[HAM] Correctamunde: Single louver horn compartment

[Kon Zissis]

Hi David and Scott and everyone.
David Anderson wrote:
> it does seem interesting to me that many things have been done to
Leslies to make them sound brighter (modern coupling 
> capacitors, removing the horn cotton, etc...), but then a recapped
organ sounds too bright. Is there a connection here?
 
Scott Hawthorn wrote :
>It would be interesting to hear what Leslie's original intention was
 
I think that there is a connection between Leslies modified to sound
brighter and recapped or red mylar capped organs sounding too shrill.
Back in the old days it seems like  a mellower sound was considered more
pleasant sounding than a harsh bright sound  and many amplifiers
including the AO28 preamp , the 31H , 21H 22H,  122 etc Leslie
amplifiers and other  amplifiers  included  treble cut capacitors as
part of the tone shaping circuitry. The key click sound  was considered
a defect and this would have been one reason for the  treble cut
capacitors in the AO28 and the Leslie 122 amplifiers. Perhaps the reason
for the damping material and also the  single row of louvres  on the
treble compartment of the 21H Leslies was to acoustically mellow  out
the sound even more and thus remove  more of the key click sound.
 
As I have found out in the past few days,  there is a noticeable
mellowing in the sound of my Leslie 122 after I added  the carpet
damping strips inside the treble horn upper compartment ( similar to how
the damping material was attached inside the treble horn upper
compartment of the single row upper louvre Leslies such as the 21H
cabinets )  and especially so when  I put the upper compartment  back
panel back in place. Without the carpet damping strips in place there is
not such a noticeable mellowing effect  when I put the back panel cover
in place. To my ears my Leslie 122 now sounds better with the carpet
damping strips in place  and the mellower treble sound of the horn seems
to be  better balanced  with the bass speaker. 
 
Over the years I have read a number of times that the Jensen V21 is a
very inefficient treble driver with a "dull" or a "muddy " sound that
just does not "cut through the mix" .  This is definitely not the case
with my own bright sounding V21 and  the V21's in all the other Leslies
that I have heard.  When a stock Leslie 122 or a 147  with a  Jensen V21
is within a few feet next to me,  the horn tends to sound too loud
compared to the bass speaker  especially when playing on the top octave
of the manuals. A Leslie 122 or 147 with  modern treble driver such as
an Atlas PD-60 or a Hammond Suzuki ferro fluid driver that has not been
filtered and tamed down with resistors or inductors sounds way too
shrill to my ears even with wax capped organs.  
 
 The main bulk of the Hammond recordings that I have are from the 1960's
and 70's and in those days the B3 , C3 , RT3 ,A100, D100 etc organs
built between 1955 to 1964 that had wax capacitors would still have
sounded bright and more similar to the post 1964 red mylar capped organs
because the wax capacitors  would not yet have significantly drifted off
spec with age. Many Jazz / Blues recordings such as the Jimmy Smith
recordings with Rudy Van Gelder's 1959 C3 have warm and mellow  organ
sounds even though these organs were still new at that time. I have
played 40 + year old wax capped stock organs  that sounded  brighter and
sharper than the organs on the 1960's Jazz, Blues and Rock recordings.
 
 Of course the analog recording techniques and the  EQing and tape
compression would contribute to the mellower sound heard on the old
recordings but if you want to learn how to recreate this sound as
closely as possible then I think that it is very important to know the
details about the actual organs and Leslies that were used  on the
recordings especially  when it comes to things like the specific Leslie
model that was used on the recordings. I have read that Rudy Van
Gelder's 1959 C3 was  connected to a 21H Leslie and I would imagine that
this 21H had the damping material in the treble horn compartment and I
assume that this 21H  Leslie was recorded with the treble compartment
back panel cover in place and if this assumption  is correct then this
Leslie 21H would have sounded noticeably mellower than a Leslie 122 or
147.  
As well as the sonic effect of the damping material , another factor
that might affect the tremolo sound of the Leslie 21H is  that the horn
was  located  more to the centre of the  treble compartment  instead of
being off centre towards the right side in most of the other Leslies
including the 122 and the 147.
 
All the best.
Kon 
 
 
 
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