Many people are lust for that Hammond Growl, a combination of Hammond, Leslie and distortion.
If you want just a little, the first step is to adjust the preamp output level of your organ. (Also, of course, you can adjust the level control on your Leslie(s).)
Some people have experimented with replacing various tubes in the preamp (and/or Leslie amp) with other higher gain tubes. I have not tried this. Reports from those who have have not been compelling.
KonZissis has designed and built a 12AX7 valve based circuit.
IN tube LESIES YOU CAN SWOP THE OC3 STABILIZER tube for an OD3 this will change the suply to preamp and to G2 screens of the 6550's resulting in sooner breakup and distortion and some loss in power it is usefull in situations that you want the distortion and growl to come in sooner at lower volume levels like house room or studio work , It WILL NOT HARM your leslie at all . the OA/OB/OC series are gastubes with different voltages between 75/90/145 volts they are normally used as stabilizer tubes but in leslies they are used to lower some Suply voltages . this mod is used several times by Benji Massy , Belgium
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