More Pokey Module Audio
There is now one completely-built Pokey module prototype (though without panel artwork). The FPGA code is around 90% done. It still needs some minor usability tweaks and top secret configuration features.
More importantly, I made a few audio clips to show some of the current features.
This first clip plays a major scale on the 6 different wave settings. I’m running a Kenton Pro Solo into the pitch CV input on channel 1. A Doepfer A-141 VCADSR is going into the channel 1 volume CV input. The different types of noise have different amounts of pitchability. The notes that sound like they’re missing in a couple spots are a side-effect of how the Atari chip generates noise. There’s a little more info about why it happens in this post.
The second clip runs a Blacet Micro LFO into the CV wave input for channel 1. It’s set to a sawtooth wave to sweep through the different noise types. I’m tweaking two knobs: LFO rate and Atari channel 1 pitch. I also change the pitch resolution of the channel from 8-bit to 16-bit about halfway through, making the trip back down sound less steppy. Each channel has a switch on the front panel to jump between pitch resolutions.
The previous two clips have both been one voice by itself. This third clip starts as one voice, but then adds in the second voice slightly de-tuned. I flip the “highpass” switch that gives a nice octave effect, and then over-drive the channels via their volume knobs. The louder one channel is, the more it will modulate the other. The very end is back to one channel.
This last clip is more experimental. It combines the Aux input with low frequency noise. The signal path is a Blacet Micro LFO triangle wave into the Pokey synth AUX input. I’m also running one of the Atari channels set to noise at a sub-audio frequency. The low frequency noise creates rhythmic patterns that vary with pitch and modulate the volume of the AUX input. When the rhythm is changing it’s because I’m tweaking the sub-audio frequency and new patterns form automatically. The changes in pitch and timbre are because I’m also tweaking the Sample Rate knob for the aux input.
Keep in mind that even though the channels modulate each other to varying amounts, there are three independent channels on this thing mixed to a single output.
Channel 1: Atari oscillator #1
Channel 2: Atari oscillator #2
Channel 3: Aux input
The two oscillator channels are identical in terms of features and controls. The Aux input has a gain/attenuation control and controllable sample rate.
June 7th, 2010 at 11:05 pm
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