5E3 mods - Switch/Pot locations?

Discussion in 'Shock Brother's DIY Amps' started by GoKart Mozart, Jul 30, 2019.

  1. GoKart Mozart

    GoKart Mozart Tele-Meister

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    Howdy guys,
    I've been enjoying the heck out of my 5E3 build since I put it together about 2 years ago. Having had ample time to experience the un-modified glory of it, I'm about to do a few tweaks.

    1) Rob's switched negative feedback
    2) Pre-PIMV (variable PI grid stopper)
    3) Switchable coupling caps on Bright Channel (.022uf & .1uf).

    With these three mods, I'm looking at the addition of 1 pot and two mini-switches. My plan is to add the PPIMV pot to the Lo jack location on the Normal channel. I don't have any shielded wire at the moment, so I'm going to attempt to run as much of the wire behind the board and against the chassis as possible. Have any of you guys had good luck with keeping the noise at bay by doing it this way?

    As much as I'd like to keep both of the mini switches up top for accessibility I can't find any pics of anyone adding mini switches to a location other than to the left of V2. Have any of you guys added it to another location?


    Here's my original thread & a couple of pics. The only thing different about the amp from these last pics is that I'm running JJ power tubes and I flipped the speaker to keep the excess speaker wire from rattling against the dust cap.
    https://www.tdpri.com/threads/jacobs-5e3-boothill-build.723650/

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    Last edited: Jul 30, 2019
  2. Bill Moore

    Bill Moore Tele-Afflicted Silver Supporter

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    I built mine with both nfb, and switchable "fixed" bias, both switches fit on either side of the speaker jacks.
    5E311.jpg.JPG
     
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  3. Jorgen83

    Jorgen83 TDPRI Member

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    You don’t really need the standby switch, so scrap that and put either the master volume or the NFB there. And you could also scrap two of the four input jacks, or do the switchable input mod so you’d have three switches and one jack instead of 4 jacks.

    I put my nfb in the speaker extension jack hole, and to be honest it’s not something I use a lot so that’s perfect.

    Mind you, the standby switch hole does give some difficulties as far as knob selection goes. Chicken heads won’t turn on my cabinet.
     
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  4. GoKart Mozart

    GoKart Mozart Tele-Meister

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    As much as I'd like to lose the useless standby switch, I had pretty much decided against putting anything in that location due to all of the AC signal in that area. It would be some pretty long wire runs to hook up either the NFB or the master volume (I'm trying to not have to buy $20 worth of shielded cable).

    Man, I wish I would've thought of that! I never use the extension jack but I already ordered some mini-switches!! GRRR. I think I will go with the NFB there and just order a full size switch if I can't find one in my parts stash.

    Yeah, I noticed over the weekend that either the standby hole or the Lo input hole would be pretty close to the cabinet edge, so I ordered some extra narrow knobs to try out.
     
  5. GoKart Mozart

    GoKart Mozart Tele-Meister

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    I went ahead and removed the Lo-Normal jack in order to put the PPIMV pot there. I test fitted another pot to see how everything is going to line up; one thing that's a bummer is that I'm going to have to rotate it 90 degrees in order for the lugs to clear the jack above it. :rolleyes:

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    As far as drilling a hole for the mini-toggle (switchable coupling caps, a.k.a. "humbucker switch"), would I be better off going with the left or the right of the Bright jacks? I don't mind redoing a bit of wiring to clear the switch; preventing unnecessary noise is the main thing I'm after.
     
  6. mherrcat

    mherrcat Tele-Holic

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    That's where I put my MV.

    I would put the NFB between the auxillary speaker jack and V2; that's where all the wiring is going to be connected. (That's where I put mine.)
     
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  7. GoKart Mozart

    GoKart Mozart Tele-Meister

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    Did you use shielded wire for the leads going to it? Any noise issues?
     
  8. Intubator

    Intubator Tele-Meister

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    Those switches don't have to be "mini" switches. You can use full size Carling toggles on/off, on/on/on switch and mount them on top for various uses... As mentioned, get rid of the standby to open up a spot and the fuse socket as well. I relocated the fuse on my Champ to the base of the chassis just below the PT for the facilitation of a reduced power switch. I don't miss looking at it and it doesn't do much on the top of the chassis anyway...
     
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  9. mherrcat

    mherrcat Tele-Holic

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    I did use shielded wiring. I haven't noticed any noise. The picture of the 5E3 MV and NFB wiring on Rob's site is my amp. In the NFB picture you can see the other end of the MV wiring; there are yellow, white and red leads, and the blue is the heat-shrinked shield going back to the ground bus.
     
    Last edited: Jul 31, 2019
  10. Paul G.

    Paul G. Friend of Leo's

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    If you're not going near all the AC, you don't need shielded wire. Run wires near the chassis, twist wires if you can. Keep cable runs short -- by all means put the NFB switch near the speaker jacks.
     
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  11. GoKart Mozart

    GoKart Mozart Tele-Meister

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    Understand that, I just hadn't considered using some of the preexisting 1/2" holes (standby switch, extra speaker jack) and went ahead and ordered mini-switches since they don't require as large of a hole to be drilled into the chassis.
     
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  12. BobSmith

    BobSmith Tele-Meister

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    I’m curious about the negative feedback switch location.

    Has anyone tried putting it at the bypass/ground switch location on the front panel. Or is that a bad idea (i.e. too far away)?
     
  13. BobSmith

    BobSmith Tele-Meister

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    Can you post a picture of how you wired that? I’m interested in the wire routing.
     
  14. Intubator

    Intubator Tele-Meister

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    I would think that you would ideally want that switch near the instrument input side of the chassis since its dealing with a low ma ac signal. If you mount it too close to the filter caps/PT side you may get some undesirable frequency intrusion. Maybe a shielded cable would help too?... I'm pondering all of this right now for an upcoming 5E5/5E3 build in the planning stages of.
     
  15. Intubator

    Intubator Tele-Meister

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    Sure, here it is and pic of the amp. fuse lower left of the chassis. the diode you see just above the fuse housing is in series with the PT center tap to reduce the voltage to original 5F1 specs.

    20190801_124346_resized.jpg

    20190801_124139_resized.jpg
     
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  16. GoKart Mozart

    GoKart Mozart Tele-Meister

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    I had some time to do some work on it tonight and went ahead and did the coupling cap switch/“humucker switch”. Since I put the switch up top, I used the now empty turret as a mounting location for a terminal strip. Worked out pretty well. Unfortunately it was late by the time I got finished, so I didn’t get to test it cranked up to see how well it works. At low volume I could definitely tell a difference in low end once I switched to the .022uf cap.

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  17. Intubator

    Intubator Tele-Meister

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    Nice! So that 0.1uf switching option is a bass booster?
     
  18. GoKart Mozart

    GoKart Mozart Tele-Meister

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    The idea is to get rid of some of the flubb/woofiness that you get with hotter pickups or boost pedals. The .1uf is the standard cap, so you switch to the .022uf when you n something hotter through it.
     
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  19. Intubator

    Intubator Tele-Meister

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    yeah, actually makes more sense. Reducing capacitance increases mid and high frequency pass through..
     
  20. GoKart Mozart

    GoKart Mozart Tele-Meister

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    I finished up the Pre-PI master volume over the weekend; I wasn’t doing this particular mod to control the volume but to fine tune the grid stopper value. The first half of travel on the pot when turning down is subtle; there’s a noticeable decrease in flubb and harshness when the channel volume is cranked. I haven’t had a chance to run any pedals since doing any of these mods, but I’ll be sure to report back with my thoughts on that afterward.

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    Since I had to turn the pot sideways in the chassis, the orientation of min and max travel doesn’t line up with the other pots. However, what I did do was measure the resistance when the pot is right at the “sweet spot” of 470k that Rob mentions on his site, and then set the knob pointer to line up with the “2” mark on the chassis as a quick reference. To put it pack to stock value, all you have to do is give the knob a quick turn all the way to the right. Note: if you use one of the Normal jack holes for this pot, be aware of knob size. I ordered this one from AES. It’s the perfect size on my Mojo cab.

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    I finished up the 3-way NFB this evening. I ended up removing the 2nd speaker jack and putting the switch in its place. This is DEFINITELY the most noticeable change in tone and I really dig the versatility that the 3 way offers. With NFB added it really reminds me more of my Deluxe Reverb reissue. I’ve got a feeling that I’m going to wish that this switch was up top since I’ll be using it a lot!

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    I bought the misc resistors to do the Lead Channel mod, but I’m going to hold off on that for a while and explore these mods.

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    @robrob can’t think you enough for the great resources on your website. I can’t imagine how many hours you’ve labored putting all of that info together.
     
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