Microwired - LMC1992 for Musicians
The LMC1992 is the piece of silicon that gives bass, treble, volume and panning controls on quite a few Atari 16/32 machines. Microwire is the low-level interface which allows the LMC to be setup. So strictly speaking there is a difference between LMC1992 and microwire, but in Atari 16/32 tech-speak the terms are used interchangably ;)
The three computers that include a LMC1992 and microwire are the STe, Mega STe and TT. Microwire is not available on ST, Mega ST or Falcon... However volume and panning microwire features are emulated in maxYMiser on Falcon.
LMC1992 software features have been available ever since the STe first came out, and music programs like TCB Tracker and ProTracker usually include a little interface to setup the microwire. But maxYMiser DMA is the first software to allow the musician creative use of LMC1992, and you can set up the chip each step with effect commands. The family of microwire effect commands look like this: U??.
I didn't explore using microwire too much in music so far, and in reality there may not actually be too many possibilities. On the other hand microwire is too cool to ignore, and you should definately at least try using it ;)
Microwire definately has its disadvantages:
- Microwire works on ALL the audio output!
Microwire setting affects the YM and DMA sound output equally, and there is no way to avoid this. That can make microwire effects a little cheap sounding.
- Falcon has no microwire!
One of the most popular computers for YM tracking is the Falcon because of its clean sound, SPDIF support etc... but F030 has no microwire :( On the other hand it does have the possibility to set left and right volume levels. With some cunning coding, master volume and panning can be emulated using this. The result is not quite the same, and no bass or treble control is possible, however the main useful stuff works ok.
- ST, ST+, STM, STF, STFM, Mega ST has no microwire
Also true, but IMHO STe hardware is fairly common these days... maybe its time to move on and use the extra enhancements. Its not like its a dramatic improvement ;)
- STeem does not support microwire properly
The authors are aware of this and I think in future versions it should be better.
The holy grail of chip musicians! YM only gives 16 volume levels - not enough for a smooth fade out. Microwire answers our prayers and at last there is the possibility to smoothly fade in and out our music. For example, set up a series of effect codes like this:
UA0 -0dB Maximum volume
U80 -64dB Minimum volume
Fix STe output distortion
You've probably noticed maximum microwire volume on STe gives quite some distortion :( This is easy to fix by lowering the master volume with something like a U9F or a U9E at the start of your music. You might also notice some distortion when you boost the bass or treble levels. Again you can reduce this distortion by lowering the master volume.
You can pan your music to any position in the stereo field. Heres an example of a panning sweep from left to right:
UC0 Hand left panning
UD0 Center panning
UE0 Hard right panning
You'll notice the panning does not quite give 'correct' levels around the center position. Actually I copied the FastTracker2 panning system. If there are complaints I'll implement an acoustically correct version.
Bass/treble boost and cut
Microwire gives some simple tone control:
U00 -12dB bass
U06 0dB bass
U0C +12dB bass
and similarly for the treble:
U00 -12dB treble
U06 0dB treble
U0C +12dB treble
RA and Damo both independantly explained to me an idea for a filter effect achieved by manipulating the bass and treble controls together. I tried it and found you often need to adjust the master volume control also to avoid distortions... but YES it is possible to achieve some kinds of filtering this way!
However, the bass and treble controls aren't very strong, and I personally found the different effects a little weak and to be honest slightly lame :( However, 505 and Dma-Sc sent me some maxYMiser test songs where they tried some LMC filtering with OK results. Go ahead and try it - but don't get too excited, and be prepared for slight dissapointment.
Try boosting or cutting the treble and bass together each step:
A different filter effect can be found by increasing the bass while reducing the treble and visa versa:
You'll also need to adjust the master volume slightly to avoid distortions, but these adjustments are best made by ear. Other filter effects are possible with different adjustments, just experiment ;)
Have fun - get microwired ;)
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