0 Members and 1 Guest are viewing this topic. Read 4146 times.
This is a 2 part video. Part 1: http://www.youtube.com/watch?v=Thwfz6qqklc and Part 2: http://www.youtube.com/watch?v=z46PInHdmXIAnd don't forget to watch in HD and subscribe to my channel.
Really appreciate the videos. My only request is to monitor the focus - the dissembling of the tube for instance is blurred, losing some of the value of the instruction, meanwhile the schematic drawing in the background is in perfect focus and even distracting. The closer you move your hands to the lens the blurrier the image. Though it may be counterintuitive we would be able to discern a lot more if you kept the movement further back or conversely refocus the camera to accommodate your hands being closer. You can just tape down a small piece of the schematic for instance or some text, picture etc. as both a focus aid for the camera and marker for where to confine your actions. It's cool's that a tube is being taken apart, but frustrating to not really be able see the parts! These videos are a GREAT idea btw.
May I ask another dumb, newbie question? Too bad! I'm going to ask anyway! The signal applied to the grid is merely an AC voltage, right? And the tube has a voltage flowing through it whether there is a signal or not, right? Then how come we are not able to hear the idle current running through the tube? To elaborate, if the applied grid signal merely modulates the idle current to resemble the grid signal waveform (but at larger voltage) why then is that same tube current (albeit DC) inaudible without the signal?
Hi Roger,I've seen a number of newer circuit designs that use LEDs in place of cathode bias resistors. What are your thoughts on this practice?I look forward to video #3 with great anticipation!
Roger...Thanks for the videos. I started a thread "How Do Vacuum Tubes Work?" a month ago to try to gain a better understanding of the circuit. Wish I had waited!A few other questions...1) Is this a good illustration of the relationship between the input voltage, the grid voltage, and the voltage output the plate? I think the 150 should really be +150.2) The coupling cap can be very small because the load after it is very high? I'm used to crossovers, in which case the driver is the load, and an 8 ohm load with a 1uf cap would only send frequencies above ~ 13k Hz to the driver. With the load on your drawing, everything above 4 or 5 hz will pass.3) The voltage drop measured from the "bottom" of the cathode resistor to the "top" of the cathode resistor equals the grid bias?4) What, if anything, happens during "tube break in"? Seems like the only thing would be the getter finishing the gas removal and from that point forward maintaining the vacuum.Thanks again for the "class".Mike