[HAM] Actual measured mVpp readings and peak filter capacitor mfd values of a 1960 RT3 , was Wax caps measured and then placed in four pans at the Hammond factoryKon Zissis kziss at ozemail.com.auWed Nov 22 22:18:37 CST 2006
Hi everyone. One night two years ago I temporarily disconnected one end of the wax caps of a 1960 RT3 in a church and I then meticulously worked out the capacitor mfd values that were needed to produce the peak filter output levels from each of the transformer coil filters of the TG notes 49 to 91. I did this by connecting two alligator clips to the capacitor connections on the transformer coil bobbins and I started with a capacitor whose mfd value was way below the proper mfd range and I then added 0.001 mfd or 0.22 mfd capacitors in parallel until I got the maximum signal output level readings from each of the transformer filter coils . This experiment took me over four hour to complete. Further down below I will show a table with the actual measured mfd values required for each of the transformer coil filters and the actual millivolts peak to peak ( mVpp ) readings of the TG notes with the peaked filters. The example below should help to explain why the preselected close tolerance caps in a bag method is not technically speaking the correct best way to recap the TG but instead the correct capacitor mfd values need to be individually worked out for each transformer coil filter and that each TG will require different capacitor mfd values. Having said that , in the practical real world situation it is possible get away with using preselected matched capacitors and still get a good organ sound as John Haburay has pointed out and also my friend's recapped 1959 C3 sounds very nice and creamy instead of being shrill even though it has generic 630 volt rated brown polyester ''greencaps'' that were not even tested or selected to be at a close tolerance to each other and the output levels of the TG notes 49 to 91 are uneven with peaks and dips. However it is also possible to get a very bad sounding organ as Scott Hawthorn and others have pointed out if the capacitors are mismatched . This seems to be a ''luck of the draw'' type situation but it might also be dependent on how meticulously the TG was calibrated at the factory in the first place because a sloppily calibrated organ will once again sound bad once it has been recapped properly . Finally there is the subjective matter of personal taste and this will be the factor that decides if a recapped organ or a wax capped organ is considered to sound great or lousy. Look at the table below with the measured mVpp output levels and the measured nano farad ( nf ) values of the capacitors required to produce the peak output levels or resonance of each of the transformer filter coils in a 1960 RT3 that I measured and you can see that each transformer coil filter needs a different capacitor mfd value thus proving that the pedantically technically correct recapping method is to individually match the required capacitor mfd values instead of using a pre selected cap kit where all the capacitors are of the same close tolerance. The overall output curve of the TG notes 1 to 91 of this 1960 RT3 including the peaked filters of the TG notes 49 to 91 more or less follows the typical stock factory output curve of organs from the late 50's to the mid 60's.however even with the filters peaked you can see that the TG notes 64 , 65, 69, 79, 80 , 81, 83, 84, 85, 86, 88 and 89 are weaker than the rest of the adjacent TG notes and the TG notes 77 , 82 and 90 are a little higher than the adjacent TG notes thus suggesting the possibility of a slightly sloppy calibration from the factory. These TG notes would need to be recalibrated if they are audibly weaker or louder than the adjacent TG notes. Alternatively the above mentioned peaks and dips might possibly be due to the slight side to side movement of the tone wheels when the TG is moved or shaken instead of being because of a sloppy calibration from the factory because these particular out of balance tone wheels might not have been centred properly across the narrow pickup tips when I measured the RT3 . Hopefully this table will appear properly on Hammond zeni without being jumbled up by the computer server. MEASURED MVPP OUTPUT LEVELS AND THE AGED WAX CAP NF VALUES AND THE NEW CAP NF VALUES NEEDED TO PEAK THE FILTER OUTPUTS OF THE 1960 RT3. Please note that 255 nf =0.255 mfd and 105 nf = 0.105 mfd TG NOTE# Millivolts Peak to Peak ( mVpp ) 1 69 2 69 3 68.8 4 68 5 69 6 68.1 7 66.5 8 66.1 9 65.5 10 63.9 11 63.2 12 62.9 13 17 14 16.6 15 15.9 16 15.7 17 14.8 18 14.1 19 14 20 13.3 21 12.9 22 12.1 23 11.5 24 11.1 25 11 26 10.4 27 9.8 28 10.3 29 10.5 30 10.1 31 11 32 10.4 33 11.2 34 10.4 35 11 36 10.5 37 10.5 38 10.4 39 10.4 40 11 41 11.5 42 11.5 43 11.2 44 11.8 45 12.2 46 12 47 12.4 48 13.4 Aged wax caps mVpp Peak filter nf values mVpp 49 392 nf 5.5 239 nf 15.4 50 368 nf 5.8 248 nf 13.8 51 375 nf 6.4 248 nf 15.1 52 398 nf 6 248 nf 14.5 53 364 nf 7.5 248 nf 15.8 54 383 nf 6.8 248 nf 15.8 55 137.9 nf 8 104.5 nf 16.1 56 158.6 nf 5 99.8 nf 17 57 168.2 nf 4.2 110 nf 15 58 156.5 nf 6 99.8 nf 18 59 133.1 nf 7.8 95.8 nf 16 60 163.9 nf 7 110 nf 17.5 61 171.1 nf 6.1 99.8 nf 17.6 62 159.3 nf 7 104.5 nf 17 63 165.5 nf 6.4 99.8 nf 17.2 64 146 nf 6.5 105.4 nf 14 65 138.4 nf 6.7 105.4 nf 12.5 66 171 nf 6.8 102 nf 18.2 67 173.2 nf 7.8 104.5 nf 20.2 68 166.8 nf 8.2 104.5 nf 20.4 69 136.4 nf 10 99.8 nf 17.6 70 150.3 nf 9.8 95.6 nf 20.4 71 164.2 nf 8.8 95.6 nf 21 72 170.8 nf 9.2 99.8 nf 20 73 158.7 nf 7.5 99.8 nf 20.3 74 166.2 nf 7 99.8 nf 19 75 166 nf 7 104.5 nf 19 76 164.2 nf 7.8 104.5 nf 19.3 77 158.1 nf 8 97.8 nf 22 78 163.2 nf 8 103.8 nf 19.6 79 134.1 nf 9.7 99.8 nf 18.6 80 163.3 nf 7 105.4 nf 16.8 81 171.6 nf 7.2 104.5 nf 18.3 82 168.9 nf 8.2 99.8 nf 21 83 163.3 nf 7.5 102 nf 16 84 156.7 nf 7.2 110 nf 15 85 164.4 nf 8.7 104.5 nf 17.7 86 169.4 nf 7.4 105.4 nf 17 87 167.1 nf 9.8 99.8 nf 20.2 88 163.7 nf 8.2 99.8 nf 18 89 167.5 nf 8.6 99.8 nf 18.5 90 160.9 nf 11 99.8 nf 21.1 91 168.2 nf 9 99.8 nf 19.8 All the best. Kon
More information about the hammond mailing list |