How much does frequency response actually matter?

This is what I was attempting to hint to - the rest is in the review, accessible to everyone.
How is it possible that 3. and 4. order distortions are significantly reduced?


The effect is that by taking out the oscillation source, the distortion effects it produces are also removed.
Nothing in real life is absolute - removing means reducing to a significant degree, not deleting.

You can view break up mode like a separate signal source that is related to the rest of the moving membrane but not in linear manner.
Yes the PEQ applies to fr response, but the fr-resp is not detached from distortion effects - and vice-versa.
That is why it can and will significantly alter timbre, perceived resolution and even soundstage performance.
This can not be explained by simply lowering energy at some region. It is predominantly the nonlinear distortions that mess up the fine things.
I know because I use these circuits in speakers.
It does not make regular ceramic membrane to a cvd diamond - but it does get quarter of the way there.

Take another driver that would not have the break up mode there and apply the same dip - you'd have hard time noticing any difference.
Now speculatively, add mega spike there, it would get annoying tonally but the soundstage, resolution etc stuff will be more or less the same - because you would mostly add quantity, not nonlinear distortion components. I should try this at some point and report back.

I agree wrt headphones or perhaps even widebander drivers - too much going on at once to hope a crude trick like a notch filter at some annoyance will be sum total helpful.
With well made speaker drivers the breakup crap is well out of filter bandwidth - you only need a bit extra help to clean it up. The point is that many people are mistaken in that the spike in tonality itself is the only problem, the other crap that comes along the ride is just as harmful or more.

 

Corrected or not - the notch filter targeted to breakup mode would do something.
He did not do the IMD with the notch filter.
You'd see some changes as with the H3 and H4 - where he did measure it.
The observable changes would be mostly around the break up mode zone not at 1 kHz.

 

I think much of the out of band peak that is still noticeable comes down to the phase response. When we use a notch filter to tame the peak the phase response also improves.

This is what I suspect happens with the ceramic tweeters.

Another example with my Hathor speakers: Shallow XO at 200Hz. Woofer breakup at 6kHz. It absolutely needs to be corrected! In this case a notch filter isn't the most elegant solution, but it also works.

@purr1n A notch filter and widebander can absolutely give good results, but it has to be meticulously measured and simulated. And the parts quality has to be sufficient of course. PIO caps. High quality resistors and coils.
At least it gives good results to my ears with the flat cone widebander. However breakup is quite high in frequency, roughly 8 and 14kHz.

This is a fantastic result. That M142A driver is something really special. M142T + M74B + M34B is something I am dreaming of building some day. Imagine a hard cone, wide dispersion speaker with a 97dB sensitivity! Not possible before.

 

Yeah, I remember that. For some drivers it makes sense to spend more on xover parts than the driver itself. In your case the coil is quite large and the driver isn't very resolving (I've heard them a couple times), so really no need.

For the widebander in Hathor the coil needs to be absolutely tiny and have virtually zero DCR to get the the Q high enough. Hence why I use cored coils not usually intended for audio. And the woofer is maybe my favorite in this size range (sounds very responsive) hence why spending money on the XO parts pays off. It's not stupid to spend 1k on the like 8 crossover parts. But I'm not sure I'd throw Duelund CAST PIO caps at a high Q notch filter. The treble already sounds very good to my ears.

Wasn't intentional. However for speakers I think it's somewhat different than for headphones, anyway.

Spoiler: Side argument: Dispersion

Dispersion can really change the way a speaker images. Domes sound different from cones. Seriously, you need to hear those Bliesma dome mids. Or the flat cone Al-Sandwich drivers. And the off axis response can show issues that aren't visible on axis. Like how soft domes go into breakup at audible frequencies and as a result have sharp notches in the top octave off axis.

Or how my OB speakers sound totally different from the cardioid monitors which have a totally different sound projection from the LS50 Meta.

The LS50 Meta is as beamy at 1kHz as Hathor is at 100Hz! Yet in the treble the LS50 Meta is actually the beamier speaker. In this sense you could say that Hathor is more of a constant directivity speaker. I think the way Hathor images is very, very special (good).

 

More like a 4.5" driver, even. Larger drivers will be more beamy. It's the baffle width that's the limiting factor, I think.

I meant at a show or something. Marten Coltrane Quintet uses those drivers. I thought it was very good.

However 240Hz projector sounds awesome!

 

I've blind tested myself on just my dx240 (ESS 9038pro) dig filters and I always opt for #5 which is APODIZING FAST LINEAR PHASE or something like than. Doesn't matter the earphone or amp board as long as it's one I like.

No idea why.