HELP! ROG Marshall Eighteen

[frank]

I've made the ROG Marshall Eighteen and have etched 3 boards.  I have used one and I am not satisfied with the tone.  I find it too grainy and harsh, and the tone control is not very effective.  Does anybody would propose some mods to the circuit without changing the existing PCB?  I would like to build an other one to test the soldering mask technique that I have proposed to Darron and Zach B.., at the same time.

http://www.diystompboxes.com/smfforum/index.php?topic=63043.40

Help would be appreciated and I would be able to do a feedback on the wax masking method.
Thanks !   

[morcey2]

Can't help on the solder mask thing, but for the eighteen, try changing the tone/volume setup to match that on the Professor Tweed.  The tone control on the normal channel of an 18-watt amp is kind of useless and one of the most effective mods is to change it to be the same as the tremolo channel effectively making it a princeton tone control.

Matt.

[frank]

OK, Thanks Matt,
I am also looking to change the FET type and their bias to have less dist.
I am preparing the PCB now for the mask and will take signal measures on the original to see what I can do.  If anyone still have some ideas I'll look at that.
THANKS AGAIN!

[petemoore]

  I did a Supreaux yesterday.
  Took some serious fiddling with to find what I wanted.
  Some transistors are certainly different than any other [even same brand/model].
  So then I twisted the trimpots for...
  Loud.
  Clear.
  Fizzy.
  etc.
  1/2v bias.
  A little lower than 1/2v
  a little higher than 1/2v
  then a compromise between loud/clear/ and 1/2v.
  Started off with J201's, nice and higher gain distortion sound, grainier.
  then ended up with J201 // 2n5457 // MPF102.
  Just managed to put this in RACO with the Green Ringer [packed in there to be sure with 2 LED's and bypass switches.
  It didn't take too long for me to start appreciating how much getting used to character of the tone and how that works with amp and other effects it would take, and how beneficial I'm finding the new alternatives.
  @@ Rate it took a 'little bit' of fiddling with, and some getting used to.
  The grainey-ness is probably 'adjustable for' like it is in Supreaux [bias and transistor choices.
  But also the LP filters at the end, those 2n2's could be 3n3's for less HF response...I wanted more on the Supreaux [partly because I had the caps right there] and used 2n2 in place of the 3n3's 10ks' instead of 12k's...
  If the tone control and transistor swaps and what not isn't enough, consider adding a LP filtercap between Q1G and Gnd. to tame some' HF's at the input, changing the way the tone control would then work. 
 

[frank]

1- ended up with J201 // 2n5457 // MPF102.
2- Just managed to put this in RACO
3- The grainey-ness is probably 'adjustable for' like it is in Supreaux [bias and transistor choices.
4- But also the LP filters at the end, those 2n2's could be 3n3's for less HF response...I wanted more on the Supreaux [partly because I had the caps right there] and used 2n2 in place of the 3n3's 10ks' instead of 12k's...
5- If the tone control and transistor swaps and what not isn't enough, consider adding a LP filtercap between Q1G and Gnd. to tame some' HF's at the input, changing the way the tone control would then work. 

1- I have to look at what is in my bins and perhaps go to the store, gonna put sockets also.
2- What is RACO?
3- I have played with the original trimpot for too long, I have to look at something else.
4- I want to change the output filter, I am going to experiment with that and plot some bode graphs, I think I want to test an old gain-phase rack measument appartus that I have to see if the beast works.
5- Noted

Now it's WAX MASK time!

This is kind Pete, BIG thanks !!!!