Triangular speaker cabinets.

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Daniel Quinn
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#31 Re: Triangular speaker cabinets.

Post by Daniel Quinn »

pre65 wrote: Thu Apr 20, 2017 1:17 pm Re standing waves Daniel, how do you like the sound of them on any of your speakers ?
Ive only quoted the bit that is not meaningless .

I have no idea . The theory says , my speakers will have standing waves , yet they are the best I have heard : Go figure .
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#32 Re: Triangular speaker cabinets.

Post by pre65 »

Daniel Quinn wrote: Thu Apr 20, 2017 1:20 pm

I have no idea . The theory says , my speakers will have standing waves , yet they are the best I have heard : Go figure .
Good for you. :)

Do you imagine your speakers might sound
A) Better

B) Worse

C) Different

D) No difference


If you had diffused standing waves ?

*
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#33 Re: Triangular speaker cabinets.

Post by Daniel Quinn »

Diffusing standing waves the theory says in box shaped enclosures is achieved by internal wadding .

I am 100% certain anybody who listened to them would prefer then without wadding and I have tried everything available .

Wadding is said to damp reflections , it doesn't it attenuates and attenuates unevenly across the frequency spectrum . The sound in preferable without wadding .
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#34 Re: Triangular speaker cabinets.

Post by pre65 »

So, does steel plate make for more reflections ?
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#35 Re: Triangular speaker cabinets.

Post by Daniel Quinn »

How do I know , I don't believe the theory and listen with my ears .

you know a way to measure it :bounce:
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#36 Re: Triangular speaker cabinets.

Post by Nick »

Look, its very simple. The world is not simple, making things are not simple, things are complex.

To attempt to understand the complex world, we have to abstract. By abstracting we reduce the size of the problem to the point where we can start to derive hypothesises as to the actions that are happening in reality (which cares not a jot about what we think about it). This process of abstraction and subdivision leads to the possibility of understanding and prediction, and we can then synthesize these individual abstract models together and produce a thing, which hopefully will perform in the way we expect. If it does, it lends strength to the hypotheses that were used in its design, if not, it causes us to question them further. In the case of a loudspeaker, there are many things taking place at once, we can't hope to understand them as a gestalt, so we (as described) abstract. We know, that changing the shape of a flat surface will alter how that surface will vibrate when a exciting force is applied, and we can make predictions about that, and that’s what Scott did, he made a observation based on the expected behaviour of a small part of the entirety of a loudspeaker.

But to then ask "what does that abstraction" sound like, has little or no meaning, as its its only when its combined with all the other models each of which will have its own set of choices giving rise to causality towards the final object, that we arrive at a object that can "make sound".

The real world is complex.
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#37 Re: Triangular speaker cabinets.

Post by cressy »

What is a standing wave? As I understand it (in my limited understanding) it is a pressure? Wave inside the box that bounces off the interior panels and doesnt come out of the port.
Instead, it interferes with those that do come out, altering thir energy by adding some of its own or taking some of theirs away. It hits the panels and causes them to vibrate, adding this vibration to the signal that the speaker is trying to reproduce.
In a straight box, they produce a fruquency based on the distance between the panels they hit.
In a tapered box, they will disperse as the box sides where they hit are not at the same angle so they will reflect and hit a different point on the opposite side, changing the wavelength of the pressure? Wave.
Thus the energy it initially carries is dispersed into the air inside, and doesnt excite the panels in the same way

Im sure I will be corrected
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#38 Re: Triangular speaker cabinets.

Post by pre65 »

Daniel Quinn wrote: Thu Apr 20, 2017 1:38 pm How do I know , I don't believe the theory and listen with my ears .

you know a way to measure it :bounce:
I don't, but there may be ways.

I use open baffle speakers, and one thing that most people notice is how you don't hear the box. So the "box" of any sort must have an effect ?

Perhaps steel plate gives stronger reflections which might (or might not) reinforce the sound you hear at some (or all) frequencies ?

This is where measurements might tell you something.
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#39 Re: Triangular speaker cabinets.

Post by Nick »

Diffusing standing waves the theory says in box shaped enclosures is achieved by internal wadding .
Yes, but preventing standing waves forming can be achieved by avoiding a single (or harmonic sequence of) frequencie(s) at which the space in the speaker can resonate.
I am 100% certain anybody who listened to them would prefer then without wadding and I have tried everything available .
Does that everything include non parallel sided enclosures?
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#40 Re: Triangular speaker cabinets.

Post by Daniel Quinn »

Nick wrote: Thu Apr 20, 2017 1:41 pm Look, its very simple. The world is not simple, making things are not simple, things are complex.

To attempt to understand the complex world, we have to abstract. By abstracting we reduce the size of the problem to the point where we can start to derive hypothesises as to the actions that are happening in reality (which cares not a jot about what we think about it). This process of abstraction and subdivision leads to the possibility of understanding and prediction, and we can then synthesize these individual abstract models together and produce a thing, which hopefully will perform in the way we expect. If it does, it lends strength to the hypotheses that were used in its design, if not, it causes us to question them further. In the case of a loudspeaker, there are many things taking place at once, we can't hope to understand them as a gestalt, so we (as described) abstract. We know, that changing the shape of a flat surface will alter how that surface will vibrate when a exciting force is applied, and we can make predictions about that, and that’s what Scott did, he made a observation based on the expected behaviour of a small part of the entirety of a loudspeaker.

But to then ask "what does that abstraction" sound like, has little or no meaning, as its its only when its combined with all the other models each of which will have its own set of choices giving rise to causality towards the final object, that we arrive at a object that can "make sound".

The real world is complex.
I agree with all this totally , it is the reason why quoting theory to answer questions is silly and largely meaningless and is the reason why just doing is best . Because by definition if you use theory to justify your speaker construction choice , you are necessarily abstracting to a point were it becomes useless .


You also appear to be missing my point , my point was to highlight theory is nonsense by and large for DIY speaker builders.

I accept all boxes have a sound .
my room is not big enough or ugly enough to investigate OB'S , you need wide baffles and large drivers
I have no idea if I placed my drivers in a none parralell box if they would sound better

I like my speakers , i have no desire to change or modify them .
Last edited by Daniel Quinn on Thu Apr 20, 2017 2:00 pm, edited 1 time in total.
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#41 Re: Triangular speaker cabinets.

Post by Nick »

How do I know , I don't believe the theory and listen with my ears .
I would be interested to know what other organ you might listen with.

However, a theory does not require belief, it however may require understanding. Understanding is normally a harder task than memorising the text of a theory.

As always there is a Feynman quote "There's a big difference between knowing the name of something and knowing something."
you know a way to measure it :bounce:
Assuming thats a question, yes, there is a way to measure it, but it wont in itself tell you what you want to know.

BTW, I agree, in practice quoting theory is not a way to answer a question, but sometimes there are no ways to answer a question other than "go and learn the science and engineering". That doesn’t make for what looks like a useful answer (but in fact is). The biggest problem with the sort of question Phil asked is that the question itself is not well defined. If it was well defined, the process of defining it would have produced the answer.
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#42 Re: Triangular speaker cabinets.

Post by Scottmoose »

'What do standing waves sound like'

A question that demonstrates you have not the first conception of what you are talking about, Daniel.

If you are asking about 'sound', then your question should be what the effects of standing waves 'sound like', which if you had even the slightest understanding of the subject, you would know varies depending upon the specifics, i.e. the enclosure, its dimensions, those of any vents present, and the type of damping employed when relevant.

I have told you what happens. In the case of a 'regular' vented box derived on a Helmholtz basis, unwanted standing waves cause an unintended and undesired spike or spikes in output, the delayed output of which relative to the direct output from the driver causes destructive interference and a null in the response at that frequency. What that will 'sound like' is dependent upon the frequency and the severity of the null[s], and to a point the hearing of the person or persons listening. Please note that this is not 'theory': it happens, is well-understood, easily demonstrated in both measurements and listening, has been for decades (and stretches back to Ancient Greece), and is a key factor involved in developing many loudspeakers.

Similarly, a standing wave in a sealed enclosure can prevent the driver from oscillating as it is supposed to (i.e. according to the signal fed to it, not its own lights) due to the additional load that is placed on the powertrain. The same remarks as above apply to what it will 'sound like', and your claims that this is 'theory'. No. It happens, is well-understood, easily demonstrated in both measurements and listening, has been for decades, and is a key factor in developing many loudspeakers.

Your constant refrain of 'you only quote theory' is starting to get very silly indeed. Wrong. Laughably so. For your information I started out designing and building transmission lines, QW variations. horns etc. and am probably best known for developing such enclosures, as for very obvious reasons is Martin King, who occasionally drops by here, and Steve, who designed the Metronomes. So we know what the acoustic results of standing waves are like, on enclosures of these types, and on the behaviour of more conventional enclosure types. People like Martin, and in a less formally mathematical way Ed, Steve and myself, work with this on a regular (daily) basis. So, if you want to exhibit a 'superior' attitude Daniel, you would be well advised not to attempt it with people who actually know a lot more about the matter than you do.
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#43 Re: Triangular speaker cabinets.

Post by pre65 »

I think that the Doc mods are probably a positive thing to do with old speakers, potential gains with little financial outlay.

But, if you were wanting to build a speaker from scratch, where would you start ?

Some form of "theory" (my definition not Daniels) would establish parameters for the cabinet size, and things like the "golden ratio" might help to get the panel dimensions right.

I asked Richard for advice on this project, and he had not a clue, but why should he ? Do I spend 20 years pissing about with hundreds of possible alternatives, or do I turn to someone like Scott who would investigate the problem and use the data available to him to suggest a good starting point ?

To me, all the information available is of value in these instances. There will still be an element of AOT to get the final subjective result though, but we all know that, don't we.
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#44 Re: Triangular speaker cabinets.

Post by Scottmoose »

Nick wrote: Thu Apr 20, 2017 1:47 pm
Diffusing standing waves the theory says in box shaped enclosures is achieved by internal wadding .
Yes, but preventing standing waves forming can be achieved by avoiding a single (or harmonic sequence of) frequencie(s) at which the space in the speaker can resonate.
Right. The total amount of energy in the enclosure is the same, but it's spread over a wider range of frequencies. Hence the use of Golden or another acoustic ratio in many enclosures (and rooms, a la Cardas's room setup / proportion guide, which is quite effective), or diffusers.

The ideal is to use the minimum quantity of damping necessary in an enclosure (for a given alignment / goal) while also avoiding undesirable colourations.
Last edited by Scottmoose on Thu Apr 20, 2017 2:13 pm, edited 1 time in total.
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#45 Re: Triangular speaker cabinets.

Post by Daniel Quinn »

As always you are the voice of reason Nick and I find little I can disagree with.

However , your wisdom to my mind does not negate my point .

So lets redress the question . I want to make some Triangle shaped boxes to place my drivers in ,these drivers are currently in a box shaped enclosure. I will keep the volume the same . Is the best answer to this question .

1] it will reduce standing waves and aid stereo image due to different diffraction characteristic and would thus give a preferable sound .

2] or i do not have a bloody clue , try it and tell me .

:D

And
Moose you are blinded by your investment in your knowledge . and so you produce more theory and pedantry . my what do sound waves sound like was of course sarcasm !

but you say vis-à-vis standing waves "No. It happens, is well-understood, easily demonstrated in both measurements and listening, has been for decades, and is a key factor in developing many loudspeakers. "

what measurements show the effect, what did the listeners in these listening tests hear ?
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