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Fixed tone stack in 5f1?

Discussion in 'Shock Brother's DIY Amps' started by SOYRAFA, Jan 12, 2021.

  1. SOYRAFA

    SOYRAFA TDPRI Member

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    Would it be possible to install a fixed tone stack (Without any pot), in 5f1 as for example the Champion 600 reissue has it?. (Blackface style).
    How would it be reflected in the layout so that a non-technician could make it easy with the soldering iron / resistors / capacitors? Any response welcome.
     
  2. Uncle Daddy

    Uncle Daddy Tele-Afflicted

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    Are you trying to reduce the mids? It may be easier to swap the V1 bypass cap, or a lower value coupling cap. Another way to clean it up is a smaller NFB resistor.
     
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  3. SOYRAFA

    SOYRAFA TDPRI Member

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    Well, I find the 5f1 is very focused on mid frequencies, with little bass and few treble, if I try to raise one of them, through different values of the coupling caps, it usually directly affects the descent of the other. The fixed tone stack of the champion 600 sounds good to my ears, I intend to copy it. Perhaps the effect of lowering the mids, would enhance treble and bass, or would it be like lowering them all? I can test if it is easy to do with the soldering iron;)
    upload_2021-1-12_22-1-2.png
     
  4. Uncle Daddy

    Uncle Daddy Tele-Afflicted

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    The lack of bottom end is caused largely by the small cab and speaker. I plugged mine into my 5e3 cab, and it was huge!
     
  5. NTC

    NTC Tele-Meister

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    The tone stack will cut the mids, but it also cuts a LOT of gain. Would a simple bright cap help? Or a 5F2 tone control?
     
  6. dlaroe

    dlaroe Tele-Meister

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    Like is said above, try an external speaker cab first to be aware you might be "fixing" a cab/speaker issue with a circuit change and there will be a huge loss of gain with the TMB tone stack.

    The unlike the 5f1, the C600ri has 22uf bypass caps on both it's preamp gain stages and you may need to add one, like the 5f2a does, or both to get back the same volume. Shouldn't be too hard to replace the preamp coupling cap with the C600ri's fixed tone stack. Adjust the Mid resistor to taste, 100k dials tone stack is mostly out.

    I've modified my C600ri this way, making the Mids adjustable and bypass caps switchable.
     
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  7. SOYRAFA

    SOYRAFA TDPRI Member

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    I've tried several things, including a tone control, but this only cuts high frequencies, etc. I'm looking for something similar to a fixed equalization, like champion 600 reissue, that works well for my ears, maybe a classic blackface fixed mid-cut could be useful, specially if it makes the bass and treble frequencies more noticeable at the same time.

    So how would a fixed resistor to cut mids looks like in layout?
     
    Last edited: Jan 13, 2021
  8. jimgchord

    jimgchord Tele-Afflicted

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    Switch to a blackface circuit
     
  9. sds1

    sds1 Tele-Afflicted

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    A fixed BF tone stack will have 4-5 resistors and 3 capacitors.

    I reckon you are a little short on space for that, you'll have to get creative.
     
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  10. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    Soyrafa, I see you're in Spain. You seem amp smart -- at least, you know there's a fixed tone stack in a Champion 600, which I didn't. We might ask if you're building a new circuit or trying to mod an existing 5F1? If modding, are you doing this in the tiny 5F1 chassis?

    The reason I ask? It's like this old joke. Man asks Vermont farmer: "How do I get to Barre?" Farmer says, "If I was going to Barre, I wouldn't start from here." Mainly, I suspect it's what our smart friend @sds1 says -- too many parts, too little space. A blackface tone stack is a whole mash-up of tone cuts, too, so it'd steal a lot of your signal.

    As mentioned, a bigger brighter speaker could help, bringing up the bass and treble. Beyond that, maybe a good EQ pedal?
     
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  11. SOYRAFA

    SOYRAFA TDPRI Member

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    The amp is a '57 Custom fender champ. I'm a musician, not a technician, but determined enough to take a soldering iron, tin, and change add capacitors, resistors, or potentiometers, but not much else.

    Currently I have improved my amp following connoisseurs' instructions, with a treble bleed, change of coupling caps, and filter caps.

    Indeed, the interesting thing about this amplifier is the small size and light weight, ideal for home and study. But I find that other small combos also produce fuller-range tones, especially more bass frequencies.

    By modifying I have been able to take out high frequencies with ease, always reducing the bass, but not vice versa, only achieving the effect of lowering a tone control not increasing low frequencies.

    I find it curious that an amplifier like the champion 600 reissue with a 6 '' loudspeaker is capable of taking out much more bass frequencies, so I am sure that the problem is not a cabinet, speaker or small transformers.

    There is something in that fixed tone control, which without much knowledge, I see as 3 capacitors and 4 resistors, that manages to achieve it.

    That is why I ask questions in case some skillful expert, beyond copying a stack of tones from a blackface scheme with its 2 potentiometers, somewhat simple if there were space and holes to place 2 pots, could implement an ingenious fixed solution that would fit the 5f1 In a simple way.

    For example and being more specific. Is it possible to install a typical fixed mid frequency blackface resistor on the 5f1? How? Where?. Maybe a fixed tone stack like in champion 600 raised over the circuit? That's it ;)
     
  12. D'tar

    D'tar Friend of Leo's

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    Well... I would say yes you can with minimal changes. I can not guarantee the outcome good or bad. This is a layout from Robs site that I just modified with the 600 tone stack values. You may find room by moving the input grid resistors off the board.

    Please check for errors and point and laugh!

    The 600 fixed stack

    upload_2021-1-13_14-54-40.png

    The 5f600

    upload_2021-1-14_9-47-36.png
     

    Attached Files:

    Last edited: Jan 14, 2021
  13. D'tar

    D'tar Friend of Leo's

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    Well.. I just looked at the 57 custom champ and you may have less room in there than an actual 5f1.LOL

    One could put the tone stack on a small supplemental board and attach to the side wall of the amp chassis. May make for some long runs to the volume but shielded cable may work fine.
     
    Last edited: Jan 13, 2021
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  14. gusfinley

    gusfinley Tele-Afflicted

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    If room is an issue you could always remove the back panel and install a custom back panel and place the tone controls on it.
     
  15. SOYRAFA

    SOYRAFA TDPRI Member

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    This is fantastic! Thank you very much!
    I can try to assemble it in 3D, the long legs of the components give a lot of play, and if it gives a good result, fix all the components with a bit of suitable glue.

    Very grateful for the solution and the layout! Good job!, thank you very much.
     
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