Buchardt S400 Speaker Review

[amirm]

Sorry to play it hard here, but please firstly understand the NFS system, before commenting any further on this. This is exactly why this is such a valuable tool for engineers.

Well, those engineers should have fully documented the production changes that resulted in my measurements being different than what you had published. I suggest having a strong talk with them about this Mads. A lot of effort was spent here trying to rationalize my measurements against yours, only to find out that our take was the correct one due to fundamental changes to tweeter/crossover. They had plenty of time to come forward with this data during the few months it took us to get the speaker for me to test it. I know I would have appreciated a heads up of the change in the product.

Arguing now about extreme low frequency response (15 Hz in a bookshelf speaker -- are you kidding me?) in a measurement system they themselves don't use day in and day out, is not going to earn them any points in my book.

 

[QMuse]

@amirm IMHO I believe this is the part that needs to be cleared out as that is where you and Mads differ the most:

"Sorry, but I need to correct your understanding of the visualization tool here. All data of the visualization tool are shown as they are at the actual shown distance. The only exceptions are:

• Sensitivity data, which is referenced from 10m SPL curve to 1m distance. Below is the headline of sensitivity plot shown, where you can see how it is noted when data is referenced to new radius:

• CEA2034 curve, which is 2m SPL curve referenced to 1m distance.

This is the entire point of the use of NFS system, that we as designers can optimize a speaker to work well at all distances without having to redo the measurements. We had a call with Klippel (C.B., name left out, but I think you know him) yesterday, to sort this misunderstanding out – and they confirmed to us, that our understanding of the system is correct.

You will see this clearly, if you show our S400 contour plot at 10m distance instead of 66cm distance. You will see clearly that the patterns are not the same – and that true far-field data looks like the one we present in our documentation. "

 

[amirm]

This is the entire point of the use of NFS system, that we as designers can optimize a speaker to work well at all distances without having to redo the measurements. We had a call with Klippel (C.B., name left out, but I think you know him) yesterday, to sort this misunderstanding out – and they confirmed to us, that our understanding of the system is correct.

You will see this clearly, if you show our S400 contour plot at 10m distance instead of 66cm distance. You will see clearly that the patterns are not the same – and that true far-field data looks like the one we present in our documentation.

As I just noted, your documentation is for speakers that are not in production so I would not mention that if I were you. Your measurements were also made with earlier revision of the software which computed some of the graphs incorrectly. This is a bug that we found and worked with Klippel to solve with a patch I use. There is another bug beyond that which I have a fix for as well. No one has put these CEA-2034 measurements to use like we have. Not even remotely close. The power of the membership here together with my measurements of some 50 speakers so far, has really put the magnifying glass on what the system is doing.

You have an idealistic view of the system, lacking hands on experience with it on day to day use. Christian is a wonderful resource (and architect of the system) but you have to hold your own when you talk to him to have a meaningful discussion.

Anyway, our use of the directivity plot is for issues above bass. Indeed I routinely filter everything below 70 Hz for that reason. We use it to see how the crossover is handled and how wide and smooth it is as we travel from a few hundred hertz to 20 kHz. Have your engineers read my reviews to understand how we use it and how their objections even if true, are immaterial to usage of the graph in general and ours in the specific.

 

[amirm]

@amirm IMHO I believe this is the part that needs to be cleared out as that is where you and Mads differ the most:

"Sorry, but I need to correct your understanding of the visualization tool here. All data of the visualization tool are shown as they are at the actual shown distance. The only exceptions are:

I don't know what needs resolving. These are the two graphs they post at two different distances:

As I noted in my last post, everything we use this graph for is identical in their two images.

 

[QMuse]

Well, this:

The module that generates the directivity plot is a *visualization* tool. The sound field data is already computed in a different module and remains unchanged.

When you change the "distance" all it does is change the computational gain. This changes the false color pallet making it look like things are different due to very low resolution of these graphs. All major acoustic events are identical in both measurements. They would not be so if were in near field.

vs

this:

Sorry, but I need to correct your understanding of the visualization tool here. All data of the visualization tool are shown as they are at the actual shown distance. The only exceptions are:

• Sensitivity data, which is referenced from 10m SPL curve to 1m distance. Below is the headline of sensitivity plot shown, where you can see how it is noted when data is referenced to new radius:

View attachment 61955

• CEA2034 curve, which is 2m SPL curve referenced to 1m distance.

This is the entire point of the use of NFS system, that we as designers can optimize a speaker to work well at all distances without having to redo the measurements. We had a call with Klippel (C.B., name left out, but I think you know him) yesterday, to sort this misunderstanding out – and they confirmed to us, that our understanding of the system is correct.

You will see this clearly, if you show our S400 contour plot at 10m distance instead of 66cm distance. You will see clearly that the patterns are not the same – and that true far-field data looks like the one we present in our documentation.

The reason for us to highlight this is that since you choose to show objective measurements in your reviews, which we fully support, it is important that the measurements are shown with the right backgrounds. Our recommendation remains – always show far field data for speakers >2m distance. These near-field data will be misinterpreted by users unfamiliar with how the NFS data works, and will show near-field artefacts, that are not to be considered correct.

 

[richard12511]

Well, those engineers should have fully documented the production changes that resulted in my measurements being different than what you had published. I suggest having a strong talk with them about this Mads. A lot of effort was spent here trying to rationalize my measurements against yours, only to find out that our take was the correct one due to fundamental changes to tweeter/crossover. They had plenty of time to come forward with this data during the few months it took us to get the speaker for me to test it. I know I would have appreciated a heads up of the change in the product.

Arguing now about extreme low frequency response (15 Hz in a bookshelf speaker -- are you kidding me?) in a measurement system they themselves don't use day in and day out, is not going to earn them any points in my book.

Looking at this from the outside, as someone who is less knowledgable than both parties, my only request is that y'all both carefully consider the other parties' view. It's easy to dig your heels in and fight to protect your own point of view. It's much harder to admit you were wrong and adjust. This applies to both sides.

 

[Thomas savage]

Looking at this from the outside, as someone who is less knowledgable than both parties, my only request is that y'all both carefully consider the other parties' view. It's easy to dig your heels in and fight to protect your own point of view. It's much harder to admit you were wrong and adjust. This applies to both sides.

Yes , please don't forget the poor sod's who don't know what horse to back .

If you do many just end up rejecting both views and go off thinking it's all a mystery so just ' trust your ears '.

 

[BYRTT]

.....it's all a mystery so just ' trust your ears '.

objective curves.....

 

[QMuse]

objective curves.....

I'm starting to wonder if there is a single person on this planet that actually understand how Klippel works.

 

[MZKM]

I mean, wouldn’t simply recomputing out 1m & 5m plots easily dispel any arguments?

That said, the only difference I am seeing is slight and in the bass, which could simply be explained as difference in output (Amir showing more red hot output shows that what is considered “0dB” is different).

 

[RMW_NJ]

Yes , please don't forget the poor sod's who don't know what horse to back .

If you do many just end up rejecting both views and go off thinking it's all a mystery so just ' trust your ears '.

I am one of those that knows only slightly more than nothing, and honestly, the hardest part for me is reconciling how the JBL HDI-3600 gets a stamp of approval but the S400 seems to have gotten picked apart a bit. But then again I have my own biases, so maybe I'm reading too much into it.

 

[QMuse]

I mean, wouldn’t simply recomputing out 1m & 5m plots easily dispel any arguments?

That said, the only differences I am seeing is slight and in the bass, which could simply be explained as difference in output (Amir showing more red hot output shows that what is considered “0dB” is different).

I would actually stick with what @edechamps proposed in his post on previous page:

"Seems like there's an easy way to end this debate and determine if the data truly is computed near-field or not: recompute the polar maps at a crazy short distance, say 5 centimeters. If @Mads Buchardt is right, the data should look very different (similar to a close-mic tweeter measurement, I'd expect). If @amirm is right, the data will look basically identical, only the absolute SPL will be much higher. "

 

[QMuse]

I am one of those that knows only slightly more than nothing, and honestly, the hardest part for me is reconciling how the JBL HDI-3600 gets a stamp of approval but the S400 seems to have gotten picked apart a bit. But then again I have my own biases, so maybe I'm reading too much into it.

This discussion is about Klippel measurements and related preference ratings where JBL got score 4.9 and S400 got 5.5, so let's get panther ratings out of this.

 

[Haint]

I admittedly don't really know what I'm doing, but the only thing I use the contour plots for is to eyeball how smooth and even the red heat maps and fall offs are from ~1Khz onward. One of Mad's earlier posts had better looking horizontal plots, but I think (correct me here Mads) they're from the early model with the old crossover. I believe Amirm is saying the 1kHz - 20kHz region is identical whether he plots it at 66cm, 2m, or 10m, and the difference Mads posted are due to the old crossover design, not the distance.

 

[QMuse]

I admittedly don't really know what I'm doing, but the only thing I use the contour plots for is to eyeball how smooth and even the red heat maps are from ~1Khz onward. One of Mad's earlier posts had better looking horizontal plots, but I think (correct me here Mads) they're from early model with the old crossover. I believe Amirm is saying the 1kHz - 20kHz contour is identical whether he plots it at 66cm, 2m, or 10m.

Yes, that is what he is saying. So let's see how they look at 5cm to check who is right.

 

[napilopez]

Taking a step back and a broader view, the change in crossover and choice of reference axis explain most of the meaningful original differences at this point.

I have some academic curiosities in the difference between Amir and Buchardt's klippel interpretation/processing, and I think the discussion is useful because this will likely be the only opportunity we to compare two parties using the same anechoic system, and I think the discussion of data presentation will continue to come up, so it's good to have multiple perspectives with the same equipment.

But for practical evaluation now, at least if you've been following the thread for added context, the data isn't so different.

I admittedly don't really know what I'm doing, but the only thing I use the contour plots for is to eyeball how smooth and even the red heat maps are from ~1Khz onward. One of Mad's earlier posts had better looking horizontal plots, but I think (correct me here Mads) they're from early model with the old crossover. I believe Amirm is saying the 1kHz - 20kHz region is identical whether he plots it at 66cm, 2m, or 10m, and the difference Mads posted are due to the old crossover design.

No, that directivity plot is a new one - note the dips occur at the new crossover point. The difference in the contour plot seems to be directly tied to the reference axis (tweeter vs between woofer and waveguide), and the fact that the graph, not normalized to the on-axis simply reflects the existing dip on the on-axis data. Buchardt's isn't normalized on-axis either, but their on-axis is flatter.

 

[QMuse]

I have some academic curiosities in the difference between Amir and Buchardt's klippel interpretation/processing, and I think the discussion is useful because this will likely be the only opportunity we to compare two parties using the same anechoic system. But for practical evaluation now, the data isn't so different.

In spite of that, the truth is out there and we need to find it!

 

[napilopez]

In spite of that, the truth is out there and we need to find it!

Haha I edited my posted a bit. But truly this is more insight into an anechoic measurements process than I think has ever been available in a public forum... So I'm grateful for that.

 

[NTK]

I would actually stick with what @edechamps proposed in his post on previous page:

"Seems like there's an easy way to end this debate and determine if the data truly is computed near-field or not: recompute the polar maps at a crazy short distance, say 5 centimeters. If @Mads Buchardt is right, the data should look very different (similar to a close-mic tweeter measurement, I'd expect). If @amirm is right, the data will look basically identical, only the absolute SPL will be much higher. "

Yes. Just not at 5 cm. Klippel only reconstructs outside the scanned surface. Reconstruction inside of the scanned surface is an "inverse problem" and is mathematically ill posed. Errors grow to the power of the ratio between scan radius and the reconstruction radius.

This is from the Klippel NFS app notes (page 4).

 

[QMuse]

Yes. Just not at 5 cm. Klippel only reconstructs outside the scanned surface. Reconstruction inside of the scanned surface is an "inverse problem" and is mathematically ill posed. Errors grow to the power of the ratio between scan radius and the reconstruction radius.

This is from the Klippel NFS app notes (page 4).

View attachment 62041

Ok, I see. Let's go on the far side then, maybe 4 meters? The logic stays the same, either only SPL will reduce (and Amir is right) or the response would be different (and Mads is right).