need schematic reading help

[jaymanaa]

Hi, after much reading and a few headaches I am trying to build my first amp. I am using a schematic that I found on boozehound labs. This being my first attempt at reading one, I have had several hurdles. The 2 that have me stumped are how to know watt values on the resistors, and where can I find tube pin connection diagrams. My thinking is that building this (simple) single ended amp will help me in my quest to understand tube audio circuits. Many many thanks in advance to anyone who has any advice. jayman

[Sherman]

Jayman,

Welcome to the world of vacuum tubes! A simple SE design really is a good place to start when trying to learn about tube audio.

Check the notes in the margins of the schematics (if there are any) for the wattage of the resistors. In general you can use 1/2W resistors everywhere in the amp circuit except for the plate resistor and the cathode resistor of the output. You can calculate the required wattage for those resistors by using Ohm's law.

You know the voltage to the resistor and the current draw of the amp section (input our output). So calculate the power through the resistor. To be safe double that amount. If your calculation says for instance there is 1/2W there use at least a 1W resistor.

For pinouts check the data sheets for the tubes. Another great resource is Duncan Amps TDSL (Tube Data Sheet Locator). There is also a free downloadable version of TDSL you can run on your computer that has data about hundreds (thousands?) of tubes including pinouts and links to their data sheets.

[jaymanaa]

Thanks Sherman, There was a note stating that resistors were vishay 1/2 watt and 3 watt from mouser. I will however do the calculations as a math exercise! I am amazed at how helpful everyone in this hobby seems to be! Thanks again, Jayman