What Do You Think . . . and How Does It Work?


While watching vids on YouTube, I came across this pipe speaker design from a Dr. Linkwitz (see below).   The sound of this speaker is said to be impressive.  I was wondering if you know about this, how it works and what you think of this speaker design.  Also, what do you think would be the best room placement for such a speaker, and would you be tempted to build them?

https://www.linkwitzlab.com/Pluto/intro.htm
bob540
I wish I could hear them — I don’t really need more speakers, but if these things are as good as you say, plus very affordable, that’s an opportunity that needs to be seized!   
You have attacked the character of everyone on this forum in one way or another.

You have accused me and my kind (speaker designers) of incompetence and dishonesty.
There are many problems within the industry that i have identified.
The inability of audiophiles to hear problems is in itself a problem.
All these problems involve people so it is impossible to discuss them without mentioning the people involved.

The fact that you see it as an insult rather than a problem misses the point. The fact that you attack my character rather than the arguments i make is a fallacy.

You provide no solutions or reasons to refute what i say. You have nothing to offer duke.

You attacked Siegfried Linkwitz in this thread

Wrong. I attacked his design. I cast doubt on his method of using pvc as its not really rigid which is obvious to anybody that has used it. Linkwitz himself admits pipes have other serious problems if you read his website.

Somebody claimed he was a brilliant speaker designer, and i challenged this assertion. Im allowed to. I reasonably asked why if he was so brilliant, his designs have not achieved much commercial success.
In response you cited an obscure review in stereophile, which doesnt convince me. The fact is its all opinions. There is no agreement on what tests to use to decide how good a speaker is.

The linkwitz riley crossover which bears his name is not the only game in town. Plenty of designers dont use it. Plenty of designers including b&w choose the humble first order electrical design, and b&w has still sold untold pairs of speakers.

I am primarily an audiophile rather than a designer. As audiophiles we must be sceptical. We are entitled to be, given the amount of misinformation in this hobby and exaggerated or unproven claims. The onus is on your kind to show proof.

Kenjit ~ Perfectionist bar none "

Way too easy to identify these as narcissism.

Wrong again. You’re just choosing to misinterpret what i say in order to support your nasty accusations against me. There can be more than one interpretation (eg. a joke ) and there are no nonverbal cues on here that would help you to decide.

@ctstereo
I have listened to the LXmini and own the LX521.4, I have listened to B&W speakers costing 5 times more than the LX521 and the Linkwitz design still wins.

Thats just your preference. It says nothing about how well the design performs and there is no agreement on what measurements matter when deciding that anyway, so there is no way to tell.

In conclusion, there is no evidence that the linkwitz pluto speakers are superior to conventional boxes. Its all hearsay. The driver he refers to as a tweeter is in fact a full range mini driver. It goes lower than a typical tweeter at the expense of other factors such as high frequency extension and dispersion. Distortion on the driver seems high as well. Despite all the supposed advances in driver technology the linkwitz speaker uses a fairly ordinary 5 inch woofer.
It seems odd to claim that a speaker using such ordinary parts can achieve extraordinary performance. Are we being duped by the industry into thinking that driver quality is more important than it really is?
Tell us something we didn't know.

I am primarily an audiophile rather than a designer.

kenjit,

Like many of us here you also seem to be searching for definitive answers and ultimate truths when it comes to loudspeaker performance. Unfortunately, there may not be any. 

Whilst it's always advisable to keep an open and inquisitive mind, isn't there also a corresponding danger of falling into the trap of excessive paranoia and suspicion?

From my point of view when a designer has spent decades looking at every facet of loudspeaker performance in as much precise detail as Siegfried Linkwitz obviously did, I feel compelled to pay attention to his words.

You need an example? 

How about this one taken from his website?



N - Mounting a driver to a baffle

"There is yet another potential problem with the driver to baffle interface, even if the baffle is perfectly inert. It is related to the mechanical construction of the driver itself and how it can become a mechanical resonator of its own.

Typically a loudspeaker driver has screw holes in its basket for mounting it to a baffle. Usually a sealing gasket is placed between the driver basket rim and the baffle. The driver becomes in effect stiffly clamped to the baffle. This method sets up a mechanically resonant structure which is formed by the compliance of the basket and the mass of the magnet as seen in figure (A). 


A) Drivers with a stamped metal baskets are prone to exhibit a high Q resonance when tightly clamped to the baffle. The magnet moves relative to the voice coil at the resonance frequency. Energy is stored and also readily transmitted from the moving mass of the cone into the cabinet.

B) Soft mounting the driver basket to the baffle using rubber grommets reduces the resonance frequency. A 2nd order lowpass filter is formed that reduces the transmission of vibration energy from the moving cone to the baffle and cabinet. The resonance must occur below the operating range of the driver.

C) If the driver is mounted from the magnet and the basket rim touches the baffle only softly, then the magnet-basket resonance cannot occur and the transmission of vibration energy into the baffle is minimized.

The basket-magnet resonance can be measured with an accelerometer that is mounted to the magnet. The drive signal is optimally a shaped toneburst. Its energy is concentrated in a narrow frequency band. When tuned to the right frequency a long decay tail becomes visible on an oscilloscope. Often the resonance can be seen as a small bump in the driver's impedance curve in the few hundred Hz range. It should not be confused with the higher frequency bump due to cone breakup.

An early example of a box loudspeaker where a KEF B110 midrange/woofer driver magnet is clamped to a support structure. The clamp can be tightened from the outside of the box. The basket rim is floating.


Often the effects due to driver mounting are deemed to be of secondary importance to the overall sound quality of a loudspeaker. 

They are usually costly to remedy

They cannot be ignored when the goal is to design a loudspeaker of the highest accuracy."


https://www.linkwitzlab.com/frontiers_2.htm#N


In which case how do you explain this pair of $7600 bookshelf speakers that is described as "AK's All Time Best Performing Domestic System"
https://jamesromeyn.com/audiokinesis-speaker-models/gina/

Theres no evidence of performance provided and i see that the driver is screwed in. Linkwitz advises against this and he says that it "cannot be ignored when the goal is to design a loudspeaker of the highest accuracy."

Speaker designers need to be questioned otherwise there is nothing to stop them making any claim. 

Ive been accused of trolling and narcississm and now youre suggesting paranoia. What next? Ive just told you my thoughts on the linkwitz pluto. Why dont you respond to that instead of using an excuse to avoid discussing the real issues?

There is no such thing as falling into the trap of paranoia or suspicion. The real danger is being duped by all kinds of unproven claims which there are many of. Most of these claims are just based on the say so of the speaker companies and theres rarely any independently verified evidence. Theres every reason to be suspicious. We have to rely on the voluntary action of reviewers to obtain some measurements that ought to be provided by the manufacturers. It is shocking considering the extortionate prices.
The prices clearly have no limits yet theres no evidence that the quality goes up with price as youd rightly expect. 

However even reviewers measurements should not be relied on. They can be biased too. Measurements can vary and we dont yet have a complete understanding of the correct measurements to use. Manufacturers must be held to account and paranoia is never an excuse to avoid doing that. The loudspeaker industry has taken us for a ride for long enough and now we must demand evidence. 
We deserve it. 

Long live the Kenjit!

Kenjit~