ of the keyboard switches to the theme level while the remaining half stays at the accompaniment level.
> For theming, I understand there are 2 perforations ('snake-bites'?)
> that activate the theming unit.
Right.
> Q. Do the theming peforations affect only the notes that are
> playing at the exact same time the theming perforations are
> 'playing'? Or is there some time delay between theme
> perforations and the affected notes?
Yes. No delay. The expression holes are located so that the theme levels are set up just before they are required and the snakebites trigger them at the same time the note is played.
> Q. Is there only one set of 'snake-bites' on the roll for the
> whole keyboard.?
No, two. See above.
>Thanks for any help.
>
>Robert
Hope it does.
Jim in Sechelt
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(Message sent Fri 25 Oct 1996, 18:17:26 GMT, from time zone GMT-0700.) |
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