Marshall 1930 Popular Clone

Discussion in 'Building the Classics' started by Timbo, Apr 28, 2018.

  1. Timbo

    Timbo Member

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    Hi guys, I think I've got this one sorted.
    [​IMG]
    I'm thinking the insertion of the reverb mixing resistors were causing some problems.
    Also converting the 220k/100k plate resistors back to the original schematic is working much better and finding the right valve to do the job is needed.
    The 5k trim is needed to find the sweat spot to make the trem function.

    On the schematic I have shown the grounding, this also has helped with some of the hum.

    The reverb is huge.
    And connecting it as shown on the schematic has worked well.
     
    Gspotxremesports likes this.
  2. Timbo

    Timbo Member

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    Hi guys, Doing some hard thinking to get this one sorted.

    Adding another valve seems to be the only option.
    [​IMG]
    With some info from sluckey's 18w
    http://sluckeyamps.com/18w/18w.pdf
    The 6av6 should do the job nicely, as the smaller heater draw will be less stress on the PT.
     
  3. Timbo

    Timbo Member

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    Hi guys, I shelved this one to gather some more info.
    After some rearranging of components I still was not happy with the amount of hum it was producing.
    With some poking around I was convinced the hum was coming from the reverb circuit.
    Again removing components I was able to isolate it to the reverb driver transformer.
    Luck would have it I found another schematic that have transformer connected to node "B" on the power supply.
    Happy days this remove the hum completely and the reverb is lush and strong.

    SO, This hum was what was annoying me with the original circuit build.
    Now I will have to build the original circuit again to see what it is like.
     
  4. ampmadscientist

    ampmadscientist Well-Known Member

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    Dude,
    what I noticed about you right away is: you do some nice work. :dude:

    Can the heater Artifical CT be connected to just one 6GW8 cathode, is 8v DC be enough??

    Low level hum
    if the volumes are all down, does it still hum?
    (power supply ripple)

    When you turn up the volumes (no guitar plugged in) does the hum increase?
    (filament hum)

    Basically,
    filament hum is going to come from preamp tubes.
     
  5. Timbo

    Timbo Member

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    Hey mate, Thanks for the reply.
    I did connect the artificial CT to one of the 6GW8 and there was no decrease in hum.
    The amp as it is wired now is quiet enough to what I believe is acceptable level.

    I will be doing another build soon.
    This time I will be using 14GW8s and a power transformer that has a 14v heater tap.
     
  6. Timbo

    Timbo Member

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    Hi guys, The Marshall Popular MKII is now on the bench.
    My local supplier has a bunch of 14GW8s on hand and so they have sourced a transformer with a 14.5v tap and 6.3v for the preamp valves.
    [​IMG]
    [​IMG]
     
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  7. Timbo

    Timbo Member

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    Hi guys, New board done.
    I changed the value of a couple of the capacitors as this is all I have.
    I don't think it will change the tone/sound that much.
    [​IMG]
     
  8. Timbo

    Timbo Member

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    Hi guys, new board is in and wired up.
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    Updated schematic.
    As you can see the OT is Ultra Linear, for no real reason other than this is the OT I had on hand.
    So it's worth a try.
     
  9. slagg

    slagg Active Member

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    Can't wait :applause:I played a original 1930 and loved that little sucker.
     
  10. Timbo

    Timbo Member

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    Hey slagg, Are they as noisy as they say???
     
  11. slagg

    slagg Active Member

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    Yes,very noisey
     
  12. Timbo

    Timbo Member

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    Hi guys, The Popular II has kicked off well.
    The reverb circuit was not connected as I was wanting to see what the original circuit noise level was like.
    As stated before there is a background hum of an acceptable level, some buzz is present, but I'm hoping that will reduce once inside the cab.
    Reverb circuit was connected, this did not add any additional hum.
    Reverb is lush and plenty of it.
    [​IMG]
    [​IMG]
     
  13. slagg

    slagg Active Member

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    Gotta have a clip :jam:
     
  14. Timbo

    Timbo Member

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    Hey mate, I'm in the process of build the cab and I'll get one ASAP
     
  15. Timbo

    Timbo Member

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    Hi guys, A mate was kind enough drop in to have a bash.
    I think it does the Marshall thing well and does sound similar to the video clip in the first post.

    Noise wise, it is more than acceptable at about half volume but is much nosier at full volume.
    If this and was sold as a "cheap" practise amp half volume is more than enough volume for bedroom practise.

    Tone pots have two rolls, tone of course with a good range between dark and light.
    When turned to the bass sound is muddy and dull, turned to treble sound is bright and gainy. Me like it.
    Roll the guitar back and cleans are great with a bit of hair. ( P90's in a LP JR)
    Guitar at max and it's Marshall all the way.

    Very happy with the end result.
    [​IMG]
    [​IMG]
     

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