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I have begun a build of an amp based on the orange OR120. I have made a few changes that will most likely need tweaking once things are up and running. I am giving it a post phase-inverter master volume and controllable presence. The main difference to this amp is that I have changed the output stage to handle KT88/6550 tube I'm aiming in the 150 watt range. I'm gonna post pictures very soon of the progress...
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Okay so no pictures just yet, but I would like to post a question, I have noticed that the drive control on the third and last gain stage seems to be a variable cathode resistor, is this the case and if so is this simply varying the bias of the stage? and is prehaps regulated by the inductor and capacitor circuit on the wiper?
http://users.telenet.be/orangefg/OFG...0_72output.jpg -
Just figured it out, I missed the 1.5k resistor in my redrawn schematic, I answered my own question yet again...Comment
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Well this is a very intresting schematic of the orange power section. I would like to see more schematic. You mention the post PS master and I would like to see that implemented in a quad power section.
You caught my attention!Comment
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For that mod I referenced the Weber 6O100 as it has that feature and the presence control, which I thought could be a welcome control for a bass amp. but their schematic is what confused me about the drive control, as their schematic leaves out the 1.5k cathode resistor, I am sure it would make for a rather warm biased stage if built that way. here is there schematic.
https://taweber.powweb.com/store/6o100_schem.jpg
if anyone else catches something awry here let me know, but I have looked over this and the various orange schematic way too much.Comment
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