[saldsald]

Indeed, the smaller unit is much less prominent in response.

It is definitely not an electret - either some magnetostat or some flat suspended membrane.

Here are the inner parts:

Two symmetric coils inside the ring magnets (8 Ohm each connected in parallel, so the total impedance is 4 Ohm).
In between is the rigid metal membrane that is at the bottom of the image. Interestingly, it is magnetic but not magnetized.

I am not sure whether this design is similar to other MSTs or some unique construction of KZ/CCA.

Because of the very rigid membrane, the amount of sound it can produce is fairly limited, and the range is limited as well: some output is from 1.2 kHz to 12.5 kHz, while the sound can be heard reasonably in the range of ca. 3.5 kHz to 7 kHz then decaying to oblivion by 12.5 kHz.

P. S. It was really hard to disassemble, please do kids-friendly designs next time, KZ/CCA

Lol you have gone so far!

Yeah I think due to the much higher efficiency of DD, for lower driver count IEMs, the DD is always full frequency and all BAs, EST and MST, electret etc. are for the purpose of adding detail or note weight.

No idea how an electret unit should look like but you mentioned ring magnets being 8 ohms each, are they just copper coils since you shouldn't be able to measure the resistance of a magnet I assume? And the membrane maybe polarized so it can feel the magnetic field?

You can use nail polish remover or resin softener to remove the resin between the drivers and the shell cavity to extract thr drivers, and then use a hairdryer to apply excessive heat to the drivers and they may just come apart.

So have you tried the NRA without the electret/MST driver?

 

[PhonoPhi]

Lol you have gone so far!

Yeah I think due to the much higher efficiency of DD, for lower driver count IEMs, the DD is always full frequency and all BAs, EST and MST, electret etc. are for the purpose of adding detail or note weight.

No idea how an electret unit should look like but you mentioned ring magnets being 8 ohms each, are they just copper coils since you shouldn't be able to measure the resistance of a magnet I assume? And the membrane maybe polarized so it can feel the magnetic field?

You can use nail polish remover or resin softener to remove the resin between the drivers and the shell cavity to extract thr drivers, and then use a hairdryer to apply excessive heat to the drivers and they may just come apart.

So have you tried the NRA without the electret/MST driver?

Thank for a good advice.

Electrets use high voltage.
Magnetostats are driven by high currents, so NRA driver with low-resistance coils can only qualify for the latter
The coils are just inside the circular magnet rings (everything is there in the image); the magnetic rings are not a part of the circuit. I was expecting some flexible membrane, so I am not sure what would be advantage of this design compared to piezo drivers that have ultimate rigidity.

I did measure the current of the frequency swep for the whole unit and the smaller driver alone. The latter contribution is definitely below 20%. I have not tried the sound while disconnecting, seeing it in measurements and trusting your judgement.

Overall, I quite like NRA, but its sound is definitely DD-dominated. Hppefully, ZEX will be more engaging.

P. S. CCA confirmed to me stating explicitly than CA24 differences with AST are only cosmetic. Also why "CA24" and not "C24" , given that CA16 ia a hybrid design, is really mindboggling!
So CA24 is off my list.
Waiting for Tempotec dongles and really enjoying my modified ASX meanwhile

 

[saldsald]

Thank for a good advice.

Electrets use high voltage.
Magnetostats are driven by high currents, so NRA driver with low-resistance coils can only qualify for the latter
The coils are just inside the circular magnet rings (everything is there in the image); the magnetic rings are not a part of the circuit. I was expecting some flexible membrane, so I am not sure what would be advantage of this design compared to piezo drivers that have ultimate rigidity.

I did measure the current of the frequency swep for the whole unit and the smaller driver alone. The latter contribution is definitely below 20%. I have not tried the sound while disconnecting, seeing it in measurements and trusting your judgement.

Overall, I quite like NRA, but its sound is definitely DD-dominated. Hppefully, ZEX will be more engaging.

P. S. CCA confirmed to me stating explicitly than CA24 differences with AST are only cosmetic. Also why "CA24" and not "C24" , given that CA16 ia a hybrid design, is really mindboggling!
So CA24 is off my list.
Waiting for Tempotec dongles and really enjoying my modified ASX meanwhile

I think it is advertised as low-voltage electret. TBH I have no idea what these are and how they work and I took a little time to translate one of their advert picture:


Thanks for the clarification with CCA. Good that I don't have to get an AST clone! I really wonder what they are thinking and I am sure the ZEX will be identical to the NRA!

 

[Musicoflife]

Love the sound of the NRA. But.

Anyone noticed how prone to wind noise the NRA is? The 2 vents at the bottom apex of the shell can't be helping things. In hot weather with the fan blowing its too noisy to listen to music.

I covered the vents with micropore tape and the wind noise is reduced, but still louder than most IEMs

 

[baskingshark]

Love the sound of the NRA. But.

Anyone noticed how prone to wind noise the NRA is? The 2 vents at the bottom apex of the shell can't be helping things. In hot weather with the fan blowing its too noisy to listen to music.

I covered the vents with micropore tape and the wind noise is reduced, but still louder than most IEMs

Nothing much that can be done if that is the case. I had some other iems with huge vents that sounded like a flushing toilet bowl when wind blew eg BLON Cardinal

 

[Musicoflife]

Perhaps the shell is too thin and picking up wind as well. I don't get thar much wind noise in the much maligned plastic shell of the GK10.

 

[Musicoflife]

The thin aluminum faceplate is likely contributing to wind noise. Anyone with opened NRAs could put some dampening material like tape on the underside of the thin aluminum faceplate and see if it helps. Who knows with internal damping it may improve SQ too...

 

[sfrsfr]

Haven't tried balanced out yet, since I just got back from my summer vacation. I haven't had much time to mess with my gear, since I'm spending more hours at work now. But, in my honest opinion, I like both the NRA and the GK10 after they sent me the second pair of the GK10, which had no problems (so far). And, even though they do sound slightly different from each other where the NRA has better sub-bass extension and their overall signature is open and clear, while the GK10 has a rich and smoother approach and also clear. To me, both have kind of like a 3D, life-like, holographic signature, and both are identically good. But, since QC can be a problem for the GK10, I can safely recommend the NRA for now.

-Clear

I wonder if you could compare the NRA with another MST (or EST?) hybrid, the SF MT300.

 

[PhonoPhi]

I wonder if you could compare the NRA with another MST (or EST?) hybrid, the SF MT300.

Briefly, NRA and MT300 are in different leagues for me. Understandably, since MT300 was intended to be sold at $200.

MT300 have more ample refined sound. An upper range is quite unique, very nice vinyl-like impression. One of the best implementation of a DD for me - tight and coherent. Some timbral distortions in the mids though, common for piezo hybrids/tribrids. MT300 likely have a piezo driver not MST (TDK never made MST drivers but made piezo that are very similar to what is shown for MT300, as it was discussed in one of the threads).

NRA sound is DD-dominated and definitely not as rich and resolving as MT300. Nothing above 12-13 kHz.
I prefer DQ6 to NRA, but to me they both seem comparable and both are very competitive at below $25.

 

[SpaceOperaVillain]

To my ears, the big difference with DQ6 and NRA is how they respond to better source and mods. With shallow wide bore tips, SPC 8 core cable, and a balanced source the NRA sounds like a $100 set. When I try the same with the DQ6, it sounds like a $10 set, not a decently tuned $25 set.

¯\_(ツ)_/¯

AKG's old K340 with an electret-dynamic hybrid worked very similarly to these NRA/ZEX. It's almost like a throwback headphone boiled down into an IEM.

 

[PhonoPhi]

To my ears, the big difference with DQ6 and NRA is how they respond to better source and mods. With shallow wide bore tips, SPC 8 core cable, and a balanced source the NRA sounds like a $100 set. When I try the same with the DQ6, it sounds like a $10 set, not a decently tuned $25 set.

¯\_(ツ)_/¯

AKG's old K340 with an electret-dynamic hybrid worked very similarly to these NRA/ZEX. It's almost like a throwback headphone boiled down into an IEM.

I use wide-bore shallow tips with all my IEMs (nothing to cut/filter, just to get a good fit & seal with the tips).
I do use balanced with different sources.
Not starting on SPC...

So yes, NRA are a worthy IEM.
$100 - not sure.
DQ6 - an $10 IEM, not agreed!

Do you have AST?
With your treble preference they can work nicely for you.

 

[RikudouGoku]

I use wide-bore shallow tips with all my IEMs (nothing to cut/filter, just to get a good fit & seal with the tips).
I do use balanced with different sources.
Not starting on SPC...

So yes, NRA are a worthy IEM.
$100 - not sure.
DQ6 - an $10 IEM, not agreed!

Do you have AST?
With your treble preference they can work nicely for you.

Yeah, I do not agree on the NRA being worth 100 usd....

 

[r31ya]

Yeah, I do not agree on the NRA being worth 100 usd....

Something about MST and Piezo able to bewitched whole lot of people.

I didn't own GK10 or NRA so i cannot say much but its makes me wanna ask what bewitched these people GK10/NRA SQ?
Is it the great details or the Sparkle that MST and Piezo gives?

 

[RikudouGoku]

Something about MST and Piezo able to bewitched whole lot of people.

I didn't own GK10 or NRA so i cannot say much but its makes me wanna ask what bewitched these people GK10/NRA SQ?
Is it the great details or the Sparkle that MST and Piezo gives?

Probably their more unique (unnatural) timbre. They generally have more air than DD/BAs but not on the NRA though.

 

[Wgibson]

The NRA electret is based on a microphone. Usually (not all technologies) anything that can be used as a speaker can also be used as a microphone (and vice cersa) just not very efficiently most of the time.

The CCA NRA for me is a new non-sibilant take on treble, unique from BA or DD. Lows/mids not great, but still definitely worth 25 bucks.