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In the Forum: Horn-Loaded Speakers
In the Thread: Canadian Speaker Proposal
Post Subject: Audio Gravity force and drivers’ integrationPosted by haralanov on: 6/24/2013
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 de charlus wrote:
I propose to array the drivers, and horns, as laid out beneath, from top to bottom;

Ale Acoustics 160Super (15hZ-1000hZ, 110db/w)15hZ - 150hZ Lower bass

Vitavox AK 151 (50HZ-8kHZ, 100db/w)              150hZ - 350hZ Upper bass

Vitavox S2 (200hZ-16kHZ, 110db/w)                 350hZ - 1500hZ Lower mid

Ale Acoustics 45Super (500hZ-20kHZ, 115db/w) 1500hZ - 6kHZ Upper mid

Acapella TW1S (5kHZ-50kHZ, 110db/w)             6kHZ - 50kHZ+ Tweeter

Charlus, maybe you realize it, or maybe not, but you are in the beginning of a very very long journey. The journey could easily be walking in a simple circle (or multiple circles) or a straight road – it all depends on how well you know your inner world. This is more about discovering yourself and much less about applying different audio methods.

First you should learn/discover the simple rules of the game – the rest is how you play with them. With an audio project of this scale, you certainly need to know a lot about human perception – on cultural level and on purely anatomic/psychoacoustic level.  This knowledge comes with listening practice and experimenting with practically everything you could.

Reading the first post of this thread, I see the very typical mistake most of the audio people repeat and repeat – you are determining the crossover frequencies between the channels, thus trying to construct a theoretically correct acoustic system, but you are not trying to create sound. If you try to accomplish some kind of very exact sound, it is impossible to know where your crossover points will be, and also it is impossible to know if a certain driver will meet your requirements. There is no such thing as default sound of a driver – it can sound as anything, depending on how you use it.   
Your strategy is to let your uppermid channel to play in the range 1,5-6kHz, your HF channel from the 6kHz up, and to achieve very good integration of the channels. This is the first difficulty you will meet when starting to experiment. Not because the ALE driver will have different sound signature compared to the Acapella tweeter, but because these two channels have very similar audio gravity forces and each of them will “pull” the sound at its axis, so it will be extremely difficult to focus the sound at the axis of any of them. First of all, I should define what I call “Audio gravity”, because it is very important “parameter”. This is purely psychoacoustic measure of the ability of a certain source of sound to “pull” the sound of the surrounding complementary sound sources. Actually it is not the driver that “pulls” the sound – it is how your brain reacts on the incoming to the ears sound and interprets it as a sound images. I will mention some of the easily understandable rules: the audio gravity is stronger when: 1) the sound of the driver is focused within itself, 2) has extended frequency response towards the UHFs, 3) has relatively mid or big size for better intelligibility, 4) has a correct ratio between sound energy vs. sound amplitude level (!), 5) has extended frequency response towards lower part of the sound spectrum and so on and so on.

Now let see what you have with your predetermined crossover frequency of 6kHz between your upper mid and HF channel. First of all, your ion tweeter has very little energy at 6kHz (not to mention lower than that) compared to its 16+kHz range. You will immediately notice there is some kind of thinness and dynamic efforts in the sound, and you will experience lack of physical density in the sound, which directly relates to the ability of your system to express the musical messages with the required “full breathe” magnitude. You can measure all day long, but you will not recognize the problem by performing measurements – the frequency response will be exactly as you expect it to be, but you will still experience the deficiency of energy in the sound. Second of all, the audio gravity of your upper mid channel is relatively weak. What do I mean by saying that? If you lowpass it at 6kHz, let say it has 10 Cockooricones of audio gravity force. Allowing it to play up to 10-11kHz will raise its gravitational “pull” not with 200%, but with 400% and then it will have 40 Cockooricones of psychoacoustic pulling force and now there is much higher chance to successfully pull the sound of the HF channel at its axis.  But keep in mind this is a very simplistic type of integration success – to adjust the adjacent channels to appear like a focused source of sound. Usually this is where most of the audio people stop (if they ever achieve it). The much higher level of integration is the super structural integration - it affects the inner structure of the sound – I have never heard commercial loudspeakers which have it. This type of integration is only possible when using a main channel having very high audio gravity, which is positioned on a virtual center of audio gravity, formed by several drivers with very low gravity force. Each of these channels should have clear (the reverse of foggy or blurred) but very diffused/unfocused within itself type of sound and it must not have a focused center, because otherwise it will immediately multiply the amount of the Cockooricones.

Audio gravity.JPG

Another important requirement for these surrounding channels is none of them to sound physically shallow (for example most of the direct radiating cones sound very shallow, just like a drivers in the air – they sound like sound efforts and not like flowing music) and it must have depth. I mean depth as a dimensional property, not as a frequency response depth. When you succeed to accomplish/build that type of sound, then the effect of integration will gratify you with some audio properties you haven’t met at the audio shows. One of those properties is the very convincing illusion of physical density and solidity of the sound images. The sound images will became so solid, that if you throw a stone at the sound image, when the “stone” “hits” the “target”, it will not penetrate through the image, but will bounce back. This is exactly the opposite effect of the ghosty sound images that most of the so called high end systems produce. I know it is slightly stupid example, but it is a correct example of what happens when you hit this level of integration.

So if you want to build a serious sound in your home, one of the many many things you should reconsider is how to use your Acapella ion driver and to spend some 5-10-30 years until you find a way how to eliminate your HF channel and to build an upper mid channel that does not need a tweeter support to sound as there isn’t something missing in it.  Hell, I have to stop writing – I haven’t said a word about the musical aspects, and this is a veery deep ocean. I hope you already read the threads in the “Playback listening” section…

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