Question: Does it matter which wire, red or black, that comes from the power amp's OT, feeds one side or the other of the crossover? And does anyone know the name/type of crossover this is? Drawing, schematic attached below.
Since I don't need 40w's, I'm setting it up to use any guitar amp I want, probably a smaller 15 or 20w guitar amp.
From the Leslie 47 power amp, to the crossover, there's a twisted pair of wires that comes from the 47's OT secondary, a red and a black.
*But* the 47 power amp's OT's secondary has a CT that stands on a 150R/10w bypassed with a 200uF/50v cap. So the OT is grounded through the CT, through the R/C, not 1 end of the OT secondary wind directly to chassis ground.
So does it make any difference if the guitar amp's OT's + goes to P7 - L (plug 7, large pin) or to P7 - S (plug 7, small pin)? (The Leslie 122 drawing attached below is different at the OT secondary CT, it has no R/C bypass cap. Look at the 47 amp schematic just below the 122 crossover drawing, crossovers are exactly the same.)
The 12.5uF and 7.8uF were both reading ~30uF. So, I just put new caps in the crossover.
Full story;
I bought a '59 Leslie 45/47 cab/amp, it's a single speed model, short cab, walnut stain. I bought a Hampton MK II speed conversion kit, that you can get fast/slow/off with a 2 button Ft Sw. -or- with an expression peddle you can get 9 speeds and off. It's in ~8 out of 10 shape? It's never been gigged, was in some school here where I live. The 47 power amp was rebuilt before I bought it and has all NOS tubes. It's a 40w, K bias, 6550's, 12AU7 PI and OC3 regulator tube.
It was a little musty smelling and needed a little work. So I took the whole thing apart, washed the inside of the cab with diluted Murphy's Oil wood soap and left the cab outside in the sunshine for ~2.5 days, UV light. Much better now. The motors were free and surprisingly clean, but a little gummed up, decades of old oil/dust. Bass rotor bearings were originals, were turning, but getting stiff/dry inside. Before I cleaned/oiled the motors and horn spindle and installed the new drum bearings, the horn and bass drum would spin on the fast speed pretty well. But when I got the speed conversion kit installed and tried the slow speed, the horn would stop right away and the bass drum would sometimes stop also.
So I took apart the motors, cleaned and oiled them, installed new bass rotor bearings/grommets, new motor and drum grommets and oiled every nut and machine bolt before putting it all back together. Horn and bass drum now spin freely, like they should. Jensen horn driver and Jensen P15LL bass speaker, both original, work fine, very clean and in very good shape.
Thanks, Willabe
Topic: Leslie 45cab/47 power amp (Read 4509 times)