While most audio knowledgeable people think nothing these days of the availability of 1% precision resistors, or capacitors that have 5% or 2% tolerances, often the most important parts go quite ungraded - the discrete transistors that determine the real functional characteristics in a given circuity. Well most Reel to Reel sets these days are no longer functioning as best they can. What good is having the long life GX low friction, low-wear Crystal Glass Ferrite Heads and then connecting them to circuitry where the transistors are way, way out of spec ??? Most sets are in that unfortunate condition today.
These rare / obsolete and out of production low-noise transistors were used by the tens of thousands in almost every Akai Reel to Reel made since the switch from vaccuum tubes. The reason ? They are very low noise and were originally thought to be very stable in their characteristics. That is why the typical Akai has 12 of these particular parts in the Microphone Preamp, and Head Preamp and Recording / Playback Audio circuits. Unfortunately, in Akai circuits, they are also required to be used in closely matched pairs, in all Akai GX sets from the earliest GX-365D to the later GX-636, or the Recording and Playback circuitry simply will not work correctly. Bad effects seen and heard from 'mis-matched' transistors include: exhibiting excessive distortion on Record / Playback, and Frequency Response anomalies. The only way to get the best performance in an Akai, is to use the original type of transistors - ones that are in closely matched adjacent pairs.
Offered herein, these Hand-Matched Pairs are later parts (1990's) made long after all Akai Reel to Reel production had ceased. These parts are closely hand-matched to +/-5%, +/-2%, or +/- 1% for the lowest distortion when used in the audio circuits of any Akai GX Head Reel to Reel Deck in the GX Series: GX-2xx (GX-230D, GX-255, GX-265D, GX-266D, GX-266DII, GX-267D, GX-270D, GX-270D-ss, GX-280D/D-ss, GX-285D, GX-286D, GX-297D-ss); GX-3xx (GX-365D, GX-370D); GX-4xx (GX-400D, GX-400D-PRO, GX-400D-ss); GX-6xx (GX-600D/DB, GX-620, GX-625, GX-630D/DB/PRO, GX-635D/DB, GX-636, GX-650D), and the PRO-1000.
Most transistors Akai used between 1972-1982 in these sets are found to have lost their gain over time, making the differences in gain between adjacent parts from 2:1 (50%) to 6:1 (300%). Once the transistors gains are off by more than 20% the circuitry will start distorting badly; by 50% the audio circuits stop working. A Limited Number of Closely Matched Pairs of these rarely seen transistors are now available: