Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: sluckey on April 03, 2011, 10:20:26 am
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Don't look if you have a weak stomach!
http://www.modsbydarrel.com/national_6800_guitar_tube_amp/index.html
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At least it is "point-to-point"
/Leevi
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Valco made some funky stuffs.
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Wow! One of the gut shots makes a great screen saver. I could look at that all day.
Schematics anyone?
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That's one of those Gibbs reverb tanks that the Hammond amps use. I guess proper layout wasn't much of a consideration or worry back in the day? Or maybe it's proof that it isn't that big a deal?
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And we spent a lot of time talking about how to prevent hum ! :w2: :w2: :w2: ......................:l2:
Kagliostro
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I wouldnt know where to start looking for a problem if it had one
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I guess I won't be posting gut shots of any of my builds here then. :smiley:
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I guess I won't be posting gut shots of any of my builds here then. :smiley:
Really ? :icon_biggrin:
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Schematics anyone?
Nah. Piece of cake to draw your own! :l2:
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Really ? :icon_biggrin:
Nope. No amp porn from me. They sound great (at least to my ears) but they can't compete with the boutique level stuff that's displayed here.
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How did they even get a soldering iron in there?
How does it even work with out osilating?
Brad :icon_biggrin:
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Oh my goodness thats a busy wiring job. :l2:
Bill
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FWIW - there's Illinois caps in there that still look good. :icon_biggrin:
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Pass the parmesan.
What's the buzzer?
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That's neat work. The larger Webcor tape recorders were much less organized. Before PCBs, tube TVs took the cake.
I wish (not!) that I could take a picture of my house wiring. Even to an old Webcor fixer, it's messy. So messy that last week I turned off a breaker, cut a wire, and heard the breaker snap. Wrong circuit. Just can't be sure where anything goes. Started a long-term project to organize.
At least the last wirer was honest. One of the disconnected wires has written on it "I dont know where this wire goes to!"
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>"I dont know where this wire goes to!"
I love finding things like this. I've left a few note behind myself, especially when you find something really misleading such as a 2 directional feed thru box. If you can't fix it, try to make it safe for the next guy.
I would suspect this is not the highest gain amp in the world + it's dual output. You can break a few more rules as gain goes down.
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i worked on a grestch chet atkins that looked like that - not quite as bad though. it was a 6169. the compliment was called the fury whp's cabinet had 2 x12" and the chet atkis cabinet had 1 x15" and 1 x12".
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My uncle job was about methane pipeline protection against stray currents
so his job was to build or fix some units along to the pipeline that give a little voltage to the pipe to prevent it to be perforated,
there was one of that units that don't want to do his job and many technical worked for many weeks to try to fix it
my uncle fixed it in 3 days
he removed all the wires inside the unit and rebuild each connection, that was the only way to answer the question "I dont know where this wire goes to!"
Kagliostro
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That's neat work. The larger Webcor tape recorders were much less organized. Before PCBs, tube TVs took the cake.
I wish (not!) that I could take a picture of my house wiring. Even to an old Webcor fixer, it's messy. So messy that last week I turned off a breaker, cut a wire, and heard the breaker snap. Wrong circuit. Just can't be sure where anything goes. Started a long-term project to organize.
At least the last wirer was honest. One of the disconnected wires has written on it "I dont know where this wire goes to!"
Sounds like Fox & Hound time...
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Lots of nice pic's. I cant find them now! I wanted to add a part that was missing!
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http://www.modsbydarrel.com/national_6800_guitar_tube_amp/0%20290.html
One of the niftier 404 pages I've seen though. :worthy1:
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The link was tied to this ebay auction (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&rt=nc&nma=true&item=110667277955&si=%252BgX030GSbhos6g1HhHwPW59S4Oc%253D&viewitem=&sspagename=). Nothing lasts forever. :grin:
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I always called that "rat's nest wiring" :icon_biggrin: My old National, isn't nearly that bad, since it's only 5 tubes! I've built 6 clones of it, but only one with that wiring mess. Rolled the schematic over into turret board layouts for the rest, which really spoils us for changing parts and finding problems.
That one in the pics would be fun to work on !
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i have a philips AG9015. the cool thing about this rats nest is that the service manual has a layout drawing, with all those wires!
http://frank.pocnet.net/instruments/Philips/AG9015/AG9015.pdf (scroll through the pdf to find it)
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I know poeple throw around the term LOL pretty loosely but that last page really made me laugh out loud.
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That is one of the busist ones I've seen. Kinda resembles the mod I just did on my Revere 5DC3 or in the same spirit. Hay! this is a tube amp tradition we got to keep going now :laugh:
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At least you can see and get at everything.
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If the National 6800 was called Spaghetti Amp, how we can call this Zenith chassis, ratatouille ?
(http://i.imgur.com/lxkU91i.jpg)
:l2: :l2: :l2:
Franco
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That looks like every tv set from the early '60s.
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As fsr as the Ratatouille amp goes, it must be quiet, I can only see one filter cap at the top middle! I don't know about the spaghetti it won't let me view it but I'm guessing it has a tone perfect for Sergio Leone movies.
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That looks like every tv set from the early '60s.
This suddenly puts "Muntzing" into perspective...
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Muntz: "Why do you need all these parts? What does this circuit do over here?"
Engineer: "Well that's a high gain stabilized stage for long-range.."
Muntz: [SNIP!!]
Engineer: "Hey what's the idea?!? Why'd you cut that out??"
Muntz: "The t.v. seems to work fine without it. You're killing our margins with all these parts & wires..." SNIP! SNIP! SNIP!
Engineer: "Great you just killed the picture."
Muntz: "Oops, put that last one back in..."
Apparently Muntz sold t.v. sets mainly to urban markets with nearby transmitters. Beautifully engineered circuits with lots of parts to help reception of distant stations had parts cut out seemingly at random to find the minimum parts necessary to make the t.v. work for local recpetion and to just cross the warranty finish-line.
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That looks like every tv set from the early '60s.
yes it does! I did some TV repair in the late 70's and actually loved chasing around inside the oldies moldies, getting them outta the 'ol folks car...... :think1:
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> Muntz sold t.v. sets mainly to urban markets with nearby transmitters.
No fool.
RCA/GE made sets with 100 mile range. Who lives 100 miles from a city? Some hundreds of farmers or loggers. Meanwhile IN the 10-20 mile area of the city is 100K-5Meg potential buyers who don't have any use for 100 mile range, 10 miles is often ample. Hundreds of times more buyers who can enjoy a half-price set. (Not half because as you shrink the little stuff, the massive CRT becomes the sticking-point; also Muntz was doing fine without cutting profits as much as circuits.)
Some of this later became a problem. Muntzes had poor selectivity. When there was one TV station in town, OK. Three stations could be spaced 3-6-10 and a Muntz would get just one (unless another was very nearby). But when 12 was allocated above 10, and the wind was blowing right, baseball would crap-up educational TV. An RCA would nail the station you wanted.