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Old 27th April 2008, 01:05 PM   #281
tinitus is offline tinitus  Europe
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I dont believe any of it...sounds too much like wanted/wishfull theory

If you have a plate with 500hz ressonance and strike it with 200hz
It wont be silent but ressonate with 500hz and more
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Old 27th April 2008, 02:23 PM   #282
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Quote:
Originally posted by tinitus
I dont believe any of it...sounds too much like wanted/wishfull theory

If you have a plate with 500hz ressonance and strike it with 200hz
It wont be silent but ressonate with 500hz and more
Agreed Tinitus.

The stimulus doesn't need to centred on the resonance for it to be excited. But level with be lower of course.
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Old 27th April 2008, 02:33 PM   #283
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Quote:
Originally posted by ShinOBIWAN


Agreed Tinitus.

The stimulus doesn't need to centred on the resonance for it to be excited. But level with be lower of course.
Removal of the stimulus is also a form of stimulus.
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Old 27th April 2008, 02:40 PM   #284
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Originally posted by MJL21193



Hi Ant,
It's not that simple. It's been long established that to build a box that doesn't vibrate, you brace. Not only do you brace, you damp as well. Also, it helps if the walls are massive and thick.
This is all absolutely correct, of course and works very well (I know from doing it).
What I was daft about, what I was told repeatedly and ignored, was that there is a more efficient way of reaching this same end. There isn't any reason to make the walls thick. There isn't any reason to line the box with roofing membrane, or lead sheets or carpet. CLD is unnecessary.
All you need to do is effectively brace the box so that no panel will resonate below 1KHz.
OK I understand now, you've been made aware of another approach to bracing.

But I find the claims that say method X is more efficient than method Z dubious without defining efficiency. Would such a thing mean less weight, minimum cost and minimum material for a given target of panel resonance damping? Or is it to be taken as the method that delivers the largest reduction of cabinet borne noise?

P10 braces the way he does for a reason - he sells loudspeakers, ships them and, above all, has a preference. He needs something light that's still doing an OK job. I don't think that can be stated as superior, correct, more efficient or whatever over the methods already mentioned in this thread.

If you don't have a specific target and a reason for efficient bracing but instead have a goal of the most dead cabinet possible then brute force will likely get you further and that's where my preference comes in.

What annoys me is when someone says something is wrong or is unsuitable compared to another method(usually what they use) especially if it flies in the face of experience and the realm of audibility from other parties. What that person should have said is that its their preference and if they want to get all high and mighty then they better show some evidence. Even then people approach problems differently and with bracing there isn't one correct method, just the goal of making the cabinet an inaudible part of the playback chain.
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Old 27th April 2008, 02:50 PM   #285
soongsc is offline soongsc  Taiwan
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Originally posted by ShinOBIWAN


...
What annoys me is when someone says something is wrong or is unsuitable compared to another method(usually what they use) especially if it flies in the face of experience and the realm of audibility from other parties. What that person should have said is that its their preference and if they want to get all high and mighty then they better show some evidence. Even then people approach problems differently and with bracing there isn't one correct method, just the goal of making the cabinet an inaudible part of the playback chain.
I think if they have actually done the research, it seems quite acceptable if the test or analysis conditions and methods were specified without actually showing the data. It will also allow others that with doubts to kind of follow a similar route to verify whether they conclude the same results or not.

One thing that I find is lots of people asking for proof are really just asking others to do work for them.
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Old 27th April 2008, 03:04 PM   #286
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Originally posted by ShinOBIWAN


Agreed Tinitus.

The stimulus doesn't need to centred on the resonance for it to be excited. But level with be lower of course.

Explain to me how a 200Hz tone will excite a 500Hz resonance?

Quote:
Originally posted by ShinOBIWAN


What annoys me is when someone says something is wrong or is unsuitable compared to another method(usually what they use)

I completely agree. There are many effective ways of dealing with resonance. The drawbacks with Dave's are dissipation of the energy in a sealed box, when panel vibration doesn't do any and increased construction complexity.


A side note: It is ridiculous to suggest that these methods don't work, and the contribution to this thread saying such, shows a complete lack of understanding of the subject matter and a fully closed mind. Some of these remarks seem to be aimed directly at my comments, with the intent to incite an argument.
I will only discuss reasonable things, not BS.
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Old 27th April 2008, 03:10 PM   #287
gedlee is offline gedlee  United States
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Originally posted by soongsc

I think if they have actually done the research, it seems quite acceptable if the test or analysis conditions and methods were specified without actually showing the data. It will also allow others that with doubts to kind of follow a similar route to verify whether they conclude the same results or not.

One thing that I find is lots of people asking for proof are really just asking others to do work for them.

In these forums this is a real problem. I for one am not about to go out and take data to prove a point that I make here - its just not going to happen. If I have data, then I will quote it, but I won't create it. These places are for fun, not work.

And this is what makes them so dangerous. Its easy to shut me up with a barage of posts, I'm simply not going to respond. What is the reader to conclude? - all too often the appearance is one of concession to the contrary points made, which need not be the case at all.

This leads to a tremendous propagation of misinformation by the shear weight of the posts and not by any science or relavance. It then becomes difficult to correct these misconceptions because the previous falty arguments are raised as "proof".

I'm not sure that the truth ever gets through on these long winded arguments.

Over on another post, I alluded to the idea that the voice coil will heat instantaneously and this could be what we hear as "dynamics" differences in tweeters. Then someone posted some very well done mathematical analysis of the situation and showed that this was unlikely to be an audible effect. End of discussion.

If the discussion goes on and on its usually because it is pointless and going nowhere.
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Old 27th April 2008, 03:15 PM   #288
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Originally posted by soongsc
[B]
I think if they have actually done the research, it seems quite acceptable if the test or analysis conditions and methods were specified without actually showing the data. It will also allow others that with doubts to kind of follow a similar route to verify whether they conclude the same results or not.
Yes but in this case that hasn't happened. The question was posed as to MDF's unsuitability to loudspeaker construction.

Isn't it easier to say the word preference? If you say MDF is unsuitable for loudspeaker construction or a particular bracing scheme is more effective than another then surely you need a pretty conclusive data set to affirm these absolutes?

Why would others want to tread down a path that is obviously just someone's preference. Shame that P10 didn't say as such and hid such things behind arguments proving nothing.

Quote:
One thing that I find is lots of people asking for proof are really just asking others to do work for them.
The Enabl threads are, ahem, special. Please don't bring the sentiments spilling over in those into this one. Yes I have seen the sentence you typed a number of times in Enable topics.

Any claim needs to backed up especially if its touted as making the others methods unsuitable. If your sceptical then asking someone to define, quantify and prove a claim is natural.

The way you put it would have us believe its wrong to do so because your then effectively become a leech.
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Old 27th April 2008, 03:17 PM   #289
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Quote:
Originally posted by gedlee



This leads to a tremendous propagation of misinformation by the shear weight of the posts and not by any science or relavance. It then becomes difficult to correct these misconceptions because the previous falty arguments are raised as "proof".

I'm not sure that the truth ever gets through on these long winded arguments.


The person who is finished learning, who knows it all and refuses to accept other ideas will gain nothing from any lengthy discussion.
The person with an open mind will gain volumes though, when he takes the time to consider the new ideas and research the validity of it.
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Old 27th April 2008, 03:28 PM   #290
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Default Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: and???

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Originally posted by MJL21193



The person who is finished learning, who knows it all and refuses to accept other ideas will gain nothing from any lengthy discussion.
The person with an open mind will gain volumes though, when he takes the time to consider the new ideas and research the validity of it.
There's a difference between learning and misinformation. The talk relating to MDF is misinformation. Nothing to be learned from that.
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