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Multi-Way Conventional loudspeakers with crossovers

In Pursuit of a 20-20k Dipole Loudspeaker
In Pursuit of a 20-20k Dipole Loudspeaker
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Old 12th June 2019, 03:48 PM   #311
bentoronto is online now bentoronto  Canada
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In Pursuit of a 20-20k Dipole Loudspeaker
Quote:
Originally Posted by CharlieLaub View Post
Well, but what about all that "bouncing around"? Well, now you are talking about something different: the influence of the room. This is a completely different issue to tackle and has nothing to do with the source - it's two decoupled problems, really. So "bouncing around" has nothing to do with how a dipole source radiates sound and the roof effect is not the subject of this thread. Likewise, you will get about the same amount of "bouncing around" whether you have a monopole or dipole source.
Pardon me, I didn't realize this thread was only about listening to music in anechoic chambers.

B.
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Last edited by bentoronto; 12th June 2019 at 03:53 PM.
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Old 12th June 2019, 04:22 PM   #312
bentoronto is online now bentoronto  Canada
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In Pursuit of a 20-20k Dipole Loudspeaker
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Originally Posted by Neil Davis View Post
I could never bring myself to finish this project, because...
Sounds like some of my old projects.

But for the simple four test runs, just a matter of connecting ordinary base-band audio signals to the woofers. Since nothing but freq response matters, almost any amp can be used.

B.
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Old 12th June 2019, 04:35 PM   #313
CharlieLaub is offline CharlieLaub  United States
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Quote:
Originally Posted by bentoronto View Post
Pardon me, I didn't realize this thread was only about listening to music in anechoic chambers.

B.
No, sorry, that was not my intended point.

I consider the design of the loudspeaker, and the consideration of how a particular room will influence the sound from the loudspeaker, to be to completely separate problems. As a result, I design a loudspeaker and measure it under quasi-free-field (2pi space) conditions. One is always able to add EQ or room correction later, and no two rooms are alike.
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Old 12th June 2019, 08:46 PM   #314
Gerrit Boers is offline Gerrit Boers  Netherlands
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Quote:
Originally Posted by CharlieLaub View Post
YES! I find that really cool, actually. In one of my prototypes I rotated the speakers outwards so that the 90deg null pointed at the listening position so that I was only hearing the reverberant field. Wow.

I find that with a real dipole type loudspeaker I can walk around to the side and in between the speaker and hear a very consistent sound.
Indeed, same here. The timbre does not change when I walk around the loudspeakers, or the room for that matter. A direct result of the constant directivity of a real dipole as opposed to a generic open baffle system.
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Old 13th June 2019, 08:53 PM   #315
kgrlee is online now kgrlee
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Quote:
Originally Posted by CharlieLaub View Post
I thought I would show the responses I measured previously with the driver hanging by wires and away from boundaries, for the drivers that I plan to use in my 3-way dipole system (e.g. a stereo SWT arrangement, with S=Subwoofer, W=Woofer and T=Tweeter).
I see 9 curves in each of your 3 measurement pics. Are these at 10 degree intervals from on-axis to 90 degrees?

Are these measured in a room? If so, could you post a diagram of the room dimensions (including height) and exactly where the dipole & mike were place? Did you rotate the speaker?

What software are you using?
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Old 13th June 2019, 09:25 PM   #316
bentoronto is online now bentoronto  Canada
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In Pursuit of a 20-20k Dipole Loudspeaker
Just to introduce some data into the discussion, see:

Subs with reversed polarity (surprise!)

Naive to think EQ fixes rooms, maybe a bit... at least until you move your measurement mic a few inches and find you got it all wrong. Likewise for the reductionist model: why not start by studying dipoles in vacuums. Then add air, then add rooms, then add the preferences of the listener. As the link above shows, real gap between understanding a dipole in the abstract and making a speaker that sounds good in your room, Linkwitz Transform or not.

B.
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Old 13th June 2019, 10:08 PM   #317
CharlieLaub is offline CharlieLaub  United States
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Quote:
Originally Posted by kgrlee View Post
I see 9 curves in each of your 3 measurement pics. Are these at 10 degree intervals from on-axis to 90 degrees?

Are these measured in a room? If so, could you post a diagram of the room dimensions (including height) and exactly where the dipole & mike were place? Did you rotate the speaker?

What software are you using?
This was a large, 2 story high room in my previous home. So it might be 30x30 and 20 feet high. I was able to get about 50Hz resolution on my measurements. It helps that dipoles do not radiate much energy down towards the floor, so the floor reflection is minimal.

I set up the drivers between a couple of PA speaker posts, between which I ran a piece of wood. The drivers were hung by wires from the piece of wood. Then I marked out angles on the floor using tape. I use a rudimentary system where I can easily mark out 0-45-90 and then I fill in between those at 22, 66 and then in between those at 11, 33, 57, etc. I don't find a need to be any more precise.

If you hover over each image you should be able to see the filename in the browser at bottom and that is descriptive regarding angle and so on.
Attached Images
File Type: jpg IMG_2854.jpg (588.3 KB, 85 views)
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Old 13th June 2019, 10:15 PM   #318
kgrlee is online now kgrlee
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Originally Posted by [B
Gerrit Boers[/B] Click the image to open in full size. ] The front-back cancellation is clearly audible with my system. Standing between the loudspeakers facing the side of one there's no sound emanating from the loudspeaker, you only hear the reflections from the side(front and back wall), it's a strange sensation.
Quote:
Originally Posted by CharlieLaub View Post
I find that with a real dipole type loudspeaker I can walk around to the side and in between the speaker and hear a very consistent sound.
In post #250 I show a pic of the Listening Area for good stereo with Option 1.

But in fact, the Listening Area actually covers more than the back 2/3 of the whole room .. including the areas OUTSIDE the 2 dashed lines which are the Nulls of the 2 dipoles.

Outside the 2 lines, you have a clear impression of a large door to a performing space defined by the speakers with a performance happening inside. When you move across the line, the impression isn't that you have moved in front of the door. Instead the aural impression is as though you have moved through the door INTO the performing space.

There's more of what you will HEAR in the Option 1 User Manual. As I said, there is only slight Marketing BS. The descriptions of what you HEAR are pukka.
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Old 13th June 2019, 10:16 PM   #319
CharlieLaub is offline CharlieLaub  United States
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Well, let's see what you are up to Ben. Here's your report "with data" from the thread you started today:

Quote:
Originally Posted by bentoronto View Post
It is an Article of Faith that polarities must be preserved. And for dipoles, that the phase annihilation diagram for woofer frequencies in the textbook is an Eternal Truth.

On the other side, anybody with experience fooling with phase and even with polarity and certainly with dipoles, knows that the sound hits walls and is in a multiple of ways shaken from its phase locksteps.

So I figured there's a real simple way for a person with a Behringer DCX2496 - the all-singing all-dancing DSP - to explore the notion with about 6 button presses of the DSP box.

The subs are in the front corners of the room. L is a 5-cu ft sealed box and the R a 17-foot labyrinth. Both with some EQ. A mic was placed mid-way between the subs and near my listening chair. The REW sweep is 10-500 Hz (OK, 10 Hz is pushing it a bit with my 1980 JVC receiver amp, but you can see for yourself what the mic picks up).

The first illustration shows the (1) L and (2) R traces when run separately. Many similarities are reflections of the room (literally, of course).

The second illustration shows the (1) R sub trace and the (2) R sub with polarity inverted trace. Many readers will notice a certain overlap.

The third illustration shows results when (1) both subs are running and when the (2) R sub is inverted. Needless to say, the reversed trace is the lower one. But not annihilated. Far from it.

The fourth illustration repeats the inverted trace shown in the third illustration. Funny, it looks so much better than the non-inverted trace. Maybe I'll raise the volume control and keep that. I bet just the thought of somebody doing such a thing would cause indigestion among many members here.

B.
You little experiment has absolutely nothing to do with a dipole or dipole source. According to what you wrote, you just tossed some subs into the corners of the room:
Quote:
The subs are in the front corners of the room
and you reversed the phase of one of them. Then you did "in room" measurements. Is it any surprise you are measuring the room response here, and nothing much about the sources themselves? Did you even bother to do any gating? What made you think that two subs in the corners with one having reversed phase is anything like what I am doing with dipoles???

When you have something that resembles a dipole source set up, and can figure out how to make some proper measurements, let us know.
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Old 13th June 2019, 10:24 PM   #320
CharlieLaub is offline CharlieLaub  United States
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Quote:
Originally Posted by kgrlee View Post
In post #250 I show a pic of the Listening Area for good stereo with Option 1.

But in fact, the Listening Area actually covers more than the back 2/3 of the whole room .. including the areas OUTSIDE the 2 dashed lines which are the Nulls of the 2 dipoles.

Outside the 2 lines, you have a clear impression of a large door to a performing space defined by the speakers with a performance happening inside. When you move across the line, the impression isn't that you have moved in front of the door. Instead the aural impression is as though you have moved through the door INTO the performing space.

There's more of what you will HEAR in the Option 1 User Manual. As I said, there is only slight Marketing BS. The descriptions of what you HEAR are pukka.
Although that is an interesting (but definitely plausible) way to set up a dipole loudspeaker, that is not how I generally do it. Instead I position the speakers in the usual way, with drivers facing the listener and away from the rear wall by at least 1-1.5m and away from the side walls by 2m if possible, but at least by 1m from each wall. I do not like to toe the speaker inwards.
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