Plexi 50 done!

Discussion in 'Shock Brother's DIY Amps' started by JohnnyCrash, Mar 20, 2009.

  1. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

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    Photos coming soon... though beware, the cab is a gaudy orange covered smallbox (got it on clearance from Mojo and couldn't eBay it after I saw how hideous it was in person).

    The guts are an awful mess on the transformer side. I haven't made spaghetti out of an amp in a while :)

    MODS
    Only mods I've done were to add external bias plugs and pot, as well as a PPIMV Master Volume control on the back panel.

    At first I put in a 1M push-pull switch to cascade (the simple old "one wire mod" switch) the Bright into the Normal. I've since pulled it out.

    SOUND
    I've gotta say - being a child of the '80s/'90s I was huge into the metal (early Metallica, Slayer, Pantera) and punk (NYDolls, The Clash, Sex Pistols, etc) and hard rock (The Cult, Black Crowes, GnR) and I love the sounds of JCM800's... being an even bigger ACDC fan though, I think I've found my #1 amp for Rhythm guitar tracking for my band in this Plexi.

    As a JCM800 freak I worried I wouldn't have enough gain on tap... I was wrong.

    With the PPIMV I can dime the Volume and turn down the actual level at the PI. Musical chiming overdrive (think ACDC's Back in Black album), crunch, sustain, and great pick dynamics.

    The Normal channel (330uF bypass cap) has a gigantic subsonic bass, maybe a bit dark though. The Bright channel is a rocker, even at lower levels where it's still warm and almost overdriven in it's attitude regardless of Volume settings.

    Plexi = my #1 Rhythm amp (and maybe a lot of leads).
    JCM800 = my #1 Lead amp.

    Plexis are just downright awesome. There's a reason they're classics.

    PS (Normal channel):
    1. Any thoughts on brightening that dark Normal channel? I don't want to stray to far afield but that 330uF might be a tad overkill.

    2. Perhaps it'll make a good channel for Bass Guitars?

    3. Perhaps it beefs up the Bright when jumpered (about to try that)?

    Should I tweak the Normal channel, or leave it alone?
     
  2. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

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    Nevermind... I just jumpered the channels and let er rip...

    Holy crap.

    Yesterday when I test drove the amp build for my girlfriend, she was intrigued by the subsonic bass on the Normal channel... makes sense, she's a Bass player! I was not as impressed though - until I jumpered the channels.

    Blending in the jumpered Normal channel to a bass sweetspot makes for a heavy amp.

    I'm leaving the 330uF in there (though I was considering a 250uF, then a 50uF, but not anymore) - it may make a great bass amp channel AND it fattens up the guitar beautifully when jumpered and blended in just right.
     
  3. muchxs

    muchxs Doctor of Teleocity

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    Crashmeister, You're almost as fast as I am! :lol:

    No "One wire"? :(

    Most modern high-gainers are using 4.7 microfarads max on preamp cathodes. We're comparing apples to oranges because yours isn't a modern high gainer but in that context 330 microfarads is excessive, no?

    Stick a Soldano rip 1.2k / 4.7 uf in there and see what you think. There might be some useful values between that and your 820 / 330.

    Are you running a jumper on the inputs? (Beat me to it... never mind!) Thats the massive Plexi tone. Crank your normal channel for the body and drive of your tone, then add your bright channel for edge and sparkle. It tends to wash out at high volume but you're moving furniture by then, anyway. Mixing bright and dark with your master around halfway might get you where you want to be without diddling with your cathodes..
     
  4. Scotty Lonesome

    Scotty Lonesome Tele-Holic

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    Pictures! And, when I can I play my '74 LP deluxe thru it (gain dimed, of course).
    Scotty.
     
  5. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

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    Since I'm a high gain junkie, I thought I'd need a switchable "one-wire mod" too, but after cranking this thing up I realized this old grand-daddy goes FAST and needs no high octane in the preamp.

    Pure, unadulterated, Malcolm and Angus Young, ACDC b@!!$ to the wall - with huge body and a musicallity a JCM800 does not have.

    Jumpered, I prefer cranking the Bright and adding the Normal to taste - a 330uF adds so much body and bass I feel it in my body and through the floor.

    Not only does it do ACDC/The Cult, and GnR tones but I can also get Jimmy Page, Jimi Hendrix, and other classic sounds.

    CLEANS
    The cleans are great - better cleans than my JCM800 by a long shot and comparable to my 5E7/5F4 tweed Fender head clone. Cleans nearly (sorta) as nice as my 40 watt BF Fender Reverb head clone - but lacking the complexity in the sparkle and chime on the top end with a stiffer/blander midrange... which is fine since this aint for very many clean uses anyway :)





    I'll have photos by tonight.

    Anytime you want to drive to Fullerton CA with a 12 pack of beer - you can test drive this beast... any of my amps for that matter (depending on the beer HAHA).

    By the way Scotty... I've been playing my Les Paul Junior Lite through it so far. It has a P-90 in the bridge and a reissue minihumbucker in the neck - not exactly an LP Deluxe, but sorta in the ballpark.

    Which reminds me, I need to plug my '57 RI Les Paul Custom into this monster... even with a MV, my neighbors are not too happy right now... I'll be back (or not - it depends when the cops show up, my hands cramp, or an angry neighbor bangs on the door).


    Edit:
    I just plugged in my '57 RI LP Custom. Awesome sounds. Too awesome for words - I need to fix my computer and post clips.
     
    Last edited: Mar 20, 2009
  6. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

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    PHOTOS!!!



    [​IMG]



    [​IMG]



    DETAILS
    F&T cap cans.
    Illinois onboard Filter and a few bypass caps.
    SoZo coupling caps.
    Metal film resistors.
    Carbon composite plate resistors for the PI, tonestack, and preamp tubes.
    JJ tubes.
    Electro-Harmonix preamp tube in the V1 spot.

    1. I left off the Mains fuse and put in an international PT Voltage selector instead (120, 220, 240).

    2. The AC receptacle has a small fuse holder in it for the Mains fuse.

    3. The PPIMV can be seen in the rear photo as well.
     
  7. Stuco

    Stuco Poster Extraordinaire

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    Cool! I don't think the orange is that bad.
     
  8. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

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    I think if I saw a guy roll up to a gig with that thing, I might question his taste in fashion and music.

    In person it's even uglier.

    It's growing on me though, only because the thing sounds so damn good. I've never built an amp that has grabbed me like this one... it seems to stand out in a good way (though the orange tolex makes it stand out in a bad way).
     
  9. muchxs

    muchxs Doctor of Teleocity

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    I'd be surprised if you didn't get AC/DC, Led Zep, etc. out of that amp.

    I like the orange. I have about half a yard of Marshall orange levant kickin' around. That's left over from an amp that was wild green (neon) on the sides, Marshall orange on the top, bottom and back panels with oxblood (no stripe) grille. Kinda like fruit salad, we got tangarine, cranberry and kiwi innards all on one amp. Or maybe restaurant garbage, orange peels smeared with avocado with a couple tablespoons of pickled beets. I called it an amp with "passive anti-theft features"...

    Apologies to whoever has it now. :lol:

    You need a custom color Marshall 4x12" to go with it. Everyone knows purple amps sound better but custom colors in general sound better than everything else... :lol:
     
  10. TelZilla

    TelZilla Friend of Leo's

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    I bet that is a super cool amp.

    The orange flat kicks as5.
     
  11. Jack Knife

    Jack Knife Friend of Leo's

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    It might shock you to look at initially, but when it cranks up and melts your face, it doesn't matter what it looks like!

    I think it looks great personally!
     
  12. Scotty Lonesome

    Scotty Lonesome Tele-Holic

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    Holy shoot! I love it. Not quite taken with the orange? Lemme think on it.
    :)
    Scotty
     
  13. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

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    I guess it's like kids... sure some of them are ugly, but they're yours, so you love em anyway.

    This thing is glorious. I'm a Viagra commercial everytime I fire it up.

    I'm fine with the black 2x12" - I'm running out of room and 4x12"s are a pain to drag to gigs.
     
  14. Scotty Lonesome

    Scotty Lonesome Tele-Holic

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    Ok, it's DONE. The orange is the shiznit! Is the the "elephant" or "levant" tolex? The only thing it's missing is some white lettering (in the same "cursive" script as the Marshall). Oh, I don't know - how about "Crash"? If it sounds as good as it looks, I wonder if you don't have a little boutique amp building business on your hands?
    :)
    Scotty.
     
  15. Southpaw Tele

    Southpaw Tele Friend of Leo's

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    Thumbs up on the orange. I get tired of the same old color schemes on amps. Well done!
     
  16. Scott McCray

    Scott McCray Tele-Meister

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    Johnny -

    That ORANGE is *Horrible*! :cool:

    Send it over here and I will dispose of it for you! :D

    Seriously - add "Crash" in white Marshall-type script and if she sounds as good as she looks - wow...

    That's a keeper fer sure.

    Scott
     
  17. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

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    I may retolex it.

    I like the idea to have a Marshall style script saying Crash or something...
     
  18. Scott McCray

    Scott McCray Tele-Meister

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    Man!

    Don't re-Tolex it! It looks awesome as is...:cool:

    Scott
     
  19. muchxs

    muchxs Doctor of Teleocity

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    NOOOOOOooooooo!!!!!! :lol:

    You could cut up a "Marshall" script logo, stick parts of it back together maybe on a piece of black FR4 for backing... that gets you "rash".

    Break the "C" off the logo from an old Coupe D'Ville, spray paint it white...

    Or you could change your handle to "JohnnyRash"... :lol:
     
  20. Tim Armstrong

    Tim Armstrong Super Moderator Ad Free Member

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    Johnny, orange is the COOOOOOOOOLEST!

    Anyone can have a black tolex amp. Pah!

    Tim
     
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