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Speakers Vertically Stacked

#142
Originally Posted by billfitzmaurice
Yes, there is.

Art of Assembly Language Programming and HLA by Randall Hyde
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It should be noted that this is a simplistic look at acoustic summing and does not consider the off axis response and especially the off axis response versus frequency polars that are probably more responsable for what we hear in the real world.

To explain to others who are following this, and so that my comments are not taken out of context by those with an agenda, a big part of how a speaker's acoustic response sums has a lot to do with the smoothness and uniformity of the horn's pattern. In the good 'ol days, efficiency and raw output even down to fairly low frequencies (by today's standards) were generally more important parameters than uniformity of pattern, off axis response, distortion and frequency response extension. This is because HF devices were expensive, amplifier power was expensive, and the lower a HF (actually more like MF) horn could retain some semblence of pattern control and adequate loading on the driver, the better.

As HF devices and phase plugs became better, as new diaphragm materials emerged, as amplifier power got less expensive, as higher ordered active xovers w/ constant power summing, HF lift networks, and as people's tastes/expectations matured, the market began to shift away from the high sensitivity horns that had as a byproduct pretty ragged off axis response and even ragged on axis response with significant HF beaming to lower sensitivity horns, with smoother more uniform responses. Beaming was much reduced, off axis edges were MUCH smoother, HF response was improved and many of the old rules of thumb began to fall away. The actual results of summing at high frequencies are still there but in practice are MUCH less pronounced and less of a problem. Sometimes it's a very adequate or even "best solution for the application", sometimes not BUT IMO it's important to listen to this in application rather than dismissing it out of hand without condsideration.

As a general note, many of the graphical prediction modeling programs are horribly misleading... not because they are wrong but because they fail to take into account many of the important variables that affect the real world applications... and sometimes the amount of time and resources to make a model accurate enough to rely on also makes it impractical to implement as it becomes overly time consuming. I have seen modeling take more time than the installation, tuning and commissioning of a system and even then the measurements showed resembelence to the model but not very closely. This is usually because of things that either changed in the field, the inability to maintain close tolerances over materials within the acoustic space, or were inaccurately represented in the original modeling.

Just something to think about. Bass cabinet are "easy" compared to other areas in which I work.
 
#143
agedhorse said:
As a general note, many of the graphical prediction modeling programs are horribly misleading...
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If anything they barely scratch the surface of how problematic speakers placed side by side are. For the sake of clarity the models only consider one frequency at a time. In real use situations literally thousands of frequencies are present, each with its own radiation pattern, each pattern different. If one pattern seems to be confusing imagine thousands of dissimilar patterns all superimposed. That's the acoustical confusion that your brain has to contend with. The job of an acoustical engineer is to make that task as easy as possible, not more difficult by ignoring the laws that govern how sound works.
 
#144
Then very fact that there are thousands of frequencies (a continuous span actually) is what makes the models so poor at translating what is seen visually into what the ear and brain hear/process. Fortunately, the ear/eye/brain as a system are quite forgiving and there is a great amount of spatial averaging that goes on with everything we perceive... and in real time. It's amazing and fantastic at the same time.
 
#146
Ever done FOH sound with too much bass on stage, J? You know there's too much when you turn off the PA support and it sounds far better, but weaker. I go with weaker because I dig tone over loud mud. I estimate that happens a lot more often than guys realise, going by the general TB loud ethos and the average size of gigs.

Everyone playing with PA support should be breaking out their smallest rig that can get them hearing themselves and leave the rest to the FOH.
 
#148
johnsonabq said:
Kinda makes you wonder how we find any of it pleasant to listen to.
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Yeah, except that for the most part even things that "theoretically" shouldn't work well often work just fine because upon examining the theory we see how many assumptions are made that cause the theory to deviate from real world conditions.

The difference between a scientist and an engineer is that a scientist is always stating how theory says it can't work and stops at that point. An engineer studies the big picture, better understands how the real world relates to (and deviates from) the stated theory, adjusts the equations and/or adjusts the theory, then designs products that work in the real world. It happens time and again too.
 
#149
Downunderwonder said:
Everyone playing with PA support should be breaking out their smallest rig that can get them hearing themselves and leave the rest to the FOH.
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Or you should learn to communicate, learn what to give to the engineer, and learn to trust that those full range monitors we give you can literally levitate themselves. Except for the Behringer ones.

End rant.

EDIT: and by this, I mean amp on stage, 210 cab with a 50' speaker cable in a broom closet.

EDIT AGAIN: Adding Smileys :p:p:p
 
#150
johnsonabq said:
Kinda makes you wonder how we find any of it pleasant to listen to.
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That's the brain at work. To understand how well just listen to a recording you've made of your band, which seldom sounds anything like what it did to you in person. On sight your brain filters out most of the room modes, so you mostly hear the band. When you play it back later your brain can't filter those modes, as all the directional cues required to do so aren't present, so then you hear what was actually there before your brain applied its own acoustical masking program.
This brings up the topic of bootleg live recordings. Most bands forbid it, ostensibly fearing that bootlegs will detract from sales of their authorized recordings. The 'Dead' encouraged bootlegs. That was partly because the Dead were very technically astute, and knew that someone sitting in the audience with a mic could not produce a recording of sufficient quality to cause the loss of a single sale of a record/CD. Rather, the poor quality could only encourage said fan to buy a record/CD so that they could hear the songs as they were supposed to sound.
 
#151
billfitzmaurice said:
That's the brain at work. To understand how well just listen to a recording you've made of your band, which seldom sounds anything like what it did to you in person. On sight your brain filters out most of the room modes, so you mostly hear the band. When you play it back later your brain can't filter those modes, as all the directional cues required to do so aren't present, so then you hear what was actually there before your brain applied its own acoustical masking program.
This brings up the topic of bootleg live recordings. Most bands forbid it, ostensibly fearing that bootlegs will detract from sales of their authorized recordings. The 'Dead' encouraged bootlegs. That was partly because the Dead were very technically astute, and knew that someone sitting in the audience with a mic could not produce a recording of sufficient quality to cause the loss of a single sale of a record/CD. Rather, the poor quality could only encourage said fan to buy a record/CD so that they could hear the songs as they were supposed to sound.
Click to expand...

Well, actually the recordings are good enough that people go out of their way to trade them still to this day. And a lot of folks became very proficient with stereo mic technique and squeezing surprisingly high fidelity out of their Sony and marantz tape decks. Not a dead fan by any stretch btw.
 
#152
dave_p said:
Well, actually the recordings are good enough that people go out of their way to trade them still to this day.
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Mainly for souvenir value. I was never a Dead Head myself, but a friend of mine saw them at least 50 times, has at least 20 bootlegs, and will pay for them from any of the concerts he was at. How he'd know I can't say, maybe he memorized the set lists.
 

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