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Ascend CBM-170 SE Speaker Review

TimVG

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Listening window correction filters + alternative filter to compensate somewhat for the off-axis bloom which could be perceived as 'softer' in case of untreated early reflection points


 
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krabapple

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I think I gotta send Amir one my Behringer Truth (2030P) passive speakers ( 10.9 x 10.9 x 14.9, 6.75" woofer) I was using before the Ascend CBM170SEs....the Behringers are a little too big to use in my new digs but they do have a waveguide, and I'd be interested to see the comparison to other brands/models tested so far.
 

617

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I think I gotta send Amir one my Behringer Truth (2030P) passive speakers ( 10.9 x 10.9 x 14.9, 6.75" woofer) I was using before the Ascend CBM170SEs....the Behringers are a little too big to use in my new digs but they do have a waveguide, and I'd be interested to see the comparison to other brands/models tested so far.
The larger Behringer truths have excellent measurements and I suspect the smaller ones would as well. From what I know, they're very well made. I would not be surprised if they beat the LSR 305. Please send it in!
 

tuga

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The problem of a small tweeter and larger woofer without directivity control (e.g. waveguide) is seen above but magnified more when we look at directivity index:

index.php


The dashed blue line is difference between what you hear directly from the speaker and important (loudest) reflections around the room. Ideally these two match each other, sans a gradual reduction in high frequencies which makes the graph point up. Here, the blue line deviates a lot from the straight line meaning the off-axis response is colored relative to direct sound.

The scale of this graph can be deceitful if you are not paying attention, and extremelly misleading for the uninitiated.

Given the nature and target audience of ASR reviews I would refrain from including them in the main post.
Alternatively show it for all speakers.

Also, it is of the utmost importance that the range in all X, Y and Z axis remains constant from review to review.
 
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TimVG

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The scale of this graph can be deceitful if you are not paying attention, and extremelly misleading for the uninitiated.

Given the nature and target audience of ASR reviews I would refrain from including them in the main post.


This is still audioSCIENCEreview. Directivity is part of said scientific research into loudspeakers. Just because some loudspeaker designers have recently started posting their personal -opinion- on the matter does not change the actual science which is the driving force behind these measurements.
 
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tuga

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If one can't look at a scale on a graph, he shouldn't be in ASR's audience.

Really?
What's the point of all those comments in the graphs then or of the subjective loudspeaker listening assessment?
After all, we're all grown-ups here...
 
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tuga

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This is still audioSCIENCEforum. Directivity is part of said scientific research into loudspeakers. Just because some loudspeaker designers have recently started posting their personal -opinion- on the matter does not change the actual science which is the driving force behind these measurements.

I am perfectly able to download the measurements and compare them on REW but posting measurements that have no point of comparison is misleading.
Scales must be constant from review to review. Or isn't that science?

As for personal opinion, are you referring to preference?
 

TimVG

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Scales must be constant from review to review. Or isn't that science?

Yes, make them consistent - don't discard them.


As for personal opinion, are you referring to preference?

Yes. Which they are fully entitled to - but I felt your remark was in line with recent postings that give off the impression that off-axis behaviour is not as important, and that it's more of a 'herd mentality' obsessed with waveguides as if they are a fad. They may have and share that opinion, but that doesn't mean I have to agree with it. The known science, based on years of controlled testing, doesn't agree with it.
 

tuga

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A 15dB-wide DI plot of the CBM170 doesn't look too bad when compared to those of some of the other speakers at the same scale.
In fact it's identical to that of the M22.

934rFap.jpg
 
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tecnogadget

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It would be nice to revisit all speakers reviews in order to make them plot/scale consistent and fill in missing graphs, etc. Otherwise some reviews could be biased.
Maybe Amir could ask for some help and delegate this task to the members, it’s just a thought...
 

Shazb0t

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A 15dB-wide DI plot of the CBM170 doesn't look too bad when compared to those of some of the other speakers at the same scale.
In fact it's identical to that of the M22.

934rFap.jpg
M22 also doesn't have a waveguide.
 

MZKM

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@edechamps and others are creating comparison tools to slice and dice the graphs any way you like. For example, here's Ascend CBM-170 SE vs. Revel M22 frequency response with identical scaling:

View attachment 57355
I've also been trying to by using Sheets. The only way I can do it is a bit tedious for me, it can't be a drop-down, and it's a live document so any changes as to what graphs are visible are implemented to everyone who is viewing it. You sadly can't edit the graph parameters and zoom in like @edechamps' one, but hey, it's something.

I've done 4 speakers and just the on-axis for now:
https://docs.google.com/spreadsheet...H1cr1la8rINVJoEg8uQVxgTIw8/edit#gid=282562128
 

tuga

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@edechamps and others are creating comparison tools to slice and dice the graphs any way you like. For example, here's Ascend CBM-170 SE vs. Revel M22 frequency response with identical scaling:

View attachment 57355


Firstly, being able to use external sources is not an excuse for not producing plots with consistent scaling from review to review.
You don't see that in Stereophile, Soundstage, Hi-Fi News, Australian Hi-Fi or any of the other magazine that perform measurements.

Secondly, and more importantly, exaggerating or caricaturing an issue without providing any comparative references is not "good science".
As @tecnogadget said, it's a form of bias and you don't see that anywhere else either.


Performance is relative and you can't just change the scale to prove a point.

The comparative DI plot I posted above shows that even waveguided speakers look bad in such an extreme close-up situation.
 

infinitesymphony

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I'm with you there, @tuga. I went looking through several reviews just now to compare Directivity Index charts and about half of them did not have the chart posted at all. *shrug*

It's not an excuse, but at this point I think we are all glad to have any accurate information at all. Making it presentable in the review thread is important, though that may have to take a backseat to the data as the speaker review format starts to become more consistent. At least we have options in the meantime.
 

tuga

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I'm with you there, @tuga. I went looking through several reviews just now to compare Directivity Index charts and about half of them did not have the chart posted at all. *shrug*

It's not an excuse, but at this point I think we are all glad to have any accurate information at all. Making it presentable in the review thread is important, though that may have to take a backseat to the data as the speaker review format starts to become more consistent. At least we have options in the meantime.

There's no questioning that @amirm is providing valuable information.
 

TimVG

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A 15dB-wide DI plot of the CBM170 doesn't look too bad when compared to those of some of the other speakers at the same scale.
In fact it's identical to that of the M22.

934rFap.jpg
While you are correct, we also have to consider that the ER and SP directivity index encompass the vertical reflections, which compromise the measurements for any vertically oriented multi-driver system. The most important reflection is in my book the early sidewall reflection. If we calculate and compare a directivity index for, in this example, the Revel M16 (with optimal waveguide) to this particular Ascend (or you can also use the M22 of course, since it also lacks this waveguide). We can see the effect of the waveguide more clearly.

wg.jpg


The Infinity being a budget product has a less optimal waveguide which shows itself in this kind of direct comparison



wg2.jpg
 

TimVG

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Also surprising to see that even the JBL 530, with its substantial horn/waveguide has a less even (albeit narrower which -was- expected) sidewall reflection in terms of directivity compared to the Revel.

wg3.jpg
 
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