March Audio Sointuva Speaker

[MZKM]

Im not sure about this. My reading is that with a 10:1 the x axis would be twice as wide as the Y axis assuming a 20kHz span. Amirs plots conform to this.

Here is the example Spin from the 2034 paper:

The graphs from SoundStage/NRC also follow this:

@napilopez has me filmed this as well:
https://www.audiosciencereview.com/...ds/erinsaudiocorner.11219/page-16#post-424133

This graph of your's following the correct aspect ratio very closely it looks like:

 

[March Audio]

Here is the example Spin from the 2034 paper:
View attachment 95560
The graphs from SoundStage/NRC also follow this:

@napilopez has me filmed this as well:
https://www.audiosciencereview.com/...ds/erinsaudiocorner.11219/page-16#post-424133

So the standard is wrong. Haha no wonder I was struggling to interpret it, both the terms it uses are wrong. I thought it was me being daft

REW 25dB/octave setting. Sorted!

 

[MZKM]

So the standard is wrong. Haha

REW 25dB/octave setting. Sorted!


View attachment 95564

Yeah, the revision of the standard is slated to be completed this year, although the website stated only 25% completed.

As to what is claimed in the revision:

The standard is being revised to incorporate new rating methods and to make additional edits as needed

The other major typo is the calculation of Early Reflections, as even the Klippel NFS is doing it wrong (Amir has contacted them); as it only uses the + & - 90 degree angles and 180 degrees, when it should be using everything from + to - 90 degrees from the rear (180 degrees) hemisphere.

How did you make your PIR curve? As besides the ER curve error, if calculating manually (like I do), you also need to do the proper angular weights for Sound Power which also includes going to and from Pascals & Decibels.

 

[March Audio]

@amirm and @March Audio in this case you both were right somehow.
The chosen scaling and smoothing does not correspond to the common representation here. But the display chosen by March Audio is not misleading (visually maybe a little bit).
The diagram below shows the frequency response of KH310 (1/20 oct smoothing), Sointuva 1/24 oct smoothing and Sointuva 1/3 smoothing (the smoothing called "Psychoacoustic smoothing" by @March Audio)

If you look at the "ripple" of the speaker in the range 0.1-10kHz, it is 5.6dB with 1/24 oct smoothing and 4.9dB with 1/3 oct smoothing - this is not dramatically different.

Just for info 1/3rd and psychoacoustic smoothing arent the same.

 

[ctrl]

Just for info 1/3rd and psychoacoustic smoothing arent the same.

Since I don't use REW, I thought you were using the term "psychoacoustic smoothing" to refer to the critical bands

 

[March Audio]

.

How did you make your PIR curve? As besides the ER curve error, if calculating manually (like I do), you also need to do the proper angular weights for Sound Power which also includes going to and from Pascals & Decibels.

REW to Virtuixcad.

 

[MZKM]

REW to Virtuixcad.

Ok, I assume it‘s doing the correct calculation unlike the Klippel software.

 

[March Audio]

Since I don't use REW, I thought you were using the term "psychoacoustic smoothing" to refer to the critical bands

Psychoacoustic smoothing uses 1/3 octave below 100Hz, 1/6 octave above 1 kHz and varies from 1/3 octave to 1/6 octave between 100 Hz and 1 kHz. It also applies more weighting to peaks by using a cubic mean (cube root of the average of the cubed values) to produce a plot that more closely corresponds to the perceived frequency response

 

[ctrl]

Ok, I assume it‘s doing the correct calculation unlike the Klippel software.

VituixCAD offers a variety of settings to manipulate the displayed curves.
But with the correct settings and complete measurements the CEA2034 should be calculated correctly.

 

[CtheArgie]

@March Audio , should we then “worry” about the 3k dip or not?
Anyway, I thought that the debate was unnecessarily bitter.

 

[March Audio]

@March Audio , should we then “worry” about the 3k dip or not?
Anyway, I thought that the debate was unnecessarily bitter.

It was completely unnecessary full stop but let's move on.

Speaker design is about balancing compromises. The objective is to choose the compromises that have the least negative impact.

Ideally of course it wouldn't be there. However you need to be careful. If tweaked to minimise it there would be knock on effect in the sound power, the sound radiated in different directions in the vicinity around that dip.

If you look at the predicted in room response the dip is only very small.

However, as mentioned one of the objectives of the final measurements is to look at this in detail, minimise it without upsetting the in room response.

BTW dips are generally less audible than peaks. The link @ctrl provided earlier provides some further insight on this.

Subjective testing has not shown it to be an issue.

 

[March Audio]

Better conditions today. Measurements close to the model, F3 at about 45Hz and F6 at about 40Hz

 

[McFly]

In jest - Alan, with audiosciencereview, you need to slap big red disclaimers ON all the measurement images, because noone (you know what I mean) actually reads the text.

Also, that 3khz dip looks like edge diffraction, which is a phenomenon with virtually all commercially available direct radiating box speakers available today have, that would likely disappear in-room, as you've simulated and shown. 3khz wavelength is 11.4cm, is that not the length from your tweeter to edge?

 

[March Audio]

In jest - Alan, with audiosciencereview, you need to slap big red disclaimers ON all the measurement images, because noone (you know what I mean) actually reads the text.

Also, that 3khz dip looks like edge diffraction, which is a phenomenon with virtually all commercially available direct radiating box speakers available today have, that would likely disappear in-room, as you've simulated and shown. 3khz wavelength is 11.4cm, is that not the length from your tweeter to edge?

Oh for sure, its shown in the model. Was expecting it.

However the reality is more pronounced than expected, so investigating tweaking the xo slightly.

 

[MZKM]

Oh for sure, its shown in the model. Was expecting it.

View attachment 95682

However the reality is more pronounced than expected, so investigating tweaking the xo slightly.

While on this topic, and this is a question to anyone:
Why do some companies use offset tweeters? Is it so that while it makes 2 different diffraction frequencies, they are less pronounced?

 

[McFly]

While on this topic, and this is a question to anyone:
Why do some companies use offset tweeters? Is it so that while it makes 2 different diffraction frequencies, they are less pronounced?

Bingo. - ideally 3 different diffraction frequencies by keeping the tweeters distance from the TOP and TWO sides of the cabinet different lengths.

But most people prefer a centered tweeter, myself included. Look at any of the revel speakers, heck KEFs, Elacs ... I could go on. The aesthetic trade-off is much preferred. The first question on the showroom floor is always "why arent the tweeters centered it looks funny doesn't it?".

Almost all of the time the on-axis dip does not turn up "in-room". Might be a problem near-field? IDK, I don't do near-field.

 

[March Audio]

While on this topic, and this is a question to anyone:
Why do some companies use offset tweeters? Is it so that while it makes 2 different diffraction frequencies, they are less pronounced?

It certainly changes it.

Whether its useful or not will depend on a number of factors and specific design.

 

[Juhazi]

Tweeter placement on the baffle is tricky. Equidistant to three nearest edges is worst scenario... Fortunately we have sims like Edge and Vituixcad!

 

[DrDardis]

@March Audio Curtin University used to have a pretty good anechoic chamber from recollection in the engineering department, perhaps you could see if you can get time in it?

 

[March Audio]

@March Audio Curtin University used to have a pretty good anechoic chamber from recollection in the engineering department, perhaps you could see if you can get time in it?

They do have an RF anechoic chamber but I cant find any reference to an acoustic. chamber