Magnepan LRS Speaker Review

[richard12511]

Thanks for taking this step. Hope this can be included in all speaker measurements.

This is very different from the predicted Klippel in-room response and what people interpreted based on that and the subjective interpretation. You have to look at it with a filter of room modes especially with a single location measurement. It can be very, very different a few inches away. This is why either a multi-position or RTA sweep (as I had suggested) is necessary for any meaningful room correction. You can do this with REW on a PC with no additional set up necessary. Less than a minute for RTA waving your arms about like a music conductor!

First of all there is no 300hz exaggerated response (this should raise eye-brows about interpreting based on Klippel measurement). Note that some of the interpretation was based on this fall off from 300hz implicitly or explicitly.

The bass extension target is influenced by the deep nulls at 100hz and at 40hz. These are room mode characteristics. If you used this target for REW it would justifiably complain that too much of the area is below the target (primarily because of the below 1khz fit). The target could be quite different if the 100hz null didn't exist.

If I were to equalize this as-is I would pick a +75db flat line for the region below 1khz and ignore any corrections for the nulls or below 60hz. And use a shelf filter to lower the entire tweeter range by about 5db to get a better balance if it could not be achieved by changing the attenuators. The localized nulls would have some effect on clarity and fidelity of lower bass but not necessarily tonal balance.

If I were to evaluate this graph on its own to optimize it, I would say the tweeter range seems to be elevated relative to the low/mid range. This can provide a perception of lower bass content. One can justifiably knock the LRS for this tweeter vs low/mid ribbon balance if it wasn't related to room modes. Or one of the the supplied attenuators might balance it better. With this as is, it would sound too bright and thin.

I would then experiment with both distance from the back wall and the toe-in to affect the null. This is where some of the well-deserved "reputation" for Maggies to be picky about placement comes in.

I don't think it's really fair to say "the target could be quite different if the 100Hz null didn't exist". While true, you could also say "the target could be quite different if the 70Hz peak didn't exist. It would be much lower". The 70Hz peak is as much of a room node as the 100Hz null. I think Amir did a good job of drawing an average line through both the peaks and nulls. This is also why I like the PIR approach of drawing an "average", though in this case it does seem like the PIR calculation doesn't work all that well for panels. It looks to be about 100Hz off(300Hz vs 200Hz) in where the roll off begins.

I agree with your idea of shelving everything down 5db or so. That does cut into the already limited headroom, but it gives you enough extension to reasonably cross to subs(imo).

 

[amirm]

This is also why I like the PIR approach of drawing an "average", though in this case it does seem like the PIR calculation doesn't work all that well for panels.

I think lack of phase in the computation of early window reflection sum must be the problem for dipole speakers.

 

[Vasr]

I don't think it's really fair to say "the target could be quite different if the 100Hz null didn't exist". While true, you could also say "the target could be quite different if the 70Hz peak didn't exist. It would be much lower". The 70Hz peak is as much of a room node as the 100Hz null. I think Amir did a good job of drawing an average line through both the peaks and nulls. This is also why I like the PIR approach of drawing an "average", though in this case it does seem like the PIR calculation doesn't work all that well for panels. It looks to be about 100Hz off(300Hz vs 200Hz) in where the roll off begins.

I agree with your idea of shelving everything down 5db or so. That does cut into the already limited headroom, but it gives you enough extension to reasonably cross to subs(imo).

The difference is that the 70hz peak does not seem to be a room mode being in line with the other peaks (yes, you can say it is from a much lower base!). But my point is that the 100hz null trough is artificially creating a roll-off at 200hz just as the Klippel measurement did at 300hz from the exaggerated peak above it which does not exist here. It is a really bad idea to "average" a line through a measurement when you have room modes in any case. This is another reason why you would EQ a RTA or a multi-position measurement.

I would only shelf lower the range above 800hz not the frequencies below it. I don't know what the cross-over frequency is for the LRS to say if this is a tweeter vs mid/bass driver imbalance but that level discrepancy between below and above 800hz or so is very odd and seems out of balance.

Personally, I would never use an LRS if I had one without a sub so some of this discussion is academic but I would also not buy a LRS if the bass extension was only down to 300hz and a roll-off after that as the original review indicated that no sub could fix. The REW measurement changes that equation quite a bit. A standard 80 or 60hz crossover to sub would be just fine if that 100hz null could be tamed with positioning.

 

[Blumlein 88]

As I just explained, the AP is easier since it is always connected to my workstation. But yes, I will see if I can modify the setup for the future to run REW.

Usually I run REW using my laptop but lugging that up to the listening room has been a hassle.

I didn't realize you had the AP already there. Just continue using it. I was looking to make it easier and convenient for you.

 

[MRC01]

I believe a dipole has the opposite behavior regarding SBIR against the front (behind the speaker) wall, because its rear-facing wave leaves the speaker having inverted amplitude from the front wave.
For example, consider a speaker 3' away from the front wall. It travels 6 feet going back, reflecting forward. That's a full wavelength of about 175 Hz. With a conventional speaker this strengthens 175 Hz, making a peak. With a dipole it weakens 175 Hz, making a dip. This may be a factor contributing to Amir's in-room measurements where the speakers had reverse swings at the same frequencies.

 

[BYRTT]

.....As I note though, overall response is smoother and cleaner than I expected.....

But also under anechoic analyze it was very sensitive to actual microphone axis, thousand thanks do this and have best other duties

Amir in room overlaid to LRS spinorama..

 

[RayDunzl]

Can you repost with 50 dB vertical scale?

Post edited.

 

[BYRTT]

.....LRS is very close to the old MMG and SMG in terms of the actual "voice cone" area. So, the magic if anything would be how they made it much worse than those if the measurements were a true indicator of its response.

Much worse Magnespan MMG measured in room at 100cm by Dick Olsher, offset and overlaid to PIR curve (orange) of Amir's anechoic spindata..

 

[BYRTT]

Thanks for taking this step. Hope this can be included in all speaker measurements.

This is very different from the predicted Klippel in-room response and what people interpreted based on that and the subjective interpretation. You have to look at it with a filter of room modes especially with a single location measurement. It can be very, very different a few inches away. This is why either a multi-position or RTA sweep (as I had suggested) is necessary for any meaningful room correction. You can do this with REW on a PC with no additional set up necessary. Less than a minute for RTA waving your arms about like a music conductor!

First of all there is no 300hz exaggerated response (this should raise eye-brows about interpreting based on Klippel measurement). Note that some of the interpretation was based on this fall off from 300hz implicitly or explicitly.

The bass extension target is influenced by the deep nulls at 100hz and at 40hz. These are room mode characteristics. If you used this target for REW it would justifiably complain that too much of the area is below the target (primarily because of the below 1khz fit). The target could be quite different if the 100hz null didn't exist.

If I were to equalize this as-is I would pick a +75db flat line for the region below 1khz and ignore any corrections for the nulls or below 60hz. And use a shelf filter to lower the entire tweeter range by about 5db to get a better balance if it could not be achieved by changing the attenuators. The localized nulls would have some effect on clarity and fidelity of lower bass but not necessarily tonal balance.

If I were to evaluate this graph on its own to optimize it, I would say the tweeter range seems to be elevated relative to the low/mid range. This can provide a perception of lower bass content. One can justifiably knock the LRS for this tweeter vs low/mid ribbon balance if it wasn't related to room modes. Or one of the the supplied attenuators might balance it better. With this as is, it would sound too bright and thin.

I would then experiment with both distance from the back wall and the toe-in to affect the null. This is where some of the well-deserved "reputation" for Maggies to be picky about placement comes in. Not that different from a sub with backside porting.

Think your conclusions or comments for Amir's anechoic LRS analyze often is bit far from others, admit graphs over and over be it here or from other sources have different X/Y ratio and scale resolution so interpret them right is hard for most, therefor in it sounds REW is solid ground for you have prepared one attached zipfolder including below pictured txt-files so Magnespan LRS spinomara plus Amir's distortion and in room measurement plus the Dick Olsher MMG panel can be loaded and viewed overlaid onto REW's "All SPL" tab and then interpreted onto same scales, hope critic is taken for good or reasonable okay and the share of the attached zip-folder is some way constructive we can interpret curves more the same and conclude they in reasonable within of what CTA2034 PIR (predicted in room) calculation predicted minus per room unique standing wavefronts..

 

[BYRTT]

Dipole panel (over 180Hz) with sealed woofer vs conventional here, adjacent speaker locations, at the listening position, 1/6th smoothing, no EQ

View attachment 85258

Interesting thanks but please edit what is what of the curves, is panel/sub hybrid the purple one ?..

 

[Blumlein 88]

@amirm Since your first panel review was so satisfying are you committed to publishing one panel review per month for the next 6 months?

Just thought I remind you that despite all the sniping, questioning of methods and other stuff we only do it because we care about sound, and because you alone are providing us with such measures in the first place. So don't forget many of us are highly appreciative of your efforts. (and jealous of your gardening bounty ).

I think you should do a modern Quad next. Then we can disbelieve the results wondering if the segmented rings having delay are measured correctly by the Klippel or not.

If you thought DACs, and amps and stuff could get people sideways, you should have known a panel speaker which many love that measures almost off the bottom of the scale would get some pushback. Everyone who owns a small Maggie has to look at this and think, "no way, what BS is this!"

 

[amirm]

@amirm Since your first panel review was so satisfying are you committed to publishing one panel review per month for the next 6 months?

If I had more to measure, I would. Personally I got a lot of satisfaction out of the original measurements because the speaker is so unusual. That's why I spent the time to develop the other graphs/animations.

I only know one member that has a acoustat speaker. I don't know if he is interested in loaning it to me for testing though.

Thanks a lot for the sentiments. It is much appreciated.

 

[richard12511]

Thanks @BYRTT

Here are some other comparisons

PIR vs In Room response

and PIR vs Distortion measurement

Seems to track better than I thought. Big difference in the treble response though between PIR and In Room.

 

[BYRTT]

.....Big difference in the treble response though between PIR and In Room.

Imagine that is the relative difference of distance from one point in space to whatever acoustic point in the long line is never the same and comb filtering occurs verse traditional point sources, not stuff marketing like to talk about even it is real but probably very hard or impossible to sense live for the ear that it exist, animation below was for another example about floor as gain boundary relative to acoustic distances of tranducer locations but the mid and treble response comb filtering will probably look ala that animation but up at higher frequencyes, we get a avarage as in the grey curve suggest but the riples exists at static physical points in space..

 

[Vasr]

Think your conclusions or comments for Amir's anechoic LRS analyze often is bit far from others, admit graphs over and over be it here or from other sources have different X/Y ratio and scale resolution so interpret them right is hard for most, therefor in it sounds REW is solid ground for you have prepared one attached zipfolder including below pictured txt-files so Magnespan LRS spinomara plus Amir's distortion and in room measurement plus the Dick Olsher MMG panel can be loaded and viewed overlaid onto REW's "All SPL" tab and then interpreted onto same scales, hope critic is taken for good or reasonable okay and the share of the attached zip-folder is some way constructive we can interpret curves more the same and conclude they in reasonable within of what CTA2034 PIR (predicted in room) calculation predicted minus per room unique standing wavefronts..

View attachment 85276

Thanks for putting it together but I would have no idea what to do with all that measurebating (borrowing someone else's term in these forums).

It does not seem to be creating any more insight (if not actually providing an incorrect indication) than a simple single REW measurement did as far as frequency response is concerned (even as flawed it may be given the test limitations and the difficulty in separating it from room modes). This was my point all along and hence the need to corroborate. The measurements using Klippel would be much more useful, I think, in understanding effects as you move horizontally or vertically, etc., to qualitatively evaluate whether something has a narrow sweet-spot, etc. This would be very difficult to do by other means.

The danger with generating a lot of data with measurement and fancy charting without a good sense of what it relates to in reality is losing track of what is a model derived inference and what is reality. Quantity of data is not a substitute for reality.

I think this particular experience has sufficiently demonstrated it. Hopefully, we will get more "field data" (REW measurement) in the future from people who have purchased this that would improve our understanding of what this speaker does.

 

[whazzup]

Tangential to above discussions, but are all planar speakers dipole designs? As in the ones readily available on the market.

 

[Blumlein 88]

Tangential to above discussions, but are all planar speakers dipole designs? As in the ones readily available on the market.

Yes to my knowledge.

You could have a panel with an enclosure behind it. There has been at least one or two in the past I think.
EDIT: as you see down thread Wisdom speakers do this. I was not aware they were made that way.

Or you could have a double membrane panel I suppose with sound in phase from both sides. Don't know of anyone making one of those. There would be some design issues to work around for such a design.

 

[RayDunzl]

Tangential to above discussions, but are all planar speakers dipole designs? As in the ones readily available on the market.

Big ones probably are.

Smaller may not be. NXT as an example.

Planar headphones often list "closed back".

 

[BYRTT]

Thanks for putting it together but I would have no idea what to do with all that measurebating (borrowing someone else's term in these forums).

It does not seem to be creating any more insight (if not actually providing an incorrect indication) than a simple single REW measurement did as far as frequency response is concerned (even as flawed it may be given the test limitations and the difficulty in separating it from room modes). This was my point all along and hence the need to corroborate. The measurements using Klippel would be much more useful, I think, in understanding effects as you move horizontally or vertically, etc., to qualitatively evaluate whether something has a narrow sweet-spot, etc. This would be very difficult to do by other means.

The danger with generating a lot of data with measurement and fancy charting without a good sense of what it relates to in reality is losing track of what is a model derived inference and what is reality. Quantity of data is not a substitute for reality.

I think this particular experience has sufficiently demonstrated it. Hopefully, we will get more "field data" (REW measurement) in the future from people who have purchased this that would improve our understanding of what this speaker does.

Welcome, ha ha measurebating is great term or humor but hech can see yourself go high up in measurements into room responses but how would that ever be anything that bad science when anyone knows its almost doable for any reasonable wide enough acoustic bandpass plus some room help get whatever nice curve and bandpass coverage using that polated method of measurements, its probably like talking to a door get understanding from your side that resolute higher than in room measurement is way forward and that a acoustic transducer need be smooth in tonality but also even in dispersion else it mostly will become a effect box that can look alright into REW in room measurements but have its own effect box signature painted on any track material, effects are good enough for induvidual instruments such as their tonality or dispersion but for reproduction of artists finalized recordings it would be advantage not add any spurs onto the track material, not shure you ever got it read curves that directivity and response linearity is a mess here, it seems consentration is more on critizise ASR for doing bad science and we dont agree much on that front but good luck hope for the best get into the stuff and understanding the progress in better sound trust resolution of REW in room measurements.

Spinorama listening window for LRS horizontals of -30º/-20º/-10º/0º/+10º/+20º/+30º plus verticals of -10º/+10º normalized flat as a pancake on axis, do you think your REW in room corrections will help on that differences or that a live singer into same room will have that dispersion signature..

All the 72 times diretivities and some radars..

 

[amirm]

Tangential to above discussions, but are all planar speakers dipole designs? As in the ones readily available on the market.

Wisdom speakers are not. They have a small backbox.

They are hybrid though with the planar playing from 400 Hz up.