A place to document whatever it is I might do with this gift from a fellow player. I've got a grounded 3-wire cord in place to see if stable, bringing up/down on a Variac. I made the absolute sophomoric mistake of plugging my new set of Soviet "6V6 equivalent" tubes in it, plus another two 6V6 from the tube box, to see what would happen. Surprised I even had 8 6V6s on hand.
Ended up red-plating two of my new Soviets, instead of the two randos from the tube box - my idiocy / luck with the sox I happened to plug them into.
Replaced C10 / C11, which just one was leaky enough to put zero negative bias on the tube set that red plated. They were some kind of "Vitamin Q" look-alike, while C19 / C20 for the bass side are more std wax dipped jobs, that arent leaking. ~-15V on all 8 6L6 grids now, of course pairs tied. She idles fine now at full AC line.
This amp has the cool cathode windings in both OPTs, in the kinda-sorta McIntosh vein. Unsure what the coils L1, L2, L5 and L6 do, never seen anything like it. One of the pins of the protruding connector had 250V on it, so I snipped off that wire connecting through a large WW resistor to the B+. It's so nice to have found the schematic online, courtesy of captain-foldback.com which I've posted below. I'll mark it up as I go along.
T1 is an interesting bit under the hood - it's big. I've always wanted to do a guitar amp with transformer interstage coupling; maybe it'll work for that. But, what a gift; all I need to do is come across a spring set and connect it - there's my reverb channel with it's own amp / speaker. I have to wonder if this tranny once drove the big, tall Hammond necklace reverb, or one of the more ordinary 18" cans?
Ended up red-plating two of my new Soviets, instead of the two randos from the tube box - my idiocy / luck with the sox I happened to plug them into.
Replaced C10 / C11, which just one was leaky enough to put zero negative bias on the tube set that red plated. They were some kind of "Vitamin Q" look-alike, while C19 / C20 for the bass side are more std wax dipped jobs, that arent leaking. ~-15V on all 8 6L6 grids now, of course pairs tied. She idles fine now at full AC line.
This amp has the cool cathode windings in both OPTs, in the kinda-sorta McIntosh vein. Unsure what the coils L1, L2, L5 and L6 do, never seen anything like it. One of the pins of the protruding connector had 250V on it, so I snipped off that wire connecting through a large WW resistor to the B+. It's so nice to have found the schematic online, courtesy of captain-foldback.com which I've posted below. I'll mark it up as I go along.
T1 is an interesting bit under the hood - it's big. I've always wanted to do a guitar amp with transformer interstage coupling; maybe it'll work for that. But, what a gift; all I need to do is come across a spring set and connect it - there's my reverb channel with it's own amp / speaker. I have to wonder if this tranny once drove the big, tall Hammond necklace reverb, or one of the more ordinary 18" cans?
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Sitting within the forest from the trees, I "see" this amp is of differential or balanced design. Back before I was born, they knew. Was hum ever a problem in a properly working Hammond, or was that more in the realm of SE guitar signals? One has to wonder if a center tap were placed within a single coil pickup winding, that was run to the amp using a simple TRS cord...
Or if Les Paul had a pretty decent idea with his low Z "studio" guitar, that worked more like any standard Low-Z microphone in its output connection. Were players, effects/amp manufacturers at the time just stoned or stupid to not grasp the advantages? Is the High Z SE sound we have all been accustomed to by today in part due to "it's cheaper to use half the tubes"? Someone specifying the way things were to be done at Hammond didnt think so.
By design I can see this amp doesnt really lend itself "easily" to conversion to a standard 1/4" Hi-Z input guitar amp. I could tap a TRS balanced output from my Bogen amp taken from the wipers of the "post" volume and use that signaling to drive this "beast" perhaps. Which would sit I suppose in the bottom of its own wheeled cabinet, with perhaps a 15 and a 10, a set of reverb springs and reverb control brought up to a front panel. As if I'll ever actually use such a construction performing music in this lifetime. But, it's still fun to dream, spend a little money - and build things.
And wonder when the day comes that it's sitting on the floor of a Goodwill somewhere, someone comes in, sees it and exclaims "WTF!" -
Or if Les Paul had a pretty decent idea with his low Z "studio" guitar, that worked more like any standard Low-Z microphone in its output connection. Were players, effects/amp manufacturers at the time just stoned or stupid to not grasp the advantages? Is the High Z SE sound we have all been accustomed to by today in part due to "it's cheaper to use half the tubes"? Someone specifying the way things were to be done at Hammond didnt think so.
By design I can see this amp doesnt really lend itself "easily" to conversion to a standard 1/4" Hi-Z input guitar amp. I could tap a TRS balanced output from my Bogen amp taken from the wipers of the "post" volume and use that signaling to drive this "beast" perhaps. Which would sit I suppose in the bottom of its own wheeled cabinet, with perhaps a 15 and a 10, a set of reverb springs and reverb control brought up to a front panel. As if I'll ever actually use such a construction performing music in this lifetime. But, it's still fun to dream, spend a little money - and build things.
And wonder when the day comes that it's sitting on the floor of a Goodwill somewhere, someone comes in, sees it and exclaims "WTF!" -
