After some waiting for Sonica 1’s PCB they have arrived. As usual, the quality was very good. I had made a few mistakes, but nothing serious. I will take a few minutes to explain what I had to fix and how the assembly and rebuild of the original amplifier went. The end result was as expected, no change in sound quality.
A month ago I started thinking about rebuilding my good old headphone amplifier with TPA6120A. I didn’t realize it was that old until I decided to translate the original article in English. It’s been 7 years and I though it was 3 or 4. Time passes quickly, it seems. I spent some time thinking how to improve it. Now the PCB and components are ordered and once I get them, assembly will take place in the same chassis. What’s new and improved? A number of things in fact.
The list of updates is as follows:
- Single PCB to include all blocks except input and output connectors
- Encapsulated toroidal transformer for PCB mounting
- Double the capacitors in the regulator (2x2200uF for each polarity)
- All electrolytic capacitors are now Panasonic FR series (newer and better than FC)
- All 100nF decoupling capacitors are now polyester WIMA MKS02 (smaller, allowing them to be closer to TPA6120A). Not as great as the polypropylene Panasonic, but more than sufficient
- ALPS Blue Velvet potentiometer
- New heatsinks for the voltage regulators
- All possible components switched to SMD
- Rectifier diodes changed to 2A model
- Delay On circuit has now its own voltage regulator
- Delay On circuit error fixed – output was switched off when the large capacitors discharged, now this happens when the switch is turned off (well, around 50ms later)
- Delay setting trim potentiometer is replaced with Bourns precise model for easier setting of desired delay
- Power LED will now turn on and off together with the headphone relay
- The new PCB has option for 115V in addition to 230V (supported by the new transformer)
- New volume knob
Let’s take a closer look at the design decisions made, updates and why they were needed.
Continue reading “Sonica 1 – Headphone Amplifier With TPA6120A Part I – Schematic And PCB Design”