[HAM] Leslie 147's

[William Mark Bristow]

Jordan,
It won't work without using a different cable:
Black wire Pin 1 is Signal ground
Yellow wire Pin 2 is AC mains relay control (fast/slow)
Grey wire Pin 3 is AC mains supply
Blue wire Pin 4 is AC mains supply
Brown wire Pin 5 is AC mains relay control (fast/slow)
Red wire Pin 6 is Unbalanced Signal in

A 122 uses:
Black wire Pin 1 is Balanced Signal in
Yellow wire Pin 2 is Signal Ground
Grey Wire Pin 3 is AC mains supply
Blue wire Pin 4 is AC mains supply
Brown wire Pin 5 is B+ return (for older Hammonds requiring B+ for the
preamp)
Red wire Pin 6 is Balanced Signal in

Switching to slow (un-switched is fast speed) in a 122 is accomplished by
overlaying 70 volts DC on the 1 & 6 signal lines - and isolating that from
the preamp and Leslie amp by either a transformer or Capacitors.  (As used
in various 122 control hookup kits.)

There really shouldn't be much hum in a standard 30 foot (or shorter) cable
that is in good condition.  There are many sources of hum in a Hammond - the
things are just a big guitar pick-up basically.  Anything on top of the
organ near the matching transformers will cause hum.  AC mains wiring
running in various places in the console's interior can cause hum.  Using
straight leads rather than twisted leads in the tube from the console shelf
down to the pedal / line-out box can cause hum.  All of my Hammonds (Bob
Schleicher Chop of 1961 C3 with 2 of Bill Beer's High Power 122's, 1953 B3 &
145, 1961 A-101 with 11 pin out kit currently hooked to 2 760's) have slight
hum - background noise - mostly generator crosstalk pickup with the
expression pedal at maximum and no notes played.  The Schleicher Chop & Beer
Leslies have the least with the solid state preamp and solid state Leslies
and everything being a complete rebuilt about 5 years ago on the organ - but
there is some at full throttle.  We have the same problem with 9 pin Leslies
(760's and such).  Using a good computer equipment AC mains filter will
eliminate such as fluorescent light buzz and pops when using a 147 or 9 pin
or 11 pin hookup.

Any respectable Hammond especially with the gain in the swell capacitor
doghouse turned up a bit to give a good overdrive growl should have a little
"eggs frying" noise and crosstalk in the background when played anywhere
near full throttle.  Where is your gain set?  Factory is somewhere near 1
1/4 turns.  I have seen organs with the little screws turned out nearly 10
turns to try and get the John Lord sound thru a Leslie (requires having
plenty of spare treble drivers on hand).

One major hum culprit is the isolating strips on the patch panel.  Each
attachment panel has little isolator strips that look like a long sideways
"L" in the back of each screwed terminal panel.  If those have slipped out a
bit there will be noticeable hum.  Just push the isolator up until the tail
of the L is flush.  This creates the same type of hum sound as when you
press two or more preset keys at once.

Another major hum culprit is a loose generator cover.  It might be tight.
Playing the organ with the generator locked down can induce hum.  If you
want to lock the generator permanently to the shelf - use one of the
isolation kits available.

I had hum and scratchy popping and strange (read not-good) treble distortion
with the old B2 & 145.  It turned out to be a 30 year old dried and stiff as
a board Leslie Cable.  A New cable solved the problem immediately.
Good luck,
Mark