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Channel Switching Real McTube?
Channel Switching Real McTube?
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Old 22nd July 2005, 12:42 AM   #1
jjai is offline jjai  United States
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Default Channel Switching Real McTube?

I'm thinking about building Fred Nachbaur's classic Real McTube II 12Ax7 tube stompbox:


... but I want to modify it so that I basically end up with a two-channel preamp in a stompbox that can switch between clean-ish tones, dirty tones, and full bypass.

I'm wondering if I should build two real McTubes (sharing one power supply) that cascade into each other, or instead, if I should try pulling an output off of the first gain stage for mild boost, and another off of the second gain stage for dirty, with an A/B switch between the two?

Does gain stage 1 provide enough boost to really do anything by itself?

(A potential problem I see with option B is that the phase would be inverted between the two channels -- but I'm not sure if that would really affect anything?)

I'm really interested in only mild overdrive -- not maniacal metal-shred-master distortion, so cascading 2 McTubes seems like overkill, but maybe that's the best option?

Has anyone tried anything like this, or have any thoughts or warnings?

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Old 22nd July 2005, 08:24 AM   #2
Giaime is offline Giaime  Italy
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Methinks it's better to build 2 Real McTubes but not using them in series, but rather switching between them, keeping them at different drive levels and maybe some circuit changes. For the clean one, look at the component values of the tipical Fender amp. For the dirty one, look at some Marshalls. So you can set up a switch (or better some relay controlled switching) to provide switching between Fenderish clean, Marshall roar and full bypass.

Phase isn't absolutely important, but remember to design a good supply to power 2 McTubes (watch out for heater current!!!)
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