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Kii Three - my impressions and pro reviews


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Other than that Bxt plays up to 250 hz, I haven't seen any specs. I want to know how loud they can play at 20 hz continuously and how hot they get at, say, sustained 85 dB over a period of time.

 

I'm not overly confident that passive cooling is sufficient when the top plate is covered by another heat source (Kiis) and I'm certainly not confident that my living room will be survivable when another 8-16 amps start throwing heat around.

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8 hours ago, TheStupidOne said:

Other than that Bxt plays up to 250 hz, I haven't seen any specs. I want to know how loud they can play at 20 hz continuously and how hot they get at, say, sustained 85 dB over a period of time.

 

I'm not overly confident that passive cooling is sufficient when the top plate is covered by another heat source (Kiis) and I'm certainly not confident that my living room will be survivable when another 8-16 amps start throwing heat around.

Hmmm?  Do you listen to music with a constant 20 Hz drone at 85 dB?  This is a really weird request.  Indeed it would take some energy to produce that level at 20 Hz, constantly, in room, but consider that the class D amps used are around 85 % efficient.  Now, consider that if you wanted to create that same level using class A/B amps, which are around 50% efficient at best, you can see that the class A/B amps in a conventional system would heat up your room much more than the Kiis, so I am not understanding what your concern really is?

Just because Kii uses many small amps to produce the SPLs does make them produce more heat, many small amps will work no harder (total output watts) to produce a given SPL than one big amp.

 

On the other hand, it sounds like you might be looking for a PA system rather than an audio system: are you looking to DJ with them for dance parties in convention halls or something?  Then get a PA.

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On 10/10/2018 at 5:07 PM, barrows said:

Hmmm?  Do you listen to music with a constant 20 Hz drone at 85 dB?  This is a really weird request.  Indeed it would take some energy to produce that level at 20 Hz, constantly, in room, but consider that the class D amps used are around 85 % efficient.  Now, consider that if you wanted to create that same level using class A/B amps, which are around 50% efficient at best, you can see that the class A/B amps in a conventional system would heat up your room much more than the Kiis, so I am not understanding what your concern really is?

Just because Kii uses many small amps to produce the SPLs does make them produce more heat, many small amps will work no harder (total output watts) to produce a given SPL than one big amp.

 

On the other hand, it sounds like you might be looking for a PA system rather than an audio system: are you looking to DJ with them for dance parties in convention halls or something?  Then get a PA.

No, I don't listen to a constant 20 hz drone at 85 dB. What a weird question. ?

 

I want to know what output they can do at 20 hz because I want to know if BXT can replace the need for subwoofers in a dedicated room; tilted room-curve, ear sensitivity and headroom all taken into consideration.

Why continuous output? Because I want to know the real-world performance; thermal compression, thermal distortion and heat protection included, not the hypothetical best-case scenario.

 

Why continuous 85 dB sound level? Because I listen to music mostly around 70 dB on average, maybe 75 dB when I get frisky. Taking the tilted room-curve I like (roughly +6 dB from 200-20 hz) into account and allowing for some headroom for electronic music and movies where there can be sustained low frequency output, I'd say 85 dB for reference level is quite reasonable for a bass system. You can actually barely hear 20 hz at 85 dB.

 

Why worry about temperature? Because Class D amplifiers, although efficient, still emits about 2-3 % of their rated power output as heat - at idle. I don't know if there will be 4 or 8 amplifiers per side, but there will nevertheless be quite a few heat-sources within a confined cabinet without active cooling. Heat will not be dissipated as quickly through passive cooling inside that cabinet as it would be if the amplifiers were out in free air, so heat will build up to a certain extent and - disregarding concerns about over-heating - will act as two more ovens in the room.

Of course, this issue is no different from the Kii Threes themselves, but I'm concerned it could be one of those things that builds up to become a problem. With more heat emitting from the surrounding airspace, passive cooling will become less effective, which will lead to more heat build-up which will lead to even less efficient heat dissipation which will... possibly make it damn hot in a room.

 

So that's the practical part of the equation, the theoretical part has to do with thermal distortion. Considering the price, I need to compare BXT to other solutions which may or may not give more for less and I need to do it by getting some facts I can work with.

 

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Kii were quick at getting back to me with this:

 

you are absolutely right that we are a bit late with this.
We will post this on the website in the coming days.
Its a bit busy right now with about three trade shows every weekend.
I am sure you will understand.

The serial base plates are in production and will ship with the serial production models of course - with spikes and all.

I hope you can find the chance to give the Kii THREE BXT System a listen on one of our many occasions.

All the best and thanks a lot for your interest.
 


Chris Reichardt
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Kii Audio says that  BXT is 16 drivers with 7000 watts of amplification.

Probably half of those drivers are working to create the cardioid forward pattern and don't contribute to the

final sound pressure*. 8x 6 inch drivers have the area equivalent to 3 x 10 inch drivers. Without knowing

the excursion it's difficult to compare displacement. Let's assume it is similar.

The 7000 watts is obviously  the peak power of n-core amplification. The continuous thermal limited

power will be max. 1000 watts (see nc-500oem data).  The cooling is through the aluminum driver membranes.

By comparison a Geddes style distributed sub system (eg. Audiokinesis Swarm)  will deliver  at least the same total SPL (probably more) for a quarter of the price. It goes down to real 20Hz too. Quality-wise I bet on 4 distributed subs along the walls vs  two cardioid ones. I tested Kii Three in that respect and if BXT is more of

the same thing, distributed subs win for me.

*obvious oversimplification

 

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2 hours ago, sapporo said:

PS the cardioid pattern is limited to some frequency, can’t find the exact figure now.

The Kii controls the relative phase and timing between its rear and front drivers and between its side and front drivers to create a cardioid dispersion pattern from 1kHz down to below 80Hz. Above 1kHz, the directivity of the front-firing drivers, due to their size and location, dominates. Below 80Hz, as boundary gain dominates, the Kii becomes increasingly omnidirectional, but that can be dealt with by a relatively simple adjustment of output level in that passband.
Read more at https://www.stereophile.com/content/kii-audio-three-loudspeaker#EBiRuAEorp7LvYMm.99

Kal Rubinson

Senior Contributing Editor, Stereophile

 

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There's no question that several distributed subwoofers will outperform BXT in out-and-out bass performance with the added benefit of dealing effectively with the room modes, so that in itself shouldn't come as a surprise.

I've already shown in this thread how much better two cheap subwoofers + Minidsp placed on opposite walls perform in-room vs Kii Three alone, but I don't think I mentioned that a single 15" sub far outperforms them in sheer output and physicality because it kind of goes without saying.

 

If you are considering BXT then you should consider the benefits (better sound due to less floor-bounce reflections, more punch and more dynamic capability) against potential downsides (might vary depending on perspective) and price.

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18 minutes ago, Emlin said:

Bruno Putzeys has made it clear that they are not subs. Line array and increased headroom are what they bring to the party.

 

 

a lot more than that - did you read Kal's post?  or his review?

 

BTW, bdy gain is often called bdy loading

 

Nonetheless, they are very expensive and have some other 'relative detriments' so some of use will just have to hobble along with Maggies for awhile...

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2 minutes ago, Ralf11 said:

 

a lot more than that - did you read Kal's post?  or his review?

 

BTW, bdy gain is often called bdy loading

 

Nonetheless, they are very expensive and have some other 'relative detriments' so some of use will just have to hobble along with Maggies for awhile...

I was talking about the bxt only.

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