A few months ago, Kenji sent me a gift of some DAC parts, enough to make the entire digital and audio filter section of a high-end DAC! I'd never played with digital audio before (but plenty of experience with digital circuits of other kinds), nor much experience with SMD chips.
The DAC comprises the FN1242A "fluency" DAC chip (described fully on Kenji's web) with the Cirrus 8416 digital receiver plus the op-amp audio filter / balance-unbalance converter (RAC output) and 5V + 3V regulators etc.
This project took me a lot longer than I'd anticipated, mainly due to lack of time to "get on with it" but also due to initially having a (well-hidden) dry joint on the 8416 ground side that generated lots of 20MHz noise.
I also played around a bit with the ECC88 buffer; currently it's a cathode follower (gain of unity, low output impedance) but I might change it sometime. Also, there's a trace of annoying PSU noise: I'm not sure where it comes from but suspect the mains contains a lot of garbage. Currently I am trying to establish exactly where the buzz is entering the audio chain in the buffer (there's nothing but silence from the DAC front end).
The DAC is currently running off a cheap DVD player's digital O/P but also worked well off Mac optical signals (and of course is way better than the Mac analogue audio!).
The FN1242A is a rare chip and appears to be somewhat similar to NOS in terms of its audio qualities but in addition extends the audio range well above the normal CD's 19KHz.
The DAC comprises the FN1242A "fluency" DAC chip (described fully on Kenji's web) with the Cirrus 8416 digital receiver plus the op-amp audio filter / balance-unbalance converter (RAC output) and 5V + 3V regulators etc.
This project took me a lot longer than I'd anticipated, mainly due to lack of time to "get on with it" but also due to initially having a (well-hidden) dry joint on the 8416 ground side that generated lots of 20MHz noise.
I also played around a bit with the ECC88 buffer; currently it's a cathode follower (gain of unity, low output impedance) but I might change it sometime. Also, there's a trace of annoying PSU noise: I'm not sure where it comes from but suspect the mains contains a lot of garbage. Currently I am trying to establish exactly where the buzz is entering the audio chain in the buffer (there's nothing but silence from the DAC front end).
The DAC is currently running off a cheap DVD player's digital O/P but also worked well off Mac optical signals (and of course is way better than the Mac analogue audio!).
The FN1242A is a rare chip and appears to be somewhat similar to NOS in terms of its audio qualities but in addition extends the audio range well above the normal CD's 19KHz.
Internal view of my Fluency DAC: transformer is R core custom unit from VT4C, buffer circuit is P-P wired (centre), DAC digital part on RHS, 5V and 15V basic rectifiers and regulators on LHS.
My DAC sitting beside the 300B amp. It's fed by a cheap and cheerful Philips DVD player via RCA digital line.