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Post by Bob Olhsson on Mar 18, 2016 14:08:30 GMT -6
www.aes.org/tmpFiles/elib/20160318/17839.pdf This is an excellent paper about reproduction science. "Equalization is very limited in what it can “correct,” yet the notion that changing the signal supplied to a sound system consisting of an unknown loudspeaker in an unknown room can “equalize” or “calibrate” a system is widespread. In the context of a practical application where there is an audience of several listeners conventional equalization cannot: • Add or remove reflections • Change reverberation time • Reduce seat-to-seat variations in bass • Correct frequency dependent directivity in loudspeakers • Compensate for frequency dependent absorption in acoustical materials and furnishings. The exception is in the highly reflective sound field at very low frequencies. It is essential to separate events above and below the transition/Schroeder frequency. Above it, at middle and high frequencies, constructive and destructive acoustical interference occurs when direct and reflected sounds combine at a microphone. If the frequency resolution of the measurement is sufficiently high—typically 1/3-octave or higher—the resulting peaks and dips can look alarming when seen in room curve. The tendency for a calibrating technician or automated equalization algorithm might be to attempt to smooth the curve. These are non-minimum-phase phenomena that are not correctable by minimum-phase equalization. However, the direct and reflected sounds generally come from different directions, which a microphone cannot differentiate, but binaural hearing can. References [1, 2,12– 14] focus on several of the perceptual consequences of reflections. It turns out that in most small-to-medium sized sound-reproduction spaces human listeners find these multi-directional reflected sounds to be mostly benign, even beneficial if the loudspeaker has relatively constant directivity. A common perception is spaciousness—information about the listening space, not timbre damaging comb filtering. This is certainly true for recreational listening, but professionals may find that a less reflective space is preferred for mixing but perhaps not for mastering recordings [12]. These measurements are therefore misleading, and even if equalization were capable of removing such reflections, there is the decision of whether it is necessary. Overall, equalizing the spectral fluctuation “errors” found at a few measurement locations, can add new spectral variations to the total sound output of the loudspeaker that is radiated to all locations throughout the room. There is a significant risk of degrading the performance of good loudspeakers.
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Post by M57 on Mar 19, 2016 7:57:30 GMT -6
I probably interpreted this all wrong but..
..in layman's terms (for dilettantes like me) - Equalizing against the room to make your monitors more accurate in their space is a worthless endeavor?
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Post by tonycamphd on Mar 19, 2016 8:16:21 GMT -6
what I got from it is probably conformation bias? 8) and that is... treat your small room until you get it sounding great, if not on the more absorbed side, leave the "monitor calibration eq" off the monitors, it seems that anything less than a binaural head microphone being used for the calibration would render the result useless? much in the same way moving your head less than an inch off the sweet spot would,... or ?
I'm no expert on those calibration EQ's, the always struck me as a splint on a compound fracture(for lack of a better analogy haha)
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Post by Bob Olhsson on Mar 19, 2016 8:43:54 GMT -6
Pretty much. This idea from the 1970s was pretty much debunked during the '90s but with the rise of cheap electronics manufacturing a number of manufacturers and software developers have revived it. Eq. can correct the anechoic response of a speaker which can be measured using a technique called time delay spectrography using impulses to eliminate room reflections but forget about just a mike and pink noise.
I actually worked in the world's first equalized control room at Motown in Detroit. After they got the control room speaker measuring flat in 1964 or 5, they took the measurement mike out into the studio and found it sounded terrible on our speakers that now supposedly had flat response. A call to Brüel & Kjær to ask what had been done wrong got a response from the microphone's designer. He had never heard of anybody trying to correct a loudspeaker and explained how the physics of diaphragm and speaker diffraction would make it inaccurate outside of direct response in an anechoic chamber. We had to settle for just using the measurement gear for setting the amplifier gain on out tri-amped monitor.
Meanwhile we've learned a lot more about hearing which only compounds what the man from Brüel & Kjær told us.
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Post by Bob Olhsson on Mar 19, 2016 8:51:19 GMT -6
Even a binaural head mike can't work because we hear the direct and reflected sound mostly separately. A common problem is that you can only absorb frequencies above a certain frequency unless you use anechoic chamber-sized absorbers that wouldn't even fit in most small rooms. Even then all you've accomplished is to make speakers sound like headphones. Room reflections are an important part of monitoring. It's just that you want them to be uncolored. Too much padding can make them all low end.
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Post by mrholmes on Mar 19, 2016 19:16:30 GMT -6
Pretty much. This idea from the 1970s was pretty much debunked during the '90s but with the rise of cheap electronics manufacturing a number of manufacturers and software developers have revived it. Eq. can correct the anechoic response of a speaker which can be measured using a technique called time delay spectrography using impulses to eliminate room reflections but forget about just a mike and pink noise. I actually worked in the world's first equalized control room at Motown in Detroit. After they got the control room speaker measuring flat in 1964 or 5, they took the measurement mike out into the studio and found it sounded terrible on our speakers that now supposedly had flat response. A call to Brüel & Kjær to ask what had been done wrong got a response from the microphone's designer. He had never heard of anybody trying to correct a loudspeaker and explained how the physics of diaphragm and speaker diffraction would make it inaccurate outside of direct response in an anechoic chamber. We had to settle for just using the measurement gear for setting the amplifier gain on out tri-amped monitor. Meanwhile we've learned a lot more about hearing which only compounds what the man from Brüel & Kjær told us. This is the Company which did research about the room response in typical living rooms.  |
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Post by Bob Olhsson on Mar 20, 2016 11:17:55 GMT -6
There's the engineering department and then there's the sales department!
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Post by sozocaps on Mar 20, 2016 15:38:40 GMT -6
Do not try to get your room flat, it does not sound natural. We like to hear sound with a emphasis in the 100 region then a slope down in amplitude to 10k... most like a slight a dip in the mids. www.studiotips.com/gfx/rta_small.gif |
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Post by Bob Olhsson on Mar 20, 2016 15:57:31 GMT -6
It's actually diffraction causing a measurement problem. Once you get rid of speaker and microphone diffraction I've found that measured and perceived sound begin to agree. "House curves" were a work-around for faulty measurement.
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Post by mrholmes on Mar 20, 2016 16:45:42 GMT -6
There's the engineering department and then there's the sales department! Makes sense. BTW PDF is down still would like to read it.... |
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Post by mrholmes on Mar 20, 2016 16:58:43 GMT -6
Do not try to get your room flat, it does not sound natural. We like to hear sound with a emphasis in the 100 region then a slope down in amplitude to 10k... most like a slight a dip in the mids. www.studiotips.com/gfx/rta_small.gifI reached out for a fairly flat base response and it makes sense when I check the mixes on other systems. Before the new treatment it was not bad but not tight enough. If I listen to old mixes I now can say within seconds - that sounds odd in the base range. If there would be enough spare time I would remix nearly all the old songs. BTW we can see that in a single spot, listening position, the internal EQ of the Genelec 8040 helped to tame down 2 db between 100-300 Hz. But this is only at a fixed point. If you move your head / Microphone everything is equal but not exactly the same.  |
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Post by sozocaps on Mar 20, 2016 19:58:11 GMT -6
Do not try to get your room flat, it does not sound natural. We like to hear sound with a emphasis in the 100 region then a slope down in amplitude to 10k... most like a slight a dip in the mids. www.studiotips.com/gfx/rta_small.gifI reached out for a fairly flat base response and it makes sense when I check the mixes on other systems. Before the new treatment it was not bad but not tight enough. If I listen to old mixes I now can say within seconds - that sounds odd in the base range. If there would be enough spare time I would remix nearly all the old songs. BTW we can see that in a single spot, listening position, the internal EQ of the Genelec 8040 helped to tame down 2 db between 100-300 Hz. But this is only at a fixed point. If you move your head / Microphone everything is equal but not exactly the same. That speaker/room looks real good for bass response. I do not think you are going to get much better then that |
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