DASP-2002 Digital Audio SignalProcessor

not just for the copybit

This circuit can be included in every S/PDIF link between two digital audio devices (CD player, DVD player, CD recorder or MD recorder). Besides allowing the notorious copybit to be modified, it can be regarded as a sort of universal processor for digital audio signals.Unlike a similar circuit design previously published in Elektor Electronics, this new design is thus truly more than just a ‘copybit killer’. Naturally, this application is the key feature here — certainly since we have become aware that the DVD Serial Copy Management System often makes it impossible to make the permitted single copy. For audiophiles who want to compile and process their own versions of digital audio signals, the copybit is thus always a major hindrance. However, the circuit described here has more to offer. For instance, the audio data can also be processed, possibly using a DSP, and the circuit can also convert a coax signal to an optical signal and vice versa, which is a handy extra feature that makes this device quite a bit more universal in use.

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Materials

020091-21.zip

020091-PCB.pdf

Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD members can exclusively download these files for free as part of their membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service.

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PCB

Download Gerber file: 020091-1.zip

Component list

Resistors:
R1,R16,R18 = 75Ohm
R2 = 470Ohm
R3,R13 = 4Ohm 7
R4,R10 = 4-way 10kOhm SIL array
R5,R12 = 10kOhm
R6...R9 = 22Ohm
R11 = 8-way 10kOhm SIL array
R14 = 8kOhm 2
R15,R17 = 270Ohm
R19 = 4-way 47kOhm SIL array
R20 = 4kOhm 7
R21,R22 = 1kOhm
Capacitors:
C1,C2 = 10nF ceramic, lead pitch 5mm
C3 = 68nF
C4 = 100nF ceramic, lead pitch 5mm
C11,C13,C17-C22 = 100nF ceramic
C5,C8 = 10µ F 63V radial
C6,C9 = 47nF ceramic, lead pitch 5mm
C7 = 100µ F 25V radial
C10 = 47µ F 25V radial
C12 = 22µ F 40V radial
C14,C15 = 47nF
C16 = 100pF
C23 = 220µ F 25V radial
Inductors:
L1,l2,L3 = 47µ H
Semiconductors:
D1-D5 = BAT85
T1 = BS170
IC1 = CS8412-CP Crystal/Cirrus Logic (RS Components)
IC2 = CS8402A-CP Crystal/Cirrus Logic (RS Components)
IC3 = TORX173 (Toshiba)
IC4 = TOTX173 (Toshiba)
IC5 = 74HC74IC6 = 74HC590
IC7 = EPROM 27C256, programmed, order code 020091-21
IC8 = 74HC32
IC9 = 74HC86
Miscellaneous:
JP1,JP2 = 3-way pinheader with jumper
K1,K3,K4 = cinch (RCA) socket, PCB mount (e.g., T-709G from Monarch/Monacor)
K2 = 16-way boxheader with 4 jumpers
S1,S2,S4 = 4-way DIP-switch
S3 = 8-way DIP-switch
Tr1 = primary 20 turns 0.5 mm ECW, secondary 2 x 2 turns on Ferroxcube core TN13/7,5/5-3E25
PCB, order code 020091-1