Linkwitz LX521.4 Review (and measurements!)

[Sylvanus]

Well, the "zoomed" display doesn't change the measured data. Assuming it was captured in a viable manner, it is not useless.

There are some fallacies in the post though. Example...open baffle speakers do indeed pressurize the room and the ears. Otherwise you wouldn't hear anything. His point (poorly explained) is that open-baffle speakers have an inherent 4.8db advantage in excitation of room modes because of the radiation pattern.

 

[JeyB]

You have gone the other way of the OP, and your graph is so far zoomed out that it is useless. The range on the y-axis should not be more than about 50 dB. If fine tuning a single speaker, you might zoom in more. Hope this helps!

Hi Rick, thanks for posting.

Here is the frequency response with Y axis at 50 dB.

And here, referenced to Standard Harman Average House Curve.

Finally, with my own personal prefered house curve. I'm not a bass head guy. I much prefer a flattish LF response in my room.

The main issue is that all these graphs are unable to describe the sound in my room. And given the constant directivity offered by true dipolar systems, which engage the room adequately from every angle, ie flat on-axis and also flat off-axis response, there is no cue about how it's the true sound from these graphs. There is no way to measure my brain perception (sound processor inside my head) to describe the phantom sources that fill the room in every 3D plane from the listening position.

Best regards

 

[JeyB]

Well, the "zoomed" display doesn't change the measured data. Assuming it was captured in a viable manner, it is not useless.

There are some fallacies in the post though. Example...open baffle speakers do indeed pressurize the room and the ears. Otherwise you wouldn't hear anything. His point (poorly explained) is that open-baffle speakers have an inherent 4.8db advantage in excitation of room modes because of the radiation pattern.

Hi Sylvanus.

My recomendation is to listen any constant direcitvity transducer just to discover what means the lack of pressurization in a room, but at the same time lots of decibels reaching your eardrums. Quite an experience IMHO.

Of course there are variations of pressure produced by the drivers. I said there is lack of pressurization in the room, pointing to the "lack" or reduction of pressure compared to a sealed or ported subwoofer which alter the real volume of the room. A dipolar subwoofer can't alter the real volume because it's comprised of a moving membrane in free space, the room itself. A conventional sub only faces one side of the room, the backside is contended inside its box. The directional performance of a dipolar sub is another great advantage, which is responsible of the 4.8 dBs less room excitation as you have indicated.

Here I show some points of constant directivity LX521 properties in my own dedicated listening room, 50 sqm. You can translate it with Google Chrome web browser, clicking on the 3 dots on the right upper corner.

Linkwitz LX521.4MG. Una experiencia asombrosa.

Buenas tardes y bienvenidos a mi sala Linkwitz, situada en Pontevedra, mi tributo personal al tristemente desaparecido Siegfried Linkwitz (1935-2018). Genio vis

www.audioplanet.biz

Best regards

 

[Sylvanus]

My recommendation is to listen any constant directivity transducer just to discover what means the lack of pressurization in a room, but at the same time lots of decibels reaching your eardrums. Quite an experience IMHO.

Your presumption is incorrect. The primary speakers in my listening room have been some sort of dipolar design for the last 50 years. I'm well familiar with the concept and many implementations.
But thanks for your comments.

 

[JeyB]

Rick, In the past months I've also been tweaking the LF response to get more evenness. Here is the actual response from 20-100 Hz on axis.

I've added two more Seas L26RO4Y drivers to my system, so in total there are six L26RO4Y drivers. As a result I have flattened the response to my taste. AS you can see, the Y axis is in 2 dBs increments, no smoothing applied, more in line with what you have asked.

As you can see, the response is quite flat and with no room modes at all. That's the virtue of a true dipolar subwoofer system. The room is quite big and symmetrical (9,75 x 5,2 m) and almost absolutely empty. There is no acoustical treatment except a LF absorber behind the listening position. Main walls are purely reflective but some carpets in the floor. Conversation in this listening room is pleasant and comfortable. You can take a look of this room in the link I added in my previous post. It's open to any interested person who want to be exposed to the full stereo capabilities, to discover by himself about what is really possible to reach with the stereophonic system.

Best regards

 

[JeyB]

Your presumption is incorrect. The primary speakers in my listening room have been some sort of dipolar design for the last 50 years. I'm well familiar with the concept and many implementations.
But thanks for your comments.

Hi Sylvanus

Well, I don't presume anything, you seem to like to assure what is right or not. I simply suggested to listen to a constant directivity design. If you have had some experience with some sort of dipolar design, then great for you. But in my book, Open Baffle and "sort of dipolar" is not enough. My aim is full constant directivity from 20 to 20 KHz, which is a rather different animal from the aforementioned designs.

My LX521 greatly approaches to a full CD design and it sounds very, very well, real-like and impressive. Lately what I have been questioning myself is if removing completely the deflector (nude drivers) would yield a sound improvement or not. Or even changing some drivers, like high mid driver and tweeters for another ones with better dipolar directivity. And this is what I'm figuring out how to do it.

Charlie Laub, Gerrit Boers and Rudolf Finke have done it.

Best regards

 

[Sylvanus]

Well, I don't presume anything,....

Yet, you clearly did. "My recomendation is to listen any constant direcitvity transducer just to discover what means the lack of pressurization in a room, but at the same time lots of decibels reaching your eardrums. Quite an experience IMHO."

Just for the record, my current speakers are LX521's, which I've been experiencing since 2012.
I'm well familiar with the concept and implementation.

Have a nice day.

 

[JeyB]

There are some fallacies in the post though. Example...open baffle speakers do indeed pressurize the room and the ears... His point (poorly explained) is that open-baffle speakers have an...

What a polite way to start a conversation with someone you don't know: "There are some fallacies in the post though [...] His point (poorly explained) is that..."

In Spain, where I was born and I live, a fallacy is a lie and poorly explained means lack of habilities to write, in this case.

End of conversation.

 

[Everett T]

Here is a psychoacoustically smoothed response graph from my listening space. Definitely some issues going on here. Not sure if it's room related, or system related.
I have the latest version of the LX 521.4 MG, being driven by 10×250 W per channel NCore amplifiers, and the latest analogue signal processor. My front end is a benchmark DAC3/ HPA4 being fed by various sources, mainly a MacBook computer for music streaming. It's strictly a two channel system, which I use for music and home theatre. it's a very large open space with ceilings that peak at 15 feet. The speakers are about 14 feet apart, and listening position is about 14 or 15 feet from the speakers. All connections are fully balanced, XLR cables. Speaker cables are Canare star quad 4S11.
I've also included a couple of pictures of my listening space. The home theatre screen drops down from the beam above the fireplace.
I would love to see more room response curves from other LX 521 owners. Our better still have a pair tested on this site
My experience is that they sound incredible on certain music, but not all.
When they are working well, and on the right kind of music, nothing I've heard gives a more magical illusion of the live event.
But it definitely seems to be missing something in the bass/mid bass/mid range area and is a little bright in some of the higher frequencies.
I'm currently looking into a system, which has a more complete and even frequency response, yet at the same time can create that magical illusion of live sound that Sigfried's dipoles have always been great at. I originally built his Orion speakers, which I still feel in some respects, sounded better than the 521's
The cardioid designs in particular have piqued my interest


View attachment 369925View attachment 369926View attachment 369927

Definitely pull them out into the room. When people first hear bass that isn't greatly coupled to the room, it usually sounds off. Having had electrostatics long ago, I prefer to add a closed box or bass reflex sub to augment the lfe and with some music.

 

[Sylvanus]

What a polite way to start a conversation with someone you don't know: "There are some fallacies in the post though [...] His point (poorly explained) is that..."

In Spain, where I was born and I live, a fallacy is a lie and poorly explained means lack of habilities to write, in this case.

End of conversation.

Well, I don't think it's polite to make presumptions about people you don't know. Which, by the way, you've just done again.
The "fallacy" in this case could have easily been ignorance and not lying. Which is why I didn't call you a liar. And I still don't think you are.

I appreciate English is not your native language, but I think you should effort to be more clear in your postings.

Just for the record, you're not going to tell me anything about the LX521 system that I don't already know.

Have a nice day.

 

[AudioJester]

Well, we can all constabtly learn things, I do every day and it is one of the joys of living!

My experience with my Lx521 is they upgraded the wrong driver. I have not found any issue with the lower midrange driver which now has an expensive replacement. And while the upper midrange driver measures perfectly and I can tune any which way with my pc based crossover/dsp - i just find it sounds "harsh" compared to other speakers I have - Genelec, Neuman etc. I just dont think its a nice sounding driver no matter what I do. Considering how little the tweetets actually do, I dont think they need replacing, but do need shelving down. The bass is phenomenal!

 

[Sylvanus]

My experience with my Lx521 is they upgraded the wrong driver. I have not found any issue with the lower midrange driver which now has an expensive replacement. And while the upper midrange driver measures perfectly and I can tune any which way with my pc based crossover/dsp - i just find it sounds "harsh" compared to other speakers I have - Genelec, Neuman etc. I just dont think its a nice sounding driver no matter what I do. Considering how little the tweetets actually do, I dont think they need replacing, but do need shelving down. The bass is phenomenal!

Yes, that is correct.
The upper-midrange driver scheme is the weak link in the system. It's not a driver problem, but rather the low-slope electrical HP filter. This causes the driver distress at higher playing levels and gives it that harsh sound you've noticed.

 

[JPA]

Well, the "zoomed" display doesn't change the measured data. Assuming it was captured in a viable manner, it is not useless.

There are some fallacies in the post though. Example...open baffle speakers do indeed pressurize the room and the ears. Otherwise you wouldn't hear anything. His point (poorly explained) is that open-baffle speakers have an inherent 4.8db advantage in excitation of room modes because of the radiation pattern.

You're half right, half wrong. All speakers pressurize the ears, otherwise we wouldn't hear anything. But dipole speakers do not pressurize the room. The positive pressure in front when a driver is moving forward is canceled by the negative pressure in back, so the sum of the pressures is zero.

 

[Sylvanus]

@JPA Symmetrical dipoles being velocity sources, that is indeed true.
Re-reading my statement, I should have left "room" out of the sentence.
Thank you.

 

[jhaider]

Well, we can all constabtly learn things, I do every day and it is one of the joys of living!

My experience with my Lx521 is they upgraded the wrong driver. I have not found any issue with the lower midrange driver which now has an expensive replacement. And while the upper midrange driver measures perfectly and I can tune any which way with my pc based crossover/dsp - i just find it sounds "harsh" compared to other speakers I have - Genelec, Neuman etc. I just dont think its a nice sounding driver no matter what I do. Considering how little the tweetets actually do, I dont think they need replacing, but do need shelving down. The bass is phenomenal!

I wonder if some of the issue is the fairly obstructive motor structure. Unfortunately Seas doesn't have a neo version of that driver, and I guess SL (RIP) wanted to stick with Seas so the ScanSpeak 10F (IMO a better driver) was not an option.

 

[Sylvanus]

The original version of the LX521 had a steeper HP filter on the upper-midrange driver. This alleviated much of the issue.
I agree the ScanSpeak 10F is the superior driver. At the time SL was working with Seas and desired to have an all-Seas system.

 

[Burning Sounds]

Hi Sylvanus

Well, I don't presume anything, you seem to like to assure what is right or not. I simply suggested to listen to a constant directivity design. If you have had some experience with some sort of dipolar design, then great for you. But in my book, Open Baffle and "sort of dipolar" is not enough. My aim is full constant directivity from 20 to 20 KHz, which is a rather different animal from the aforementioned designs.

My LX521 greatly approaches to a full CD design and it sounds very, very well, real-like and impressive. Lately what I have been questioning myself is if removing completely the deflector (nude drivers) would yield a sound improvement or not. Or even changing some drivers, like high mid driver and tweeters for another ones with better dipolar directivity. And this is what I'm figuring out how to do it.

Charlie Laub, Gerrit Boers and Rudolf Finke have done it.

Best regards

Do you have any links to the work done by Laub, Boers and Finke?

 

[Burning Sounds]

The original version of the LX521 had a steeper HP filter on the upper-midrange driver. This alleviated much of the issue.
I agree the ScanSpeak 10F is the superior driver. At the time SL was working with Seas and desired to have an all-Seas system.

If you mean between the LM and UM driver, no, it was the other way round the original passive filter was first order.

 

[Sylvanus]

If you mean between the LM and UM driver, no, it was the other way round the original passive filter was first order.

No, I'm talking about the steep 120Hz high-pass filter that was in the path of both drivers in the original version, but not in the later version.
The crossover between the two midrange drivers was the same in either case.

 

[Burning Sounds]

No, I'm talking about the steep 120Hz high-pass filter that was in the path of both drivers in the original version, but not in the later version.
The crossover between the two midrange drivers was the same in either case.

So, are you talking about the cascaded x-over?