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A 5F1 for both guitar and bass?

Discussion in 'Shock Brother's DIY Amps' started by Big Fred, Oct 4, 2020.

  1. Big Fred

    Big Fred NEW MEMBER!

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    Hi guys, I have a newbie question: I am planning my first tube amp build, and I have been studying Robrob's site for a while.
    I would like to build a micro 5f1. I also play bass sometimes, so I was thinking of modding the original plan so I could use it also for bass. I have searched on the forum and I know that it may have a low volume, but it will be literally a bedroom amp. I am sure that it will be fine for guitar, but I have some doubts about bass.
    I found on the internet some caps values for the V1A bypass cap (from 25uF to 2uF or 1uF) and for the coupling cap (from .022uF to .01uF, or even 500pF) that could be good when playing bass. I would put these caps on a switch so I could have the "original" values and also these ones with simply a switch. The space inside the case won't be an issue because I will be building an head and it will be built from scratch. I will start from a long fiberglass board so it won't be a problem to find some space for two extra caps.
    Honestly, is it a bad idea? I am sure that I will build a Micro 5F1, but I am not sure about this mod.
    I know about the risks of high voltages, and I am obsessed with safety (also because of my job).
    Lastly, I am sorry if my English is not so good, but I am not a native speaker.
     
    screefer, Jlwctn and sds1 like this.
  2. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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    Switching off the bypassed cathode on the first gain stage, and a grid stopper on the output (looks like Rob's has this already).
     
  3. screefer

    screefer Tele-Holic Silver Supporter

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  4. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    I think you will run into issues with the ease at which the 5F1 circuit will distort. Of course a bass speaker will be needed because the xmax for the typical 5F1 speaker will be exceeded with bass guitar frequencies.
     
    Last edited: Oct 4, 2020
  5. marshman

    marshman Poster Extraordinaire Silver Supporter

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    The amp itself won’t care much what you play through it, but speakers made for guitar do not like bass frequencies much. There are tweaks that will make the amp more bass-friendly, and they’re switchable, as you’re planning. Since you’re building a head, simply using different cabinets/speakers should be the way to go.

    But if space in your room is tight, you’ve got a new problem.
     
  6. Big Fred

    Big Fred NEW MEMBER!

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    I must add that I already have a small bass cabinet and I would use that for bass. My main concern was about the better way to mod the amp in order to have a switch to make it (kinda) bass-friendly. I'll check the grid stopper on the output too!!!
     
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