All Metal Octal

Discussion in 'Shock Brother's DIY Amps' started by shortcircuit, Nov 30, 2019.

  1. shortcircuit

    shortcircuit Tele-Meister

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    Criminy, the solder from my last built hasn't fully cooled, and here I am with another one. Winter's coming and I need something to keep me warm. A nice and hot all metal tube amp should do the trick.

    Heater wiring and power supply done.

    Heater-PS.jpg

    3 preamp tubes, 1 phase inverter, and a pair of output tubes, in addition to the rectifier, all metal cased. No top caps.

    I'll post the schematic when you guys and gals guess the tubes.
     
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  2. shortcircuit

    shortcircuit Tele-Meister

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    Almost done. Need to install the transformers. I'm out of #8 nuts and bolts, so it's a trip to the hardware store tomorrow.

    Almost Done.jpg

    If you guys thought laced ground bus was hot stuff, check this out:

    Braided.jpg

    That's right, braided 24 AWG copper wires connecting the cathodes of the output tubes. The three strand braided conduit will balance out even the most mismatched tubes. The Tufnel-St. Hubbins effect clearly states it!
     
    Last edited: Dec 2, 2019
  3. Peegoo

    Peegoo Tele-Holic

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    That is nice tidy work right there!
     
  4. BigDaddy23

    BigDaddy23 Tele-Meister

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    OMG!!
     
  5. Nickfl

    Nickfl Tele-Afflicted

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    Metal octals huh? I'll give it a shot, lets start with the obvious candidates: 6sj7, 6sc7, 6sq7?

    6f6 output?

    Or are we taking something more obscure, Maybe some TV tubes?
     
  6. printer2

    printer2 Poster Extraordinaire

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    Metal 6V6's are plenty enough. I have a handful of 6F6's all glass, no metal.
     
  7. shortcircuit

    shortcircuit Tele-Meister

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    6SJ7 input, then 2 high mu triodes (no diodes in them), 6SC7 for the phase inverter, and a pair of 6V6's.

    A bit more on the Tufnel-St. Hubbins effect for the uninitiated. In addition to being members of one of the greatest rock band ever existed, Tufnel and St. Hubbins also did some ground-breaking work in amplifier technology. The legend goes that Tufnel, unsatisfied with "11", was searching for the mythical "12", when several pubic hairs from groupies fell from his head onto the exposed circuit of his amplifier. The tangled hair strands made contact with high voltage and was instantly carbonized. Fearing a short circuit, he blew on the filaments, and they drifted onto the cathodes of the output tubes, where briefly, the voices of angels sounded from the amplifier, and Tufnel found the elusive "12". Alas, the effect was short-lived as the delicate strands vaporized in an instant. Tufnel and St. Hubbins experimented for years, trying to replicate the ephemeral miracle, eventually finding that a braided wire came close, and they were able to achieve "11 1/3". The effect was attributed to magic. No mention was made of Smalls, who apparently spent that time stuffing cucumbers down his trousers.
     
    Last edited: Dec 3, 2019
  8. muchxs

    muchxs Doctor of Teleocity

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    Like me, the legendary Mr. Tufnel was blissfully unaware of Fender tweed amps in the '70s and '80s. I never saw or heard them. Part of it was living way out in the boonies, the other part of it was Boyd's Music was an hour and a half away. We only went to town once or twice a year. Boyd's sold new Fender and Peavey amps. It never dawned on me that early Peaveys that looked like Fender tweeds looked like anything other than Peaveys.

    Anyway, Fender tweeds all go up to "12".

    They sound like angels with hoarse throats.
     
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  9. shortcircuit

    shortcircuit Tele-Meister

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    Heavy Metal SH.png

    All done. Everything wrapped up except for the pot for the cathode of the first triode. I had initially drew it up with a 25K linear pot 'cause that's what I had on hand, but a log pot should work a lot better. I got one ordered.

    06 Finished.jpg

    07 Metal Tubes.jpg

    This is the quietest amp that I'd built so far. Credit the metal tubes--all the pin 1's are grounded. All the tubes are somewhat microphonic, but as a separate unit, I have no problems with feedback and oscillations. With the first triode bypassed, there's a very rich clean tone with the gain turned down. With all the tubes in circuit and the gain and volume turned up, the OD is really raw with the first triode hot, but smooths out nicely as the cathode resistance is increased.

    Oh yeah, the "SH" stands for space heater.:D
     
    Last edited: Dec 4, 2019
    muscmp, Asmith, FRANKENJAG and 8 others like this.
  10. Mexitele Blues

    Mexitele Blues Tele-Holic

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    Well now you're just showing off!
     
  11. MickM

    MickM Friend of Leo's Ad Free Member

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    Good looking work. Can you do a sound clip?
     
  12. Teleguy61

    Teleguy61 Friend of Leo's

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    No **** man!
    You knew Boyd, the Cheeseman?
    Ha!
    Lived in northern VT in the 70s, Boyd's was much hipper than Peterson's, though I did make some good deals with Alden Peterson, and he was the head of the local AFM, and I did make good use MPTF money to stay alive.
    Boyd was kind of an okay guy, after all, right there at the corner of Main and Winooski.
     
  13. shortcircuit

    shortcircuit Tele-Meister

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    I need to get on the ball. The only recording equipment I had was an old Fostex 4-tracker and a Shure microphone of unknown provenance, both from the early 90's. I had been using the Fostex as a sound input device, connected to the audio input of my computer, but it gave up the ghost a while back. I need to get an USB audio interface.
     
  14. muchxs

    muchxs Doctor of Teleocity

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    I still have my Peavey Artist I bought brand spankin' new at Boyd's.

    I keep it around to remind me not to bring home every stray Classic and Deuce I find. They made a lot of 'em.

    Although a Classic with its phasor would be cool...

    So would a Gorilla with its built in chorus.

    :D :D :D

    Spent far more time at CBGB than I ever did at Nectar's...

    CBGB is all gone. Nectar's is still there.

    Boyd's is long gone.
     
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  15. Teleguy61

    Teleguy61 Friend of Leo's

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    Many, many gigs at Nector's back then.
    If you were a musician, Nector would feed you the biggest hot turkey or ham sandwich you ever had in your life.
    Yes, yes.
    Many gigs at 101 Main St, that became RW Hunt's, had a sit down gig at the (then) Radisson.
    Yes yes.
    Them were days.
     
  16. muchxs

    muchxs Doctor of Teleocity

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    We could swap Burlington stories all day even though I lived north of Saint Johbnsbury back then. We only made it into town once or twice a year.

    Allegedly similar lifestyle further south:



    I could tell a few Saint Johnsbury stories. G.G. Allin went to Concord High School a town or two up Route 2.

    Saint Grimsbury. I highly recommend it as a vacation destination. The perennially dysfunctional economy is showing through the pretty scenery if you know what you're lookin' at. It will give you a fresh appreciation of where you came from.

    Got a VIP All Access Pass to the Jerry Jam last year. No charge. I'm a VIP! :cool: Everyone backstage was from Littleton. Told 'em I'm from Saint Johnsbury. G.G. is the common ground so that's who and what we talked about.


    Still have the Stratocaster I bought from Advance Music in Burlington. Flew in from Oakland not having slept since days ago somewhere in Nevada. My ride wanted to stop at Adavnce 'cuz he drove all the way from Saint Grimsbury. I was groggy and sleep deprived but that Stratocaster just called out to me. I didn't want to make any bad decisions so I slept on it. Drove all the way back the next day.



    Hey! Looks like Music Go Round in Natick. I was there yesterday.
     
    Last edited: Dec 6, 2019 at 11:31 AM
  17. Teleguy61

    Teleguy61 Friend of Leo's

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    All cool, and true.
    Yow! Getting close. I'm in Framingham.
    Be well my friend!
     
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