The Voicing Of The Silver Jubilee's Distortion Channel

Discussion in 'Marshall Amps' started by JacksonCharvelAddict, Nov 29, 2018.

  1. JacksonCharvelAddict

    JacksonCharvelAddict Well-Known Member

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    Anyone have an insight into how the Jubilee pre-amp is voice when it comes to metal? It seems to me that the gain seems lower when the highs are rolled back slightly. I have heard that a lot of the controls interact with eachother similarly to the way a Mesa Mark amp does. The main thing I have noticed is the higher the gain the more bottom end the amp seems to have.
     
  2. SonVolt

    SonVolt Well-Known Member VIP Member

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  3. JacksonCharvelAddict

    JacksonCharvelAddict Well-Known Member

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    Guess not..hah
     
  4. mickeydg5

    mickeydg5 Well-Known Member

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    Describe highs rolled back.

    Like most other musical amplifiers this one also has a bright capacitor on the GAIN control. That allows more high frequency to pass when the GAIN is at lower settings. So that is attenuating more lower frequency until it is turned up enough.
     
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  5. Jethro Rocker

    Jethro Rocker Well-Known Member Silver Supporting Member

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    I've certainly noticed more low end as gain is increased as it does with many amp designs. I'm suspecting what you're finding might be the slight lack of zip you get by dropping treble or mid on such a responsive amp thus seeming to have less gain?
     
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  6. SonVolt

    SonVolt Well-Known Member VIP Member

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    so this probably deserves its own thread, but what's the reasoning for including a bright cap and having it tapper off at high volumes? why not just leave the cap out altogether?
     
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  7. mickeydg5

    mickeydg5 Well-Known Member

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    I does not taper off. It becomes negligible as the resistance of the potentiometer lowers because higher frequencies naturally pass with less resistance.

    When you drop the GAIN to low settings it attenuates more high frequency than low. The bright capacitor helps combat that issue of operation, though it is not perfect.
     
  8. JacksonCharvelAddict

    JacksonCharvelAddict Well-Known Member

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    What you just described sounds exactly like I am hearing it. When I first got the amp I ran most of the EQ at 5 on everything. I started with the gain at 5 and it sounded good but I wanted a little more dirt so I turned the gain up to about 7 or 8. I noticed it got a lot thicker and darker sounding so I would raise my treble from half way to about 6 or 7.
     
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  9. mickeydg5

    mickeydg5 Well-Known Member

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    My settings most always stay around these numbers but the MASTER VOLUME stays at about 4 or 5:
    G=3, L=6, MV=4, T=6.5, M=5, B=8, P=6.5
    It is a combo so a head and cabinet setup will vary a little.

    I do use outboard EQ with a scoop (about 4dB) towards 400Hz, extra outboard distortion as needed and set my power tube bias high since my Master never really goes past 6. Stock Marshall Vintage speakers of course.

    Anyway adjust your EQ according to the gear present. If you are not boosting bass a bit then yes it helps to adjust the GAIN higher but that also adds more distortion/growl.
     
    Last edited: Nov 30, 2018
  10. Angus Rhoads

    Angus Rhoads Well-Known Member

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    I recently got the Mini Jubilee but I think it's the same preamp as the 100W head. Mine reacts the same way as well, if I turn the gain past 6.5 to 7 it starts getting boomy and loses some bite, so I back off the Bass and give it a little more Treble. I don't know that it's unique to the Jubilee, though, as my JVM and DSL do this somewhat too (not as pronounced, though). Must be something about the Marshall circuit because I used to have high gain Peavey tube amps that did not do this.

    FWIW my current favorite settings on the Mini Jubilee are Lead Channel, Gain 7, Lead Master to taste, Output Master 7, Treb 4, Mid 6, Bass 5, Pres 3.
     
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  11. JacksonCharvelAddict

    JacksonCharvelAddict Well-Known Member

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    So you are using the Lead Master as your volume? I have found that works pretty well if I want a great tone at lower volumes. I think the bass increase with the gain is fairly normal for a Marshall but the drop in treble is the unusual part.
     
  12. mickeydg5

    mickeydg5 Well-Known Member

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    The Jubilee has always been noted as a bit darker amplifier. So turn your Treble and Presence up as needed.

    Things that make a difference as well would be devices that cut or do not put out all the available higher frequencies like guitar, pickups, instrument/patch cords, the preamp tubes (especially V1) and anything in the effects loop. Also periodically clean your cable plugs and all jacks with a decent lubricating electronics contact cleaner. Less than good connections can rob you of higher frequencies as well.
     
  13. Angus Rhoads

    Angus Rhoads Well-Known Member

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    Yeah, exactly, Lead Maioster for volume. Sounds fuller & smoother that way, but the other way sounds good too, more aggressive (I mean Lead Master high or on 10 and Output Master to adjust volume).
     
  14. JacksonCharvelAddict

    JacksonCharvelAddict Well-Known Member

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    I seem to go back and forth between which sounds better to me but the running one master high trick seems to be a must for the jubilee at lower volumes.
     
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  15. Angus Rhoads

    Angus Rhoads Well-Known Member

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    Agreed, if you run them both at half or less it seems like the amp loses some guts and gets a little harsher. I think that's why some people who try out a Jubilee in the store and don't like it complain about it being bright/harsh/thin. At anything less than gig volume I really think one of the Masters needs to be cranked up for it to sound right.

    One thing I've noticed running it the way I do is that there's a noticeable difference on the Lead channel if the Rhythm Clip/Input Gain is pulled out - I definitely like the Lead channel better with the Input Gain pushed it. It's subtle, but it's there.

    I wonder if what you're hearing as a drop in treble is just the other frequencies filling out, which balances out the tone vs actually losing high end. I switched the first preamp slot in my JVM combo to an ECC823 to cut the gain on the Orange and Red modes of the OD channel (never used to run the gain much above 3/3.5 anyway) and now I run the gain at about 7 for the same amount of OD as before, the sound is a lot less bright, more full, noticeably more mids and bass probably because of the treble bleed cap. I used to back the Treble off to about 3.5 on OD Orange before and now I can keep it around 5.
     
  16. Angus Rhoads

    Angus Rhoads Well-Known Member

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    This is a good point too, my Les Pauls have way, way more top end energy than my Jackson (EMG 81/15) or Charvel (Jackson J50C bridge with JE-1200 mid-boost). Surprising, considering they both have ceramic magnet high-output pickups but I actually have to add in a couple of notches of Treble and Presence when I play them versus where I have things set for the LPs.
     
  17. RickyLee

    RickyLee Well-Known Member VIP Member

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    As Mickey stated, any preamp circuit with a typical first interstage gain pot and paralleled bright cap of 470pF to 1000pF will give you that reaction of noticing more low end with the gain pot run close to 10. The Jubilee has 1000pF bright cap, and then the 2203/4 uses one as well as many other amp circuits. The DSL Red channel has a 470pF bright cap.

    The Jubilee Rhythm Clip is primarily in circuit when the amp is on the Rhythm channel. But you will notice some bleed or interaction on the Lead channel when "Rhythm Clip" is engaged/on.

    If you are able to crank the volume quite high on a Jubilee circuit, you can get a similar clean midrange emphasized roar of a 2203/4 with the Jubilee Gain pot set at lower settings, in the 3 to 5 range. But the volume has to be extremely high.

    I prefer my Lead Master setting 7 to 10 myself.
     
  18. Angus Rhoads

    Angus Rhoads Well-Known Member

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    Are the clipping diodes always at a constant proportion of the signal regardless of the Input Gain setting, or does their affect vary at all with the gain pot? In other words, is there a setting at which they are less present in the circuit and a setting at which they are contributing more to the signal?
     
  19. RickyLee

    RickyLee Well-Known Member VIP Member

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    There is a clipping circuit on each mode/side/channel of the Jubilee. the Lead channels clipping circuit is slightly more complex and is always in the circuit.

    The Rhythm channels clipping circuit is a simpler one and is switched in/out via the "Rhythm Clip" function.

    Regarding your question about the clipper affect in relation to the gain setting, the Lead channel clipper would be more pronounced at higher gain settings. There might be a gain setting quite low that would pass signal lower than the clipper threshold, but I am not remembering if I tested for that one. I am figuring somewhere in the 0 to 3 range with a good hot bridge humbucker hitting the input.
     
  20. Angus Rhoads

    Angus Rhoads Well-Known Member

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    Great info, thanks!
     

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