Effects Processor:
Ensoniq DP4

Digital signal processor for audio applications (ESP2 chip patent)

DP4 Manual (English) / (German)

ESP2 Chip

Ensoniq DP4+ Schematics

Ensoniq Parallel Effects Processor DP4 demo

Time Compressor:
Lexicon Model 2400 Stereo Time Compressor/Expander

Real-time pitch processor from the 2400 (the Confidence board)

Electronic Apparatus for Modification of Time Duration or Pitch of Music and Speech

Using Digital Signal Processor Chips in a Stereo Audio Time Compressor/Expander

Lexicon 2400 Stereo Audio Time Compressor/Expander Service Manual

Hearing Aid:
Inverse Fit by graphic equalizer

Projection on fit-bounded polyhedral cone sans linear programming
earO - Inverse Fit by Convex Optimization, canonic Op Amp realization of Arbitrary Magnitude

earO hearing test

discrimination test
FIR Digital Filter:
Analog Devices A/D 1878/1879 ΣΔ converter

High Performance 16-/18-Bit ΣΔ Stereo ADCs

Analog Devices Application Note: Sigma-Delta ADCs & DACs

Decimation filter as for a sigma-delta analog-to-digital converter (patent)

Implementation of Digital Filters for High-Fidelity Audio,
from
AUDIO IN DIGITAL TIMES, 7th INTERNATIONAL CONFERENCE of the AES

Part II - One-Stage Multirate 64:1 FIR Decimator for 1-Bit ΣΔ A/D


Laptop Supercomputer:
Perceptual Pitch Detector