Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Ifudontlikebees on November 20, 2021, 01:33:00 pm
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Hey everyone, nice to meet you all! This is my first post on this forum and I’m new to modding/building tube amps so bear with me. I picked up a bogen k10 for a guitar amp conversion and wanted to add a master volume. I was going to use rob robinettes pre phase inverter master volume but was unsure on what kind of PI the K10 had. From my basic and inexperienced understanding I believe it’s a cathodyne PI but I don’t want to add the master volume until I’m sure of it. Could anyone please look this schematic over and let me know? Thanks! Sorry for the newbie questions hahaha
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It's NOT a cathodyne. It's a paraphase inverter.
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Thank you for clearing that up! What would be the best place to add a master volume then? Also if possible could u explain why it’s a paraphrase inverter and not a cathodyne?
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compare: http://www.valvewizard.co.uk/cathodyne.html
http://www.valvewizard.co.uk/paraphase.html
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There is no good place to put a MV in that circuit.
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L-pad on the output.
As implied, Bogen already made the most of a low-low parts budget, there's little to "mod" that makes sense.
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Thanks for those links! That helps a lot. If possible I would really like to add a master volume. What I’ve done so far is added a 1/4 input jack in place of the phono jack and routed it directed to the .033uf cap before the 6au6. I left the mic input there hoping I can also use the amp as a mic pre too. What is the L-pad on the output?