The B2, C2, and the RT2 organs with the AO10 preamplifier, and the A-100 series, B3, C3, D150 series and the RT3 organs with the AO28 preamplifier and the M3 and the M-100 series organs with the AO29 or the AO67 amplifier used a treble cut filter consisting of very small value capacitors in series with very high value resistors wired as part of the negative feedback circuit between the input grid and the output plate of the input tube of the non vibrato channel and the input tube of the vibrato channel. This 20K or 22K resistor/ 0.001 uf capacitor treble cut filter reduced the key click by rolling off the treble response, as well as bringing down the levels of the "premphasized" midrange and treble TG notes so that their volume levels through the preamplifier were better balanced with the lower frequency TG notes. The secondary winding of the drawbar matching transformer on the early era organs of the 1930's and 40's such as the Model A, AB, B, BA, BC, BV, CV, D, E, G and the RT organs had a very simple treble cut filter consisting of a 0.001 uf ( 1 nf) capacitor wired in series with a 20K or 22K resistor between the output wire of the secondary winding and the ground.
Hammond reduced the key click by calibrating the tonewheel generator to have the "pre-emphasis" in the midrange and the treble TG notes which meant that the midrange and the treble TG notes were set to have a progressively upward rising output curve in their output levels. Whilst dirty key contacts or busbars and also deteriorated grounding connections can enhance the key click, the key click is always present even with perfectly functioning and clean key contacts and busbars and perfect grounding connections so therefore Laurens Hammond and the subsequent Hammond designers tried to suppress the key click sound right from the start in 1935 until the end of Hammond tonewheel production in 1975. did the new hammonds have key click? also is there a way on a Hammond to increase or decrease key click. Just wondering if key click becomes more pronounced with the amount of usage on the organ and the age of the organ.
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