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marshall 800 -4210

  • 28-06-2009 10:36AM
    #1
    georgelowden
    Closed Accounts Posts: 22 ✭


    marshall 800 combo 4210 sounds woefull ,I was about to change the valves but ,there is a ecc82 ,in there ? ( first on the right /view from back)
    tone wise ther is way to much trebble/chainsaw going on....
    the Schematic I got on the web says 5 ecc83s ??


Comments

  • #2
    jimmy99
    Closed Accounts Posts: 47 ✭jimmy99


    georgelowden wrote: »
    marshall 800 combo 4210 sounds woefull ,I was about to change the valves but ,there is a ecc82 ,in there ? ( first on the right /view from back)
    tone wise ther is way to much trebble/chainsaw going on....
    the Schematic I got on the web says 5 ecc83s ??
    As far as i can remember 4210 had 4 ECC 83 and 2 EL 34.


  • #3
    georgelowden
    Closed Accounts Posts: 22 ✭georgelowden


    on the diagram it says v1- v5 ecc83/12ax7
    but I dont know much ,any one got any ideas ?
    can i stick an ecc83 in there????????


  • #4
    Eoin Madsen
    Registered Users, Registered Users 2 Posts: 2,117 ✭✭✭Eoin Madsen


    Yes. ECC82 and ECC83 are more or less interchangeable. ECC82 is a much lower gain triode than ECC83. In first position, it should lower the volume and make it harder to overdrive the amp. I would put an ECC83 back in there, as per the original specs.


  • #5
    Eoin Madsen
    Registered Users, Registered Users 2 Posts: 2,117 ✭✭✭Eoin Madsen


    Incidentally, if we were to try and pin down the chainsawing to a single main cause, my vote is for that nice bridge of clipping diodes sitting between the cathode of V2B and ground.


  • #6
    Paolo_M
    Registered Users, Registered Users 2 Posts: 880 ✭✭✭Paolo_M


    Overly trebly, buzzy tone can be from an overbiased amp ie. bias current to low.
    When was the last time the amp was serviced?

    As Eoin, mentioned the diode clipping circuit wont help things, removing one of the diodes and replacing it with a jumper should warm it up a bit, without having to remove the whole lot.

    There are a few other parts of the circuit where you could warm things up but I'd start by making sure everything is stock, correct valves, general service and biased up properly and then decide if further refinements are needed.


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  • #7
    georgelowden
    Closed Accounts Posts: 22 ✭georgelowden


    about a month ago I took it for a check up - guy said the valves were ok ?
    however I will get some ecc83,s and some el34s ,and have it biased ,I don't have the gear to bias it ,and its safer anyway
    and hopefully have the diode thing done at the same time .
    I miss my old vadis - left it in australia .I have tried a few amps but -no good .....
    thanks for the help ,


  • #8
    Eoin Madsen
    Registered Users, Registered Users 2 Posts: 2,117 ✭✭✭Eoin Madsen


    How long have the valves been in the amp? Like I said, the ECC82 is okay - there are reasons why one might choose to use one instead of the spec ECC83. It is unusual though, so a tech should at least have remarked on it.

    Realistically, I'm not sure I'd actually recommend messing with them diodes. It's the sort of mod that might require some trial and error, which having it done by a tech won't afford you. Put in some nice new valves and see where that gets you first.


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