5E3 almost, what do these differences do?

Discussion in 'Amp Tech Center' started by dragonfly66, Apr 16, 2019.

  1. dragonfly66

    dragonfly66 Friend of Leo's Silver Supporter

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    So I ran across this "5E3" but in comparing it to the original circuit there are some values that are not the same. I was wondering what these differences actually do. Any help would be appreciated in understanding the choices made by the builder.

    I've attached photos and the layout with the differences I could see.

    Summary of the differences with associated photos below:
    • Bypass caps are 22uf 50V instead of 25uf 25V
      Not sure what these differences would cause.
    • Filter caps are 22uf 500V instead of 16uf 450V
      Not sure what these differences would cause.
    • Coupling caps are same values, but with 600V-630V instead of 200V-400V.
      This seems like it would be of no consequence.
    • One "dropping" resister is 5100 instead of 5000.
      This seems like it would be of no consequence.
    • Bright cap is .00056 instead of .0005
      This seems like it would be of no consequence.
    • 2 100Ohm resisters added to V4 (the last power tube) from pin 2 (filament) and pin 7 (filament) to pin 8 (cathode)
      I found someone said this was to reduce hum and it could act as a fuse if there was a failure.
    • 4 pin #83 Mercury Vapor Rectifier (used in Tweed Twin 5F8 and Tweed Bassman 5F6)
      I don't see a key or pin numbers on the 83 tube, do the pins have to go in a certain way? I pulled it out and not sure how it should go back in. - Actually there is only one why it will fit in easily. Two of the post are larger than the other and you can tell when putting it in that it only fit easily one way.
      Does using this rectifier add something special to the tone as I was wondering what the point of using it would be seeing as there is a risk of mercury poisoning and environmental hazard if the tube breaks. To be safe should it be replaced?
      I have seen solid state rectifier replacement though couldn't the circuit be changed to accomodate a more modern rectifier?
    • Mercury FTDO-M Output Transformer
      4/8/16 taps with 8k primary
    • Mercury Power Transformer
      Don't see any markings on the PT
    • There is a second speaker output
      Is it meant as a DI output or as a parallel external cabinet output?
    Boutique_5E3_differences.png

    Chassis
    5e3_chassis_and tubes.jpg
    5e3_closeup_of_board.jpg

    Speaker outputs
    5e3_speaker_outs.jpg

    100O hm resisters on power tube socket
    5e3_100ohm_on_power_tube.jpg

    4 Pin 83 Rectifier
    5e3_83_rectifier.jpg
    5e3_recitifer_socket.jpg

    Transformers
    5e3_output_transformer.jpg
    5e3_power_transformer.jpg
     
    Last edited: Apr 16, 2019
  2. Lynxtrap

    Lynxtrap Tele-Holic

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    None of that makes any real difference. The voltage rating of the caps tells you how much voltage they can handle, makes no difference to the performance of the caps. The higher, the safer.
    That is a so called artificial center tap for the heater circuit, the transformer obviously doesn't have a center tap for the heater winding.
    Connecting the resistors to the cathode is a bit odd. They need to be connected to ground, wherever it's convenient and safe. Later on, Fender often grounded them at the pilot lamp, as the lamp was fed by the heater circuit.

    Using resistors as fuses is not a good idea. But yes, older amps seldom have fuses on the heater circuit, and the old low wattage carbon comp resistors basically function as fuses. The smell is horrendous and there might be flames.

    Power Transformer: If it's unmarked, to know how it performs you need to measure voltages. Don't do this if you don't know how to do it.
     
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  3. Uncle Daddy

    Uncle Daddy Tele-Holic

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    The whole thing looks well put together, but normally the filter caps are separated between the 2nd and 3rd cap (from the left) to reduce the chance of hum. I'd like to see a bit more distance between the ground bus and the board mounting nut above the filter caps.

    How does it sound? The stock Deluxe is a firm favourite for modding, most of which improve the tone but make it less like a 50's woody sound. Depends on what you like.
     
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  4. bblumentritt

    bblumentritt Tele-Afflicted Platinum Supporter

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    • Bypass caps are 22uf 50V instead of 25uf 25V
      That's OK. Probably what the builder had available. There's very little real-world sonic difference between a 22µF and 25µF cathode bypass cap. The 50V thing... well, I prefer 25V, but the 50V won't hurt. There's less than 2V on that cap.
    • Filter caps are 22uf 500V instead of 16uf 450V
      Not sure what these differences would cause. Better power supply filtering and a slightly "tighter" response.
    • Coupling caps are same values, but with 600V-630V instead of 200V-400V.
      This seems like it would be of no consequence. Better, actually.
    • One "dropping" resister is 5100 instead of 5000.
      This seems like it would be of no consequence. Correct. 5100Ω is a standard value.
    • Bright cap is .00056 instead of .0005
      This seems like it would be of no consequence. Correct.
    • 2 100Ohm resisters added to V4 (the last power tube) from pin 2 (filament) and pin 7 (filament) to pin 8 (cathode)
      I found someone said this was to reduce hum and it could act as a fuse if there was a failure. The answer is two-fold. 1) the two 100Ω resistors form an artificial center tap to the 6.33VAC heater supply. 2) "Grounding" them to the cathode elevates the heaters to the voltage of the power tube cathode (perhaps 20-30V depending on the cathode resistor. This is to reduce hum, and item 2 is often employed on amps with cathode follower tone stack drivers, which are not found on a 5E3 circuit as built by Fender.
    • 4 pin #83 Mercury Vapor Rectifier
      I don't see a key or pin numbers on the tube, do the pins have to go in a certain way?
      Does using this rectifier add something special to the tone as I was wondering what the point of using it would be seeing as there is a risk of mercury poisoning and environmental hazard if the tube breaks. To be safe should it be replaced?
      I have seen solid state rectifier replacement though couldn't the circuit be changed to accomodate a more modern rectifier?
      The 83 rectifier was probably chosen because it drops a constant 13V throught the AC cycle, whereas the standard 5Y3 rectifier drops about 50-60V and exhibit "sag" when it can't keep up with high demand during heavy amplification. The pins are different; you would have to change the socket and wiring to use a 5Y3 or 5AR4.
    • Mercury FTDO-M Output Transformer
      4/8/16 taps with 8k primary. That's not a problem. The 5E3 is 8kΩ/8Ω, and you have additional options for speakers.
    • Mercury Power Transformer
      Don't see any markings on the PT. Mercury doesn't publish specs to my knowledge.
    • There is a second speaker output. Are they marked? It's hard to tell from the photo, but it appears you have green and red on the (unused)switched jack and green only on the other. Perhaps one is 8Ω and the other 4Ω. If you can, locate an wiring diagram for the OT, and determine which wire is which. I think that using the switched jack disconnects the other one.
    I hope this helps.
     
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  5. dragonfly66

    dragonfly66 Friend of Leo's Silver Supporter

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    It sounds good, but I think I want a different speaker. There is Greenback in it. Lows are muddy at low volumes, but at higher volumes the speaker sounds more even, though it still has quite a bit of bass that isn't quite as tight as I would want. That is fine when playing alone, but won't be good when playing with my band. I need to be at 6-7 to get a clean/dirty signal from the low output P90s I have in my guitar. The amp is loud at that point, but not terrible (i.e. I can still hear myself if I singing very loudly without a mic) . I have some other 12" and 15" speakers to try. It is in a Kerry Wright 15" cabinet with a convertor ring for a 12".

    5e3_kerry_wright.jpg

    There is static at very high volumes, when I hit an A note the static is consistently noticeable. I haven't gone through the amp yet to figure it out, I'll get to that this weekend. The #1 Bright input doesn't seem to be right. All inputs I plug into but that one is loud. With nothing plugged it is quiet it makes soft popping sounds. At one point it got dead quiet after one pop. With the guitar plugged in I get the hum, but the guitar has P90s so I think that is expected.

    This amp definitely needs some attention. I did the tap test and the inputs create a lot of the static and will need cleaning and burnishing. There is noise from the rectifier and V4 power tube. The rectifier and power tube sockets need some retensioning. I'm hoping with a little clean up the amp will be right as rain.

    I want to gig this amp so after I get it all set I'll be going through speakers. Plenty of threads on here that I've gone through with recommendations on 5E3 speakers, namely the Weber 12A125A. I don't have that one of those so I will be trying the ones I have first.

    12"
    Celestion Gold
    Eminence Texas Heat
    Celestion Creamback H75
    Celestion Lil' Texas
    Celestion G12-35XC 90th Anniversary LTD

    The 16 Ohm tap on the OT looks like it was cut off which is too bad because I have some nice 16 Ohm speakers that I could try. I do have the Weber Z-Matcher I could use to try out.

    Celestion Gold
    Celestion V30
    Celestion Cream Alnico
    WGS Blackhawk HP


    15"
    Celestion Fullback G15V -100
    60's JBL D130F
    Weber DT-15
    Weber Neo
    Eminence Big Ben
     
    Last edited: Apr 16, 2019
  6. jhundt

    jhundt Doctor of Teleocity

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    that connection is called an elevated filament supply. The filaments (heaters) are receiving the proper 6 volts, but it is not referenced to ground; it is a technique to minimize noise. I have done it on a few amps. I don't know how much difference it really makes, but it is recommended by some knowledgeable sources.
     
  7. Lynxtrap

    Lynxtrap Tele-Holic

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    Yes, I should have thought of that...
     
  8. schmee

    schmee Friend of Leo's

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    I dont see much that would make a big difference, I'll just comment on a couple.
    • Filter caps are 22uf 500V instead of 16uf 450V, Not uncommon replacement. Sometimes it's easier to get 20-22uf Elytics at 500v than finding 16uf at 500 V. people want the higher voltage often. I was surprised in trying Filters up to 44uf in Princeton Reverbs that I heard no difference.
    • Coupling caps are same values, but with 600V-630V instead of 200V-400V.
      This seems like it would be of no consequence. Todays caps are mostly rated higher anyway.
    • One "dropping" resister is 5100 instead of 5000.
      no consequence.
    • Bright cap is .00056 instead of .0005
      no consequence.
    • There is a second speaker outpuIs it meant as a DI output or as a parallel external cabinet output? Depends on the wiring. Can't tell.
     
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  9. dragonfly66

    dragonfly66 Friend of Leo's Silver Supporter

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    Thanks all for your input.

    I'm checking on the speaker outputs. Have to get info on the OT and get details of how it is connected.
     
  10. dragonfly66

    dragonfly66 Friend of Leo's Silver Supporter

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    The speaker outputs are not marked, however I did get the tap info from Mercury.
    ftdo-m_ot_transformer.png
    [​IMG]

    So we know the colors, orange = 4 and green = 8. But not sure if this is a parallel situation where if I plug in a second 8 ohm speaker it would produce 4 ohms or like you suggested that plugging into the open output would disconnect the other output, meaning if I were to use the open output I would need to use a 4 ohm speaker.

    The 16 ohm tap was cut and taped.
    fullsizeoutput_23a.jpeg
    fullsizeoutput_23b.jpeg

    I took the chassis out and was able to determine the power supply, Mercury ToneClone FTDP-50.
    fullsizeoutput_240.jpeg
     
    Last edited: Apr 17, 2019
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