What Makes The 2203 (and Other Amps) So Loud?

Discussion in 'Marshall Amps' started by GuitarIV, Apr 17, 2019.

  1. GuitarIV

    GuitarIV Well-Known Member

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    I dunno if this is the right section to post in but since this is related to my 1982 2203 I figured I'd go ahead and make a thread here.

    So I just gave my 2203 a spin again and as always my MV control was at 0.8 on the dial. Being in an apartment building this is already at the "annoying the neighbours" level.

    I was just wondering... what exactly is it in the design of the 2203 and certain other amps that makes em so friggin loud? Bad taper on the MV pot or something in the way the circuit is designed?

    I welcome every tech to chime in and explain.

    Cheers!
     
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  2. Nik Henville

    Nik Henville Well-Known Member

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    At the risk of coming across like a smart-ass...
    The JCM800 2203 is a 100 Watt amplifier.
    What makes it loud is the quartet of EL34 fed by some ECC83's moving air using loud-speakers.
    Go from 100 Watt to 50 Watt - it is 3dB quieter.
    Go from 100 Watt to 30 Watt - it is 5dB quieter.
    Go from 100 Watt to 10 Watt - it is 10dB quieter - can you see where this is going?
    5 Watt is as loud as someone playing a trumpet full tilt, in the room, standing where the 5 Watt speaker was.
    Go from 100 Watt to 1 Watt - it is 20dB quieter - and sounds 1/4 as loud.
    So assuming "typical" (ballpark...) speaker efficiencies and the like, your 2203 turned from 100W down to 1W will STILL be one loud SoB. Attenuate or isolate, or move house (my personal choice...)

    Buying a Dodge Hennessey Viper Venom 1000TT and complaining about wheel-spin in 1st gear...
     
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  3. Fender

    Fender Active Member

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    one could argue that the mv pot is very inefficient in terms of volume grading (despite being a log pot)
    on my 2204, i feel that it doesn't change much between 10 o'clock and 5 o'clock (or ten)
     
  4. pedecamp

    pedecamp Well-Known Member

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    These amps were not really designed for home play, with that said, my 2204 on volume 1 is all I need for great home volume and tone. Maybe try your amp through a 1x12 cab and not through a 4x12? Me personally I get great home volume results through a 2x12 of 75's.
     
    Last edited: Apr 17, 2019
  5. Adieu

    Adieu Well-Known Member

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    Pot values and tapers.
     
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  6. Ivanock

    Ivanock Member

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    With an 1x12 you could isolate the box and get even more insolation
     
  7. anitoli

    anitoli Well-Known Member

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    It takes a 10 fold increase/decrease in wattage to raise lower the DB level by one unit. For example if 30w into a speaker with a 96db sensitivity will hypothetically produce a sound out put of 3db to raise that output to 4db you need to increase the output wattage to 300w.

    Dropping 100w to 50w does not produce a 3db reduction in output.
     
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  8. JTM1963

    JTM1963 Member

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    Simply not right.
    A change of 1db is what most people will recognise as a slight change of volume.
    To increase by 3 db a doubling of power is required, or, you can double the number of speakers to achieve the same result. As a consequence, halving the power (or the number of speakers) will reduce the level by 3db.
    The decibel scale @ Wikipedia
     
  9. anitoli

    anitoli Well-Known Member

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    Nope.
     
  10. JTM1963

    JTM1963 Member

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    OK. So you've made up your db definition. ;)
     
  11. K2JLX

    K2JLX Well-Known Member

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    I say pot volume taper: my 900/4100 needs to be on 4 or 5 to be the same level as my 800/2203 at 1.5/2.
     
  12. wakjob

    wakjob Well-Known Member

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    This. And a flawed circuit...:ohno:

    Also, on the jcm800's that had the pc mounted pots, there is an empty spot...I think it was c-13 on the board next to the Treble pot.

    I think I put something like a 120k resistor there, and it really helped with the taper on the Master Volume.

    That, and of course, we all know I like a 12au7 for the phase inverter in most amps for home use. Helps a lot. :2c:
     
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  13. GuitarIV

    GuitarIV Well-Known Member

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    Dude, you misunderstood my post. I'm fully aware of the power behind the 800, I didn't get the amp without knowing how loud it is. Every friggin post on the internet said so, I even wrote a full article here about the 2203 and my experience owning one. I am curious as to WHY it gets so loud so friggin fast. My DSL can do loud as well, however I need to bring it up to 3 or 4 on the MV to achieve the same volume levels when the 2203 has the dial on 1.

    I have a Two Notes Captor loadbox I use with the 800 at home so I can record it dead silent for when I need to. I am not an idiot that plays it cranked in his bedroom.

    So it seems from the posts here that the taper on the pot is not the best. Question answered.

    I opened my 2203 up properly once in a construction hall. Pre amp on 8, MV on 6. I fuckin shat my pants. Felt better than sex. I was trembling from the endorphines, I kid you not :D
     
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  14. charveldan

    charveldan Well-Known Member

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    [​IMG]

    [​IMG]

    You need one that "goes to eleven" ...
     
  15. marshallmellowed

    marshallmellowed Well-Known Member

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    As already mentioned, it's mostly due to the master volume pot value and taper. If it's important to play your 2203 at home on 4 or 5, you could change the volume pot to a higher value, or different taper. Or if if it's a visual annoyance for you, you could just pull the knob off, rotate it clockwise a bit, and stick it back on, wallah.
     
    Last edited: Apr 17, 2019
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  16. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    Its because Marshall liked to use huge tapers on volume potentiometers as others have mentioned and push a big signal.

    How do you set your tone stack controls? Turning them down will bring signal down before MV. Using LOW INPUT will also drop preamp signal level before the MV.
     
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  17. Solid State

    Solid State Well-Known Member

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    Output Transformer
     
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  18. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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  19. Jethro Rocker

    Jethro Rocker Well-Known Member

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    Yes it sure does. An amp with 3 dB headroom will require twice the power outpit. If I have a V30 with 100dB sensitivity at one watt I do not need 10 watts to get 101dB. Therefore a 100 watt amp is 2 dB louder than a 1 watter with the same speakers?? So max volume of a 2203 with 1 V30 is 102 db?? Not sure where you found this? It is a logarithmic scale.

    At that logic, a half power switch does nothing and a 100 watt amp runnjng at 10 watts is only 1 dB queiter. Sorry that's just wrong.
     
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  20. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    Man you guys are mixed up. Its not actually 10dB but somewhere below that but it gets rounded up for simplicity.

    10W RMS is 10dB greater than 1W RMS.
    100W RMS is 10dB greater than 10W RMS.
    And 100W RMS is 20dB greater than 1W RMS.

    3dB greater is pretty much doubling the power RMS.
     
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