Change of tone stack

[Mats A]

In what year did Marshall change the ton stack from the 56K resistor and the 270p cap on the treble control? How does this change affect the tone?

[SteveD]

I recommend you get the following book which will pretty much answer all of your usual questions Mats; -

http://www.amazon.co.uk/gp/search?index ... 0793525098

[burnsy]

+1 recommended.

A good read and a lot of useful information.

[Mats A]

Well thanks for the advice but I´ve had it for years and it doesn´t have all the answeres. It also is a little bit dated and doesn´t have any info on amps and speakers after the early 90´s. maybe it´s time for a new book!
And it don´t tell me how to get that Robbo tone

[SteveD]

The tone stack changed when the JTM changed to JMP in about 67 or 68. The later tone stack has more treble and tighter bass.