TDK was a well known Japanese manufacturer of tapes, and some of them have an excellent reputation. They started in the 1960s with formulations based on the Scotch 150, and like Sony, also called it the 150. These are type 1 (standard) tapes. Later they introduced a S-1800, also a brown oxide tape, but designated low noise (type 2). This was also sold in Japan as the “555” series.
Their real market reputation was made in the mid 1970s with their SD Series (Super Dynamic) tapes, a series of Low Noise / High Output tapes (type 3) that required a higher bias. This made these tapes sound brighter on older equipment, and when used with the older (and cheaper) machines at the time, users felt they sounded better due to their better frequency response, particularly at 3-3/4 ips. The curves published in the boxes of these tapes clearly showed this effect. Later, machines with a tape selector allowed them to be used at the proper bias, where the full capabilities of the tape could be used.
The SD series became the AUDUA in the 1980s and continued to be popular. At the time, they also released a back-coated version of the Audua, all classified as type 3 Low Noise / High Output tapes. The last line of tapes produced by TDK were the LX series (type 3), available in both back-coated and shiny backing, and a +3 tape (type 4), the back-coated GX Series.
Unfortunately the back-coated LX and GX series tapes cannot be recommended due to “White Powder” syndrome, where the lubricant oozes out and forms a white powder. They cannot be played without being cleaned first. The older Super Dynamic, Audua (both the standard and the back-coated versions) and S-Series tapes do not suffer from this problem. They are still recommended, and sold in our store, as they sound excellent and still produce great recordings.