Marshall 30th Anniversary Series thread (6100 / 6101)

Discussion in 'Marshall Amps' started by Tonton, Dec 5, 2014.

  1. Jethro Rocker

    Jethro Rocker Well-Known Member

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    Unless I'm remembering wrong, when the loop is set to Series, which I do, I think the overall volume is then also adjusted by the Mix knob. If you want to also attenuate the volume some more, leave it lower but full up simply gives you full signal. If I remember...
     
  2. anitoli

    anitoli Well-Known Member

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    Yup when set to series if you turn the effects knob counterclockwise the signal diminishes.
     
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  3. Hexenhammer

    Hexenhammer New Member

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    Hello dudes...
    i just created my account to get some answers about my 6101 Combo. btw...sorry for some grammar mistakes...i´m german.
    I would like to run a Starfield VPA 1 Tube Pre- Amp via the Power Amp of the 6101. I tried it already and it worked out for about 6 minutes. then Volume turned down. I know there is a way to connect this two beasts, but im not sure, if something could get damaged etc. Have somebody ever tried something like this...? looking forward for some ideas.cheers
     
  4. Fender

    Fender Member

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    what do you mean by "the volume turned down" ?
     
  5. anitoli

    anitoli Well-Known Member

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    Use the line input to run external units. It disconnects the preamp and the power amp is used as a slave.
     
  6. Fender

    Fender Member

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    yup but i hope you didn't fry anything down the loop.
    This line input is a blessing too as you can use your amp to amplify boutique preamps as well... most versatile amp ever, maybe...
     
  7. anitoli

    anitoli Well-Known Member

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    An easy way to check the loop is to insert a jumper cable and try the amp. It will pass signal even with the poweramp mute button pushed in.
     
  8. fyfsle

    fyfsle New Member

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    Hey folks! I'm trying to join the 6100 club. And actually my 6100 LM just arrived today... but the seller didn't remove the tubes before shipping, so I've got a shattered 5881. Lesson learned for me, I guess. I'm filing a claim w/ UPS but I hear that anyways I can replace w/ 6L6GCs? Thinking of grabbing a matched quad of 6L6GCs instead of replacing w/ 5881s. No idea how it sounds either way, I haven't gotten to turn it on yet since the tube's gone. Is there anything special I'd need to do w.r.t. replacing the 5881s w/ 6L6GCs? Sorry if this question's been answered already, first time posting on this forum and I couldn't figure out how to search the thread. Thanks in advance, I'm really looking forward to playing this thing! :) IMG_20180501_170204.jpg IMG_20180501_171353.jpg
     
  9. Jethro Rocker

    Jethro Rocker Well-Known Member

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    Nice!! You will have to re bias it. It's a killer amp!! You should get additional output with the 6L6.
     
  10. fyfsle

    fyfsle New Member

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    Thanks! I did actually get to turn it on today - checking the schematic I realized that if I ran it in "low power" I could safely rip out V8, move V11 into V10 (where the broken tube was) and then let it rip. This thing is killer! I can't wait to retube it and get it back to full health, got a friend who can help me do the rebiasing. There's really nothing more to be done than rebiasing? I thought they were different enough you might have to replace a resistor somewhere or something. Anyhow, I'm in love with this amp - it sounds great even when you're playing something other than a guitar through it.
     
  11. Jethro Rocker

    Jethro Rocker Well-Known Member

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    Yeah you could run it at 50 watts with 2 tubes. I'm not sure o the reisitor part in terms of a 6100. Just that 6L6 are a direct replacement 5881.
    Have to get used to all the modes and effects loops and settings!!
     
  12. anitoli

    anitoli Well-Known Member

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    The 5881 and the 6L6GC both use a 470 ohm Screen grid resistor, the same grid stopper resistors and bias circuit and are completely interchangeable. The half power switch not to be confused with the pentode triode switch lifts the cathode of two tubes. It affects the amp in the same manner as pulling two tubes out.
     
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  13. fyfsle

    fyfsle New Member

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    Interesting, so there was no reason for me to flip the (high/low power, not the triode/pentode) switch after pulling two tubes? Good to know. I also flipped the impedance to 8 ohms while running into a 16 ohm cab because I read in another thread that with two tubes pulled the amplifier is expecting them to pick up extra load each and something something something something, I think I saw your reply in there as well anitoli. I'm curious to confirm whether that was the right/necessary decision as well. Hopefully a moot point as I should have a matched quad of 6L6GCs in a day or two, and then I get to learn how to bias an amplifier! :)
     
  14. Kinkless Tetrode

    Kinkless Tetrode Well-Known Member

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    Commenting on if to use 5881s or 6L6GC,

    5881 is the military part number for 6L6GB. The confusion comes from the 5881 part number being used on Russian sourced 6L6GC equivalents during the 90s.

    A true 5881 has lower voltage handling capabilities than a 6L6GC. A true 5881 is okay in a JTM45, but a 6100LM series probably needs 6L6GC or 7581 spec tubes, regardless of the actual part number printed on the glass.
     
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  15. anitoli

    anitoli Well-Known Member

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    Yes this is correct. The Russian 5881's can handle the voltage whereas the US version may not do too well.
     
  16. anitoli

    anitoli Well-Known Member

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    As far as changing the impedance when running with two tubes out the first thing is if this was critical to the amps performance why wasn't it included in the manual? Secondly i have run a 6100 with two tubes out, DID NOT change the impedance to 8 ohm ( left it on 16) and cranked the livin piss out of this thing for 6 months and nothing failed. I think with the output fail circuit the OT's were designed to be able to take the mismatch.
     
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  17. Jethro Rocker

    Jethro Rocker Well-Known Member

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    That's what I wonder as well. I've played about 5 shows on half power but never changed the impedance as NO WHERE does Marshall ever state this. Lower volume mind you but still.
     
  18. anitoli

    anitoli Well-Known Member

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    I compared the amps voltages when on half power and with two tubes out and they are virtually identical. The bias only increases 2-3 watts so it really isn't hammering the tubes that hard with them out.
     
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  19. marshallmellowed

    marshallmellowed Well-Known Member

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    You guys are making me want to fire up my LM, I've been neglecting it too long. :shred2:
     
    Last edited: May 3, 2018
  20. anitoli

    anitoli Well-Known Member

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    DO IT!!!!!!!!
     

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