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Why are Filter Capacitors mounted on the top of the Tonewheel Generator?
HAMMOND Tonewheel Generator organs were manufactured with hand-matched Filter Capacitors for some of the reactor coils mounted on the top of all Tonewheel Generators. The Filter Capacitors accoustically filter certain tonewheel frequencys to remove unwanted spurious harmonics, low frequency hum, rumble and other mechanical and inductivly coupled noise. The original Filter Capacitors were military grade components, designed for an expected 15 - 20 year life, as this was the maximum electronic component life available at the time. The combination of the reactor coils and Filter Capacitors together are commonly referred to as 'Tone Generator Filters'.
Why do the Filter Capacitors require replacement?
In lieu of the fact that the last Tonewheel Generator organ was manufactured more than 20 years ago, ALL Tonewheel Generator organs should have a new set of hand-matched Filter Capacitors installed to restore factory design specification tonewheel filtering performance. Many organs are now 30, 40, 50 or even 60 years old or older (the HAMMOND Model A was introduced in 1934; the B-3 was first introduced in 1955!). In all cases, the original critical tolerance Filter Capacitors have randomly changed capacitance value due to component aging and now mask the true sound and performance of the organ's Tonewheel Generator.
Many of the original capacitors have increased in value to several times their original values, and as such, they tend to 'muffle' the sound of the organ. Others have failed completely and 'opened' causing a dead Tone in the organ. Since all capacitors age differently, the organ sound is at the very least extremely inconsistent. Although this is a very common problem in all Tonewheel Generator organs, it is generally cured with the installation of a fresh set of matched replacement Filter Capacitors, assuming all other organ components are also working correctly.
Are there different Capacitor types among the many Models?
Actually, the generator filter capacitors are very similar among ALL Tonewheel Generator organs. The numbers of capacitors may vary slightly among models, but the essential ingrediant to restoration of the 'classic' HAMMOND sound is to install a set of new very close tolerance, extremely stable, hand-matched Filter Capacitors. GOFF Professional installs these same custom kits in ALL of our touring, church and other custom organs. The new Filter Capacitors can restore the factory-fresh brightness, consistency and drawbar definition to a generator which is otherwise working as intended.
Beware --- Simply installing a set of equivalent value electronic store capacitors will NOT restore the original sound, and in many cases, will cause the organ to sound even worse than before!
Why are some Filter Capactors a brown color and others a red or purplish-color?
From 1934 to around 1963, Tonewheel Generators were equipped by the factory with brown-colored capacitors manufactured in a wax composition, covered with paper. These are commonly referred to as brown 'Wax-cap' generators. Beginning around 1963, the HAMMOND Organ factory began installing dark reddish-colored styrene capacitors in the generators. The generators are commonly referred to as 'Red Cap' generators due to the color of the capacitors.
What are R/C Networks; Why and When were they introduced by HAMMOND?
Also around 1963, as new generators were being manufactured at the factory, in many larger console models (B-3, C-3, A-100, D-100, etc.), HAMMOND began installing an additional level of special Resistor / Capacitor (R/C) Network filtering for tones numbered 37 to 48. The new R/C Network filtering was specially designed to reduce the crosstalk and 60 hz hum which generally resulted when the first brown Drawbar (16') was pulled out in conjunction with other Drawbars. The hum was most noticable in tones 37 to 48, so HAMMOND added the R/C networks and recommended that early console organs be retro-fitted with them when the Filter Capacitors were changed to further reduce hum and crosstalk in the older organs.
A short little history lesson on the reasons behind changes in Tonewheel Generator construction
There were many Tonewheel Generator design changes during the approximate 40-year time (1934 - 1974) that Tonewheel Generators were manufactured by HAMMOND Organ. Some very early organs featured larger generators which were found to cause hum and inductive noise coupling among the tonewheels themselves. In later generators, tonewheel frequencies were grouped and their physical locations moved to different 'galleries' within the generator minimize this problem. Some early organs featured 'consecutively wired' generator wiring terminal strips which were also modified to accomodate the relocation of the frequencies. That is why many early console organs have consecutively-wired terminal strips and later ones have the non-consecutively wired terminal strips.
All HAMMOND Tonewheel Generator organs can benefit tremendously from Filter Capacitor replacement, and addition of the later R/C Network filtering, if applicable to the particular model of organ.
What does the Tonewheel Generator Filter Capacitor Replacement Kit consist of?
Each GOFF Professional Tonewheel Generator Filter Capacitor Replacement Kit consists of hand-selected and matched new critical value Filter Capacitors which are assembled in individually matched sets. These Capacitors were selected specifically for their superior performance in a HAMMOND Tonewheel Generator application. They exhibit particularly high non-inductive qualities, are impervious to oil in the generator, feature a shielded-body construction, and are extremely consistet over time. The Kit also includes hand-matched resistors, capacitors and mounting lugs for building and installing R/C Network for tones 37-48 on Pre-1963 console organs which were not originally equipped with this added level of filtering.
Our Kit will upgrade early Tonewheel Generators to the latest B-3 level of filtering.
Complete Instructions and a detailed description of the technical reasoning behind the need for Filter Capacitor replacement is also included.
NOTE: Since many organs require different installation techniques, we recommend that a Qualified HAMMOND Organ Service Technician be contacted for installation help if the owner of the organ has no previous experience in electronics, particularly soldering and component removal / installation techniques. Many owners have also successfully installed our new kits themselves with excellent success!
A technical description of our Vibrato Line Box Replacement Filter Capacitor & Resistor Kit can be found in our ON LINE Catalog. We recommend that the Vibrato Line Box Kit be installed with the Tonewheel Generator Filter Capacitor Replacement Kit for best results.
Please supply your Organ Model and Serial Numbers when ordering the Tonewheel Generator Filter Capacitor Replacement Kit.