Introducing the NeoLeo! (A modern 5e3)

Discussion in 'Shock Brother's DIY Amps' started by BobSmith, Aug 1, 2019.

  1. BobSmith

    BobSmith Tele-Meister

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    Guys, I just got this off the FedX truck today. Man, it’s a beaut!

    I’ve been wanting a black tolex amp for some time, but you can’t get them anywhere! Well, that’s not true...Mojotone will make a cab reluctantly (and there’s one of those coming to me too)... and a couple of boutique builders (milkman and some others) offer them. But this is my first!

    I asked a custom builder online (who made my first 5e3 head combo, and did an awesome job, see my profile pic) to source some black/charcoal tolex for me and he came up with this. I am totally impressed by how it came out.

    You may have seen some of my other threads chronicling my two 5e3 builds trying to decide on which caps to go with, well this 3rd one (set to get started in a few weeks) will take the best of that build and modernize the resistors (a departure from carbon comps everywhere) and go with Dale resistors instead in all but a few select locations (where I will place some NOS carbon comps). The aim is to keep the tone, lower the noise floor, and raise reliability. Along with that modernization, I am ditching the cloth covered wires, and going with modern PVC jacketed wiring (sourced from valvestorm which is where I got my JTM45 parts from and thought was top notch).

    So that’s the concept, same basic design, with a modern twist. 30 seconds after pulling the head cab out of the shipping box, I came up with the name NeoLeo. I haven’t named a thing else, but this one feels right to me.

    Pictures to follow. And ask yourself, can anything top a tweed?

    More to come!
     

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  2. Robear

    Robear TDPRI Member Ad Free Member

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    Man oh man that is sweet looking. What a great update of a classic look. I saw the material swatch on Mojotone’s site and wondered what it would look like on a box. Thanks for sharing.
     
  3. BobSmith

    BobSmith Tele-Meister

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    This one didn’t come from Mojotone, but from a guy who goes by a few names online (I believe he supplies a few boutique builders.) Currently he selling under “Master built tweeds” on Reverb. His stuff is really top notch. Perfect corners. Ships fast too.

    I do have a Mojotone coming with blackout lacquered tweed (their version), but I’m still waiting for that. Just for fun I ordered an extra baffle with small cane weave. It’s the same as Two Rock Burnside. I’ll post a comparison when it arrives.
     
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  4. Robear

    Robear TDPRI Member Ad Free Member

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    Ah. I didn’t quite catch that. I’m definitely looking forward to your report. Side by side comparison can’t be beat!
     
  5. BobSmith

    BobSmith Tele-Meister

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    Still working on my other 5e3 (yellow jupiter), but another cosmetic flavor arrived today. So I’m compelled to post.

    Black one is Mojotone lacquered “Blackout” tolex. I asked for black fender style grill cloth, but it came in oxblood instead (looks like a Milkman Black Tweed). I wonder if it’s worth the trouble to have them correct it. The spare grill/baffle is small cane weave (looks like a Two Rock Burnside).

    Thoughts? I think it’s pretty sharp!
     

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  6. BobSmith

    BobSmith Tele-Meister

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    I finally prepped the edges of the Mojotone small cane grill with a thin layer of epoxy. They were just stapled, and it looked like easy to fray. The epoxy helps the ends so they won’t go anywhere. I also dabbed a bit on top where I needed to drill the mounting holes.

    Looks pretty good. The grill was supposed to come in all black like the charcoal one below it, but I wonder if that’s too black... cane definitely looks good, and the oxblood before it wasn’t that bad, so maybe it’s not worth the trouble of exchanging.
     

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  7. tele_pathic

    tele_pathic Friend of Leo's

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    Man, those look sharp. I also want a black tweed amp like what Milkman offers. I have a BJ4 and was thinking of putting in one of the Mojotone blacked out tweeds, but I assumed the grill cloth was black too, not oxblood. I don’t know if I would send it back, but I would prefer the black grill cloth, if I wan’t a totally blacked out amp. I would like the blacked out look, then murdered out like my Dodge Challenger (black on black with red highlights, like the faceplate and strap hardware, red screws. If I couldn’t get a red powder-coat faceplate, I’d at least get red chicken head knobs).
     
  8. BobSmith

    BobSmith Tele-Meister

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    They have a cool blackout model sold as a completed 5e3, including black powder coated faceplate, and more of a white speckled grill, not black. Unfortunately they don’t individually sell the appointments outside the lacquered black tweed, and even that needs some wrangling to obtain (Grill cloth is not for sale, nor is chassis or handle...I asked). You can ask for any other grill you like. I got a spare grill by itself so I can change my ‘tude if I want.

    You might like a black powder coated chassis, which there are a few available out there (?chinese but not from Mojotone), with some red chickenhead knobs. Kinda “Evil Twin” look.
     
  9. BobSmith

    BobSmith Tele-Meister

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    Ok, starting to move forward on component choices here:

    The battle for Red vs Yellow Jupiter is having a ceasefire while articles of war are drawn (more fun than just saying I’m waiting for my Headbone to test them). More on this later...

    Now for the open and inquisitive minds...
    Spread across a few of my threads I’ve had some great discussions with the well-respected builders in this community and I am ready to challenge the mystical powers of mojo by taking out some sacred carbon composition tone generators in favor of high performance (but purportedly “sterile”) Metal film Dale resistors. <gasp!>

    I’ve been pouring thru old posts, reading in other sources and observing many “gut shots” of the boutique builders out there and while there is some theoretical consensus on where is good to replacement, in actual fact, it’s a total free-for-all out there! The collective wisdom seems to agree on several practical changes:

    1. Use of CC in the input stage should be avoided (voltage too low to have large effect and high possibility of injecting noise prior to amplification)
    2. Cathode resistors would likely not benefit from tonal enhancement (decoupled by capacitor)
    3. Phase inverter plate and tail loads are theoretically good locations (relatively higher voltage drop)

    As I know this is a hotly debated area of amp building, and by no means am I an expert, I did want to gather some recommendations and opinions on where I go with my next build. I started picking locations to put my Dales and CC (I got plenty of both). Please see my chart below, color coded for type of resistor, I still have some holes to fill as you can see and I’m open to suggestions! Hopefully you are also interested in the outcomes of this, which I would like to share.

    I’ve got a control amp to compare it to (if you’ve seen my other threads), so the results should be interesting!
     

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  10. King Fan

    King Fan Friend of Leo's

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    Heh, I'd guess you’re actually joining the majority of experienced 5e3 builders here in going mostly MF. More than a few go no CC in fact.

    The smartest 5e3 board (and one of the very prettiest) I know was built by the all-seeing @D'tar ... note the highly select CCs... and the vintage-perfect Brown Devil.

    [​IMG]

    I opted to go slightly more liberal but still in keeping with what I *think* R.G. Keen suggests.

    [​IMG]

    My theory on sockets is they’re hot. I did use 1/2w Dales for the elevated artificial CT, but they ended up bent well outside the radius of the socket. For the 1.5K grid stoppers right over the socket I used MO, and for the tough job of my (added) 470R screen resistors I used ”3W reduced mass wire wound resistors” — said to be very cook-proof.

    [​IMG]



    Sent from my iPad using Tapatalk
     
    Last edited: Aug 26, 2019
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  11. BobSmith

    BobSmith Tele-Meister

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    Thanks King Fan! As always, some beautiful examples here to illustrate the exact range I’m debating. I’ve seen these gut shots across a few different threads, so I appreciate your consolidating the thoughts here.

    I’m thinking this time I should go with a more austere use of carbon comps to give more comparison to my other build. In reviewing RG Keen’s and Rob Robs postings, I think I’m going to stick with the 2 56k PI plate load and tail resistors (as in D’tar’s lovely build). Either way these should be pretty easy to rework if I want (even in my cramped chassis).

    I also appreciate your bringing up the screen resistors idea... I’m gonna give that some thought, but I’m a little hesitant given I don’t want to introduce too many variables this go-around.

    While I’m admiring your handy work, I’m curious how you did your bus bar. It seems hidden out of sight. Do you have any better shots of it? How do you think the “serviceable” will be if you have to change out components (replace pots, etc)



    So this below is what the resistor plan is...as you can see I also have these crazy 3watt Allen Bradleys in the 56k flavor, but I’m gonna use the 1/2 watt ones instead. (I wonder what a 3 watt version would do, an extra 2.5 watts of Mojo perhaps?)
     

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  12. King Fan

    King Fan Friend of Leo's

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    For sure I endorse your plan to keep the rest of this MF-rich build the same as your existing cap-test-bed schemes. We gotta change the variables one at a time, right?

    My bus bar was gonna float just above the board, as it did in my 6G2, but (oops) I did my test fit with the lo jacks rotated, tip about 10 o'clock, and only at the end of the build found that my 'as built' jacks had the tip down and badly fouling the bus. So I floated it in front of the board instead. Access won't be harder, I think; it's actually in a pretty empty space.

    As initially built:

    IMG_0037.jpg

    As revised:

    IMG_0042 (1).jpg
     
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  13. D'tar

    D'tar Friend of Leo's

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    MR. KEEN,

    "4. resistor power rating should be the minimum needed to work for a reasonable life in the circuit to maximize resistor distortion. Maybe a good guideline is that the dissipation should be selected to be as close to two times the average dissipation as possible.
    5. as a corollary to the power guideline, we should be prepared to replace CC's every few years as the life at high temp makes them drift and get noisy(-er)."


    "I" think this is key to the "MOJO" of the CC. Yes they are good in other places for other reasons but in the signal path I would use them(1/2W) modestly and in the positions your are considering.

    IMHO... Neo Leo would still be as moneywise as ever and using the best components at the lowest price! Dales are super expensive compared to a carbon film which may be the composition of choice today for mass produced circuits. Although I love my 5e3 and can't imagine it sounding any better due to resistor type!

    What coupling caps are going into this build. How about some zoso blues? Fender? Your gonna need more amps!
    upload_2019-8-27_14-9-31.png
    [​IMG]
     
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  14. BobSmith

    BobSmith Tele-Meister

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    Thanks! Appreciate the input, and highly regarded quoted sections too!

    I should have my Headbone switcher soon to face-off Yellow vs Red Jupiter’s. I can’t promise, but will try to make some recordings. I have an extra set of each in my box-o-parts, ready to go once I make up my mind.

    I haven’t seen these fenders before either in a store or amp for that matter. I also noticed they are no longer carried. I’d expect Fender would do these right, but that’s all a guess. I initially thought I’d try the Jupiter’s because I have seen (and heard) them in them in “mass produced” (relative to me) boutique amps such as Milkman.
     
  15. BobSmith

    BobSmith Tele-Meister

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    I noticed in the above pictures that the 56k PI tail resistor mysteriously morphed into a carbon comp. Spontaneous carbustion?

    I’m guessing you did that for a reason, any takes on the difference (or lack of)?

    I really like the way you did the ground bus bar. Your second version really turned out good.
     
  16. D'tar

    D'tar Friend of Leo's

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    I believe they are in the new JB Twin and likely other hand wired amps(just guessing here) Maybe they will become available to the public again who knows. All I can find now are lower voltage guitar caps or price jacked ones on ebay etc. Who knows, they may be dressed up mallory caps ;-)

    Looking forward to hearing your tone cap shootout!
     
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  17. King Fan

    King Fan Friend of Leo's

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    Thanks. As for the tail resistor (spontaneous carbustion, good one!), I’m not smart enough to know if it meets Mr. Keen's criteria, but I decided I’d follow the example set by @D'tar. As you can tell, whenever possible I try to just surf on his knowledge.

    The V1 plate resistors were a stickier choice, since that's a potentially noisy location and in fact one experts may avoid for CC. But I’d tried them there on my first 5e3 and didn’t note any extra hiss, and *think* they meet Keen criteria there, and also that they’re outside my switchable NFB loop, so decided I’d go there too. Don’t trust my reasoning here, but the amp sounds great.




    Sent from my iPad using Tapatalk
     
  18. BobSmith

    BobSmith Tele-Meister

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    Took a break, now I’m back!

    All components are present, measured and accounted for.

    I got me a cheap craftsman drill press on sale at Sears (place is going bust!) so I was able to make my chassis holes at home. No peeling this time! Finally Mojotone fixed their supplier problems it seems.

    I made some custom “gauges” from some worn out GC picks. They really helped me make sure I would get the spacing of the standoffs and turret board exactly to match my other 2 5e3s. I just trimmed the picks with some diag cutters until it matched the spacing I needed, and left a little to hold on to. (Turns out to be 0.39” which is basically 10mm). I etched the size on them and will keep them for the future.

    I got my resistor board together as well. No need to write down the component values for the Dales. They were all Spot on! (In fact they were so consistent, I now have more faith in my DMV telling the truth.)

    ok, on to the board!
     

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  19. BobSmith

    BobSmith Tele-Meister

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    Dry fitted all components and prepared wire index.

    I’m using topcoat from Valvestorm. I’ve used it before and found it very easy to work with. All 22awg which is standard for 5e3, except the heater wire and grounds will be 18awg.

    The colors will be anything but standard (just because it’s what I could find).
    Heater will be red and black
    B+ is red
    High voltage to tubes will be orange
    Signal and cathodes are white
    Grounds are black
    (Of course the transformers have their own colors)
     

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  20. muchxs

    muchxs Doctor of Teleocity

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    I go CC according to my mood and availability. For a certain period I was using CC and orange drops while scrounging period correct "cloth" wire. Then I switched to Mallorys with my CC. I recently did a few builds where 1 watt carbon films are "correct".

    I recently built one that tapped my stash of 1 watt carbon films except for the 68ks. I know I bought a hundred 68k carbon films. Try and find 'em.

    My amps are silent. No noise, no hum even with the volume dimed.



    I can use whatever I want including original Astrons or Phillips "mustard" caps. I usually use good old Mallory 150s
     
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