Drum Parameters

Let's have a look at the Drum Editor again:

As mentioned in the Drum Editor page, the Drum Editor is divided into 5 sub-groups and each one of these sub-groups contains the sound generating parameters for each of the NES's 5 voices for each Drum Patch.

Within those sub-groups, the parameters are further divided into sections which are mostly organised into vertical columns. Those columns are given 3-letter headings and the single parameters are given a single-letter ID. For example, the LFO Speed is under the LFO column, indicated by the letter 'S'

Many of the parameters are common between all Voices but there are some that are unique to particular Voices and some that perform slightly different functions depending on which Voice they are used on. We'll start off with Voice A as (along with Voice B which is identical) this is the most complicated one with the most parameters. I'll just give an overview of what the parameters do here, the Synthesis page explains what's going on in a bit more depth.

Voice A / Voice B Parameters (Square-wave)

Table Headings: Parameter is the three-letter sub-section name and the single-letter ID of each parameter of a Drum Voice. Function is a simple translation of the parameter name. Usage describes the functions of the parameters and values required to access those functions. Tx shows you the 3-letter ID that is used for the Trigger Parameters in the Auxiliary section of Drum Patches (see Drum Editor page for more detail).

Voice C Parameters (Triangle)

Voice C shares many of the same parameter types as Voice A and Voice B. OSC-C and OSC-F are exactly the same (though of course in the NES sound chip, Voice C plays back one octave lower than A and B!). LFO-D, LFO-S and LFO-W also operate exactly the same as A and B. Voice C (triangle) doesn't have either a Duty setting or variable amplitude so there are no parameters relating to these aspects. The only parameter from the AMP section is AMP-T which, like it does for Voice A and B, sets the number of ticks that the note is held for.

Voice C has one extra parameter that Voices A and B don't have:

Of course, even though Voice C does have many parameters in common with Voices A and B, it has it's own set of Tx IDs. The difference is that the three-letter codes start with 'C' instead of 'A' or 'B'.

Voice D Parameters (Noise)

Voice D (Noise) also shares some parameters with Voice A, B and C. AMP-V, AMP-E and AMP-H all behave the same way as they do for Voice A and B. Because Voice D doesn't have 'pitch' as such, OSC-C for this voice is a little different from the first three voices.

I think the 50-5F and 60-6F ranges are fairly straightforward but the relative mode might need a little explaining. Basically you've only got 32 'pitches' for the noise (16 in the 'noise' mode and another 16 in the 'tone' mode) and these are represented by the values 00-0F and 10-1F in PR8 respectively. When using the relative offset to set the pitch, the value is added to the Trigger Note so really only the first 32 notes are valid i.e. the lowest pitch note is 'A-1' which equates to 00 as noise pitch. 'A#1' is 01, 'B1' is 02 etc. If the Trigger Note plus the relative offset you set in OSC-C exceeds the valid range, the actual value written to the frequency will wrap around back to 00.

While Voice D has a full complement of LFO parameters, they behave a bit differently from their Voice A, B and C counterparts:

There are two main differences between the LFO operations for Voice D and that of the 'melodic' voices (A, B and C). First of all, the reason 'Arpeggio' is in quotation marks is because instead of 3 notes, for Noise the effect just toggles between the original pitch and the pitch value resulting from adding the LFO-W value to the original pitch. Also, whereas for Voices A, B and C, the arpeggio values are only positive (e.g. 47 would add 4 then 7 to the original pitch), for Voice D the offset in LFO-W is signed.

Secondly, because sweeping the pitch of the Noise is very low resolution (there are only 16 values compared to about 2048 values for the melodic Voices), the LFO-S parameter becomes a delay between modifying the noise pitch. Otherwise, you'd go between the limits of the noise pitch in 16 ticks.

Voice E Parameters (DCM)

OK, Voice E is completely different from the other voices. All the parameters are used to control the (DCM) sample playback and come under the heading 'DCM'