MATRIXSYNTH: LambdaSpeak & LambdaDrum for the Amstrad CPC

Monday, April 01, 2019

LambdaSpeak & LambdaDrum for the Amstrad CPC

LambdaSpeak 3 - Simple 10 Track Pattern Sequencer / Drum Sequencer

Published on Apr 1, 2019 Michael Wessel

You might remember the Next-Generation Speech Synthesizer for the Amstrad / Schneider CPC 464 from Michael Wessel. Here are a three new videos featuring the LambdaSpeak & LambdaDrum for the Amstrad CPC, in via Michael Wessel. The LambdaDrum is a High Quality 10 Track 4 Channel PCM Pattern-based Drum Computer for the Amstrad CPC (a feature of the LambdaSpeak 3.0 Speech Synthesizer).
Related: Also check out the Amstrad CPC - Vocal synthesizer by Techni Musique (1986).

Video description for the above:
"A simple 10 track pattern-based drum computer for LambdaSpeak 3 (written entirely in BASIC).

This is a demo of 4channel polyphonous PCM sample playing with LambdaSpeak 3. Here, up to 4 channels of 8 Bit 16 kHz PCM are being played in parallel.

The LambdaSpeak 3 board has a socket for an (optional) vintage GI SPO256-AL2 speech chip, which is being used in this demo as well. The SPO256-ALs has its own channel (8) and track (11), and is being used for random allophones here."

LambdaDrum CPC Drum Computer Demo - 4 Channels of 8 Bit PCM @ 16 kHz

Published on Apr 1, 2019 Michael Wessel

"Spent some more time optimizing the PCM playback capabilities of LambdaSpeak 3. By now I have 4 channels of high quality 8 Bit PCM.

In this video, 16 kHz drum samples are being used. 16 kHz are a good compromise between size and quality. The samples are from the Boss DR 660 drum computer, and can be found online. Combined, these 10 samples are about 120 KBytes in size - a good fit for LambdaSpeak's 128 KBytes of PCM EEPROM sample memory!

Some ome pre-processing needs to be applied to the samples before they can be used with LambdaSpeak - first I am using Audacity for PCM editing (cutting, fading, normalizing, ...), then the Switch Sound File Converter for conversion to 8Bit 16 kHz PCM, and finally a program to remove all file and PCM headers from the PCM files.

The resulting PCM files are then put on a standard CPC DSK file and being uploaded into LambdaSpeak's EEPROM memory using a simple CPC BASIC program (a MC program would do the 120 KByte upload in a few seconds).

The drum computer program shown here is a simple BASIC program - all the actual PCM playback is done by LambdaSpeak, not by the CPC. The CPC would be incabable of serving PCM of that quality over its databus (insufficient CPU band width and clock speed)."

LambdaDrum Pattern Sequencer in BASIC

Published on Mar 25, 2019 Michael Wessel

"A simple pattern-based drum computer in BASIC, demonstrating the polyphonous high quality PCM sample playing mode of LambdaSpeak 3.

The PCM samples are from the Boss DR-660 drum computer and have been been uploaded from the CPC into the 128 KB SPI EEPROM of LambdaSpeak 3, from which they are also being played back in realtime. The EEPROM is a standard, inexpensive 25LC1024.

The recording is direct line-out; no further audio post processing. The DAC is done by the ATmega and a simple RC; no further audio circuitry is being used.

The on-the-fly mixing of different PCM channels (for polyphony) still requires some fine tuning; there are still some artifacts."

See the Amstrad label below for more.

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