This was built in 2004. I made two mono blocks and each use 625VA transformer. It is my first Nelson Pass power amplifier and after that I trust all the Pass design is better than most other amplifiers selling in the market. Sometimes, I am still using this power amplifier in 2009.
I remember it is a very hot pre-amp! That was made in April 2004.
CS4398 is a voltage output 24bit DAC. I have tried to modify this DAC evaluation board using Audio transformer Lundahl LL7902 as the IV filter. The performance is not much different from the original design using op-amps. Overall this DAC do not sound great!
I cannot find any picture yet and I shall post it here when available.
This is a tube pre-amp using Mu-Stage. It use 6DJ8 + 12BY7 mu-stage and 5Z3P rectifier tubes. I use lot of chokes inside also and good Jenson capacitors. The casing is 100% aluminium and is self make one.
Update Sep 22, 2010:
I have upgraded the internal capacitor using some Russian PIO capacitors like KBG-I 0.01u, K40Y-9 0.22u and MBGO 0.25u. The sound become more transparent! Now this preamp is a good match for the OCL PCM1794A DAC! It introduces all the taste of tube on the sound.
See last two pictures above.
I also attached the reference document for this Mu-Stage pre-amp. I use the circuit in the last figure on page 9. Enjoy!
I also take a FFT measurement as below: Output at 2Vrms 1kHz, filter 20 to 30kHz BW.
FFT measurement mu-stage preamp SE
This DAC copy the design of Audio Note DAC using 4 pcs TDA1543 IC. The overall performance is worse than TDA1541 due to limited performance of the DAC IC itself.
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