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Multi-Way Conventional loudspeakers with crossovers

How to design a dipole surround speaker
How to design a dipole surround speaker
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Old 29th October 2013, 07:33 PM   #11
Juhazi is offline Juhazi  Finland
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Baldin, I sent you email
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Old 30th October 2013, 04:50 AM   #12
Okv is offline Okv  Norway
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Quote:
Originally Posted by Baldin View Post

Okv: do you have some pictures of your speakers? And would you share a bit more on the construction and how they measure?

Best regards Baldin
Of course, but it will have to wait until the design is published, and I don't work that fast..

One complete surround speaker consist of two units, with drivers angled outwards, and the angle depends on the configuration.
Generally, they measure very linear on-axis from one unit, and not that bad in wide cfg with both units.
Off-axis is also quite nice, but boundary reflections when mounted on to a wall will always affect the response of such designs.
Compromises need to be made when the same units are configurable to three quite different radiation patterns, and I have focused on getting the more normal wide cfg to be the best, in bipole and dipole there will be so large contributions from room reflections anyway, so that it is really most important to get the power response reasonably right.
And usually the listening position will be lower than the speaker, so that you listen off-axis vertically as well, which means the hf will roll of some.
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Old 30th October 2013, 05:18 AM   #13
Okv is offline Okv  Norway
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Found some fr plots, these are in-room at lp vertical 1m off ground, speakers mounted higher, 2.7m distance wide cfg (brown), 2m bipole (on-axis and 30 deg off horisontal, the other colours), 2m dipole (30 deg horisontal, green).

How to design a dipole surround speaker-s1_2-wide-bipole-bipole_h30-dipole_h30-png
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Old 3rd November 2013, 02:24 PM   #14
Baldin is offline Baldin  Denmark
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Originally Posted by Okv View Post
Of course, but it will have to wait until the design is published, and I don't work that fast..
So it will be a commercial speaker ... not just DIY?
Looks really good.


Anyway just came back from the yearly HiFi and Sourround exhibition in Copenhagen. The show is getting smaller and smaller each year, and fewer end fewer people attend …. Belonging to a dying race!

Best / most impressive sound was a set-up with MK sound and Datasat. Processer was the professional RS20i, used in many large cinemas, and the power amp was the 7 x 300 W RA7300. Source was Oppo. … so the front end of business was up to spec …..
The speakers was a new series, which I can’t find on their web site (MK sound). Couldn´t get a good picture as the front speakers was placed behind the screen, but they told they are now equipped with Scan Speak units, and MK is now on Danish hands and produced in DK!!!
The surrounds was also new, but based on their Tripole principle.
As for bottom it was delivered by 3 x X12 (meaning in all six 12” speakers )

The sound was simply stunning …… dynamics where through the roof, the sound simply just clear! ……… If I just had that kind of money

But back to the surrounds. The setup was 7.1 and all 4 surrounds was tripole. The sound was both diffuse, but with clear direction when panning the sound. But when playing the old THX trailer with the little guy repairing the back speakers, it was actually a little harder to follow him around than I have heard in the cinema! So I think, no matter what the concept is, monopole, dipole, tripole or something else … there will always be compromises. I didn’t have the possibility to hear any music on the system, so can’t say anything about that.

So how do they do this tripole thing??
Normal dipole on the sides, and I guess normal monopole on the front, but lowered some not to be too noticeable.
Wonder how a polarplot would look …. 3 distinct lopes, at least in the mid frequencies??

Anyone know more about these tripoles??

Baldin

PS. Would love to see more about your project Okv
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Last edited by Baldin; 3rd November 2013 at 02:28 PM.
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Old 4th November 2013, 03:37 PM   #15
Baldin is offline Baldin  Denmark
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Quote:
Originally Posted by Okv View Post
Found some fr plots, these are in-room at lp vertical 1m off ground, speakers mounted higher, 2.7m distance wide cfg (brown), 2m bipole (on-axis and 30 deg off horisontal, the other colours), 2m dipole (30 deg horisontal, green).

How to design a dipole surround speaker-s1_2-wide-bipole-bipole_h30-dipole_h30-png
Hi Okv

Just to understand the measurements corretly. do you measure 90 degrees out from the wall ... that is pointing to the front of the speaker? ... this is what you call on axis, right?
And the 30 degree off axis is 90 - 30 = 60 degree off wall.

You measure with the speaker mounted on the wall, and mounted higher the the 1m high listening position.


The curves are more similar than I would have thought. You didn't measure dipole on axis (where you would expect a null for at least some frequencies).

When you run in wide configurations, are all 3 speakers connected in phase then?
Are all 3 "sides" the same (1 way / 2 way)?

BR Baldin
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Last edited by Baldin; 4th November 2013 at 03:40 PM.
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Old 8th November 2013, 04:00 PM   #16
Baldin is offline Baldin  Denmark
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Very old but still interesting to some degree .... and measurements
http://www.soundandvision.com/conten...iguration-wars
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Old 8th November 2013, 04:17 PM   #17
Baldin is offline Baldin  Denmark
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Default Visaton ARIA Dipol 1

Information on the Visaton Dipole surround kit ARIA.

The speaker can run in mono- or dipole ..... but it's only the high frequency running in dipole ....
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Old 8th November 2013, 05:04 PM   #18
Baldin is offline Baldin  Denmark
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Interesting article .... not sure I agree with the conclusion, but it contains some interesting measurements:
Loudspeakers: Objective evaluations - Part 4: Measurements of real-world consumer loudspeakers | EE Times

Interesting is though to see that the power spectrum of different dipole designs looks quite ok ....
It is also clear to see that the 5 different speakers are of quite different desing ..... wonder which would sound best .... what pattern to go for ..... probably b or d ........
... not sure how listening window is defined ... sure this measurement angle sows a lot of combfiltering .... which would also be expected
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Last edited by Baldin; 8th November 2013 at 05:08 PM.
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Old 8th November 2013, 05:28 PM   #19
Juhazi is offline Juhazi  Finland
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On the next page of that series Floyd Toole says that a CBT (horizontal?) is nearly perfect surround peaker

Loudspeakers: Objective evaluations - Part 4: Measurements of real-world consumer loudspeakers | EE Times
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Old 9th November 2013, 01:15 AM   #20
Okv is offline Okv  Norway
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Quote:
Originally Posted by Baldin View Post
Hi Okv

Just to understand the measurements corretly. do you measure 90 degrees out from the wall ... that is pointing to the front of the speaker? ... this is what you call on axis, right?
And the 30 degree off axis is 90 - 30 = 60 degree off wall.

You measure with the speaker mounted on the wall, and mounted higher the the 1m high listening position.


The curves are more similar than I would have thought. You didn't measure dipole on axis (where you would expect a null for at least some frequencies).

When you run in wide configurations, are all 3 speakers connected in phase then?
Are all 3 "sides" the same (1 way / 2 way)?

BR Baldin
On-axis means 90deg off the wall, yes.
30 degrees off then means 30deg from on-axis, or 60deg from the wall surface.

The dipole measurement on-axis, in the null, will still show a frequency response not very different, due to room contribution - the measured response will be more like the power response.

Anechoic, or gated, measurement on-axis of the dipole shows the expected null - a very significant reduction.

These are full-range dipole, which means the bass level will be reduced in dipole mode, as the measurements show.

In all other modes (wide, bipole) all drivers are in phase, in dipole it acts like two similar speakers out of phase.

For a surround speaker, I am quite happy with the results for these speakers.
Computer simulations allowed for a significant reduction in development time, did the crossover adjustments in basically less than a week.
If this was to be an ordinary speaker intended for on-axis listening it would have a very flat on-axis frequency response.
The crossover is likely the most expensive part of the speaker, the drivers does not cost much.

If they will ever go into production I can not say now, even though the parts are not very high cost, they will be rather expensive surround speakers.
I will present the design, and then it will be easier to see how it is done, at least you can use it as an example and inspiration.

A surround speaker is not very critical - dimension for whatever SPL you need, build it, test, and if it performs well, good, if not, make some adjustments until it is good enough.

As you mention - it is easy to get the impression that the whole industry is dying, and if so, I blame the media industry - you have to go back to 80ies recordings to get good sounding music, and now they continue the destruction on movies, with low-frequency filtering, clipping and dynamic compression. No one needs a proper sound reproduction system to listen to flat and distorted noise.
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