[HAM] Wax caps measured and then placed in four pans at the Hammond factory, was Recapping

[Kon Zissis]

Mike P wrote :
>I also am curious to know -  At the factory we have discussed that the
>matchers had bins of caps to choose from .  Speaking of the .105 type
now ,
>what was the range of their selection that they had to choose from ?
Maybe
>I'm not getting the picture here ,  did they have for example a .103
bin,  a
>.104 bin,  and so on ?   What did they range from ?
 
Scott  Hawthorn replied :
>Mike Fulk has spoken on this but I don't remember the answer.
 
Hi Mike P , Scott and everyone.
I remember posts by Mike Fulk ( who mentioned that he got his knowledge
about these things  from the senior Hammond engineer Alan Young ) and
Mike Fulk wrote that because  the wax caps had a 20 % tolerance rating ,
they were measured at he Hammond factory and then placed in one of four
pans according to their actual measured mfd  values. After this each
transformer coil filter was individually measured and then matched with
a wax cap  chosen from one of the four pans that had the measured wax
caps whose mfd values was nearest to that required by each transformer
coil filter.
 
Because  the wax caps had a 20 % tolerance rating , this means that a
wax cap for the TG notes 49 to 54 labelled as 0.255 mfd could in actual
fact  be as low as 0.205 mfd or as high as 0.306 mfd  , and  a wax cap
for the TG notes 55 to 91 labelled as 0.105 mfd could in actual fact  be
as low as 0.084 mfd  or as high as 0.126 mfd . 
 
My own speculative assumption is that the bins might possibly have been
arranged something like the following pan divisions shown below. I do
not know how accurate this is to what was done at the Hammond factory
but the pan divisions shown below do seem to make sense :
 
For the  nominally labelled 0.255 mfd wax caps for the TG notes 49 to 54
:
Pan 1   0.205 to 0.230 mfd.
Pan 2   0.231 mfd to 0.255 mfd.
Pan 3   0.256 mfd to 0.280 mfd.
Pan 4  0.281 mfd to 0.306 mfd.
 
For the nominally labelled  0.105 wax caps  for the TG notes  49 to 54 :
Pan 1  0.084 mfd to 0.094 mfd.
Pan 2  0.95 mfd to 0.105 mfd .
Pan 3  0.106 mfd to 0.116 mfd .
Pan 4  0.117 mfd to 0.126 mfd.
 
The big  question now is , when a measured transformer coil filter
needed for example a 0.101 mfd  capacitor , was a wax capacitor:
1 ) randomly chosen  from the  Pan 2 with the 0.95 mfd to 0.105 mfd
capacitors in it,  or
2) where all of the capacitors in the Pan 2 then measured again so that
a 0.101 mfd capacitor or one nearest to 0.101 mfd  was finally selected
and then matched with that particular transformer coil ?
 If the latter ( 2 )  is correct then this would have been an extremely
time consuming process.
 
This raises another interesting  question in that if a wax cap from the
Pan  2 was simply randomly chosen and then matched with the transformer
coil filter that needed  a 0.101 mfd capacitor , then that wax capacitor
could have been anywhere  within 0.095 mfd  to 0.105 mfd  so therefore
it might only be APPROXIMATELY matched instead of being EXACTLY matched
with that  transformer coil filter and this means that  when someone now
uses a capacitor  decade box to work out the EXACT capacitor mfd value
needed by each individual transformer coil filter then it is possible
that the output level of that TG note would be louder than what it was
when it was set at the factory  with the less than perfectly matched
wax cap mfd value. If this is correct than this might also  be a factor
that helps to explain Scott's and other's  experience with some recapped
organs that  have a too loud or a harsh sounding upper midrange  which
is louder than what it would have been  when  the organ was new. I
remember Scott writing that he remembers  what Hammonds sounded like
when they were new and that they did not  have the excessive  upper
midrange that he now hears with some recapped organs. 
 
These particular recapped organs that now have a harsh upper midrange
would need the TG to be  recalibrated  to restore a more  pleasant
sounding tonal  balance. Although I am patient and confident and have
some experience in recalibrating a TG and I have an analog  millivolts
peak to peak ( mVpp ) meter for the sine wave TG notes 13 to 91 and a
Velleman  HPS-10 digital oscilloscope for the complex waveform TG notes
1 to 12  to measure the TG output levels and to recalibrate a TG, many
other people would be  inexperienced or lacking the confidence  or the
right equipment  to recalibrate the TG  and they would either have to
put up with an out of balance sounding organ or they would have to pay
an expensive fee to get a tech to recalibrate the TG. The Tone Control
is very useful in minimizing an excessive upper midrange or treble but a
lot of Jazz / Blues and Rock organists love the spitty key click that is
available when the Tone Control is set to the full brightness position.
a recapped organ or a post 1964 red mylar capped organ can be made to
approximately sound similar to a  wax capped  organ  by turning the Tone
Control down to  the half way position  but this  does lose the
spittiness of the key click. On my own 1962 C3 I have removed the Tone
Control  from the back left side of the AO28  and I have placed it on
the control panel of the 12AX7 based EQ / overdrive  unit which is
located on the left under side of the organ so that I am seated at the
organ I can easily reach  and change the Tone Control setting
depending on what sound I want to hear. 
 
All the best.
Kon