Is the LXmini by Siegfried Linkwitz the answer for home audio?

[Thomas_A]

This is a myth - theres always gonna be some early reflections on the wall, even from in-wall speakers, like If you throw a rock into the water and theres gonna be some waves. This sound defect can be fixed with a lot of damping material on the wall.

Further - the flawed stereosystem really needs som late reflections from walls so for the best result freestanding speakers is the way to go - my experience.

The reflections from in-wall speakers acts as an infinite baffle, which is the opposite of the LX-mini, that has no baffle. Having no baffle support means destructing comb filtering from the speaker wall in frequency regions where the speaker radiates backwards. You are efficiently creating a second sound source behind the speaker, with sound arriving later. A speaker flush with the wall is not creating another sound source.

Reflections from the other walls are natural since a natural sound source like a human voice or instrument is also reflected from those walls. As I noted in other threads, the only wall which is not natural in a sense is the speaker wall when it comes to stereo. If I remove the wall and place the musicians in the room behind it, I could sit and listen in my room to those musicians. But since I have a recording and two speakers against that said wall, I have the choice to make the speaker wall to become acoustically invisible to open up for the virtual room behind the wall. Perhaps, and I am speculating, it is so that reflection from such wall will confuse speaker location cues. However, this is IMO just artificial additions to the illusion. I prefer to open up the wall and imagine the musicians standing in front of me, in the next room instead. So speaker should not have any primary reflections from that wall other than in-phase support for bass frequencies.

 

[Tangband]

The reflections from in-wall speakers acts as an infinite baffle, which is the opposite of the LX-mini, that has no baffle. Having no baffle support means destructing comb filtering from the speaker wall in frequency regions where the speaker radiates backwards. You are efficiently creating a second sound source behind the speaker, with sound arriving later. A speaker flush with the wall is not creating another sound source.

Reflections from the other walls are natural since a natural sound source like a human voice or instrument is also reflected from those walls. As I noted in other threads, the only wall which is not natural in a sense is the speaker wall when it comes to stereo. If I remove the wall and place the musicians in the room behind it, I could sit and listen in my room to those musicians. But since I have a recording and two speakers against that said wall, I have the choice to make the speaker wall to become acoustically invisible to open up for the virtual room behind the wall. Perhaps, and I am speculating, it is so that reflection from such wall will confuse speaker location cues. However, this is IMO just artificial additions to the illusion. I prefer to open up the wall and imagine the musicians standing in front of me, in the next room instead. So speaker should not have any primary reflections from that wall other than in-phase support for bass frequencies.

Agree, but … in the case of a partly dipole speaker like lxmini you might have less reflected sound in certain angles to the speaker because of the out of phase sound coming from the backside of the 4 inch driver.
This makes up for a very specific sound dispersion in the listening room .
With a dipole speaker, some of the rooms reflections is cancelled out and might (maybe) make the sound clearer at listening position ?

 

[Tangband]

This is Linkwitz own writing of what it takes to make the stereo illusion real in a room :

The-Magic-in-2-Channel-Sound

——————

”For the magic to occur there are five requirements, which I have found to be essential:

1) The off-axis frequency response of the loudspeaker in the horizontal plane must mimic the on-axis response. The vertical polar response is not as critical but the formation of lobes should be avoided, i.e. the loudspeaker should be acoustically small. Such a loudspeaker has a neutral signature and its reflections and the reverberated sound field will have the spectral signature of the listening room. The polar pattern could be omni-directional, cardioid or dipolar with frequency independent power response. The omni pattern would produce the strongest interaction with the room and be the least desirable of the three.

2) The loudspeakers must be free of resonant radiation such as coming from vents or panels. Non-linear distortion must be low enough not to identify the speaker location during loud music passages. This demands adequate volume displacement capability of woofers and tweeters.

3) The loudspeakers must be set up at least 1 m distance from left and right side walls and 1 m from the wall behind them. The resulting time delay of about 6 ms is necessary for the ear-brain perceptual apparatus to separate direct from reflected sound streams. With neutral excitation of the room response, the listener can then withdraw attention from the room and process primarily the direct sound streams from the loudspeakers. This is similar to not hearing the ticking clock or to the cocktail party effect where attention and hearing is drawn to information streams of interest. Everything else is moved beyond the acoustic horizon as in survival mode.

4) The wall behind the loudspeakers is preferably diffusive and the wall behind the listener absorptive. The sound waves from the loudspeaker should be allowed to travel freely past the listener and not be reflected from a wall behind.

5) The listening room should have a reverberation time around 450 ms, i.e. be neither acoustically dead nor overly live but comfortable for conversation and entertainment. If anything it should err in the direction of liveliness.”

 

[ctrl]

Linkwitz vent from the orion ( wide baffle ) to the lx521 with almost no baffle to talk about - Im sure Linkwitz didnt like the reflected sound from baffles, and this was the conclusion he made later in his life.

I think you are not interpreting SL correctly in this case.

SL defines the LX521 as the reference loudspeaker. A speaker with a baffle. The baffle used is even extremely important for the radiation pattern of the speaker.
SL writes about this:

The midrange/tweeter baffle is an essential acoustic design element. It controls the interference between between front and rear radiated sound waves in order to obtain a dipolar radiation pattern over the whole frequency range.

Source
The baffle was for SL a means to an end to create a certain radiation pattern. The baffle of the LX521 enables the desired phase shift of front and back sound radiation and generates additional secondary sound sources ("reflected sound from baffle") due to the edge diffraction.

If it is achieved, as in the case of the LXmini almost without a baffle, no problem.
However, the radiation of the LXmini and LX521 should be similar only in the rough, but in detail clearly different.

 

[Tangband]

Thoughts: The lxmini:s bass tube is about 80 cm high, making the first reflection from the floor about 5 ms delayed.
The 4 inch driver is even higher mounted, making the needed 6 ms delayed floor reflections Linkwitz is writing about, real.

Edit : This was not exactly correct.

 

[Tangband]

Thomas A : maybe finding the holy grail in the magic of stereo is all about finding the right dispersion pattern , using dipole constructions in some frequency area to reach that goal in a normal room?

 

[ctrl]

Thoughts: The lxmini:s bass tube is about 80 cm high, making the first reflection from the floor about 5 ms delayed.
The 4 inch driver is even higher mounted, making the needed 6 ms delayed floor reflections Linkwitz is writing about, real.

Unfortunately, this is not correct.
The 6ms runtime delay of the reflected sound is not even close to being achieved in a normal listening room (3m listening distance) for the floor bounce.

You can easily calculate this with Pythagoras and the rate-time-distance equation d = rt.
It's only 1.16ms.

Even the ceiling reflection (of the tweeter) reaches the listener in less than 4ms in a normal listening room with 2.5m ceiling height (3m listening distance).

 

[Tangband]

Unfortunately, this is not correct.
The 6ms runtime delay of the reflected sound is not even close to being achieved in a normal listening room (3m listening distance) for the floor bounce.

You can easily calculate this with Pythagoras and the rate-time-distance equation d = rt.
It's only 1.16ms.

View attachment 228244

Even the ceiling reflection (of the tweeter) reaches the listener in less than 4ms in a normal listening room with 2.5m ceiling height (3m listening distance).

But this is depending of the distance to the speakers. If you sit near - about 1 meter from them theres gonna be an entirely different result .
But youre right , in a 3 meter distance at the listeningposition the delayed reflections will be shorter than 5 ms in time.
I have edited my print.

Edit: why do Linkwitz write :

3) The loudspeakers must be set up at least 1 m distance from left and right side walls and 1 m from the wall behind them. The resulting time delay of about 6 ms is necessary for the ear-brain perceptual apparatus to separate direct from reflected sound streams.

 

[ctrl]

But this is depending of the distance to the speakers. If you sit near - about 1 meter from them theres gonna be an entirely different result .

For floor reflection, does not change the outcome <6ms - calculate before post

 

[Thomas_A]

Thomas A : maybe finding the holy grail in the magic of stereo is all about finding the right dispersion pattern , using dipole constructions in some frequency area to reach that goal in a normal room?

As mentioned many times, stereo has many limitations and yet most recordings are made in stereo. What remains is get the most out of it and use upmixing when recordings ”allow” for it. I am satisfied with my set-up, i.e. speakers close to wall, minimizing those early reflections coming from the ”wall”, but having wide dispersion to get that natural enveloping sound. Perhaps the dispersion pattern of the human voice is the holy grail?

 

[Burning Sounds]

These have a lot of fans, and are undoubtably enjoyable speakers. But they suffer from the problem any unusual design does; namely recordings are neither mixed nor mastered using this kind of speaker. If your goal is to add your own spaciousness etc, well fine.

I don't think these are adding their own spaciousness - just reproducing what is recorded. They have their faults as Erin shows, but they add no magic sauce IMO. Same goes for the LX521.

San Fransisco Symphony producer and engineer Jack Vad seems to find them useful:

"I watched (and heard) Siegfried tackle each step of a brilliant development process and was able to see the designs finally cross his aspirational finish line spectacularly. When the time came to actually use the systems in my personal studio, I jumped at the opportunity as I didn’t have any other speakers that could reveal as accurate a sound stage, do so with tonal & timbral neutrality, and seemingly bypass the room.

As a result, both the LXmini and LX521 are used for the final production stage mix qualification of all San Francisco Symphony SACD download releases that I’ve produced during the last three years; they are an indispensable tool.”

 

[Tangband]

As mentioned many times, stereo has many limitations and yet most recordings are made in stereo. What remains is get the most out of it and use upmixing when recordings ”allow” for it. I am satisfied with my set-up, i.e. speakers close to wall, minimizing those early reflections coming from the ”wall”, but having wide dispersion to get that natural enveloping sound. Perhaps the dispersion pattern of the human voice is the holy grail?

It might be - get the sound right for human voices and get a good sound ? After all, the human voice is probably the instrument that we humans can trust the most If sounding ” real” or ” autentic” .

 

[Thomas_A]

It might be - get the sound right for human voices and get a good sound ? After all, the human voice is probably the instrument that we humans can trust the most If sounding ” real” or ” autentic” .

In that case quite wide I believe.

Facts about speech intelligibility: human voice frequency range

Recording or amplifying the voice is a technical challenge. In this article we present facts on speech intelligibility, including the voice as a sound source.

www.dpamicrophones.com

 

[Coffeeman]

I had the pleasure of hearing the LX Mini's and LX521's with subwoofers in Mr Linkwitz home. Amplification and crossover duties were from the Powerbox which is designed to pair with these speakers and uses NCore amplification modules. Music was from a Mac Book and I'm not sure of the details if these were DSD or some other files. Clarity and soundstage were extraordinary. I had heard the speakers at Burning Amp Fort Mason several times and they were always impressive but perhaps pushing their limits to play loud in such a big space. For fun, music was switched between the 521's and Mini speakers and all of us played a guessing game of which speaker was playing. I've bought the Madison kit and Nelson's kit analog crossover kit and have purchased a pair of Aiyima 07's with 1656 op amps. By powering tweeters with one and woofers with the other I'll also have level controls on each driver. Subwoofer duties will be handled by my own homage to the saying - No replacement for displacement - 18's in H Frames instead of the 10's Linkwitz designed with.

 

[Tangband]

I had the pleasure of hearing the LX Mini's and LX521's with subwoofers in Mr Linkwitz home. Amplification and crossover duties were from the Powerbox which is designed to pair with these speakers and uses NCore amplification modules. Music was from a Mac Book and I'm not sure of the details if these were DSD or some other files. Clarity and soundstage were extraordinary. I had heard the speakers at Burning Amp Fort Mason several times and they were always impressive but perhaps pushing their limits to play loud in such a big space. For fun, music was switched between the 521's and Mini speakers and all of us played a guessing game of which speaker was playing. I've bought the Madison kit and Nelson's kit analog crossover kit and have purchased a pair of Aiyima 07's with 1656 op amps. By powering tweeters with one and woofers with the other I'll also have level controls on each driver. Subwoofer duties will be handled by my own homage to the saying - No replacement for displacement - 18's in H Frames instead of the 10's Linkwitz designed with.

Im gonna build one this summer

 

[MKW]

@Coffeeman I can tell you that four 12" drivers in two Linkwitz Phoenix(alt) "W" cabinet configuraton is more than enough for LXmini. If you go with 18", and are in the US, you might check into Eminence - they make large drivers specifically for open-baffle applications. That's where Emerald Physics and Spatial Audio OB drivers came from in the past. You'll need to select the correct drivers for OB, not just any 18 (most are designed for sealed/ported applications).

 

[Coffeeman]

Tangband please share your experience once you build them. Thanks for the woofer tips MKW. Martin J King used the Goldwood 18" for his open baffle H frames. I got a pretty good deal so I bought 4 of them. Have also thought of trying dual opposed in a slot loaded open baffle. My wood working skills and tools are pretty much non existent so I'll have to find a cabinet maker who can make sense of my napkin drawings. Is it just me or do these things have a steam punk aesthetic?

 

[jeffbook]

In my system, I can tell you that the Orion bass module with uses two Peerless 830452 10" woofers per side is more than adequate to provide bass below 60 Hz when paired with the LXmini speaker. Using subwoofers with greater volume displacement is not necessary. The LXmini itself is the limiting factor in generating a higher listening sound pressure levels. This system is sufficient in generating adequate sound pressure levels in my room (12.5'x19'x8')

As far as the 6ms delay SL recommends, he also discusses speaker toe in as a method to reduce side wall reflections in a dipole based system as has been mentioned above. I have found this to be effective in my own room. Can't do much about delaying any ceiling and floor reflections in a typical domestic listening rooms without room treatments. For what it is worth, my room has wall to wall carpeting and one absorption panel on the ceiling. I am very happy with this system.