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Knowledge Zenith (KZ) impressions thread
Apr 6, 2019 at 7:15 AM Post #43,051 of 63,803
Hi all. This is my first post on this thread. I'm less experienced in audio than most members of this forum.

I see references to phase coherency of multi-driver IEMs, and whether they are coherent or incoherent. To my knowledge this has something to do with what time the signals arrive from each driver -- but I'm probably butchering that explanation.

A number of reviewers have mentioned that the ZS10 has coherency issues. I have noticed that the ZS10 sounds muddled during fast phases of music, with a lot of different instruments and sounds at play. It seems like instrument separation goes out the window and everything muddles together into one noise. It's not bad outside of those cases. On the other hand, my ES4 doesn't do this.

Is this phenomenon that which people refer to as a coherency issue? And is it the result of poor crossovers?
 
Apr 6, 2019 at 10:02 PM Post #43,054 of 63,803
Antihawk said:
Hi all. This is my first post on this thread. I'm less experienced in audio than most members of this forum.

I see references to phase coherency of multi-driver IEMs, and whether they are coherent or incoherent. To my knowledge this has something to do with what time the signals arrive from each driver -- but I'm probably butchering that explanation.

A number of reviewers have mentioned that the ZS10 has coherency issues. I have noticed that the ZS10 sounds muddled during fast phases of music, with a lot of different instruments and sounds at play. It seems like instrument separation goes out the window and everything muddles together into one noise. It's not bad outside of those cases. On the other hand, my ES4 doesn't do this.

Is this phenomenon that which people refer to as a coherency issue? And is it the result of poor crossovers?
Click to expand...

Phase coherency (and time coherency) in any multi-driver speaker or earphone is difficult to accomplish. From what I've read, all crossovers alter the phase. A well designed crossover filter will mix the low pass and high pass outputs together such that the phase and amplitude relations are re-created close to the original. I haven't seen this explored closely in most earphone discussions, but I remember seeing it talked about here:

https://www.innerfidelity.com/content/headphone-measurements-explained-square-wave-response-page-2

Shure SE535
This is one of my favorite in-ear headphones. The 30Hz square wave clearly shows a powerful and linear bass response. The 300Hz square wave shows excellent shape but for one unusual feature: a brief movement in the negative direction prior to moving upward. This is a 3-driver balanced armature headphone with a cross-over circuit. I think what we're seeing here is that the tweeter is out of phase with the other two drivers due to high order filters. Having a driver out of phase relative to other drivers in a multi-way speaker is not uncommon, but I haven't seen it elsewhere with headphones. The rise time of the front of the square wave doesn't look very fast, but you must remember that it's the tweeter going in the negative direction at first that's providing the speed. This is one of those cases where we're not seeing all of the information needed as some phase information is hidden from view.​

Time-coherency and phase-coherency in loudspeakers is discussed here:

https://www.stereophile.com/content/measuring-loudspeakers-part-two-page-3

That it is audible and that it has effects on sound and localization of sound is agreed upon, but exactly how important it is overall is debated. I think part of the reason is that there is a broad range of how out-of-align something can be... I think if things are out-of-align enough, it can be noticeably detrimental. I would guess that with the lower-cost multi-driver earphones, it's a bit of a crap shoot how much engineering time has been spent to optimize for coherency, and I'd also guess that at the lower price points these sell at, most consumers aren't that discerning either, so it's probably neglected.

Speaking personally, I have found that my best single-driver earphones seem to present the most complex passages of music in a way that my ears and brain can discern and locate all the various instruments/voices in the acoustic space better than my multi-driver earphones. (All my earphones are under $150.) It seems plausible this is due to the crossovers and phase and time coherency issues in the multi-driver designs.
 
Apr 6, 2019 at 10:25 PM Post #43,055 of 63,803
Superluc said:
oops, they are out of stock even on gearbest

Maybe they don't produce it anymore, as they have the lightning cables now
Click to expand...

That is odd. It’s not like Lightning is a direct replacement for usb-c. One is for iPhone and the other for Android.

You can order a JC Ally cable with usb-c end. They have 4-wire and 8-wire braided cables, in multiple colors.

The price is about the same or better than the KZ usb-c cables, and they’re nicer cables. So that’s what I would do if it were me.

https://s.click.aliexpress.com/e/bqdejsMs
 
Apr 7, 2019 at 3:51 PM Post #43,061 of 63,803
gbrgbr said:
Re : the KZ Type-C cable, i would contact the seller before ordering. I needed a Para-A Type-C cable and got one of the last. About 2 weeks ago.
Click to expand...
I did ask to the seller at gearbest if he still has one for sale. (both A & B "out of stock")

got automated answer:
"Hello Jerome,
You can search this product on our site with a keyword .
If you can not find it on our site, then we do not sell it."
 
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Apr 8, 2019 at 2:04 PM Post #43,062 of 63,803
Looks like a new KZ with a ZSN-like shell and connector is on the way. Found this on the KZ's AliExpress store:
TeLlV1b.jpg
 
Apr 8, 2019 at 9:40 PM Post #43,063 of 63,803
(Sorry for the cross post, but I wanted to make sure as many people as possible saw this)

I know some of you have really big ear canals, and most large tips don’t fit (forcing you to flip foam tips backwards etc).

Well, I’m here to say I found a silicone tip that will fit you. The large tips are absolutely gargantuan. I’ve never seen tips this large. I’d call them XL or even XXL, compared to most L silicone tips. The large are 14.5mm! Most L tips are ~12.0-12.5mm.

They’re a nice tip too. Good quality, wide bore, lots of colors available, and very cheap for a set. So it won’t break the bank to try them out.

Hopefully this helps some of our large-eared friends out :)

Here’s is a link to them:

https://m.aliexpress.com/item/32856640919.html

 
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