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New 5E3 build from Mable Audio kit

Discussion in 'Shock Brother's DIY Amps' started by tombob, Dec 14, 2017.

  1. tombob

    tombob Tele-Holic

    Age:
    45
    573
    Jun 25, 2010
    Sonora, TX
    I received the kit today ($220 with tubes & trannies plus shipping) and just started looking through it and sorting out parts. The parts quality looks great (I'm convinced these are made by the same manufacturer as the kits Weber sells, minus the cab and speaker(s)) there's only a few different things about it than I expected.
    It has a 10w 240r cathode bias resistor, all three filter caps are 22uf, which isn't too unusual for a modern kit, it came with a Shuguang 5ar4 rectifier tube but it looks like a more like a 5y3 than a NOS or Russian 5ar4 and the power switch was a dual pole which they hook both sides of the power cord to but I figured that had something to do with the fact they also sell the kit with a 240v PT. I have a single pole switch I plan to use and just hook the black input on the PT direct to the power cord like most kits do.
    Tomorrow I will take pictures of everything and put on here and try to show it before I start asking questions and becoming aggravating :)
     
    OneHenry and jiri_c like this.

  2. jhundt

    jhundt Doctor of Teleocity

    Age:
    64
    Mar 23, 2003
    Netherlands
    the double-pole switch is a standard safety feature on almost all amps built today. It is a requirement on amps sold in Europe. I don't know if that is true in the USA, but I know that Fender uses this type of switch in their re-issue amps. It is not something that is only used on 240v circuits.

    Many kits are based on designs from the 50s and 60s. In the interest of being a 100% authentic reproductions of an original design, the kit often comes with a single-pole switch - just like the original. That will still work, just like the original did. But the amp will still have the same safety vulnerability as the original did, too.

    The old amps had safety issues around the AC power input. Many came without grounded plugs, because grounded circuits were not yet common (or required) in buildings. Many had non-polarized two-prong AC plugs and ground-reverse switches which could either save you from electrocution, or cause you to be electrocuted, depending on which way you set the switch.

    These days, with polarized and grounded AC and double-pole on/off switches these dangers are mostly eliminated. And many old, original amps have been modified to include these features, as these do not affect the performance of the amp in any way, and can generally be done without harming or changing the appearance of the old amp.

    So, I would recommend that you use the switch as it is intended. It will not make your project any more difficult, or change anything in the sound. And you will have an amp that meets current safety requirements.

    BTW - I have several old amps that are still wired the old way, and I have built amps and kits that do NOT have the double-pole switch. So yes, that will work. But if I had the parts in front of me, I would choose for the safer version.
     

  3. ecoast

    ecoast Tele-Meister

    478
    Jan 6, 2017
    NWNJ
    great value; I bought/built similar and zero quality issues
     

  4. tombob

    tombob Tele-Holic

    Age:
    45
    573
    Jun 25, 2010
    Sonora, TX
    I guess I've got this look stuck in my head from looking at older amps I've worked on. It crossed my mind to use a couple of Carling switches I have in it but I'm going to hang on to them in case I need to replace a switch in one of my old amps so it'll match the others. I don't really get hung up on "vintage correct" on a new build so I don't know why I had the reaction I did to the double pole switch. Some of the amateur wired stages I've played on make me miss the ground switches on amps though, especially ones with half a dozen neon signs on the back wall and every wall socket wired a different polarity. Outdoor stages seem to be notorious for bad wiring.
    This kit doesn't have the brass plate behind the input jacks/pots so I'm going to add a ground bus. Last night I wasn't sleepy so I installed the tube sockets, pots, jacks, switches and misc. I only tightened the tube sockets and left the jacks/pots finger tight so I can move them if I need to. I'll take my nut driver and tighten everything once I get them wired.
    I haven't had a chance to do anything today but when I do I'll take some pics of the kit/parts and post on here. I'm very happy with the kits from Mable, The 5f6a 2x12 amp in my avatar was built from Mable parts and it's an amazing amp.
     

  5. tombob

    tombob Tele-Holic

    Age:
    45
    573
    Jun 25, 2010
    Sonora, TX
    I was going to ask if anyone else has gotten a kit that included 2 diodes? The only reason I can see they could have sent them with a 5e3 was to use as backups on the rectifier tube (which I really like the idea of) but I was a little surprised they included them in the kit.
     

  6. FenderLover

    FenderLover Friend of Leo's

    Jun 11, 2009
    Minnesota
    Extra parts are nice. It only cost them $0.05 each to cut them off of their reel, but the customer satisfaction goes a lot farther. Looking forward to your build.
     

  7. tombob

    tombob Tele-Holic

    Age:
    45
    573
    Jun 25, 2010
    Sonora, TX
    Here's a few phone pics, they're not great but you get the idea. I added a ground to the board to make sure everything is well grounded. It's not the prettiest thing in the world adding one on top image.jpeg image.jpeg image.jpeg image.jpeg image.jpeg but I had the cap already so I added a extra cap to the first (reservoir) filter cap to bring it up to 30uf for a tighter bass and to keep everything quiet.
     
    dr_tom likes this.

  8. FenderLover

    FenderLover Friend of Leo's

    Jun 11, 2009
    Minnesota
    Notice V1 pin 8 in post #7. if you wire it off of pin 3, you won't have to jump over the top of pin 1 and pin 2 plate/grid wires.
     
    tombob likes this.

  9. tombob

    tombob Tele-Holic

    Age:
    45
    573
    Jun 25, 2010
    Sonora, TX
    I wanted to get some others opinion on the standby switch. I've heard that with new, higher voltage caps they aren't necessarily. I've even read they can do more harm than good. What do all of you think about this? I was thinking if I didn't use a standby and moved the power switch down to the end I could add a mid cut pot in the power switch position. I don't want to do away with the tone but I thought it might be handy. I think I would put a switch between it and the volume to completely remove it from the circuit when not used but it might be a cool tone shaping tool to have available.
     

  10. clintj

    clintj Friend of Leo's

    Apr 4, 2015
    Idaho
    Standby switches are unnecessarily hard on rectifier tubes, and not needed. It does make a convenient spot for a mute switch or similar, though.
     

  11. jhundt

    jhundt Doctor of Teleocity

    Age:
    64
    Mar 23, 2003
    Netherlands
    are you thinking about the "Framus midrange control" as described by Merlin Blencow? That is a very nice thing, I put one on a homebuilt Matchless Spitfire-type amp, and I love it.
     

  12. FenderLover

    FenderLover Friend of Leo's

    Jun 11, 2009
    Minnesota
    I like the mid control too, but haven't used it on a 5E3 yet. I don't go out of my way to use a standby switch either, so the extra hole can help you work out the location for new controls. If you still want the standby function, you can use the Carling progressive power switch that has OFF-STDBY-ON. I think MojoTone sells them. Also, for as many times as you will change fuses, the fuse can be relocated on the back corner opposite the power cord. Another idea may be to use a concentric pot for the two volume controls. That gives you vol/vol - Mid - Tone. Skin that cat.
     

  13. tombob

    tombob Tele-Holic

    Age:
    45
    573
    Jun 25, 2010
    Sonora, TX
    I've thought about moving the fuse holder too, I figure if you are changing fuses more than rarely you've got bigger problems than where the fuse is at.
    It would be great if the indicator lamp was at end where the ground switch was but the hole for the indicator goes is so big I don't want to put a pot there. I really like the idea of using a concentric pot for both volume controls but I already have everything it takes to move the power switch to the ground spot and put a Framus mid control in the power switch spot. I'm not sure how the mid control effects the tone turned down but I want to put a bypass switch on it. I can set it and turn it off and on at the spot I want without looking for it again.
     

  14. tombob

    tombob Tele-Holic

    Age:
    45
    573
    Jun 25, 2010
    Sonora, TX
    I found one thing that makes the 240r cathode resistor make more sense. I thought it was a little low, really the 250r that comes with a lot of kits seems low with modern wall voltage to me. The dropping resistor that's normally 4.7k is a 5.1k so I'm hoping that brings down the power amp B+ enough for the 240r cathode.
     

  15. tombob

    tombob Tele-Holic

    Age:
    45
    573
    Jun 25, 2010
    Sonora, TX
    I've got a question for anyone who has done anything with the Framus Mid Control. I thought I had a 1 meg pot but I can't seem to find one, I do have a 500k push/pull. I wonder about wiring the mid control with it, even if it starts with some cut that's fine since I want to make it where you pull up the knob to engage it. Is there any reason that wouldn't work with the same value capacitors?
     

  16. FenderLover

    FenderLover Friend of Leo's

    Jun 11, 2009
    Minnesota
    I believe 500K should still work fine. It should be a linear pot. It basically pans between the input and output of the filter, and the filter determining components are the two 1n and 100K resistor. Reduce the 100K a little to shift where the center is and change the cut, but no lower than 47K.
     

  17. tombob

    tombob Tele-Holic

    Age:
    45
    573
    Jun 25, 2010
    Sonora, TX
    Thanks FenderLover. That's a great idea to shift the resistor down a little. Putting it on a switched pot I imagine once I find the spot I like I wouldn't change it a lot, just on or off for tweed/mid scooped sounds. I keep my amp behind me when I gig so it's easy enough to walk back a couple of steps and pull up/push down a knob between songs for different sounds.
     

  18. arcticbreaze

    arcticbreaze Tele-Meister

    122
    Aug 2, 2014
    Oamaru NZ
    one of these mable Kits was my first build.
    good iron in it. mine is now SERIOUSLY moded for harmonica, am running 2 6l6's into original ot @ about 25 watts havent cooked it or y 20 watt 10" weber alinco speaker yet.

    you problly will want to swap out the rectifier tube for a genuine 5y3 to get vintage sag.
     

  19. tombob

    tombob Tele-Holic

    Age:
    45
    573
    Jun 25, 2010
    Sonora, TX
    I've been thinking about running Russian 6p3s (not the -E coin based version, which by the way are very good 5881 type tubes) in this one after I get finished with it. The regular 6p3s are closer to the old 6L6G from what I understand, good for around 400v max plate voltage and 19 watts disipation. I'm glad to hear you've been running yours with 6L6s without problems. The trannies are heavy, I know for sure the output transformer is a Deluxe Reverb 25w 6k6 so I was hoping the 6p3s biased 16 watts or so even with the cathode bias should put out 18-20 watts. Those 6p3s are dirt cheap, I wouldn't trust them at 475v like most 6L6 amps run but at $14-$16 a pair it's a cheap experiment in my 5e3 and they should be great at 360-400v.
     

  20. arcticbreaze

    arcticbreaze Tele-Meister

    122
    Aug 2, 2014
    Oamaru NZ
    "Snap" just bought a pair of 6p3s's last month to go in when the old sylvanina's dye (they were secondhand and sick when i put i'm in, not this amps fault) and a pair of the -e's for a new build I'm working on. which uses 5f6a iron also from mable.
     

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