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New adventures in 5E3

Discussion in 'Shock Brother's DIY Amps' started by theprofessor, Jan 11, 2018.

  1. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    When folks said that amp-building is addictive, I thought they meant, "You'll really like it and maybe want to do it again someday." Ha! Not quite.

    I've been stewing on a 5e3 build since I completed my (lovely) 5f2a a couple of months ago. I really like the sound of the traditional 5e3, the fact that it gets hairy early, and the fact that it can push more air than the 5f2.

    So I've been parts-gathering, but also building a head cab (see also here), acquiring an extension cab, and getting a speaker for it. More on the electronic parts in a minute. For now, here's the poplar head cab I just finished for it: three coats of Minwax Polyshades Honey Pine in satin finish. The dimensions are basically Mojotone's: (H) 11'' x (W) 20'' x (D) 8'', chassis cut-out 12-1/2. Oxblood grille cloth from Mojotone, leather handle from Mojotone, and rubber feet from Mojotone. I've still got to build the back panel and put some cleats in the corners. I decided not to do box joints, because I don't love the look of the end-grain on the edges. So I rabbeted the corners and finished the edges off with a 3/8" roundover bit. I have all hand tools, so I'm very happy that it came out as well as it did. Many thanks to @Tidewater Custom Shop over at The Gear Page for sending me the fantastic baffle screws.

    IMG_9895.JPG IMG_9894.JPG IMG_9897.JPG IMG_9898.JPG IMG_9899.JPG
     
    Last edited: Jan 11, 2018

  2. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    I got a Fender lacquered tweed Hot Rod Deluxe extension cabinet used off Reverb a while back, and it's going to serve my purposes very nicely. It comes in a closed-back format, so I took the back off and built (poplar) panels for 2/3 of it so that it can be an open-back cab. After that, in a fit of excitement around this thread about Jensen P12P's, I found a used one on ebay that had already been re-coned by Ken Day in Sylvan Lake, MI (I believe he's the speaker repair person for Dean Zink). It was 75% the price of a new Weber 12A125A (my other option), and it sounds absolutely fantastic. Despite what the speaker says on the bell cover, it was re-coned with an impedance of 8 ohms and a voice coil that can supposedly handle 40W. I don't really have enough experience to say this, but I think it's the best-sounding 12" speaker I've ever heard (maybe I'm just excited?).

    IMG_9907.JPG IMG_9908.JPG IMG_9910.JPG
     

  3. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    As for parts, I finally decided on transformers after displaying some weapons-grade ignorance about the difference between a high voltage winding center tap and a heater center tap in this thread. I kind of wanted to go with the Hammond PT, but it is not quite as easy to get here in the U.S., and the price on the Classictone stuff is really hard to beat--especially since the testimonies about the 5e3 folks have built with their Deluxe Reverb PT and their 5e3 OT have been uniformly positive. So that's what I went with.

    I'm listing parts here in case others want to put together a 5e3 from scratch. It can be done more cheaply, sure, but these are the parts I decided to go with. Most stuff is from Tube Depot.

    You'll see that I've decided to build a pretty standard 5e3. The main exception is the 22uF filter capacitor in the first position, rather than 16uF. Just trying to ensure keeping ripple current out of the signal. The current plan is to use metal film through 12AY7A and 12AY7B and then switch to carbon comps from there. I believe I ordered all the metal film resistors I might need if I should decide to use them throughout.

    Please let me know if you see anything that is the wrong value or that I missed.

    Mojotone
    Narrow-panel tweed Deluxe chassis
    Chassis-mounting screws
    tweed deluxe eyelet fiberboard with backing fiberboard
    Lots of solid-core cloth-covered push-back wire, 22AWG for most and 18AWG for the heaters.
    (1) strain relief
    (1) cord clamp that attaches to cabinet

    Tube Depot

    transformers

    Classictone PT 40-18016
    Classictone OT 40-18022

    capacitors
    electrolytic
    F&T filter caps: 22uF (B+1), 16uF (B+2), 16uF (B+3)
    Sprague cathode bypass caps (3) 25uF/50V

    coupling
    Mallory 150 (4) .1uF and (1) .022uF

    silver mica
    Xicon 500pF bright cap

    metallized polypropylene
    Xicon .0047uF tone cap (I also have an Orange Drop I could use here)


    resistors

    wirewound ceramic/cement (a few options for 6V6 cathode resistor)
    (1) 250R/5W
    (1) 300R/5W
    (1) 250R/10W
    (1) 300R/10W

    ceramic composition (for 6V6 screen grid resistors)
    (2) 470R/2W

    metal oxide
    (1) 4.7k/3W voltage-dropping resistor
    (1) 22k/3W voltage-dropping resistor
    (1) 110k/2W bleeder resistor for filter capacitors
    (1) 220k/1W bleeder resistor (don't know which of these two I'll use yet)
    (1) 47k/2W resistor for pop reduction on standby switch
    (1) 100k/2W resistor for pop reduction on standby switch (I don't know which of these two I'll use)
    (2) 1.5k/2W grid stoppers for 6V6

    carbon composition
    (1) 820k cathode resistor
    (3) 100k load resistors
    (3) 1500 cathode resistors
    (2) 56k load and phase inverter tail resistors
    (1) 1M grid leak resistor
    (2) 220k grid leak resistors

    metal film (I think a few of these are redundant to the carbon comps)
    (3) 1.5k/.5W
    (4) 68k/.5W grid stoppers
    (2) 100k/.5W load resistors
    (2) 100k/.5W for artificial elevated heater center tap on the 6V6s
    (1) 820k/.5W
    (2) 1M/.5W input resistors

    sockets and clamps
    (3) Belton octal sockets
    (2) Belton 9-pin sockets with shield
    (3) "bear trap" clamps for octal tube sockets

    switches, jacks, pots, and other assemblies
    (2) Carling SPST switches
    (3) 1M CTS potentiometers with .25 inch solid shaft
    (6) Switchcraft 12A shorting jacks for 4 inputs and 2 speaker outs
    (1) NOS Bakelite fuse holder with 2-Amp slo-blo fuse
    (1) Fender-style lamp assembly
    (1) jewel for lamp assembly
    (1) #47 bayonet bulb
    (1) 18/3, 3 meter cut power cord

    Other things
    all keps nuts,washers, and bolts from local hardware store
    a bunch of 3/8" internal toothed lock washers from local hardware store
    3/8" rubber grommets from hardware store
    (3) NOS (1960's I think) bakelite oxblood-colored skirted radio knobs from Leeds Radio in NYC
    I already have NOS 6V6 pairs, 12ay7s and 12ax7s
    I have the 1N4007 1A/1000V solid state diodes for the rectifier

    Also: I already have a Carling mini toggle DPDT ON-OFF-ON switch and a 56k/.5W Dale mil-spec resistor, if I decide I want to do the 3-way switched negative feedback mod.
     
    Last edited: Jan 11, 2018

  4. Preacher

    Preacher Friend of Leo's

    Apr 17, 2007
    Big D
    Nice,
    I am really trying to decide if I want to make mine a head or a combo. I like the idea of a combo, but I have a 1x10 and a 2x10 cabinet as well as a 1x15 cabinet I used for bass just laying around. I know I can run them through the out jack but if I like the 2x10 better it would make sense to make a head.

    Nice job on the cab by the way!!
     
    theprofessor likes this.

  5. tery

    tery Poster Extraordinaire Silver Supporter

    Sep 21, 2012
    Tennessee
    Extra impressive ... you are light years ahead of me !
     
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  6. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    I'll add one item to hardware. Get some appropriately sized fender washers and modify them to fit. These are for the mounting ears on the OT to reinforce them, in case the amp takes a tumble. Place them between the screw heads and the ears. Otherwise, your transformer can end up looking like this. IMG_20180111_084205.jpg
     

  7. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    Thank you! Will do, @clintj ! I'll pick up those fender washers when I take the OT and chassis over to the hardware store to figure out what size machine screws I need to install it.
     

  8. muscmp

    muscmp Tele-Holic

    807
    Jul 1, 2008
    california
    great build you've got going!!

    my 5e3 tube depot kit included isolation washers(galvanized/neoprene) to place under the nut on the speaker. i've since purchased them at home depot and have put them on the speakers of a couple other of my amps. cheap and sure seems to eliminate any possible vibration or noise.

    play music!
     
    theprofessor likes this.

  9. Thin69

    Thin69 Friend of Leo's

    Oct 28, 2009
    Galveston, TX
    Nice build! Love the cabinet work!
     
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  10. Bristlehound

    Bristlehound Tele-Afflicted

    Age:
    58
    Jan 4, 2017
    Wales
    Great cabinet! Love it. I used tweed to hide the cheap plywood I built my cab out of.
     
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  11. SacDAve

    SacDAve Poster Extraordinaire Silver Supporter

    Age:
    66
    Dec 23, 2009
    Rocklin Ca.
    Like your Cabinet . Your list looks good.
     
    theprofessor likes this.

  12. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    Here's my populated eyelet board. Please give it a check and see if everything looks okay before I start soldering things in tomorrow. Thanks!
    IMG_9911.JPG
     

  13. The Guy

    The Guy Tele-Holic

    740
    Sep 15, 2016
    Guitarsphere
    Those boards are a pita.... I had so many noise problems with mine (mojotone) because they are conductive. At least try to isolate the v1b grid stopper resistors from v1 load resistors. Those eyelets so close from each other right there at the middle of the board are a huge source of weird crackling noises, specially with a humid climate. I had to lift both grid stopper junctions from the board.
     

  14. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    P.S. If I'm going to do the 3-way NFB switch mod, do I simply lift the positive lead of the first 25uF cathode bypass capacitor out of the eyelet and solder a wire directly to it that goes to the switch?
    5e3_Feedback_Switch.png
     
    Last edited: Jan 11, 2018
    robrob likes this.

  15. SacDAve

    SacDAve Poster Extraordinaire Silver Supporter

    Age:
    66
    Dec 23, 2009
    Rocklin Ca.
    ^ add that eyelet. I have the NFB switch in all 5 of mine...................You no what I never use them any more. As for your build. good separation on components , outer foil marked every little bit helps. Make sure to post Jumpers on back of board. Myself I run all the leads to the pins long I like to cut the length in place that seems to work for me
     
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  16. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    Looks good, with proper hooking of leads for proper mechanical joints too. I follow advice I was given when starting out, that an amp should function without solder. You're off to a good start there.
     
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  17. jsnwhite619

    jsnwhite619 Tele-Afflicted Ad Free Member

    Age:
    34
    Sep 10, 2013
    Georgia
    I'm sure there are too many variables to calculate, but I've never had any noise attributed to humidity with eyelet boards and I regularly see 90-100% humidity. The leads aren't touching the board, and I feel like a new board would have to be pretty wet to connect between eyelets.

    That nfb really kills the gain in my experience and castrates a 5e3. It works, but REALLY well. If you check out the Princeton Reverb NFB it allows the bypass cap and adds a small divider resistor and keeps the gain. Not nearly as dramatic of a change. But your original method would probably offer more of a "different amp" feel. I was looking for more of just the same but different.
     
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  18. Bristlehound

    Bristlehound Tele-Afflicted

    Age:
    58
    Jan 4, 2017
    Wales
    I love the NFB switch in my 5E3 - I keep it on the middle position all the time. I also used a .0047 coupling cap on one of the channels and use that channel all the time... so it's not very 5E3y any more, I suppose.
     
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  19. theprofessor

    theprofessor Friend of Leo's

    Aug 8, 2016
    Chattanooga, TN
    Thanks, SacDAve! Yes, I'll post some photos of the back of the board as well, once I solder up those leads. As for the eyelet and the NFB: I've never inserted an eyelet into anything before, and I don't have any. So, I'll probably just skip it and build it stock. My guess is that if I did put it in, I'd be like you and never really use it.

    Thanks, clintj! I had never heard that about an amp functioning without solder, but that is a great visual image of an ideal initial setup.

    Thanks, jsnwhite619! I really just want a 5e3. I already have loud and clean with my SFDR. I have tweed and clean with my 5f2a. I think I'll just build it stock after all. I don't want a different amp, just a stock tweed Deluxe.
     

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