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  • slope resistor mod



    So im changing the value of my slope resistor to 47K. But im really confused. The above picture is how the preamp section of my amp looks. First of all, can anyone tell me which of those resistors in the slope resistor?

    But that probably can't be answered, so i can tell you, on my amp, the resistor which is green in the center of the picture is red, and labeled 36K. But according to these schematics, it doesn't seem like that is it, unless im reading the schematic wrong which is very very possible.



    Can someone shed some light on this? Apparently i am supposed to have 2 resistors that are in the 30K range. One at 36K and one at 30K. And i dont see any other resistors with a "3" except for the one that says 36K. and according to the schematic on this website. The 30k resistor is the one to change.

    http://www.geocities.com/lupe7_99/redbear.html
    Bedrock Lead 50
    Red Bear MK 60
    Carvin 4x12 with 90s BR12 speakers
    JCM 800 Lead 4x12 with G12-65s

  • #2
    i believe that's a mistake. the diagram on that website is telling you to change the pot from 30k to 47k. i'm pretty sure the green 36k is the red resistor. let me know how it turns out cuz i'm about to do the mod myself. fyi i've seen a jcm 800 schematic with a 56k in that same spot so i'll be trying that too.
    late 70's gibson sg custom
    2006 gibson sg standard
    1985 gibson explorer
    mesa mark III blue
    peavey bravo 112
    red bear mk60

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    • #3
      it looks like that green resistor is the slope resistor.
      got a question about TITAN amps? ask me
      here

      my website

      TITAN AMPS on myspace


      My band:Last Comes Gunfire

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      • #4
        wait the pot? you mean the resistor? other than that thanks. anyone else done this or are positive about it?
        Bedrock Lead 50
        Red Bear MK 60
        Carvin 4x12 with 90s BR12 speakers
        JCM 800 Lead 4x12 with G12-65s

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        • #5
          the diagram on the website tells you to change the 30k pot that says mid next to it on the schematic. it ment to tell you to change the 33k

          not to hijack your thread but how do u go about adding the 25k resistor to the mid pot to turn it into a 50 k pot?
          late 70's gibson sg custom
          2006 gibson sg standard
          1985 gibson explorer
          mesa mark III blue
          peavey bravo 112
          red bear mk60

          Comment


          • #6
            i dont know how to do that but i would like to know ha.
            Bedrock Lead 50
            Red Bear MK 60
            Carvin 4x12 with 90s BR12 speakers
            JCM 800 Lead 4x12 with G12-65s

            Comment


            • #7
              you replace the pot. if you add a resistor, you'd have a base resistance plus the 30K sweep.

              if you want to change the slope resistor, replace the 33K resistor (based on the schematic, anyway) to whatever new value you want to try. i like 47K, but i use slightly different pot values.

              it's just a resistor swap. if you don't like the results, you can always change it back.
              got a question about TITAN amps? ask me
              here

              my website

              TITAN AMPS on myspace


              My band:Last Comes Gunfire

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              • #8
                you replace the pot. if you add a resistor, you'd have a base resistance plus the 30K sweep.

                if you want to change the slope resistor, replace the 33K resistor (based on the schematic, anyway) to whatever new value you want to try. i like 47K, but i use slightly different pot values.

                it's just a resistor swap. if you don't like the results, you can always change it back.


                would that be ok if u just wanted more mids? i ask because if you look at the pic the pots are weird and connected to pcb board
                late 70's gibson sg custom
                2006 gibson sg standard
                1985 gibson explorer
                mesa mark III blue
                peavey bravo 112
                red bear mk60

                Comment


                • #9
                  no, it wouldn't be ok. you'd have a base resistance of ~20K.

                  plus, bigger pot =/= moar mids.

                  edit: if you want to use a proper pot, just install it with flying leads to the PCB. this **************** ain't rocket science, man
                  got a question about TITAN amps? ask me
                  here

                  my website

                  TITAN AMPS on myspace


                  My band:Last Comes Gunfire

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                  • #10
                    wouldi need a linear or an audio pot for the mid pot?
                    late 70's gibson sg custom
                    2006 gibson sg standard
                    1985 gibson explorer
                    mesa mark III blue
                    peavey bravo 112
                    red bear mk60

                    Comment


                    • #11
                      How do people feel about using a pot for the slope resistor? Does it get too noisy?
                      DCC Engineering. Custom Cabs and Effects.






                      Originally Posted by -Assy-


                      Okay I summed up this entire thread in three posts. Let's go home and beat our children.

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                      • #12
                        What frequency range does this slope resistor give?
                        Originally Posted by Spacehog26


                        Sonic Maximisers are...the musical equivalent
                        of a turd polisher.




                        "This isn't 4chan you idiot"- anon.






                        Originally Posted by lfrz93


                        btw petejt,
                        is that you in your avatar?









                        Originally Posted by petejt







                        -----
                        My list of gear is here
                        Mesa/Boogie Mob

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                        • #13
                          I like 39k beter than 33k or 47k

                          33k = too fatty/farty/middy
                          47k = too focused/aggressive
                          39k = balanced
                          Originally Posted by mseriously30


                          My ****************ing life goal is to one day own a 70's Gibby such as that, a giant old Marshall stack with original 6x12 and be like, well, old and stuff, and play some loud ass doomy filthy melodies at my 70th birthday and embarrass the **************** out of everyone and maybe kill a small animal with my awesomness.

                          But secretly most everyone in hearing distance would envy me and it would only add to my lasting legacy.

                          Comment


                          • #14
                            how do you like those 6n2p preamp tubes, btw?

                            I'm really curious about them
                            you can buy a 10 piece lot of NOS tubes for like US$12
                            Originally Posted by mseriously30


                            My ****************ing life goal is to one day own a 70's Gibby such as that, a giant old Marshall stack with original 6x12 and be like, well, old and stuff, and play some loud ass doomy filthy melodies at my 70th birthday and embarrass the **************** out of everyone and maybe kill a small animal with my awesomness.

                            But secretly most everyone in hearing distance would envy me and it would only add to my lasting legacy.

                            Comment


                            • #15
                              This is a really cool FREE program that can give you theoretical frequency response curves for what happens when you change the slope resistor or other components in the tone stack with other values. It does this over the sweep of the pots. I think it's a great tool for understanding what will happen when you mod stuff in the tone stack area of an amp:

                              http://www.duncanamps.com/tsc/

                              the tone stack model you want to click on would be the "Marshall" one.

                              It seems to show that adding a 47K resistor instead of a 33K will tame the bass/mid end a little bit.
                              "I don't want to be immortalized through my work. I want to be immortalized by not dying." Woody Allen

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