DACalito - transversal modification of DAC-AH Lite
Posted 30th April 2012 at 06:46 AM by abraxalito
Plenty of audio DIYers have discovered what an excellent modding base the DAC-AH Lite is. I'm a latecomer to the party, but better late than never here's my contribution to the art of DAC-AH-alikes.
Most of the mods I've seen focus on the output stage, some upgrade the PSUs. Here's yet another variant - change the DACs. The TDA1545 is pin compatible with the TDA1543 so I swapped out 8 TDA1543s and replaced them with 8 DAC-stacks made up of 5 TDA1545s each. 32 DACs in parallel produce the normal NOS output, the additional 8 DACs are fed from a two-stage delay line (16 74HC595s) to correct for the zero-order hold. I/V conversion is done passively and differential - 1.3ohms in each polarity. The post I/V stage is a pair of AD605s giving a true differential output. In between the two is a passive filter made up of TDK ferrite beads and NP0 capacitors.
How does it all sound? - well of course one is always biassed when describing one's own offspring, but in a word - dynamic. Or if you prefer the vernacular - dynamite
Most of the mods I've seen focus on the output stage, some upgrade the PSUs. Here's yet another variant - change the DACs. The TDA1545 is pin compatible with the TDA1543 so I swapped out 8 TDA1543s and replaced them with 8 DAC-stacks made up of 5 TDA1545s each. 32 DACs in parallel produce the normal NOS output, the additional 8 DACs are fed from a two-stage delay line (16 74HC595s) to correct for the zero-order hold. I/V conversion is done passively and differential - 1.3ohms in each polarity. The post I/V stage is a pair of AD605s giving a true differential output. In between the two is a passive filter made up of TDK ferrite beads and NP0 capacitors.
How does it all sound? - well of course one is always biassed when describing one's own offspring, but in a word - dynamic. Or if you prefer the vernacular - dynamite
Total Comments 2
Comments
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For 64-bit shifting consider the HC7731. Add an HC175 to mimic the operation of up to 32 HC595 with the bonus of true/complement outputs.Posted 15th June 2012 at 02:32 PM by Tam Lin
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Thanks, I was aware of that one. Its a lot quicker to wire up than 595s for sure, but rather more pricey...Posted 16th June 2012 at 01:01 AM by abraxalito
