Bram Jacobse

Tinkering CD Players & Digital Audio

Sound decoupling caps TDA1541a

by · Published · Updated

After reading

  • A Monolithic Dual 16-Bit D/A Converter
  • IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. SC-21, NO. 3, JUNE 1986
  • HANS J. SCHOUWENAARS, EISE CAREL DIJKMANS, BEN M. J. KUP, AND ED J. M. VAN TUIJL

The clock frequency~ of the interchanging shift register is not related to the sample frequency and is generated by a free-running emitter-ccnpled oscillator which operates at about 250 kHz without affecting the accuracy. A simple low-pass filter is used to remove the ripple of the bit currents due to the interchanging operation to obtain the accuracy and is only drawn here for the MSB.

This approach requires seven non-critical external ceramic capacitors for each channel.

it made me really curious . I have seen all kind of decoupling caps,  blue ones

Green

White

Yellow

Okay enough, can we measure differents..?!

For my 8 x OS Staggered DAC , i have designed a dual DAC pcb, So I made 2 versions

  1. PPS Polyphenylene Sulphide Film caps, and Silmic Elna 2
  2. Cheap Ceramic Caps and Panasonic FR

The red wire is to create star-ground for SMD caps

All measured in my CD 160 with CDX1244 Digital Filter , 8 x OS Staggered, with Grundig DEM Clocking

My cd 160 player

THD-N with SMD star-ground

Here THD-N with SMD connect to ground plane, little better

Measured with 1 kHz unditherd 0 dBfs , Ceramic capacitors

192 kHz measure freq – 16 x avg FFT lenght 1 miljon

Measured with 1 kHz unditherd 0 dBfs , PPS capicitors

Measured with 1 kHz unditherd 0 dBfs , PPS capacitors & Ceramic capacitors

Close-up Measured with 1 kHz unditherd 0 dBfs , PPS capacitors & Ceramic capacitors

Multitone -20 dBfs Dithered ceramic capacitor

Multitone -20 dBfs Dithered PPS capacitor

Multitone -20 dBfs Dithered PPS capacitor & ceramic capacitor

Multitone -20 dBfs Dithered PPS capacitor & ceramic capacitor 10 Hz – 96 kHz

I can not measure or hear differents between PPS and ceramic, I made a third board with out caps

1 kHz  Capacitors no dithered

1 kHz no Capacitors no dither

1 kHz 0 dBfs no capacitors  VS Capacitors no dither 20- 20 kHz

1 kHz 0 dBfs no capacitors  VS Capacitors no dither 20- 96 kHz

Mutlitone -20 dBfs with and whiteout capacitors ! 10 – 20 kHz

Mutlitone -20 dBfs with and whiteout capacitors ! 10 – 96 kHz

i can not measure or hear differents between the used capacitors 

1 kHz my  CD player ( Blue )  vs  Grundig CD 9009 ( Red )