ReadMeMI.txt Miscellaneous Tube related info. Ever wonder what happens as a tube ages? 7586.ZIP contains two .jpg picture files of 7586 Nuvistor triode curves. 7586N.JPG shows curves of one particular tube when it was new, and 7586O.jpg shows curves OF THE SAME TUBE after it has worn out by use. Notice that the mu of the tube doesn't significantly change, as this is mainly geometry related. The transconductance decreases and the plate resistance increases as shown in the curves. Are all tubes of the same "type" the same? No. Ever wonder why one manufacturers tubes "sound" different than anothers? Here are four sets of 12AX7 curves. 12AX7CHI.GIF shows a Chinese 12AX7, 12AX7TES.GIF shows Tesla's 12AX7, 12AX7WA.GIF shows Sovtek 12AX7WA and 12AX7WXT.GIF shows Sovtek 12AX7WXT. These curves are all different, and will sound different in your circuit. Want to understand how an amplifier design relates to its performance? There was a series of discussions going on this topic. I'll present some information here. FB_FAQ1.txt covers poles and zeros from a very introductory viewpoint. This is followed in FB_FAQ3.txt that covers the frequency response model of a transformer. FB_FAQ4.txt covers a simple amplifier analysis, and FB_FAQ7.txt analyzes a Williamson power amplifier. Gain, frequency response and feedback effects are covered in these articles. Want to see a comparison between different topologies and how they affect amplifier performance? TESTSCH.GIF presents 7 different amplifier topologies. The accompanying description is given in TESTSCH.TXT that describes the distortion characteristics of 1. Straight 6SN7 stage, 2. 6SN7 SRPP, 3. 6SL7 stage, 4. 6SL7 SRPP, 5. Mixed stage: 6SL7 and with a 6SN7 cathode follower, 6. 417A straight amplifier, and 7. 417A SRPP stage. How long can you expect a vacuum tube to last? Information from MIL-217 is presented in TUBELIFE.txt. Ever wonder what's inside a tube? I've put a series of pictures here from a defunct 6SJ7 (octal metal small signal pentode) here. The pictures .... 6SJ7 View 1 shows metal can removed. 6SJ7 View 2 shows plate structure removed from remainder of tbe. 6SJ7 View 3 shows the remainder removed from the base. 6SJ7 View 4 shows cathode, G1, G2, G3, bottom insulator and support.