Marshall MA100H Diagnosis, Repair & Sound Demonstration

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  • Опубліковано 23 лис 2024

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  • @Crunchifyable2
    @Crunchifyable2 3 дні тому +1

    I bought one of these new back when they came out, and you know it sounds like a Marshall to someone who doesn't know exactly what a Marshall sounds like. I left mine in NY when I moved to GA. There's just something bad about the drive channel, even on lower gain settings.
    If I ever go back and get it I'm going to try a different reverb tank and see if I can mod it to be something more useful

    • @mendittoamplification
      @mendittoamplification  3 дні тому

      Before you do anything drastic or expensive, keep in mind that you are playing a musical instrument system. You, your guitar, the strings, the pick, the pickups, the effects before the amplifier or in the effects loop, the amplifier and your speakers/cabinet are an integrated system. Do not underestimate how profoundly each of these components of the system affect your overall tone. Personally, I would experiment with different speakers before I would do any modifications to this amplifier.
      Thank you for watching my video and for leaving a comment. Have a great day!

  • @matthewhirt1302
    @matthewhirt1302 4 дні тому

    Just found your channel and subscribed, great stuff looking forward to more!!

    • @mendittoamplification
      @mendittoamplification  4 дні тому

      Thank you! That really means a lot to me. I am working on part 3 of my 1964 Gibson GA 5T Skylark series right now.

  • @riffs66
    @riffs66 7 днів тому

    Nice work!

  • @paulshurmon138
    @paulshurmon138 6 днів тому

    Thanks for the video.

    • @mendittoamplification
      @mendittoamplification  6 днів тому

      You're welcome! Thank you for watching my videos and leaving comments. I really appreciate it. I have a few more projects in the works right now.

  • @HearGear
    @HearGear 4 дні тому +1

    I would say that this is one of the very least wanted Marshall amp there is, much similar to the Misfit Lead 100. The quality is really poor and they does not sound good in any way, not really even on the clean channel as a pedal platform. I´ve been working on a few of these too, loose components and bad tube/s. They can be modded on the overdrive channel, but its not worth it, its way better to just get a used Dual Super Lead 100 head because they can be heavily modded to sound really awesome, and if not, they are really good pedal platforms on the clean channel. I would suggest you get a Fluke multimeter, so it will not burn up when you measure high voltages. Thanks for the video.

    • @mendittoamplification
      @mendittoamplification  4 дні тому

      Personally, I think that the amp sounds fine. In my opinion, there is nothing wrong with it, but there is certainly nothing extraordinary about it either. I think that the introduction music that I recorded with it sounds acceptable. My issue is with the poor build quality and the cheap components. The circuit board is so thin, that you can literally see right through it. I was planning on dedicating a whole segment of this video to changing all of the electrolytic capacitors. I decided that this would be akin to a suicide mission. I would have needed to run jumpers all over the circuit board, because there is no way that any of the traces would have survived component removal and reinstallation.
      I do have a vintage Fluke 23 multimeter, but you are right, I really should replace it with a new Fluke meter.
      Thank you for watching my video and for leaving a comment!

  • @alanfarmer5730
    @alanfarmer5730 6 днів тому

    Let me guess. The cabinet LED lighting had wiring crushed together and shorting out under the steel mounting plate?

    • @mendittoamplification
      @mendittoamplification  6 днів тому

      That is a very good guess, but the lighting on this amplifier is actually an incandescent light bulb with a red light filter sleeve over it. The problems turned out to be a bad power tube, as well as some traces lifting off of the board and starting to fail under two resistors. One resistor feeds the preamplifier tubes and phase splitter, the other resistor feeds the effects loop MOSFETs and JFET.

  • @alanfarmer5730
    @alanfarmer5730 6 днів тому

    Hi from New Zealand. Worked on one of these cheapskate Amplifiers Last week.

    • @mendittoamplification
      @mendittoamplification  6 днів тому

      I hope that all is well in New Zealand. Thank you for leaving a comment! I am sorry to hear that you also had the displeasure of working on this poor quality, lackluster amplifier.

    • @mendittoamplification
      @mendittoamplification  6 днів тому

      It is a real pleasure to be able to communicate and share ideas with cool, like-minded from far off places, isn't it?!

    • @alanfarmer5730
      @alanfarmer5730 6 днів тому

      @@mendittoamplification I like the stuff you do. I repair and build valve stuff, Valve Techs are rare in NZ . I don't do Vids but I do have F/Book Anvil Amplifiers.

    • @mendittoamplification
      @mendittoamplification  6 днів тому

      Thank you! I just followed Anvil Amplifiers on Facebook. Believe it or not, there are very few people in New York City who repair, or even understand what thermionic valve devices are. My friend's music store, Maggio Music Center, is one of the last family owned music stores in the whole city. Actually, there are not many musical instrument stores left. Even the big box stores are closing down. Do you call them "big box" stores in New Zealand? Yesterday, I saw someone walk down my block with a guitar gig bag on his back, and I had to stop myself from running after him just to say hello.
      Being that you are more endangered than the national bird, you should consider making some videos!

  • @michaelmcsky
    @michaelmcsky 4 дні тому

    where do you measure die 46 volts for bias setting, at the bias test points? who do you no the correct value. thank you!

    • @mendittoamplification
      @mendittoamplification  4 дні тому

      I used the output transformer resistance method. I took my plate voltage and resistance readings from the tube pins and the center tap connection at the circuit board. Thank you for watching my video and for asking a question!

    • @mendittoamplification
      @mendittoamplification  4 дні тому

      Sorry, I just realized that I did not give you a complete answer to your question. You can find a full description of the output transformer resistance method here: robrobinette.com/How_to_Bias_a_Tube_Amp.htm
      Thank you again for watching my video!

  • @voxpathfinder15r
    @voxpathfinder15r 3 дні тому +2

    Reason why people don’t like these amplifiers is because they aren’t really Marshalls. The dirty side has 4 gain stages like a jcm800 but it’s plate fed tone stacks, fender cathode resistor and bypass capacitor values on 1st stage. And other differences

    • @mendittoamplification
      @mendittoamplification  3 дні тому +2

      I agree with your assessment. Marshall amplifiers are akin to a type cast actor. I guess we can say this about all of the classic amplifier brands. We are unsettled, uncomfortable or even jarred when they try to play a different role other than the one that we have pigeonholed them into. Over time, this MA series may have been more well received if the build quality were better.

    • @mendittoamplification
      @mendittoamplification  3 дні тому +1

      Thank you for watching my video and for leaving a comment!

    • @voxpathfinder15r
      @voxpathfinder15r 3 дні тому

      @@mendittoamplification no problem, I like working on amplifiers and greatly appreciate someone else doing the hardworking as to what potentially I am up against.

    • @voxpathfinder15r
      @voxpathfinder15r 3 дні тому +1

      @@mendittoamplification thing is plate fed tone stacks can be brash sounding and lack the compression characteristics of cathode driven tone stacks. Maybe they did it to compensate for lousy tubes that can’t take being cathode followers?

    • @mendittoamplification
      @mendittoamplification  3 дні тому

      @@voxpathfinder15r There are not many of us qualified amplifier repair guys out there. We need to stick together, share ideas and learn from one another. Have a good night!