Sounds like a plan.
*The DCG3 was primarily designed as a line level preamp. With output stage topology adequate for stability even when driving 5m+ long interconnects. But it can do headphones too due to its high enough standing current. More at ease with 55+ Ω models. See graphs in post #1.
*The DCG3 was primarily designed as a line level preamp. With output stage topology adequate for stability even when driving 5m+ long interconnects. But it can do headphones too due to its high enough standing current. More at ease with 55+ Ω models. See graphs in post #1.
She is alive! Well one channel only...
I had unfortunate ESD event. Both channels were working fine and I decided to touch the voltage regulators to sense the temperature.
One of the TPS7A3301 regulators tingled my finger and released white smoke. I have to wait for a few days to replace the regulator.
The sound is very very promising, at least on the working channel😂.
Relay volume control PCB are one their way, to be built soon. Also the case needs to be assembled and drilled.
Cant wait to finish everything.
I had unfortunate ESD event. Both channels were working fine and I decided to touch the voltage regulators to sense the temperature.
One of the TPS7A3301 regulators tingled my finger and released white smoke. I have to wait for a few days to replace the regulator.
The sound is very very promising, at least on the working channel😂.
Relay volume control PCB are one their way, to be built soon. Also the case needs to be assembled and drilled.
Cant wait to finish everything.
Touchy-feely-boom! Those awkward modern reg chip packages... But good news also, your mostly SMD layout worked on first take without bugs!
Yes. I would feel better if it didn't even work. Now that I know it works I feel worse because I know it is close to a fully working condition.
I have read that TPS7A3301 is very sensitive in general. Few people had similar issues.
I also have some questions about resistor values. Not every resistor value was in stock so I found closest ones.
Instead of 3.3k on the input, I used 3.6k
Instead of the 330R mosfet degeneration, I used 301R (bias is 130mA)
Instead of the IRF9610 33R, I used 39R
Instead of the BF256B ccs 150R, I used 169R (current through 169R is 4.86mA)
Also for gain setting, I used 750R and 2.4k.
Do you see potential problems or should everything be ok?
By the way, use your DMM's thermal probe next time. Maybe the SMPS blocks charge the PCBs with ions?
Will try that.
I also have ground loop breaker with 10R resistor and 100n capacitor between gnd and earth, and bridge rectifier.
Shouldn't PCB discharge through 10R and earth?
But was it connected to the metal chassis also? Which one SMD chip reg smoked? On the PSU or on a channel? How the surviving channel behaves for offset?
Hello Salas, for some reason, can I replace the dual AD823 op amp in the schematic with two OPA192 single op amps? Do I need to change the parameters of the components around the op amp?
Hi, you don't need to change the component parameters around the servo. High input impedance precision types like OPA192 can readily work with those components. Objectively the criterion is minimal DC offset result at the DCG3 outputs. Subjectively the criterion is the DCG3 to still sound tonally close to when simply nulled with the DC trimmer before applying a servo op-amp. The AD823 was carefully selected for fulfilling both criteria.
Thanks for your answer. Is OPA171 suitable for servo OP? Because I happen to have a pair of OPA171😕
Aaand she is clicking! Everything works as intended!
Bass is out of this world. Soundstage as well, clearly defined.
Psu rails are nice and stable, temperatures are under control. A bit of work is left on a front panel and volume level indication. As a volume indication I will put a programmable led strip underneath the front part of the case so the strip lights up the table.
Salas I must thank you for sharing this great project with community.
Bass is out of this world. Soundstage as well, clearly defined.
Psu rails are nice and stable, temperatures are under control. A bit of work is left on a front panel and volume level indication. As a volume indication I will put a programmable led strip underneath the front part of the case so the strip lights up the table.
Salas I must thank you for sharing this great project with community.
Attachments
Congratulations for final success 
You are welcome.
What is the USB connected board? Logic and remote control receiver/bluetooth?
You are welcome.What is the USB connected board? Logic and remote control receiver/bluetooth?
