[HAM] New Hammond Factory Sound / Recapping etc. PART 3

[Kon Zissis]

Here is the final part of the big post that I tried to send but it was
automatically chopped--Kon
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New Hammond Factory  Sound / Recapping etc. PART 3

Brad Baker wrote:
>All this stuff about cap matching and tolerances and procedures in the
factory is almost meaningless if in the Hammond >factory the Tone
Generators were calibrated after the caps were installed... The tonal
balance is done primarily by >the TG calibration. Having a proper filter
center frequency will perhaps make the calibration procedure easier, or
>more consistent from unit to unit.  A mistuned filter might affect
harmonic content or noise >level associated from a >tone, but not the
tone level in a calibrated TG.

Yes , regardless of how strictly perfectly or less than perfectly  the
capacitors were matched to the transformer coil filters at the factory,
the TG was calibrated to produce  the overall TG curve  after these
capacitors  were put in place. I do not think that the harmonic content
from a slightly mistuned filter would be very noticeable especially
considering  that the waveform from a filter with an aged wax capacitor
can still sound acceptable even though the noise level and the extra
harmonic content is a little more noticeable along with the very
noticeable decreased  output level.    The problem that can happen  with
recapping is that if the new capacitor is  more exactly matched to the
transformer coil filter  than what the original wax capacitor was, then
that TG note will end up a little louder than what it should be but this
can be rectified by recalibrating the TG as you mentioned. I understand
however that other people will not be willing or able to recalibrate
their TG. 

>(It doesn'tmake much sense for them to be calibrated *before* the caps
were >installed).

If this was done then the TG output levels would have ended up all over
the place and they would have  needed to be readjusted  in order to
produce a smooth output curve.

>One approach to fixing a dull organ might be a TG recalibration.  If
such an organ were one with badly mistuned >filters with wax caps whose
values were 200% of the stock values then it may not be possible to
calibrate that TG >without installing new caps.  The new caps would
approximately center the filter response on each associated tone, and
>would provide an increase in the adjustable tone level thereby.

If the wax caps are not too far gone , the weak TG notes can be
recalibrated but a problem with doing this is that the pickup might need
to be set too close to the tone wheel thus resulting in a dirtier
sounding waveform with more noise and possibly a warbling tone as well.
If the TG is recapped properly  then you can get a slightly louder than
stock TG output curve  but still with pure sounding waveforms. The
louder  than stock TG output curve  but still with pure sounding sine
waves  is  especially  possible if the organ is a late 60's or early
70's red mylar capped organ with the R/C filters and the bright red
enamelled wire on the transformer coil filter bobbins because these
transformer coils produce louder output levels than the early 1960's
transformer coils with the dark brown enamelled  wire. I have verified
this with my own 1962 C3 after I transplanted  the red mylar caps and
transformer coil filters  brass tray from a 1970 T-300 into my C3 and I
transplanted the recapped transformer  coil filters  brass tray into the
T-300. \

The reason why I transplanted  the red mylar caps tray from the  T-300
into my C3 was because the red mylar caps are still more or less
properly matched  to the transformer coils  thus ending any issues with
mismatched capacitors. I had originally replaced the wax caps  from my
1962 C3  with new capacitors , many of which  produced the peak filter
outputs  so therefore I expected that the red mylar caps tray originally
from the T-300 would  produce a slightly mellower TG output curve in my
C3 but on the contrary  the TG output  levels of the TG notes 49 to 91
were now noticeably louder and conversely the output levels of the  TG
notes 49 to 91 in the T-300 become noticeably lower  with the recapped
brass tray originally from my 1962 C3. The T-300 originally had very
high treble levels  with a resulting nasal thin sound but I had
recalibrated the whole TG to produce a typical B3 / C3 etc output curve
but with a warmer bass and lower midrange whilst the red mylar caps tray
was still in the T-300.

After I transplanted  the recapped tray from my C3 into the T-300 , the
output curve of the TG notes 49 to 91 became almost a straight line
instead of the typical upward rising curve  of the B3 / C3 etc , and
this made the  T-300 sound quite nice and fat  so therefore I decided to
leave the TG curve it as it is without  recalibrating it a second time
in order to bring back the typical B3 / C3  upward rising curve.

All the best.
Kon

END OF PART 3