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Problem with Leslie 147

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  • Problem with Leslie 147

    Hello, I'm hoping someone can help me narrow down what's happening with my 147 (could also be the B3 organ, but after this morning I suspect the cabinet).

    For I while a have had a problem with intermittent distortion that will often present itself once the organ has been running for 30 minutes or so. The distortion doesn't seem to have any connection to the pitch being generated and appears and disappears at random. It almost sounds like a 1/4" cable from a live amp touching something... it also has a scratchy quality to the sound. Typically, this hum/noise is no louder than the organ itself.

    This morning, the issue presented itself almost immediately and was distorting every note played. Shortly after, the signal completely died... until I switched the rotor speed to tremolo, at which point the sound instantly re-appeared. I tried to replicate the problem and succeeded - noisy and scratchy sounding in chorale, eventually no sound, then back on instantly in tremolo.

    Any ideas what I might be dealing with? Any help would be most appreciated.

  • #2
    This morning after reading a bunch of advice on this forum started checking tubes/pins/etc... all looked ok but while I was back there noticed the 6 pin cable didn't look quite quite right plugged into the B3. My organ was modified at some point in the 70s to run two Leslies, in theory both outputs should be the same and shouldn't matter which one I use. However, after testing... one has a tight connection w/ the 6 pin cable and one was causing noise. So looks like this issue has been solved, and happy to have learned a little more in trying to diagnose this.


    • #3
      Loose female 6 pin connectors are very common, and can cause distortion. (Any number of problems actually.)

      I can see the benefit of other connectors (such as EP-6). One of my clients has gone through 2 connectors in 3 years. That cable gets unplugged and re-plugged at least 4 or 5 times a week.


      • #4
        Brendan I am also in Calgary and have a similar problem with intermittant buzzy scratchy distortion. However I am playing a Hammond XK1 thru an XM-47 converter box to adapt the output of the XK1 to the Leslie 6 pin. I was not able to find the replies to your problem but would like to know what things I should check to determine the cause. Like you the distortion goes away sometimes by switching speed but other times I have to power the XM-47 off.


        • #5
          First thing I would do is lock some keys down* to make some sound, then go about wiggling, tapping all the cables and connectors, wiggle the Leslie's volume control, speaker connectors, etc. and see if any of that makes the noise appear or go away. I had a Leslie cable with a cracked solder connection on one of its plug pins that intermittently caused atrocious noise.

          * this can be done with a bit of folded paper or perhaps a large knife or sword
          Tom in Tulsa

          Fooling with: 1969 E100, 1955 M3, 1963 M100, Leslie 720


          • #6
            Corrosion free pins and secure socket 'grabbers' with no wobble are the only way to go.Tulsa Tom uses folded paper,
            I use cardboard drink coasters to 'engage a big fat chord'.....
            One of them says 'The Refinery,Calgary AB'.LOL.Pretty sure there's a Ranchmans too.
            A100/251 A100/147 A102/222 B2/142 BV/147 BCV/145 M3/145 M102/145 M111/770 L101/760 T222/HL722 M111/770 no B3/C3!


            • tpappano
              tpappano commented
              Editing a comment
              My first introduction to "hot wings" was in a Vancouver bar, I was changed forever 8)

          • #7
            You are running a 147 speaker on a B3, which works but has its own list of things it does odd. You may have meant it has a 122 speaker, or a converted 147 amplifier which functions as a B3. If it is a true 147 amplifier, the speed relay should have nothing to do with the sound at all, since pins 2&5 are for the 110VAC relay only. No connection to the audio path. If it IS a 122, then the relay can have everything to do with the audio path since it puts high voltage DC on the balanced line audio wires. A shorted, or bad, capacitor in the 122 Leslie kit can cause the audio to be either randomly dead or completely dead. You may also have a failing 6550 tube which if one of them loses the cathode inside the tube, causes the other 6550 to overheat and the audio will distort badly, and get very weak. BUT... in the latter case the speed switch should have no affect on the volume or distortion. Bad power supply filter caps can cause voltages to go so far off that the speed relay won't work, or distortion runs rampant, as well as weak volume. A 147 Leslie is not a good match for a B3 because of the differences in the balanced line audio of the 122, and the high-impedance input of the 147. I have had all the above items be issues in various jobs I have had over the last 45 years in business. If you have more info on other things that are going on with it, it would surely help.