So. I give you..the Swedish made mystery amp.
Thought some of you might get a kick out of this one.
What we had to go on was this emblem. Period,and as of this writing none of us are even close..and some of us at it are rather seasoned boys.
Cab sides here are made out of what seems solid mahogony. When we smash our heads together...we´ve agreed on that this thing is most likely Swedish mid -40´s.
That old?
Yep. That old.
Topology is rather simple and very reminiscent of that -37 vintage Geloso G.27 i did a while back (which btw is friggin beyond cool..). Them massive resistors to the left are pulldowns that grip right at the rectifier B+ out.
Replaced anything cap....
So i got the POS up and running. As it turns out tho,to no real avail cause ALL of it within was beyond rescue. To bad...but that´s just the way things are sometime i guess.
Seing that..better an amp that works then a boatanchor..
´N see...this is where it turns sexy! A 5U4G to the left...followed by a pair of Brimar 6L6G´s..(yeeeees..the same 6L6´s that you´ll find in your Fender,Mesa or whatever,and then a set of 6SJ7 pentodes and a 6C5 single triode. Them laughing matter large sockets are speaker out..
Just get a grasp of the SIZE of that powertransformer! It´s absolutely MASSIVE. As it turns out...lead No2 is that them were also used in Champion amps and see...Champion was bought by Goesta Baeckstroem in 1949...why PT´s looking like that were phased out. That´s how we´ve dated the amp as far as vintage.
That there and the faceplate sho is ugly tho so...
Well.
As all within was shot to kingdom come...to hell with it. A generic Tubetown turretboard...then replaced the octals with a couple of novals,kept the one octal tho.
In turn fabbed yet another board for the pts needed for the powertubes and...a fixed bias setup.
Main smoothing caps. The first hit one even. See,a 5U4G doesn´t take all that nicely to to much capacitance for first hit. Now..remember them massive white coloured pulldowns? Replaced them with more modern day n era stuff AND...a 32µF+32µF can. First of the two takes the full hit while the second one grips at the junction of them two power resistors. Sneaky huh
Went shopping. Ugly faceplate no more. Shop i run..got craploads of metal working tools so..
Resused the pilot light and the mains switch.
Circuitry wise then. The two novals are russian made 6n2p´s.The pentode in turn...one of the 6SJ7´s the amp came with. I control this by the use of LDR´s that let´s the latter tube be part of the mix or not.
Tonecontrols in turn is a James network with an added midshift switch and bass shift switch.
Fabbed a simple shield for the LDR card and input jack.
Sure enough! Up and running!
Uhu. Tells the story i guess.
Out back i added a Tubetown silicon powered loop. Works..what can i say...
So?
Well. Seat of the pants,haven´t measured,i´d say that we´ve got ourselves here is a real 40 watt mystery,and even more so now i guess. Put out an easy 40 watts even. Aimed at rocknroll,and with the 6SJ7 engaged we´re talking hardrock/metal territory.
For the better
