Following are 4 jpegs in a group for you entitled "Dick's Trumpet"
The four pictures entitled "Dick's Trumpet" are oscilloscope images of one moment in time, seen 4 ways
with different wiring changes.
The source of the pictures is a live recording I made on 27 February, 1996 of the Big Band Xpress, a local
19-piece big band, performing at a concert in the Station Theatre, China Lake Naval Weapons Center,
China Lake, CA. I also play bass in this band.
The band is arranged on the stage thusly, from the audience point-of-view:
5 Saxes seated on the left , no risers. The end of their line is dead center, minus one seat,
but the inboard end finishes 8-10 feet "up stage"; i.e., farther away from the listener.
4 trombones, seated on the right, no risers, starting "up stage" along-side the sax on the in-board end, making a straight line to the far right near-edge of the stage; so you have a giant shallow "V" of the
entire front row of saxes and bones.
5 trumpets, standing, on one riser-level[8 inches], behind the trombones, and parallel to them.
1 grand piano, no riser, behind saxes
1 string bass, two riser-levels, rear and left-center
1 drum-set, centered, rear, two riser-levels.
The Recording Set-up is:
3 omni-directional microphones, classic Left, Center, Right,
ala Bob Fine of Mercury Living Presence fame;
center mike down 4.5 dB from other two. L and R mikes=Neumann; Center
mike=AKG, Mixer=Yamaha, Recorder=Panasonic 3700 DAT,
at 48 kHz sampling rate, 16 bit word length.
The piece we're playing is a Duke Ellington composition called Black Bottom Stomp. There is a
section in it where the lead trumpet plays a really ripping solo, accompanied by short, chopped
chords by the rest of the band. The o'scope pictures are of one very exposed section
where Dick Dickson is really "out on his own", with mostly stage and hall ambience/reverb momentarily as his only accompaniment.
What You See:
Picture # 1
This clearly shows the positive-going wave forms
[o'scope CRT is rotated 45 degrees to the Right, so that I
may see the smallest changes in Left-to-Right balance, and make corrections]
[the 3-fingered spikes] of the trumpet as seen [heard] by
[from top to bottom of the spike-pattern]
1) the right mike;
2) the center mike;
3) the left mike.
It can be seen that all 3 mikes are of the same polarity.
If you're able to see it really clearly, you can see multiple images on each of the 3 spikes; these are:
1] direct sound, bell of trumpet
2] reflection off Dick's music stand
3] reflection off polished floor on stage
4] reflection off hard lath and plaster wall to the right of
the trumpet and bones; stage boundary.
When you listen to this recording, it's really evident that the saxes are left and bones and trumpets are right,
piano, bass and drums in rear, center-left; just like the visual scene.
Same spot in the music, with right channel reversed in polarity [crossing-up pins 2 and 3 on XLR connector
in recording system; mixer-to-recorder, or recorder-to-mastering system.] saxes still in left side, brasses to the right
again, same spot in music, other channel polarity-reversed.
Still same directional queues; saxes on left, brasses on right.
now, we have both channels reversed
note: if the center mike had reversed polarity, the center "finger" would be going the
opposite compass direction; that is, in the first picture, where everything's normal,
all 3 fingers are pointing "East"; the center finger of that picture would be
pointing "West". (In this particular picture,
the center "finger" would be straight down)
The purpose of all this dissertation is to demonstrate what a powerful analytical tool that even an
old oscilloscope can be; [Hewlett-Packard 130-C, 1962] . Of the four pictures we've seen, only one sounds totally "right".......
the others don't image correctly, or the trumpets and bone sound as if they are sucking loudly
through their horns, if you can imagine that!!!
Proper signal polarity throughout the recording chain is a must-do proposition!!!
The oscilloscope helps the keen operator to optimize the recording during mastering.
I have been known to cut a record without meters, but I won't cut a record without the scope!