“The Road to Your Complete DIY Equipment” 2nd Edition: The Illusive Vintage Sound! Amplified Buffer Get your hands on the legendary device exclusively used by professionals [First half, Final]

Previous blog posts can be found here↓

Thank you for your patience.
At last, we present the first half of the final chapter of the professional-grade buffer.
Despite being a homemade item, its sound quality far surpasses that of commercially available products. I hope you will use it for a long time.
After all, it is not currently sold anywhere, so if you want it, you have to make it yourself.
Only those who put in the hard work and effort to create it will be able to enjoy this superb sound.

Now, let's take a look at the internal wiring through images.
Due to the size constraints of the enclosure, there is no power switch, and the circuit board is quite cramped, but I hope you will understand.

Here is the state of the jack, switch, and other components before mounting the circuit board.

For this DIY project, since AC 100V wiring is inside the enclosure, we have taken extra precautions to prevent short circuits by guarding solder points and exposed parts with heat shrink tubing.
Every part in the image that uses heat shrink tubing either has components inside or covers soldered areas.

I have also included an image showing the area around the switch before connecting the power board and the main circuit board.

Have you noticed?
This is the input jack, and it has three terminals for soldering.
Actually, we used a switch jack to avoid open circuit noise when there is no input.

SWITCHCRAFT / 12A

Since it's a mono closed circuit, when no plug is inserted, the hot and ground are connected, creating a short circuit that prevents unwanted noise.

Now, let's move on to the power board.

At this point, check the output voltage of the power supply.
The measured voltage (no load) was 15.2V and -14.86V, but since the power for the LED is also drawn from the 15.2V side, the actual voltage will likely drop a bit more.

The reason we made this the first half of the final chapter is that we wanted to compare and verify the circuit using the specified components with a circuit using general-purpose components.

With general-purpose components, the space factor is good, so the circuit fits on a 30mm x 40mm board, but with the specified parts, it's questionable whether it will even fit into the enclosure.
For now, we'll test the circuit with general-purpose components to evaluate noise, usability, sound quality, and any areas that may need improvement.

Here is a comparison image of the power section and the circuit.

For now, I installed this circuit board into the enclosure and tested it.

Here, an unexpected issue was found.
The voltage divider resistor on the output line is not of an appropriate value, so if the connected device's input is for line level, the volume drops when turned on!
By the way, this volume drop does not occur with regular guitar or bass amps.
I will publish the corrected value next time.
Additionally, deciding on the TL-071 OP-AMP was a mistake.
It didn't produce the sound I liked.
So, in the next blog post (the second half of the final chapter), I plan to present the completed definitive version.

Actually, even though it's not my preferred sound, I'm starting to get hooked on the thick, powerful boosted core sound. Maybe it's good as it is?

Stay tuned for the second half of the final chapter.