ZX Spectrum: Octode XL, a new 1-bit engine

The news comes from the http://1bit.i-demo.pl/topic/234/octode- … te-engine/ forum.

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OK, it's been a long time coming. Attached to this post is my mod of the "Octode" engine by Shiru, which quite drastically changes its sound. Instead of the old thin-sounding "Octode" you now get a monster that can scream, shout and even overload. It is louder, it gives you a degree of volume control and it comes with new drums, which are slightly better than the old ones (I think).

> DOWNLOAD <

Just as before we have 8 channels of sound + interrupting drums. The engine comes pre-configured with 5 presets. They are different depending how loud or how clean do you want your sound to be. The presets, in order of increasing loudness (and decreasing cleanliness), are X2, M2, X4, M4, X6. Presets starting with X have equal channel volumes, presets starting with M have channels 1-4 twice as loud as channels 5-8. You can move notes around to change the volume. The note volumes are added, so if you have the same note in two channels, it will sound approximately twice as loud (this is not entirely true for M engines, but close enough).

The Night Dancer by Mister BEEP was made using present M2.
Interstellar Drift by Mister BEEP was made using preset M4.
Hornets' Assault by Mister BEEP was made using preset M4.

This is Mister BEEP's "Spring is Coming" compiled using preset X2.
This is Mister BEEP's "Psionic Activity" compiled using preset X4.

Unfortunately, old "Octode"'s .xm is not fully compatible with the new engine. This was a late decision, which I am not fully happy about, but I can see no other way to provide you with better editing experience (and preview) while in .xm tracker. I can compile old tracks into the new engine, but I decided that the setup was already complex enough without having to worry about two types of .xm files. This is what needs to be changed in the .xm file for old "Octode" to make it compatible with "Octode XL":

• Everywhere you have notes played using Instrument 2 (i.e. drums), replace them for Instrument 3;

• If you intend to compile for one of M presets, keep in mind that first 4 channels are twice louder. The included .xm file defines Instruments 1 and 2, with Instrument 2 twice as loud compared to Instrument 1, so you can reproduce this behaviour in .xm tracker;

• Job done.

This is an excerpt from the "readme.txt" explaining how to make music with this engine. Please read the whole "readme.txt" as well (you will find it in the archive).

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To compile a song with the new engines do the following:

1. Create the "music.xm" file with your song and save it into the same folder where the "make.bat" file is.

   Note that "Octode XL" uses .xm files that are a little bit different from the .xm files of the original "Octode". You cannot use old  "Octode" .xm files with the new engine without a bit of tinkering. I am not entirely happy about this, however, I felt that it will allow me to create a much more composer-friendly preset.

   The additional features of the new preset (see "music.xm") are as follows:
   

   1. These are the instructions for the original "Octode" written by Shiru (with my additions/corrections in square brackets):
      

      • There is no dedicated editor for the engine. You can make music using any tracker with XM format support [however, it seems that some popular trackers create modules that are not compatible with the converter. "MilkyTracker" definitely works, "OpenMPT" definitely does not]. You have to follow certain limitations. You can hear sound while editing using template module provided, it has sounds sampled from the engine, so the sound is somewhat similar to the end result.

      • You can use patterns with arbitrary lengths in your song. Module should have no less than eight channels. You can loop the order list to any position. You can use both tempo and BPM to change speed. To set speed, you can use global tempo and BPM settings, or use Fxx  effects on the first row of a pattern. Every pattern can have own speed. The speed will be recalculated as needed, to closest possible  in the player.

      • You can use any notes, however, there is a lot of detune in higher octaves. You can also use effect E5x on the notes (finetune).   x is 0..8..F, 8 means no change in the note frequency, 7 means a bit  higher frequency, 9 means a bit lower frequency. This could be used  to produce 'fat' sounds by putting the same note on two channels, and using E59 on every note of one of the channels. Be careful if you use E57 or lower on low notes, it could move frequency out of range. Converter will show you warning messages in this case.

      • You can put drums to any channel, only one drum can be played on a row. Different drum sounds are assigned to notes C-4,D-4,E-4,F-4,G-4,A-4,B-4,C-5 (eight sounds).

   2. The sample module "music.xm" is pre-configured with 9 channels from the outset. First 8 channels contain notes, the last channel is intended for drums.

   3. There are three instruments. Instruments 1 and 2 are for the notes, instrument 2 has twice the volume compared with instrument 1. These are approximate correspondencies between .xm and the actual engine sounds:
      X2 = using instrument 1 in all 8 channels;
      X4 = using instrument 2 in all 8 channels;
      M4 = using instrument 2 in channels 1-4 and instrument 1 in channels 5-8.
      The sound of the notes is not very close to the true sound of the engine. Unfortunately, close sound cannot be achieved even in theory due to channel interactions.

   4. The volumes of notes are added during the playback. I.e. if you have the same note repeated twice in two different channels, the volumes of instruments will be added together and you will get louder sound. The timbre of louder notes is different from the timbre of quieter notes, so you can also achieve filter-like effects by changing the number of simultaneously playing identical, or slightly detuned, notes.

   5. Instrument 3 is for drum sounds. The drum sounds have been sampled from the engine and should sound pretty close to the truth.

2. Run the file "make.bat" and, assuming everything worked correctly, it will generate five new files: "music.x2", "music.x4", "music.x6", "music.m2" and "music.m4" (each available both as a .sna snapshot and a .tap file). Snapshots may be convenient for quick testing of the sound; the .tap files are there for distributing your work. Suffices "xN" and "mN" stand for configurations of the modded engine. You can try several and choose the one that suits your music best.