joshwilson3 wrote:Bainzy,
What do you think of this mod with a 100w Master Volume?
Does this mod add resistors and/or caps to the circuit?
I know a tube has two gain stages. Do you think using both sides of the tube would be too much for a 100w Master Volume? Cause I remember you talking about having two switches, one turned the extra tube on, and the other switch turned on both sides of the tube.
The mod adds resistors and caps to the amp, but does not change
anything to the circuit path that was there before. I'll take pics of the mod in my 1959 for you guys when I get hold of a camera. I like to add the resistors and caps onto a small piece of circuit board material and turrets, but theres only 4 (5 if you use a mixer cap) components to the mod per extra gain stage so you could wire the parts straight to the tube or switch if you insulated them properly (see that Caswell pic, that's what he did with it).
Both sides of the tube could be too much for a MV - I get plenty of gain (more than I'd use) with both sides of the tube on a 1959. The thing is although you might not use both sides at once on a MV, you can have different cathode/signal cap/filter resistor/mixer cap values on each gain stage you add. So you could switch in V0a (V0 being the added tube), and have V0a as a low gain boost, or switch V0a off and switch v0b on - which could be wired for an extreme gain boost. There's so many options with this mod I haven't got round to trying out everything yet.
bmf5150 wrote:how transparent is the mod?
If you mean in terms of retaining the stock tone when off - it's totally transparent to my ears. Providing you wire it up properly (inc. lead dress), there's no reason why it should affect the stock sound.
If you mean in terms of looks, that depends on whether you use a toggle switch or a push pull pot for the DPDT switch. I drilled a hole in the back for the switch as I'm not bothered at all about harming the amps value (it's a reissue and is not getting sold), but another non-permanent method might be to replace the low input for channel 2 with a toggle switch.