John Mihevic On The Goff Capacitor Kit

This is a review of the Goff tone generator capacitor kit which was contributed by JohnMihevic. (See ToneGeneratorCapacitorReplacement for more on the subject.)

My 1956 B3 (Ser # 59520) did not have much "brightness" in the higher frequencies. I was always pulling out all the upper drawbars to get more highs. I decided to replace the wax capacitors that are part of an LC resonant filter for frequencies 49-91. I purchased the Goff capacitor kit and am very pleased with the results. There is much more clarity and brilliance in the mid to upper frequencies with increased drawbar control of tone. The volume output is increased in that range and the percussion has more "bite". Now each drawbar has more definition and each step change on the upper drawbars is more noticeable than before. I have seen some complaints that the new Goff recaps can sound too sharp and that some prefer the warm sound of the older organs with the waxed caps. I don't agree. If I want, now my B3 will really scream now or I can cut back on the drawbars and get the warm sound that was always there, it is like having the best of both worlds.

The recap job is straightforward, just time consuming. Replace one component at a time. Easiest access to the Tone Generator (TG) is from the front of the organ by lifting both manuals and supporting the front corners of the lower manual with wood blocks. I would also recommend sliding a piece of thin cardboard on either side of the manuals to prevent scratching the organ case should the manuals slide sideways. Trek II makes a pair of case scratch protectors specifically for this purpose.

The factory capacitors for frequencies 49-54 was 0.255uF and 0.105uF for frequencies 55-91. The waxed capacitors had increased in value through the years. I measured the existing capacitors and found one 0.255uF had increased to 0.590uF. A 0.105uF had increased to 0.540uF. I also measured mv RMS values before and after the recap. All mv outputs increased. Some outputs more than doubled. An example was TG freq #78 which increased from 2.96mv to 6.45mv.

The Goff capacitor kit replaces the 0.255uF capacitors with 0.224uF and the 0.105uF with 0.104uF. I checked the "tuned" value of the new capacitors by using Sprague "orange drop" capacitors to increase/decrease values from the supplied capacitors. The 0.104uF were matched very well to the reactors with peak output for the frequencies 55-91. However, I added a 0.015uF capacitor in parallel with the 0.224uF capacitors. The 0.015uF capacitor produced the best peak output for my TG with an increased output of 0.5mv to 1.0mv for frequencies 49-54. The typical output for these frequencies was 4.3mv before the parallel capacitor addition.

The Goff recap kit also comes with R/C filter networks for frequencies 37 to 48. They were factory installed on B3's and C3's after around ser # 93,000. Goff says these were to reduce crosstalk and 60Hz hum for these frequencies. Supposedly this occurred when the first brown drawbar was pulled out with other drawbars. Since this is an R/C passive filter, adding the filter will reduce the TG output. I don't have hum or crosstalk that I can hear and I didn't want any reduction in TG output, so I decided not to install these R/C filters.

I would highly recommend a TG recap for anyone with the older wax capacitors. It certainly puts new life into the old Hammond.