Hello crew,
Back from Dagogo’s Cal Audio Shows and was it fun to hear all those different systems. And beautiful too. I got to meet Steve, our founder and also our forum moderator. Glad to know we have one. That was such a pleasant surprise. He came to one of my 4 lectures.
By the way, I have typed up my lecture and can email it to anyone who wants to read it. The lecture title changed every day, even though the lecture content was pretty much the same. No script, but still I stayed on track. I talked about the 20 year evolution of my understanding about what TubeTraps do right when they get loaded into listening rooms. And I ended up at where I am today. It is a funny lecture, story actually, because it tracked the sequence of partial answers, each of which were true enough but each of which ultimately could not account for the whole effect, and therefore were not really the right answer.
I knew that whatever the answer was, it had to account for what the Golden Ear crowd said the TubeTraps did, and I’m glad I lived long enough to be able to discover what finally seems to be the end of that saga/story. My “search for the holey grail” ended happily……but then, the story is full of such happy …but short lived …false endings. So I muse, how do I know I am really at the end of this road? I’ve thought s many times before I was at the end. Just because I can finally account for what the Golden Ear crowd tells me, it probably is presumptuous of me to think that the adventure is over. At best, it’s resting place, a plateau in the learning curve. But in truth the comedy adventure goes on. It reminds me of a song my kids used to torture me with….It’s the song that never ends…..round and round it goes, never stopping…
Treble is musical treble, anything above 262 Hz, middle C. The wavelength is just over 4’ and the ¼ wavelength is 1 foot. The head is just large enough to cast a shadow over one ear compared to the other. The concept of Left and Right signal paths are just beginning to be physiologically sensible.
One of the things we are missing, when it comes to communication, is context. We need to compare apples to apples. A listening setup that is nearfield in an acoustically dark room does not image like a large setup in a fairly bright room. Maybe you guys know each other’s systems well enough that you don’t need reminders, but I know I don’t.
For one thing, we could specify the setback distance, the distance between the listener and the speaker. Another thing we can specify is bright or dark, in terms of the room reflectivity.
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Let’s stop talking about imaging for a while.
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Choose a good orchestral recording, one that uses nothing but two mics, a crossed pair of omni mics, the minimalist “Blumlien pair” setup. Many orchestral recordings are done this way.
Once we have the recording, we want to play it on our system. An orchestra in general is putting out the same sound power towards the microphones from all different locations on the stage.
This is the classic signal source for stereo auditioning of the size, shape and brightness of your sound stage. The stereo pair of mics, when listened to, see a wide uniformly thick, uniformly “bright” shaped sound stage, from left to right. In this case, brightness means loudness. Here bright does not mean lots of top end.
Imagine being in a special seat during a legitimate orchestral concert. You are suspended about 15’ above the stage floor and up and out over the seated audience about 15 to 20 feet back from the edge of the stage. That’s where the Blumlein pair happens to be located. You can imagine the huge sound stage that is sonically visible, nearly full left to right and everything is uniformly loud, uniformly present. At this point, we have no soloists, just full on orchestra. You are not too close or too far from anything. That is what the sound stage should look like upon playback in your room.
Now, what you do next is to “map” your sound stage, the one you hear. Yes it’s subjective. When I say map I mean a profile. A line that goes up and down as it moves left to right. What you do is search the loudness or presence of the orchestra, on average, using your mind to sweep the sound stage left to right or the other way. It’s as if you have a parabolic dish and you sweep it across the orchestra, noting how the volume of sound changes as you sweep from 9 o’clock left to 3 o’clock right. Well maybe it’s 9:30 to 2:30. But something like that.
You set up a paper with a line drawn horizontally, which is your axis. Then above that line, say 2 to 3” above it you draw another line, parallel. That is 100%. Then you mark angles using a protractor, every 15 degrees starting in the middle of the axis line and place the angle marks on the 100% line. What you then draw is the relative loudness, presence of sound vs angle as some % above and below 100%.
This is an effort to quantify or measure the average loudness or strength of sonic presence of the sound stage at different angles as you mentally sweep across the sound stage. The ear brain has the ability to echolocate, which means we can sonically look in certain directions, even without changing head position. The relative strength of sonic presence should not change if we do move our heads. It doesn’t matter if we move or not, we’ll still get the same answer, as long as we move pretty much the same when we compare the strength to other angles as well.
If somebody has hearing aids or a hearing impairment the process of echolocation ranges between difficult to impossible. Still, try, it is good to practice, as in practice makes perfect. Remember, draw where the sound seems to come from. Don’t let your eyes trick you into thinking they know where the sound comes from. Look with your ears.
To practice this, you can prepare your chart and then just sit in a room and map out the strength of sonic presence as it varies across the front side of you. You might hear noise from an air diffuser to the right, and your hard drive louder and to your left and community noise in through a window to your far left. You can make a double line chart and map 360 degrees.
OK, that’s the assignment. We are developing one technical skill in “critical listening”. Check in as you begin doing this.
Art Noxon