Church systems are one of their main lines of business according to their website. A lot of that stuff has been removed or changed but they were hardcore marketing on the houses of worship market.
The fact that they don't even have any products with wide dispersion (like the dispersion pattern of a regular box speaker) speaks volumes about the idea that acoustical interaction and interference is a required necessity. DSL products won't interfere with each other unless you point them at each other, they are specifically made not to interfere with each other when stacked (arrayed).
I'm pretty sure they wouldn't develop new products just for this purpose, their off the shelf products are more than good enough, and they don't do what the "organ" people considers a necessity.
Again, not a technical answer.
Sims are never wrong, you got that part right. If you sim something accurately the sim will match the measurement. The q of the resonances might be a bit different due to the fact that the enclosure is not infinitely rigid, but to suggest that a sim is actually downright WRONG is a really odd opinion. There are thousands of examples that clearly show sims match measurements when the sim and the build are accurate.
If a sim is EVER wrong it's because the sim was not done properly or things were not accounted for. This is typical user error, not a fault of sims.
I pointed out at least a couple of errors in your last post, and you respond by saying that sims are wrong. Unfortunately this type of deflection is too typical of this oddball thread.
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There you go again . . . ignoring reality.
The 32' stop will generally cover two octaves, meaning the highest note will sound around 65Hz. Your "very benign" port resonance sits right on top of the second harmonic of the high (for that rank) A# and B, and would change their timbre relative to other notes in the rank. Think that won't be noticed?
Think again . . .
We can't possibly be insisting that these speakers can be hooked up straight to the system with no type of crossover or eq, can we? I mean...
Edit: And for the record, I'm going to jump into the "sims never lie" can of worms and remind everyone that cabinets and ports aren't made of depleted uranium, and resonances are usually far, far less pronounced than a simulation would lead you to believe.
Edit: And for the record, I'm going to jump into the "sims never lie" can of worms and remind everyone that cabinets and ports aren't made of depleted uranium, and resonances are usually far, far less pronounced than a simulation would lead you to believe.
Correct. Even the best "PA" systems are not organs, and they do not produce the sound field that organs produce.
Right, within the self-referential context of the sim. When you try to map the sim to reality, however, you will often find that reality has more dimensions (parameters) than your sim does, and the mapping fails. Often miserably.
For example . . . you can simulate a resonant speaker enclosure, anyone can. There is free software that does it quite well. You cannot simulate a pipe organ, because you do not even begin to understand a pipe organ and the combined perceptual effect of the multiple, essentially independent, sound sources.
I look forward to reading it, but just so you know where I'm coming from, I've built quite a few tapped horns, a pair of OD-ML-TL subs, and my current standard BR ones, all of which showed pronounced resonances in Hornresp, however none of my measurements have ever reflected the actual resonances to be even half as bad as hornresp suggested they would be.
Right, and the harmonics are off a bit too since these are 1/2 WL [open] pipes with both odd and even harmonics, so if 1st [fundamental] = 64 Hz, then 2nd = 128 Hz, 3rd = 192 Hz, etc., every 64 Hz.......
GM
Yep. Give a me a few minutes and I will fix it up.
Just after I ate breakfast. My brain goes to sleep when I eat. Actually goes to sleep if I don't eat to!
Thanks for the correction Greg!
As for the harmonic and fundamental trade off I purposely call the fundamental the frequency at question and the harmonic the first harmonic higher than the fundamental.
I have seen it both ways as you guys have noted.
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The very benign port resonance won't be audible at all, and like I said, a small amount of stuffing will make the response curve smooth as a baby's butt if desired. A smooth response curve won't have any audible resonances.
I can't even believe this is all being brought up again. This is beginner stuff. And it's been thoroughly covered. But by all means, let's go over it all again.
This is not magic. There are concepts at play. Acoustic concepts. Frequency response, dispersion characteristics are the big ones, spaciousness (multiple speakers spread out) comes in to play as well, and there are a few other things that come in but are not as important.
You guys are trying to make it sound like producing an organ sound is a mystical endeavor that requires a wizard and a random stack of clumped speakers. This is not the case, all that's going to do is alter frequency response.
I map the sim to reality ALL THE TIME. I'm well aware of the things my simulator does not consider, and I account for them. Recently I produced a procedure for simulating high inductance drivers accurately, as far as I know, no one has ever done this before.
Multiple independent sound sources are not a mystery buried in time and space. This stuff is all very well documented and understood. A basic crossover simulator can show you EXACTLY what happens with different sound sources. Frequency response is altered, nulls are produced. That's it, that's all.
This is really basic stuff.
You haven't posted anything of any substance yet and already I've pointed out several errors in your posts.
You need to try harder.
The principle problem of using a vented box to crate accurate musical tones is the action of the vent.
You will notice in the Allen digital organ videos that they do not use a vented enclosure.
Why?
A vent adds harmonics at the point where it in transferring from and to the enclosure.
Keep in mind that in a vented box, a vent is really only in use close to it's matching resonance with the enclosure.
But the same vent acts as a resonator above that frequency. It hums along with the tune so to speak. Very few simulation programs take this into account but it is a widely known and understood effect. There are many JAES papers that have described the effects of this.
( Things you can learn from that is not readily available of the internet )
The resonance is created by a coupling of the volume of air in the enclosure and the vents own harmonic progression. So the port resonance is much higher than the tuning resonance. And just start doing a little math in the stuffing calculation to determine how thick of an absorber you would need to bandaid the problem. You need an absorbent one quarter the wavelength of the frequency you want to absorb.
As noted a crossover has to be used in any event. But the unwanted distortion coming from the enclosure vent system does not disappear, it simply gets attenuated ( turned down). Problem being that when you turn up the volume to produce a nice roaring trumpet or bombarde you are also turning up the volume on the distortions. They are ever present.
And there is no free lunch. A vented enclosure properly executed will have a 3 db peak over a sealed box. People who love sealed en=closures get all happy and say that they introduce less distortions. True within a limited scope of thought, but not true when you remember that they must have twice the excursion to keep up.
You will notice in the Allen digital organ videos that they do not use a vented enclosure.
Why?
A vent adds harmonics at the point where it in transferring from and to the enclosure.
Keep in mind that in a vented box, a vent is really only in use close to it's matching resonance with the enclosure.
But the same vent acts as a resonator above that frequency. It hums along with the tune so to speak. Very few simulation programs take this into account but it is a widely known and understood effect. There are many JAES papers that have described the effects of this.
( Things you can learn from that is not readily available of the internet )
The resonance is created by a coupling of the volume of air in the enclosure and the vents own harmonic progression. So the port resonance is much higher than the tuning resonance. And just start doing a little math in the stuffing calculation to determine how thick of an absorber you would need to bandaid the problem. You need an absorbent one quarter the wavelength of the frequency you want to absorb.
As noted a crossover has to be used in any event. But the unwanted distortion coming from the enclosure vent system does not disappear, it simply gets attenuated ( turned down). Problem being that when you turn up the volume to produce a nice roaring trumpet or bombarde you are also turning up the volume on the distortions. They are ever present.
And there is no free lunch. A vented enclosure properly executed will have a 3 db peak over a sealed box. People who love sealed en=closures get all happy and say that they introduce less distortions. True within a limited scope of thought, but not true when you remember that they must have twice the excursion to keep up.
That's also what I think. Tones of different wave shapes with a different set of partials and overtones with a different volume for each are different.
Even if some of the differences are subtle ones, I think the vibrations of the speakers would be different. If we reversed the phasing, would they cancel each other completely? I don't think so.
As has been pointed out, I'm not an acoustical engineer. But a French Trumpet Pipe sound and the sound of a Stopped Diapason Pipe are very different. In that case the difference isn't subtle. If a speaker pair is playing an 8 foot trumpet on C and another pair of speakers is playing an 8 foot diapason on C, they would sound very different to most ears. They would also look very different if viewed via an oscilloscope.
Will a sine wave cancel a saw tooth wave - if both are at the same pitch? What about the other way around?
Will an out of phase sine wave with one set of partials cancel out a sine wave with another set of partials that is in phase? I just don't think so. I think that there must be a mathematical difference between different pipes - even when the difference in sound is subtle. I can't cite an acoustical principle or rule to prove this. But the difference is a mechanical effect. 65 hertz won't interfere with 64 hertz. A 64 hertz violin pitch won't interfere with a 64 hertz clarinet pitch
Bach On
Bach On
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Here is a correction on my incorrect harmonic progression:
Taken from Harmonics overtones fundamental partials harmonic partial overtone calculation frequency fundamental and harmonics odd even frequencies relationship between frequencies of overtones and fundamental frequency flute clarinet THD organ converter distort
Fundamental frequency in Hz 64 = 1st harmonic
↓
1st overtone 128
2nd overtone 192
3rd overtone 256
4th overtone 320
5th overtone 384
6th overtone 448
7th overtone 512
8th overtone 576
9th overtone 640
10th overtone 704
11th overtone 768
12th overtone 832
13th overtone 896
14th overtone 960
15th overtone 1024
Taken from Harmonics overtones fundamental partials harmonic partial overtone calculation frequency fundamental and harmonics odd even frequencies relationship between frequencies of overtones and fundamental frequency flute clarinet THD organ converter distort
Fundamental frequency in Hz 64 = 1st harmonic
↓
1st overtone 128
2nd overtone 192
3rd overtone 256
4th overtone 320
5th overtone 384
6th overtone 448
7th overtone 512
8th overtone 576
9th overtone 640
10th overtone 704
11th overtone 768
12th overtone 832
13th overtone 896
14th overtone 960
15th overtone 1024
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The sawtooth will modulate the sine wave. Same effect with pulling a flue stop say a 16 foot prestant and an 8 foot trumpet together.
Or going the other way.
You rarely use a 32 foot stop without a 16 foot stop.
Why?
The 32 foot in combination with the 16 foot is louder, fuller and more pleasing. But the 32 foot modulates the 16 foot.
You don't need JAES papers to know that if the response curve is smooth there won't be any audible problem with resonances, or harmonics, or anything else. There's a bit of group delay which can't be avoided but that's hardly a problem.
This is the sim I posted.
An externally hosted image should be here but it was not working when we last tested it.
Those resonances are very benign, after accounting for the fact that the enclosure is not infinitely rigid, none of those spikes will be there at all. What you are left with is a very minor +/- 1 db ripple above 140 hz. That's not going to be audible.
And even if you have a problem with a +/- 1 db ripple above 140 hz, a very small amount of stuffing will reduce the ripple to LESS than +/- 1 db ripple above 140 hz.
Do you guys not know how to interpret a frequency response graph?
As if LESS than +/-1 db ripple above 140 hz wasn't good enough, TB46 simulated the cab in Akabak as an mltl to optimize port placement, which should reduce the ripple even more. AND he was using a shorter port, so the resonances would be pushed up even higher than 140 hz.
Really, this is beginner stuff. These are not advanced concepts. I'm shocked we are even discussing how ported boxes work and how to interpret frequency response graphs and correlating them to how the finished product would measure.
So now the "organ" guys would like to claim that the only way to produce an organ sound with speakers is to use non ported boxes, and to clump them tightly in a completely randomly placed stack so they can interfere with each other.
Science has left the building.
Now to DrDyna.
I have built sets of enclosures that used the same drivers and were setup using a SPL meter in tests playing the same music.
A few of them at that test were a vented box, a tapped horn with 7 db of gain and a front loaded horn with 8 to 9 db of gain.
They all used the same driver set. 2 pcs 6.5 inch.
Some people liked the sound of the tapped horn. I found it to be quite a bit of added in tone that did not serve the music that was fed into it. The vented enclosure had it's chance and again I used program material that was at the resonant frrquency (25 hertz for all the boxes) or just below the resonant frequency. Tough test for any enclosures.
What people liked about the vented and tapped horns was what they described as the fullness of the sound. What I liked the most about the front loaded horn was the clarity of the sound.
The tapped horn had an enormous case of Glenn Gould humming along with the tune. ( Can't stand that guy)
In the discussion about electronic versus real pipe organ the point was made of the limited ability to play with full stops. I blame that squarely on the problem of compression in the loudspeakers used to reproduce the sound that is generated. Not the method to generate the sound.
The commercial designs that I have designed are all done with a efficiency goal of at least 96 decibels per watt of input. Some of my design work has been on systems that are 105 db/watt. Consistently I have listened to these types of systems and found that their ability to reproduce both dynamic and complex music far outstrips their much less efficient cousins.
This is what I believe is missing in the electronic organ designs I have seen in general.
And again it boils down to bucks and what it cheaply and readily available.
I have built sets of enclosures that used the same drivers and were setup using a SPL meter in tests playing the same music.
A few of them at that test were a vented box, a tapped horn with 7 db of gain and a front loaded horn with 8 to 9 db of gain.
They all used the same driver set. 2 pcs 6.5 inch.
Some people liked the sound of the tapped horn. I found it to be quite a bit of added in tone that did not serve the music that was fed into it. The vented enclosure had it's chance and again I used program material that was at the resonant frrquency (25 hertz for all the boxes) or just below the resonant frequency. Tough test for any enclosures.
What people liked about the vented and tapped horns was what they described as the fullness of the sound. What I liked the most about the front loaded horn was the clarity of the sound.
The tapped horn had an enormous case of Glenn Gould humming along with the tune. ( Can't stand that guy)
In the discussion about electronic versus real pipe organ the point was made of the limited ability to play with full stops. I blame that squarely on the problem of compression in the loudspeakers used to reproduce the sound that is generated. Not the method to generate the sound.
The commercial designs that I have designed are all done with a efficiency goal of at least 96 decibels per watt of input. Some of my design work has been on systems that are 105 db/watt. Consistently I have listened to these types of systems and found that their ability to reproduce both dynamic and complex music far outstrips their much less efficient cousins.
This is what I believe is missing in the electronic organ designs I have seen in general.
And again it boils down to bucks and what it cheaply and readily available.
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