Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com
Asher Guitars WD Music Products Amplified Parts Mod Kits DIY Nordstarnd Pickups Warmoth.com

weber 5e3 build

Discussion in 'Shock Brother's DIY Amps' started by Finastbeans, Feb 26, 2011.

  1. Finastbeans

    Finastbeans TDPRI Member

    98
    Jan 12, 2011
    Maryland (DC area)
    Kicking off a 5e3 kit build. This is my first amp build so I'll be going painstakingly slow. Planning on 3 mods:
    - preamp voicing with cathode bypass cap mod ala Dave Hunter with 25uF/no cap/0.68uF on V2 (gain makeup). Installing switch on the underside of the chassis between the 2 preamp tubes
    - bright channel will use a .02uF coupling cap... interestingly the weber chassis labels this channel as bright but as far as I can tell the 2 channels are normally wired the same, each with a low and high (1 & 2) impedance option.
    - impedance switch -> I would like to be able to run an 8ohm extension cabinet with the stock speaker still engaged. so I think I need a switch to swap to the 4ohm tap. Planning on putting a toggle behind the 2 speaker outs.

    The kit came with 20uF/16uF/16uf filter caps. Thinking of increasing the first one to 30uF based on some of the threads on this forum, however I'll probably go back and do that later (hopefully without frying myself).

    That gives some options, at the same time leaving the stock settings available.

    Some questions for those who have done these before:
    - where did you place your preamp voice switch
    - where did you place your impedance switch
    - is it sufficient to ground everything in the signal section to the brass plate as a star ground, or should i ground them to a single point on the plate? (I have some terminal strips lying around also). I want this thing to be as quiet as possible, recognizing that it's not a quiet amp.

    Will follow up with some pics
     

  2. Finastbeans

    Finastbeans TDPRI Member

    98
    Jan 12, 2011
    Maryland (DC area)
    Pics
    - cabinet with corners added:
    [​IMG]
    - board layout, not tack soldered yet:
    [​IMG]
    - drilled hole for preamp voicing switch:
    [​IMG]
     

  3. big-daddy-59

    big-daddy-59 Tele-Holic

    737
    Mar 20, 2009
    Castlewood,VA
    Looking good. Might want to exchange the 250r 5watt resistor for a 10 watter and up grade the bypass cap for the power tubes to a 50v rated part as well.
     

  4. Finastbeans

    Finastbeans TDPRI Member

    98
    Jan 12, 2011
    Maryland (DC area)
    Another question... Thinking about using shielded cable from the input jacks to the 68k resistors. I have some 4 conductor pickup wire that could be used, would the gauge be too small?
     

  5. big-daddy-59

    big-daddy-59 Tele-Holic

    737
    Mar 20, 2009
    Castlewood,VA
    I just used the wire from an old RCA cable, you know, the kind used to hook up a dvd player to the TV before we got all fancy with HDMI.
     

  6. fernando

    fernando Tele-Afflicted

    Feb 6, 2008
    Barcelona, Spain
    the pre made rca cables are usually pretty bad (spiral shield, etc)
    Just buy some feet of good braided shield cable for it, it makes a difference
     

  7. hackworth1

    hackworth1 Friend of Leo's Vendor Member

    When using shielded cable from that volume control to pin 2 of Preamp tube V2, obviously the ground wire (shield) gets soldered to a ground point on the volume control.

    Where does the other end of that ground wire (the shield on the cable) connect on the tube socket side?

    Does it get soldered to V2's pin 3?
     

  8. Platefire

    Platefire Friend of Leo's

    Age:
    70
    Nov 3, 2003
    North Louisiana around Many
    On the 5E3 bright channel---I'm not sure how Weber did their kit as original or not but the original bright channel has the tweed one pot tone stack but because the normal channel (without a tone pot) are both tied together (without any seperation) just prior to going to the Phase Inverter--both channels interact with each other. That's part of the interesting Freaky thing about a 5E3. You can seperate the channels by using 220K isolation resistor just prior to where they join together that will stop the channel interaction-but that may not be desireable. Platefire

    The attached layout shows how I did that on one on my builds:)
     

    Attached Files:


  9. BobbyZ

    BobbyZ Doctor of Teleocity

    Jan 12, 2011
    Snellman MN
    Only ground one end of the shield cable or you get a ground loop.
    That's what "thay" say.
    Who are "thay" and why do "thay" know so much ?
     

  10. Finastbeans

    Finastbeans TDPRI Member

    98
    Jan 12, 2011
    Maryland (DC area)
    Thanks Platefire - I think I am going to leave them interactive for now...

    I still don't think I am understanding the bright channel thing - is there something about the tone stack orientation that makes one of the stock channels brighter or was the chassis printed in anticipation of the mod that I am doing, because it's so common?

    off to the shed :)
     

  11. Ricky D.

    Ricky D. Poster Extraordinaire

    Age:
    66
    Oct 22, 2006
    Garner, North Carolina
    My 5E3 build (Mission kit) is dead silent with the volume all the way up. Stock layout and original circuit.
     

  12. Finastbeans

    Finastbeans TDPRI Member

    98
    Jan 12, 2011
    Maryland (DC area)
    Great :) do you have any advice on grounding / lead dress without giving away any of Bruce's secrets?
     

  13. Finastbeans

    Finastbeans TDPRI Member

    98
    Jan 12, 2011
    Maryland (DC area)
    I thought the stock tone pot is supposed to act on both channels. Are you saying that in a stock configuration it acts differently on each one causing one channel to be brighter?
     

  14. big-daddy-59

    big-daddy-59 Tele-Holic

    737
    Mar 20, 2009
    Castlewood,VA
    tone pot only works the bright channel.
     

  15. Finastbeans

    Finastbeans TDPRI Member

    98
    Jan 12, 2011
    Maryland (DC area)
    Taking a look at the schematic again, it looks like the .0005uF cap on the upper channel acts to shunt some of the high frequencies around the volume control, while also interacting with the tone control. That would make the upper channel the bright one, while the tone control is acting on both channels.

    Would that be a fair description?
     

  16. cbass

    cbass Banned

    660
    Dec 21, 2009
    west plains MO
    Shielded cable isn't needed on lower gain amps like a 5E3.
     

  17. big-daddy-59

    big-daddy-59 Tele-Holic

    737
    Mar 20, 2009
    Castlewood,VA
    no for the tone control to work as intended, you would have to take the signal coming from c3 on the weber schematic and route it into c4, the same as the signal coming out of c2. The way that the two channels have their outputs tied together is funny, with the output from both volumes and the tone control meeting at the same point. The lack of blocking resistors causes a lot of unintended interaction.
     

  18. Platefire

    Platefire Friend of Leo's

    Age:
    70
    Nov 3, 2003
    North Louisiana around Many
    On the tone stack thing. If you look at a tweed champ, it had no tone stack. Then the next model up, the Princeton had one knob tone stack. So in the 5E3 Deluxe, next step up you have the normal channel (like the champ)with no tone stack and the bright channel with a tone stack just like a princeton.

    The inter-action happens when the normal channel output and the bright channel output are joined together in one wire/grid going to the phase inverter tube. You have bleed over from the brigt to normal and from normal to bright. The bleed over to each channel is not a bad thing--because you can get a lot of variation in tone and response by playing around with the tone and volumes.

    A technical explanation of how the 5E3 tone stack works is detailed in the tone stack circuit schematic of Figure 1 and Figure 2 below and the explanation of the guitar signal flow operation as described as follows:


    Assume no signal on the bright channel. The 'blue' indicates the normal signal path and the 'gold' indicates tone filters.

    Look at Figure 1. The tone pot and .005µF cap form a variable series shunt filter connected directly between the normal signal path and ground.

    Look at Figure 2. The bright channel volume pot and the 500pF cap interact somewhat with the normal signal also. Imagine the tone pot wiper at the top end of the pot and the bright volume pot at its bottom end. The 500pF cap is shorted out in this case and its effect on tone is minimal. Now crank the bright volume pot to the top and you will see that the 500pF is now connected directly between the normal signal path and ground, shunting some high frequency signals to ground. Moving the bright volume pot between extremes varies the amount of attenuation to the high frequencies, acting like a tone control for the normal channel. The effect is not nearly as noticeable as the real tone pot, but you can hear the effect.
     

    Attached Files:


  19. Finastbeans

    Finastbeans TDPRI Member

    98
    Jan 12, 2011
    Maryland (DC area)
    hmmm - I don't have a layout with numbered caps so struggling with that one...

    I think the tone control is designed to, and does work on both channels. if you imagine the circuit with both volumes all the way up the .0005 value shouldn't have any (significant) affect on the signal path and the tone control bleeds treble equally from both channels through the .005 value...

    [​IMG]

    ...as you turn the bright volume down, some of the high frequencies are shunted to the channel junction (assuming the tone knob is turned up).

    summarizing:
    - the .0005 value is there to make a bright channel
    - the .005 value is there to make a tone control for both channels
     

  20. Finastbeans

    Finastbeans TDPRI Member

    98
    Jan 12, 2011
    Maryland (DC area)
    That is a really great explanation of the interactivity of the channels. I'm getting super excited to finish this and actually test some of this out with a guitar :)
     

IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.