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'59 Hammond M3 Blond ~ Upper manual foldback + Lower manual lowering / bass mod
My '59 Blond M3 called Stella by my daughter was experiencing missing / static laden / weak notes and shifting the busbars didn't solve the problem. So I knew I was going to have to pull the manuals to get to the busbars. Since I have an L-102 hangar queen sitting in the garage I decided to do upper manual foldback while I had her apart. As I read about full foldback vs poor mans foldback I decided to do the full foldback. I skipped the manual tapering. I also added the lower manual bass mod where you drop the range of the lower manual by one octave.
The results are fantastic. Wow the bass really kicks. Playing the 16' + 1' registration is good ALL THE WAY UP!! What a difference in the overall tone. I don't know that I want to do another foldback mod due to how labor intensive it is but I had the time I the results were worth my effort. I will have to record the results and post them.
One advantage of going into the M3 as deep as I did is that I was able to clean places that hadn't seen any cleaning since she was built. Man I had a dryer lint screen worth of lint under both keybeds. Absolutely filthy. So now she is all clean. The electrolytic caps have been replaced, the power cord too. I found the perfect combo of tubes to get a nice sound.... RCA for the 6au6, 6ba6, 6c4 and 5u4gb tubes, Sylvania for the 12au7, 12ax7 and 6v6 tubes. Nice, real nice. The M3 feeds a homebuilt Leslie 147 sized cabinet with a Jensen V21 driver (16 ohms) and a Weber 15F200 (Jensen C15 clone)(8 ohms) homebuilt crossover adapted to 8 ohm woofer and 16 ohm mid / high frequency driver all powered by a Leslie 25 amp. Yeah I know it is only a 20 watt amp but it cranks. Besides 20 watts vs 40 watts is only a 3db difference in spl. Bass is solid and doesn't fart out as I thought it might.
If you are thinking about these mods:
Upper manual foldback: Lots of time robbing the L-102 for contacts and busbars (had to make a small mod to those). Lots of time installing the new contacts. Organ down for a week. Real improvement in sound when using four highest drawbars.
Lower manual bass mod: Much easier and a real improvement in sound. Less than a day to complete. I left the first 12 wires at stock length and extended the other wires. I installed jumper wires from 1 to 13, 2 to 14 ... 12 -24 on the terminal strip. The extended wires start on terminal 25. By doing it this way the original wiring harness can be restored to stock by removing the jumpers and I didn't stress the wiring harness by trying to get more length out of it.