Unknow mod in a Marshall 1959 Super Lead

[chocopower]

Hi!!

A friend of mine had a ´73 Super Lead with a extrange mod that was there when he bought the amp.
There are one lug of a .1 cap attached to the Presence pot and the other lug is conected to a imput in the rear panel. A shielded wire is doing the job!

Who´s that?

best regards from Galicia

[drewl]

Sounds like a crude D.I.

[Amp Kat]

Or some voicing for the presence tone itself as it's basically a treble pot in the output section.

[Trace]

Hi!! A friend of mine had a ´73 Super Lead with a extrange mod that was there when he bought the amp. There are one lug of a .1 cap attached to the Presence pot and the other lug is conected to a imput in the rear panel. A shielded wire is doing the job! Who´s that?

That's a bit odd, not sure what to tell you on that, perhaps a better question would be, what does it sound like to you?

Trace

[Alex/Tubewonder]

Plug a simple on-off foot switch into that input and listen. I think it shifts Presence downward in frequency, a bit more low end.