I have been trying to figure out how to fix the flubbiness in this amp since I got it years ago. I have tried tube rolling, then came the amps transformers (added a choke also) since the power transformer blew its 5 volt rail. so mod 1 was Classic tone PT, OT and choke.
STILL Flubby sounding. Let me state that this amp is HEAVEN when the power is JUST right (but I live in NYS where the power fluctuates from 110v-124v and at 50-55 hz is NOT stable, when the power is right, HEAVEN, when it is not (so 9 times out of 10) it is flubby garbage...so I went down the rabbit hole, mostly trying mods recommended on here, Joey mods, Europa mods, (there is another fella on here I do not know his name but his mods were cutting parts out..(I looked him up again and he was Vesperado).yes I even tried that)...nothing, no good, nada, the further down the rabbit hole I went the worse it got, SO I went my own way with the help of observations I had made of the effects of all the other mods I tried, and I came up with something REMARKABLY simple.
First the mods about cutting the transistors TR2 and TR3, are a MUST (channel switching becomes seamless and the high treble that is added to the lead channel is gone (so now you have a clean, crunch and TRUE lead sound instead of clean,. crunch and a MODIFIED HIGH TREBLE LEAD, that really no one much likes, it is the single biggest compaint I have noticed).
Now comes the hard part....(really not but THIS is where the magic happened for me)...there are two resistors in the crunch and lead boards that are supposed to be 'FAT' enhancers, specificaly lead board R6 switch from 470k resistor to 120k resistor, and the crunch board R3 switch from the 470k to 120k resistor (I should not post this, it could be worth something, but frankly I have ALWAYS felt that knowledge should be SHARED). What does this do, if you have ever thought that the bass controls were too powerful, this gives you useable bass through the whole pot and you can even use bass boost and mid cuts without it sounding like garbage....that it, thats all there is too it.
Cut tr2 , tr3, replace lead R6 with a 120k and replace crunch r3 with the same 120 k, to me this made the most difference and gave me the best tone in every situation (it did not kill the inherent tone of the amp, it made the bass and mid pots more useable and while I CAN occasionally hear that same flubbiness creap in (I am sure that is power related) I can actually EQ it out with no external eq'ing necessary!!.
You should know that any mods I did were reversed and the amp was put back original prior to this final modification attempt, so what I listed is complete...also a special shout out to Ricky Lee for his tips about not reinventing the wheel and the only other mod that I left because it helped SLIGHTLY with the flub was mainbaord c12...I did not list it because I feel that my mods would work without it but if you try what I did and no joy then look up Ricky Lee and ask him what to make the c12 mainboard cap, but I DID leave it modified, so my statement that all was returnsd to original was slightly incorrect as the Transformers stayed as well but they were to fix an actual blown transformer, and this was NOT a me issue but a Marshall made a bad transformer issue)) (they really did not make a difference much, they fixed an issue, but a choke DOES cut down on SAG and Hiss if you cannot get rid of that through tube rolling) along with the c12 mod, but like I said to the overall problem I feel the FAT resistors made MORE significant difference and made this amp what it is now.
Hope this all made sense, best wishes.
(I am not a tech, just a self taught hobbyist but I have had a background, I leanred SOME minor circuit repair in the Navy and while I was a construction worker I spent some of my off years soldering circuit boards together in a factory and also stained glass in another factory, so novice yet not level of ability)
STILL Flubby sounding. Let me state that this amp is HEAVEN when the power is JUST right (but I live in NYS where the power fluctuates from 110v-124v and at 50-55 hz is NOT stable, when the power is right, HEAVEN, when it is not (so 9 times out of 10) it is flubby garbage...so I went down the rabbit hole, mostly trying mods recommended on here, Joey mods, Europa mods, (there is another fella on here I do not know his name but his mods were cutting parts out..(I looked him up again and he was Vesperado).yes I even tried that)...nothing, no good, nada, the further down the rabbit hole I went the worse it got, SO I went my own way with the help of observations I had made of the effects of all the other mods I tried, and I came up with something REMARKABLY simple.
First the mods about cutting the transistors TR2 and TR3, are a MUST (channel switching becomes seamless and the high treble that is added to the lead channel is gone (so now you have a clean, crunch and TRUE lead sound instead of clean,. crunch and a MODIFIED HIGH TREBLE LEAD, that really no one much likes, it is the single biggest compaint I have noticed).
Now comes the hard part....(really not but THIS is where the magic happened for me)...there are two resistors in the crunch and lead boards that are supposed to be 'FAT' enhancers, specificaly lead board R6 switch from 470k resistor to 120k resistor, and the crunch board R3 switch from the 470k to 120k resistor (I should not post this, it could be worth something, but frankly I have ALWAYS felt that knowledge should be SHARED). What does this do, if you have ever thought that the bass controls were too powerful, this gives you useable bass through the whole pot and you can even use bass boost and mid cuts without it sounding like garbage....that it, thats all there is too it.
Cut tr2 , tr3, replace lead R6 with a 120k and replace crunch r3 with the same 120 k, to me this made the most difference and gave me the best tone in every situation (it did not kill the inherent tone of the amp, it made the bass and mid pots more useable and while I CAN occasionally hear that same flubbiness creap in (I am sure that is power related) I can actually EQ it out with no external eq'ing necessary!!.
You should know that any mods I did were reversed and the amp was put back original prior to this final modification attempt, so what I listed is complete...also a special shout out to Ricky Lee for his tips about not reinventing the wheel and the only other mod that I left because it helped SLIGHTLY with the flub was mainbaord c12...I did not list it because I feel that my mods would work without it but if you try what I did and no joy then look up Ricky Lee and ask him what to make the c12 mainboard cap, but I DID leave it modified, so my statement that all was returnsd to original was slightly incorrect as the Transformers stayed as well but they were to fix an actual blown transformer, and this was NOT a me issue but a Marshall made a bad transformer issue)) (they really did not make a difference much, they fixed an issue, but a choke DOES cut down on SAG and Hiss if you cannot get rid of that through tube rolling) along with the c12 mod, but like I said to the overall problem I feel the FAT resistors made MORE significant difference and made this amp what it is now.
Hope this all made sense, best wishes.
(I am not a tech, just a self taught hobbyist but I have had a background, I leanred SOME minor circuit repair in the Navy and while I was a construction worker I spent some of my off years soldering circuit boards together in a factory and also stained glass in another factory, so novice yet not level of ability)
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