Speaker arrays

I'm thinking about building an eight speaker array for a particular project. It's quite easy to get the specifications for individual speakers but less easy for me to find out how they react to the presence of other inductors (ie the other speakers in the circuit). Has anyone any practical experience of speaker arrays? In your opinion do you get better low-pass characteristics from series, parallel or series/parallel configurations? I realise I could just build them and then suck it and see but I wondered if anyone had any thoughts about the matter?
Nick
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Have a google for "Bessel arrays" of speakers.
In short: Speakers can be arranged in series and parallel so that the resulting coefficients (+1, -1, +1/2, -1/2) lead to high power, radial sound distribution, and reasonable price.
Worth looking at and even trying, just a bit of soldering....
Thomas Prufer
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On Thursday, 28 January 2016 12:32:11 UTC, Nick Odell wrote:

I can't see any way that there would be any difference.
NT

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On 28/01/2016 12:32, Nick Odell wrote:

You could ask the Koreans :-)
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Nick Odell wrote:

I have no practical experience but my instinct would be to arrange *nine* speakers in a series/parallel arrangement that presented the same impedance to the amp as one speaker. If it has to be eight speakers, I'd consider adding a dummy load to make up the number.
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On 28/01/16 15:22, Mike Barnes wrote:

Its not clear what the OP is trying to do. A Marshall 4x12 was always series parallel. tow of those in paralell makes an 8x1`2.
BUT a Marshall 4x12 isnt the 'closest approach to the original sound' cos there IS no original sound, apart from an uamplpified guitar string and its as uninteresting as hell.
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On 28/01/16 12:32, Nick Odell wrote:

In general arranging units in paparellel is considered the best as that preserves low frequency damping and means if one blows they both dont go out.,
As far as crossover design goes, don't be too prissy. a single LC and possibly a senstivity matching R is fine per filter and wont give you excess phase shifts to worry about. You are not trying to produce ideal filter shapes, just getting HF out of bass units and vice versa. Its more inporatant not to drive LF energy through tweeters, and a series cap is enough for that, but you can stick an L across them as well.
Singlee LC with Q of about 1 is close enough

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On Thursday, 28 January 2016 15:52:57 UTC, The Natural Philosopher wrote:

if the units are identical, series does too. They both see half the v at all times. If units aren't identical it's a different matter.
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On 28/01/16 17:45, snipped-for-privacy@gmail.com wrote:

its not the v. Its the impedance they see.
You are totally wrong, because you have completely missed the point.
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On Thursday, 28 January 2016 17:48:58 UTC, The Natural Philosopher wrote:

OK lets try this again.
Let's imagine speaker impedance drops to 1R at resonance (it won't IRL), and the amp's delivering 1v to a single speaker. That speaker gets 1A. Now imagine 2 speakers in series on 2v. Impedance is 1R each, so each speaker gets 1A again. IOW putting 2 identical speakers in series has no effect on their damping. I'm assuming you are familiar with what damping is.
The same happens when impedance rises, each series speaker still sees the same voltage, current & phase - and does so at every frequency. And that dictates damping.
NT
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On 28/01/2016 18:00, snipped-for-privacy@gmail.com wrote:

Which is totally correct.
Cheers
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On 28/01/16 18:06, Syd Rumpo wrote:

Which is totally incorrect.
I was a professional audio designer for many years. I do know you know

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On 28/01/2016 22:48, The Natural Philosopher wrote:

Conventional wisdom isn't always right. Look at it from the POV of one speaker in series with an identical speaker both experiencing the same displacement. Do a spice simulation if you like. Google it too.
I tried "damping in series speakers" and the first hit was...
http://www.cartchunk.org/audiotopics/SeriesSpeaker.pdf
You're wrong. That's not a sin, it happens.
Cheers
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On 28/01/16 23:33, Syd Rumpo wrote:

My whole point is they are not experienceing the same displacement.
Do a spice simulation if you like. Google it too.

I'm not wrong on this
He has made exactly the same wrong assumption as you have, and his test - putting two completely separate loudspeakers in series, is not the same as putting owo driver units in a shared air space.
As I said, if you took a loudspeaker and notionally cut the coil into two pairs, but left them wound on the same former, then you have 'two coils in series' connected to a common cone and of course its trivial; to say that the single loudpseaker coil is in fact two coils in series, notionally.
That is what you and he do. In essence.
MY point is that that stops working the moment the two coils are NOT on the same mechanical former and connected to the same cone.
The possibility of differential movement exists, and the whole assumption you and he use to 'prove' the case is no longer valid.
Connecting te speakers in antiphase in series in an infinite baffle would be the most extreme example of 'these loudspeakers no longer move as a single unit with 'half the voltage' across one or the other at resonsance.

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On 29/01/2016 09:40, The Natural Philosopher wrote:
<snipped>
They're motors with back emf. If they're identical with identical loads, then in a series connection both will see the full damping of the amplifier output.
I think you're saying that they're not seeing identical loads, because nothing real can ever be identical. This is backtracking while dancing on the head of a pin.
Look at it this way. The speakers are equal, and working together for the common good, pushing and pulling in harmony. Socialism in action.
Cheers
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On 29/01/16 10:10, Syd Rumpo wrote:

Its not, its very very real in terms of damping, because damping is exactly about what mechanical resistances the loudspeakers are involved in.
Which is why the 'only electrical' analysis gets the wrong answer.

well exactly, and as we all know, socialism in action doesn't work.
What I am really saying is that the electrical analysis alone does not provide the correct picture. The mechanical issues are relevant.
The cones are NOT mechanically coupled. The loudspeakers do not see the same mechanical load, especially when they are asymetrically situated in a cabinet.
Two electric motors in series do NOT work the same as two electric motors in parallel, This was an issue that came home to me years ago in analysing why two electric motors in series did not spin two model aircraft propellors at anything like the same speed. As the motor with a bit more load slows down, the voltage across it drops, and the voltage across the other motor rises, exacerbating the difference.
The current, and therefore the torque, is the same, but under different loads the torque being constant doesnt keep the motor speeds as near constant as having the same voltage across both motors - i.e. in parallel.
In the 'theoretical ' case of 'identical ' motors and propellors, it doesn't matter. In practice people found their twins trying to fly in circles..
worst of all, if one motor gets stopped the other one instantly burns out....

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On 29/01/2016 10:41, The Natural Philosopher wrote:
<snip>

Obfuscation and side-stepping. I used 'motor' in the scientific sense, in this case a voice coil actuator, but you knew that.
I'm done.
Cheers
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Syd

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On Fri, 29 Jan 2016 11:04:13 +0000, Syd Rumpo wrote:

I can't say I blame you for 'quitting' in this case. BTDTGT(Bloody)TS (& the Celebratory Mug) when I felt impelled to set him straight, a year or two back, on the basics of balanced line transmission circuits as used by the telephony industry and applied elsewhere in things like firewire and SATA interfaces to name but two examples from a much wider remit.
He appears to largely understand the physics of the real world but with the odd misconception thrown in here and there which, despite all reasoned arguments designed to dispel such misconceptions, he seems to prefer to ignore or side track rather than re-appraise. His attitude appears to be at odds with his chosen nom de plume.
As you pointed out, being wrong (of itself) is not a sin. Only when one is being *wilfully* wrong does it *then* become a sin. I'm afraid TNP can be rather sinful at times. :-( It's a pity really because he's generally right about most things technical most of the time and he *does* offer reasoned arguments against the railings of the eco-bollicks, anti-nuclear brigade, a character trait I wholly support. :-) There are plenty of others who post to this news group with far worse character flaws than getting stuck on an erroneous or irrelevant "technicality".
--
Johnny B Good

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On 02/02/16 21:39, Johnny B Good wrote: I'm afraid TNP can

But this time, I am 97% sure I am correct in this.
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On Wed, 03 Feb 2016 09:15:09 +0000, The Natural Philosopher wrote:

Doesn't that 3% of uncertainty impell you to research other experts' findings such as the excellent article linked to by this:
<http://www.cartchunk.org/audiotopics/SeriesSpeaker.pdf
Which Syd so obligingly located?
I have to say the author, Dick Pierce, puts, what seems so blindingly obvious to me, very eloquently indeed. If you haven't already done so, have a read and digest the argument he sets out. If you can see any flaw in this article, then you should at least be able explain where he has gone wrong.
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Johnny B Good

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