No Oversampling DAC
by Andrea Ciuffoli - starting in the October 2007

INTRODUCTION

This born to verify the sonic performances of many Non Oversampling DAC.

COMPONENTS

• Philips TDA1543 a cheap and easy reference
• Philips TDA1541A the main reference present in a kit by Hifidiy.net
• Analog Device AD1865 the AudioNote choice and present in a kit by Audiokit.ro
   
• Crystal CS8414 2 item used like receivers to obtain I2S (for the Philips) or LSB (for the AD) output from spdif input

POWER SUPPLY

To build the test I have created an evaluation board for each chip and a common environment with all the necessary power supply.

The DAC power supply use the LM317 and LM337 to create the +5V, -5V, +12V and -12V. I have used a good 50W R-Core transformer get from DIY Club at a very good price. For a fine tune of output voltage I have used a Spectrol multiturn cermet trimmer (R2) with a value of 1Kohm for the 5V and 5Kohm for the 12V. Reverse diodes and capacitors polarity to get the schematic of the negative voltage.

TEST ENVIRONMENT

• Philips TDA1543 used with the standard passive I/V converter, a resistor 1Kohm, we get half DC on output about 2.5v
• Philips TDA1541A used with the max value possible for low distortion, we get a DC voltage about 0.1v on output
• Analog Device AD1865 used with a standard load, no DC is present on output
  
   
• My new 845 ver. 2 amp.
• The my Aprostrophe' loudspeakers
• M-Audio USB Audiophile to generate a good spdif signal from my laptop

MEASUREMENTS

I have used in all the measurements the Clio system by Audiomatica with the Transit by M-Audio to use the USB port of my portable pc (instead of the PCI audio board) and with the Audiophile USB by M-Audio to have a spdif ouput.

Here some test on TDA1543 using like I/V a 1Kohm MK132 Caddock.

• 100Hz
• 10KHz

Here some test on TDA1541A using like I/V a 50ohm MK132 Caddock.

• 100Hz
• 10KHz

Here some test on AD1865 using like I/V a 200ohm MK132 Caddock.

• 100Hz
• 10KHz

SONIC RESULTS

All these 3 DAC give a more natural sound if comparated with my DAC Final with AD1896/AD1955.

The TDA1541 and TDA1543 have a very similar sound and the differences are not easy to find.

The AD1865 have a strong gap up to the TDA chips.

With the AD1865 all is natural but without lose details and compression.

I consider the AD1865 the best DAC and it is confirmed by the Audionote choice.

OUTPUT STAGE

See project DAC End