Greetings fet-fetishists, I come to you from the far-away lawless-wasteland of the Tubes/valves forum. I found a neat big heatsink-box type of enclosure in an e-waste bin at work (I think this was a big battery charge controller?) That I figured would work well for a Pass type build. Each side has a heatsink that measures approximately 1 7/8" x 3 1/2" x 8", and the opening inside is about 8" x 6" x 3" high. (Pictures attached)
I like to use tubes for gain, and am always working on something new, but the front end will likely end up something like an impasse, or similar with a source follower output for a nice low output impedance. This is the easy part, really.
So, for what I'm thinking, the F4 "crippled" or the push pull burning amp output stage is what I want to build. I know going with jfets up front for the buffer on the F4 would be more versatile, but they are way too expensive for this project for me, especially if I'm already going to be building a preamp that can drive the output stage directly. Unless someone out there wants to slip a couple pairs in the mail for me, I would of course change my mind
My main question, is would three output pairs per channel be fine on this heatsink? Basically built otherwise as per the F4 schematic. I understand that I can just crank the bias to keep the devices in a good temperature, but I'm not sure if they would need to be cranked down too far, and if I may be better off running two pairs per side hotter. I run 8 ohm speakers, and don't mind a small reduction in max power. For what it's worth, I plan on going with an Antek 300VA toroid, either 2x18 or 2x20, it will be a tight fit but not impossible!
Any ideas or comments would be appreciated!
(Special thanks to Zen Mod and their incoherent ramblings for making me look into pass designs further)
I like to use tubes for gain, and am always working on something new, but the front end will likely end up something like an impasse, or similar with a source follower output for a nice low output impedance. This is the easy part, really.
So, for what I'm thinking, the F4 "crippled" or the push pull burning amp output stage is what I want to build. I know going with jfets up front for the buffer on the F4 would be more versatile, but they are way too expensive for this project for me, especially if I'm already going to be building a preamp that can drive the output stage directly. Unless someone out there wants to slip a couple pairs in the mail for me, I would of course change my mind
My main question, is would three output pairs per channel be fine on this heatsink? Basically built otherwise as per the F4 schematic. I understand that I can just crank the bias to keep the devices in a good temperature, but I'm not sure if they would need to be cranked down too far, and if I may be better off running two pairs per side hotter. I run 8 ohm speakers, and don't mind a small reduction in max power. For what it's worth, I plan on going with an Antek 300VA toroid, either 2x18 or 2x20, it will be a tight fit but not impossible!
Any ideas or comments would be appreciated!
(Special thanks to Zen Mod and their incoherent ramblings for making me look into pass designs further
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