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Thread: Johnson Monarch M-4 schematic

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    Johnson Monarch M-4 schematic

    I just bought one of these rare Canadian made amps online (it hasn't arrived yet) but I suspect that it's been modded. Does anyone have a schematic or a gut shot?

    Thanks in advance!
    Nathan

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    Sorry, no schematic but a bit more info., if you haven't already seen it.
    Johnson Sound Systems
    Johnson Sound Systems of Manitoba circa 1951 | Preservation Sound

    Oddly enough, they may still be there at the original location, the name shows up in several phone listings. Maybe thehoj would know, I think he is in Brandon.

    Johnson Sound Systems
    1327 Rosser Avenue, Brandon, R7A 0M3, MB
    Canada
    Telephone: 204-727-7878

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    "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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    Thanks! I know the company put out some new models "recently" (recently compared to my late '50s amp!) and then discontinued production of those as well. But I suppose it won't hurt to try calling.

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    Unfortunately Johnson Sound Systems is long gone.. I'm surprised they're still listed in any directories. It's probably been 10 years since that shop closed up.

    Schematics are really hard to find in my experience. There's a guy in Winnipeg MB that's quite familiar with Johnson amps, I can shoot him an email to see if he's got something.

    There's another long shot I'll check on tomorrow. I actually work with a nephew of Albert Johnson. I'll see if he has access to any old schematics or stuff like that.

    Quote Originally Posted by g-one View Post
    Sorry, no schematic but a bit more info., if you haven't already seen it.
    Johnson Sound Systems
    Johnson Sound Systems of Manitoba circa 1951 | Preservation Sound

    Oddly enough, they may still be there at the original location, the name shows up in several phone listings. Maybe thehoj would know, I think he is in Brandon.

    Johnson Sound Systems
    1327 Rosser Avenue, Brandon, R7A 0M3, MB
    Canada
    Telephone: 204-727-7878

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    Thanks so much! I really appreciate you taking the effort to check with your contacts, even if it doesn't pan out.

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    Well, the amp arrived. All but one of the input jacks have been snipped out for some reason (other than that, the amp looks like not a single part has been changed since this amp was built in the '50s.) I drew out a schematic of the tone section and the power amp. The design seems to have been cribbed from various generations of Fender amps. The input jack wiring is incredibly confusing. They didn't wire the high/low jacks in the normal way, that's for sure.

    Click image for larger version. 

Name:	JohnsonMonarch.jpg 
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    Quote Originally Posted by octal View Post
    Well, the amp arrived. All but one of the input jacks have been snipped out for some reason (other than that, the amp looks like not a single part has been changed since this amp was built in the '50s.) I drew out a schematic of the tone section and the power amp. The design seems to have been cribbed from various generations of Fender amps. The input jack wiring is incredibly confusing. They didn't wire the high/low jacks in the normal way, that's for sure.

    Click image for larger version. 

Name:	JohnsonMonarch.jpg 
Views:	526 
Size:	147.6 KB 
ID:	25765

    Oh, I'm an idiot. I was poking around some more and the amp is almost an exact clone of the 5D8 twin. Only some very minor component value changes.

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    Quote Originally Posted by octal View Post
    Oh, I'm an idiot. I was poking around some more and the amp is almost an exact clone of the 5D8 twin. Only some very minor component value changes.
    Okay cool. I did reach out to my two sources.. Haven't heard back from the guy via email.. The nephew who I work with sent an email to a daughter of Albert Johnson who he's still in contact with.. She's apparently the only one with anything related to the old Johnson amps. If she ends up getting an official schematic I'll post it up here, although I suppose you don't really need it now. Still, I imagine it would be interesting to see.

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    Thanks for your efforts! I'll take a 5D8 Twin schematic, photoshop in the correct values and post it up here just for anyone else who might need it in the future. Also, if Mr. Johnson's daughter happens to know how many of this model were made, or has any catalogs showing this model, photos of the shop, etc. I'd love to have that info. There's really next to nothing about these on internet, so I don't think there's a ton of them out there. I've seen more photos of the combo version than the head, and I've found fewer than five photos of any version of the Monarch M-4. (Unfortunately, I don't think this is going to be one of those cases where rarity=value)

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    Alright, here it is. Please disregard the earlier hand-drawn schematic, there are some mistakes. Speaking of mistakes, this amp had the OT wired with the phase reversed from the factory... the only reason it didn't oscillate wildly was that the feedback resistor was (another mistake) 270K instead of 27K! I suspect that's why this amp was so amazingly un-used looking when I got it... it probably never played right and was put aside. It also had a terrible (bordering on unplayable) filament hum... it uses a 'one side to chassis ground' style filament scheme. Unfortunately, the "hot" branch of the filament wiring buss was routed near some very sensitive grid wiring... reversing it so the grounded side was the wire running near the grids helped a lot, and rewiring it for balanced filaments fixed the hum.

    Click image for larger version. 

Name:	Monarch M-4 .jpg 
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    Last edited by octal; 10-21-2013 at 02:17 AM. Reason: uploaded wrong photo!

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