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Magnepan LRS Speaker Review

Blumlein 88

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So, if this true, the only thing you can infer from that measurement is don't use them in an open field. And how did Amir hear what the measurement predicted if the listening test wasn't conducted in the acoustic equivalent of an open field? Something fundamentally seems odd here.

Why are people complicating this with all kinds of technical jargon? I think we need to understand intuitively what is going on here and what has been measured.

You can design a speaker that is flat in response in LF and use EQ to cut down on room gain to "hear flat". You can design a speaker to cut down on LF so you "hear flat" with room gain. Maggies seem to be the latter (they came into existence long before any roomeq were available in consumer equipment). We can debate which design philosophy is the right one but that is different from what the measurements are supposed to mean.

I see the reflection from the back wall as a fundamental ("room gain") requirement for using these speakers and fairly consistent with distance from the back wall. Without it you aren't really measuring what you would be hearing but everybody is making that leap in terms of LF behavior.

It is like saying we know how to measure a sealed subwoofer but because the ported subwoofer is different, we will measure with the port blocked so we can compare as to how they will sound. Huh?

What have I got wrong here in interpreting the measurements without getting lost in poles and nulls and axis and verticals and horizontals?
No, I don't agree with your conclusions.

Amir's 1st goal is to get you measurements showing the anechoic response of a speaker. The Klippel does that. No use arguing about it.

The unit using the measurements give a predicted in room response which should take room boundaries into account. It uses results from studying multiple actual rooms, but I don't know which position it uses in the room dimensions for the PIR. It is possible with dipoles to cleverly position it to keep bass response going an octave or so lower than its natural roll-off. The LRS appears to start dropping near 400 hz. Basic physics says a dipole source 15 inches wide like the LRS will loose bass response at 6 db/octave starting about 400 hz. So no surprise. The PIR shows a response dropping at that frequency. It doesn't quite drop at 6 db/octave, but close.

I've seen some REW measures of an LRS in room which looked like much lower droop between 400 hz and 100 hz (though it still was sloping down) , and the same droop below that. So that is probably all you'll get with this small panel. I think even in room it likely sounds as Amir described it. I've not heard this one, but believe Amir's graph of the PIR is likely closer to reality than that of JA in Stereophile.

Mainly I suppose we need Amir to measure at least a couple or three more panels if he gets the chance before we say much one way or the other.

And before anyone asks, I've owned 3 pairs of Maggies, and 4 pairs of ESLs. The best Maggie I owned was the 3.3R. The smaller Maggies didn't sound too different to me than Amir's description of them.
 

richard12511

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Just for reference for those that can't grasp the inherent testing issue here. The proper way to characterize the bass response of a speaker like this is to tip it over on the side and make a ground-plane measurement from a couple meters away. THAT will yield a measured response that is a pretty good indication of how it will perform in normal usage......bass wise.
I've used that approach for many years testing planar speakers.

For those that are still questioning the results here.....the basic speaker here (the MMG/LRS) has been shipping since 1997. Earlier versions of a smallish Magnepan speaker have been shipping since well before that.
There are literally thousands of pairs of these in the field all over the world providing enjoyable music reproduction. You might want to consider that before labeling these speakers "not a product finished and fit for use by a consumer."

Dave.

But the listening test was done in a real room, and it still had no bass...
 

tjf

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Heh, well, yes, that was an attempt to apply the Magnepan dipole EQ patent to dynamics speakers. Never thought about the trapezoid -- I guess I saw it as half of Olsen's truncated pyramid. :)

Magenpan's "dipole EQ patent"?
Never heard of this....I know they tried to fight off attempts by Apogee to copy their "true-ribbon" tech by trying to sue over this in the late 80's/early 90's...

from Google patent search: from 1975...


Abstract

A sound generating transducer or speaker including a vibratable diaphragm on a frame and in spaced and confronting relation with a polarity defining backing, preferably magnetic in nature, conductive means on the diaphragm to receive an audio frequency electric signal to cause attraction and repulsion between the diaphragm and the backing, the diaphragm being divided into definite vibratable areas by divider strips bearing against the diaphragm such that each diaphragm area has a fundamental resonant frequency different than other adjacent areas. The ends of the divider strips are spaced from one edge of the diaphragm to define a long strip-like edge portion of the diaphragm which transcends the several vibratable areas of the diaphragm. The conductive means are separate bass and mid-range audio frequency signal conductors and high range audio frequency signal conductors on the diaphragm and separated in distinct zones, the high range audio frequency signal conductors located in a zone extending along the strip-like edge portion and defining a long, narrow tweeter transcending the several vibratable areas and through the edge areas of the several vibratable areas or woofers which are excited by the signal current in the bass and mid-range audio frequency signal conductors. The mid-range audio frequency signals may be separately applied along another edge portion or zone of the diaphragm in a separate conductor on the diaphragm.
 

MZKM

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One is that you need the output from both bass panels because they are asymmetrical (as you observed)
The tweeters are asymmetrical, but I don’t see what impact that has in the bass in regards to them playing at the same time.

I don’t see how the deep bass will be different than a normal speaker (omni below ~100Hz), but be a dipole should let the upper bass be more emphasized than what the anechoic measurements tell us.
 

RayDunzl

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Dipole vs conventional:

Here's a MartinLogan dipole vs JBL LSR 308, adjacent to each other in my room.

This is a "no EQ" sweep for both types, left and right speakers playing, 1/48 smoothing, within the range of the dipole, at the listening position.

1600574296729.png


Bass not shown since it isn't dipole - sealed 12" - so not pertinent at this time.

I'm sorry I don't have an LRS to flog for you.
 
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mac

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Dipole vs conventional:

Here's a MartinLogan dipole vs JBL LSR 308, adjacent to each other in my room.

This is a "no EQ" sweep for both types, left and right speakers playing, 1/48 smoothing, within the range of the dipole, at the listening position.

View attachment 83850

I'd expect so see tremendous comb filter effects measuring both left and right speakers at the same time from your listening chair. I'm learning how my thinking has been so wrong on several counts by following this thread.

Edit: Wild vertical scale makes poor curves look smooth, but I'd still expect it to look worse.
 

bobbooo

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Dipole vs conventional:

Here's a MartinLogan dipole vs JBL LSR 308, adjacent to each other in my room.

This is a "no EQ" sweep for both types, left and right speakers playing, 1/48 smoothing, within the range of the dipole, at the listening position.

View attachment 83850

Bass not shown since it isn't dipole - sealed 12" - so not pertinent at this time.

I'm sorry I don't have an LRS to flog for you.

Most speakers will look flat on a graph with a 100dB vertical scale and only going down to 240Hz...
 

Vasr

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No, I don't agree with your conclusions.

Amir's 1st goal is to get you measurements showing the anechoic response of a speaker. The Klippel does that. No use arguing about it.
I am not going to argue whether these are good speakers or not. Or what people heard in their own experience.

I have never had or heard the LRS. What I am trying to understand is whether the measurements reflect reality and how.

When you do a scientific experiment and you get unexpected results compared to common observations, you try to understand the reasons. But first you check if the experiment is measuring what it is supposed to measure and second if the interpretation of that is related to reality especially if it conflicts with other experience/observations/measurements.

It is fairly non-controversial that small Maggies are bass-deficient. But the rolling off starting at 300hz seems very odd. This is not reflective of small Maggies (unless the LRS is really hosed). The Maggies are a trade-off of a number of things. If they were that deficient in general for all of their smaller ones, I very much doubt that people would have kept them in the numbers they did. But that is subjective and NOT my point. But it does cause one to say "wait a minute"...

I did a quick measurement of the 25 year old SMGa using REW. Restored as described here ( https://www.audiosciencereview.com/...n-makes-a-video-for-the-lrs.14769/post-477571 )

Here are my L and R measurements (no EQ, no processing, nothing in the way).

L+RMainRew.PNG


There is some room mode effects especially below 100hz, but in no way can this be considered as rolling off from 300hz. The mids around 500-700hz have a bump up, not sure whether that is a room mode or the an effect of the crossover at 800hz is not clear. As I had mentioned earlier in this thread, I cross them at 100hz (by disabled for this measurements) to the sub. But they are relatively flat down to about 90hz or so. And no, they don't sound anywhere near what Amir described it as although it is difficult to calibrate such subjective descriptions.

So
1. The measured 300 hz roll-off is definitely not a given for small Maggies (not even for this 25 year old model). This would be a wrong conclusion to draw from this review.
2. Unless the LRS is really screwed up in which case, I think they should be burnt to have shows such a dismal measurement, one has to explore reasons.

Repeatability (not just in one experiment) but by others is one significant requirement for establishing validity of a scientific experiment. Is there a single REW of the LRS anywhere else that shows such a roll-off? A valid question to ask. Next, is the measurement that has a huge discrepancy valid?

Now one might say, there may be something odd or unusual about my set up that is causing it to measure better than it is. So I did a control measurement that actually is similar to what a 300hz roll-off might look like (exact same audio chain but for center).

Center_MMG-W.PNG


Once can even credibly claim that this starts to roll off around 500. This is for another model of Maggie, a pair of wall-mounted $325/pair MMG-Ws used as phantom center. MMG-W is the tiniest of the Maggies and not designed for low extension but does well as a phantom center to match bigger Maggie mains. So, there is nothing compensating to make any of them sound better than they are.

Is the LRS really more like the tiny MMG-Ws (I would find it hard to believe) or is there a discrepancy that needs to be explained? Can we find one corroborating measurement of the LRS that supports the measurements here? These are valid questions to ask in the interests of science alone.

Nothing to do with whether one likes or does not like these speakers.
 
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richard12511

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Yeah, when science proves your beliefs are fundamentally flawed.....

I can imagine this is hard to deal with, and no doubt is responsible for much of this reviews criticism. I really do sympathize with owners.

That said, it is also possible that the measurements simply don't capture the magic of these speakers. Everyone who's heard them praises their imaging and soundstage.
 
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amirm

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The other I think is that with one speaker, you'll miss one of the main reasons people love planar line sources, despite their limitations -- the awesome imaging.
Not really. The imaging is apparent with a single speaker just as well. Try it.

Testing two speakers will multiply the nightmare of setup with these speakers times two.
 

Sancus

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I did a quick measurement of the 25 year old SMGa using REW.

SMGa is 24 x 48", no? So that would make it 1152sqin, closer to the panel area of the 1.7i(1235) than to the LRS(696). I haven't seen nearly as much rolloff in measurements of my 1.7i either.
 
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amirm

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But the rolling off starting at 300hz seems very odd.
It is not odd if you look at it in reverse in how I eq the speaker:

index.php


There is peaking in the output from 250 Hz to about 900 kHz. Take that out and the bass response is would then be in-line with the rest of the response (more or less for this speaker). This is why I applied this eq:

index.php


See how I pulled down that peaking? Once there, the problem is lack of output which I compensated by shifting all other frequencies higher. Once there, the response was far superior. So no question that the peaking is the problem.

Now that fix doesn't do a lot for the lower bass drop so it still lacks dynamics.
 

bunkbail

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ruinevil

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Qmmiazf.jpg


This is the AutoEQ to my listening space via the dbx PA2 system using the dbx RTA mic at my listening position... you can ignore the stuff below 80 Hz because I have my subwoofer crossed over there. It's sitting to the side of a 90ftx30ftx8ft room.
 
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amirm

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Repeatability (not just in one experiment) but by others is one significant requirement for establishing validity of a scientific experiment.
My measurements are highly consistent with Warkwyn's which was published in AudioExpress magazine. Granted they also used Klippel NFS but otherwise, we both independently measured and arrived at the same results. Theirs is at a different acoustic center which I also got but then corrected:

1600576350972.png


You can see identical vertical directivity measurements:

1600576390061.png
 
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amirm

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This is the AutoEQ to my listening space via the dbx PA2 system using the dbx RTA mic at my listening position...
Looks like Filter #1 is doing exactly what I did in my EQ and reflective of the response of the speaker.
 

RayDunzl

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I'd expect so see tremendous comb filter effects measuring both left and right speakers at the same time from your listening chair.

If the speakers are equidistant from the listening/measuring point, their direct sound should have no comb effect at all. Add room reflections, yes.
Wild vertical scale makes poor curves look smooth, but I'd still expect it to look worse.

That's my standard scale. Here's the not quite quiet room at the moment:

1600575749659.png

The point is less how much different, as, how similar.

Which is which?

Most speakers will look flat on a graph with a 100dB vertical scale and only going down to 240Hz...


Oh, all right.

1600576057555.png

Which is which?
 
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amirm

amirm

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-- however -- in my opinion, it'd be cool to see in-room measurements, especially with/without room correction, etc., etc...
Not quite what you are asking but most of the time I present the in-room frequency response in the 96 dB SPL graph:

index.php


Granted, the speaker is still 5 foot in the air but otherwise this is a single measurement like anyone would make. Here, we clearly see the same peaking of on-axis above 350 Hz. The treble response is lower than spinorama because this was made at my first guess at the acoustic center.
 
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