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Started by joecool85, August 11, 2007, 12:30:04 PM
Quote from: teemuk on August 11, 2007, 01:42:22 PM5000 uF seems awful a lot. You need that kind of capacitance for high power amps; I think that circuit would work perfectly with less than that. 12V supply should work, just make sure it can supply enough current for the filaments.The volume pot is in your guitar but I think you can convert either R5 or R6 to a potentiometer to get a volume/gain control to the amp itself.Biasing tubes is pretty similar process to biasing JFETs. Why worry; it looks like the circuit has pretty fixed bias already. Anyway, if you look at the page you provided the link to more carefully you will find a "Theory" section with some information about biasing the gain stages. I assume AX84 site (and several other tube sites) should contain plenty of info about biasing.
Quote from: joecool85 on February 17, 2008, 08:44:07 PMAlright, so R5 for the "gain" control. Now how do I find out if switching out R6 or R8 would effect the bias?
QuoteHi Joseph, is the secondary of the transformer connected to an 8 ohmspeaker / load? Not sure that you can judge a transformer by measuringresistance. What you are seeing is that the 10W has less windings thanthe 0.62W and therefore, an 8 ohm on the secondary will reflect less load(i.e. 500 ohm on the 10W) than the 0.62W (probably close that 5000 ohm).I would start with the 10W and see how it sounds.
QuoteHow do I know what pins go to what wire? I'm working from this schematic: http://www.sophtamps.ca/schematics/sopht_12al8-v2.jpgIt says about how to wire the heaters, but that's it.