"Touch sensitive" mod?

[azrael]

What exactly is this mod doing?
Marshall Touch Response Mod

[guitarmike2107]

It’s a very poorly described mod of paralleling the first two triodes. Its an easy mod but don’t start to do it unless you understand what you are doing.

IMHO I think some of the mods at schematic heaven are often a bit suspect. Use with caution

[Gtr_tech]

To me "touch sensitivity" involves a somewhat conservative (3 stage cascade) pre with the gain of each stage spread out fairly evenly. That would be in contrast to a design that either uses a hot first stage to "run the show" or uses many stages in series. Any amp that cleans up when you back down the guitar's vol ctrl is touch sensitive, but its up to the player to use it properly.

[azrael]

I wasn't planning to, my amp has a PCB so it's far too involved to try this just for kicks.

So what exactly happens when you parallel the triode?


Oh, and I mostly just schematic heaven for schematics, no worries.

[greekie]

From my experience: Fatter sound, as said a bit more touch sensitive. Lower input resistance, and lower output resistance.

[guitarmike2107]

Using a 100k anode resistor with the parallel triode will give the first stage slightly more gain then just a single stage with 100k resistor.
This will be the biggest difference you will hear and will make the amp more touch sensitive, as long as you are a touch sensitive player! i.e.
Do you use your volume knob to roll back the amp gain. if not and you mostly just use pedals then I would not bother with this on a stock circuit board type amp.

I use parallel first stages as a matter of course. but I like to play cranked amps and fiddle with my knob…. Volume knob that is.