This is a TS-9 built using the experience and knowledge gained from modifying SD-9s for over two and a half years. Similar to the SD-9 MOD, this is a method aimed at upgrading the sound quality without modifying the circuit board (parts). To keep the selling price down, this product has fewer modification points than the full MOD done on the SD-9, and is limited to: ● Solder replacement ● Op-amp replacement ● High-brightness LED (yellow) replacement Ideally, I'd like to replace the jacks with Puretone, which is one of the three essential upgrades for improving sound quality, but I've decided against it because the jacks are quite expensive. (I can replace them for an additional 2500 yen) Also, I'd like to use a JRC4558D op-amp from 1980 or 1981, but to keep the price down, I'm using a slightly cheaper JRC4558DV from 1981. ※The JRC4558DV is a low-noise selected version of the JRC4558D, and is, so to speak, an honor student. It was selected for equipment that requires precision parts, such as synthesizers, and the concept is the same as the JRC4558DD, but it seems that the JRC4558DV was shipped to specific customers. In terms of sound quality, when used in distortion effects, it is said to be "more refined" and "harder" than the 4558D, but I think it's a level that you wouldn't notice unless you compared them side by side. Regarding solder. The SD-9 MOD has currently progressed to Ver.10, but I stopped at Ver.6, and at that time, I sold the remaining Ver.1 to Ver.5 here, and they were sold out. Those were not made for sale, but for my own hobby, so I sold them at a huge loss. After that, I restarted research, and from Ver.7, I drastically upgraded the grade of solder and conducted research and development, and this product uses vintage solder from the 1920s to 1930s American company, DIVISION LEAD. It is a very expensive solder, and the highest value in my collection is 30,000 yen/m. I have also cut the wires of the pots and jacks once, removed the original solder, and reattached them. At that time, I only replaced the wires that were too short to reuse. I have kept the price as low as possible, so please refrain from asking for a discount.