Cube Audio F8 Neo Driver - Possible Cabinet Designs?

Normally, 5000 Euro/pair drivers of this category are out of reach and never to be touched by the likes of my hands. The 10in bigger brother of this driver was very favorably reviewed by AVSHowrooms:
YouTube

Basically, a custom CNC'd frame with custom Nd motor and a multi-whizzer cone design utilizing a unique spring suspension.

The possibility of me getting to play with this driver is becoming more and more real as I have been commissioned to design a cabinet for it. Anyhow, I am looking at all possibilities but a few are intriguing me more than others.

A quick summary of the driver in photos and manufacturer's data...

Cube Audio F8 Neo driver
Cube Audio F8 Neo Fullrange Drivers

Photo:
dbb9c8_b7b2413878ae4e9fb23228dc021079ca~mv2.jpg


Closeup of whizzers and phase plug:
dbb9c8_f4ca914ba0dc468bb21ad0967e8473cb~mv2.jpg


Closeup of Nd Motor Assembly:
img%20(21%20of%2021).webp


Frequency Response:
dbb9c8_d08ae7cf1875486bbc6c211179e13c80~mv2.jpg


T/S Parameters:
Fs = 39 Hz
Re = 10 ohms
Le = 0.008 mH
Qts = 0.36
Qes = 0.37
Qms = 21.7
Cms = 0.74 mm/N
Vas = 54 liters
Sd= 230 cm^2
Bl = 11.5 Tm
Xmax = +/- 3 mm*
Xdamage = +/- 6 mm
Sensitivity = 91 dB (assuming 2.83v at 1m)

Driver Dimensions 220mm x220mm bezel wit a 183mm x 183mm octagonal cutout hole:
https://02637fff-b463-452b-ba09-792...d/dbb9c8_d2a69b2bcaa542929b76496e8cb7edcf.pdf

Suggested Cabinets by the Manufacturer include a bass reflex, tall MLTL, compact standmount MLTL, and Voigt pipe are on the manufacturer's website.

Standmount BR (I htink):
dbb9c8_3d4e1b3e70b04b32a590e63f9dc9ee93~mv2_d_1300_1500_s_2.jpg


Floor standing MLTL:
F10_black_cabinet_345x345@2x.jpg


This looks like their version of BR mounted on top of a powered side-firing sub:
dbb9c8_26fcb59fb7924de88fdf623543b8475b~mv2.jpg


But I think I am going with something else...

The two fullrange designs that really have worked well and impressed me are the FAST (2-way with low crossover) and a tapered TL (PMC style).

Just wanted to see if folks have any other ideas for a great speaker cabinet for this driver that will give nice articulate and deep bass, great lifelike imaging, and super dynamics.

The Qts, Vas, and Fs are remarkably similar to the RS225-8. What coincidence, hence a simple drop-in replacement to an existing detailed Akabak model was waiting and ready. Here is the predicted frequency response in such a TL - F6 of 37Hz and in 4pi space with 6dB of bass fall-off gives an overall sensitivity of 85dB (no boundary assists).

820610d1582809062-praise-10-fullrange-driver-based-loudspeaker-43d0dfbe-1fe2-45f0-a590-526df1fa8fb7-png


The TL cabinet looks something like this:
803725d1576909032-10f-8424-rs225-8-fast-waw-ref-monitor-10f-rs225-fast-tl-render-png


For the RS225-8, this cabinet has been verified in XPS/wood baffle to sound very good. Another option is to have a pair of substantial 10in woofers doing bass duties in a FAST with the F8 Neo serving fullrange duties in a transient perfect 1st order XO.
 
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mp9

Member
2006-06-07 7:00 am
Looking forward to your follow up's as the commissioned project progresses.

It would be interesting to see what @ScottMoose could design for the driver but I don't think he will spend time thinking about it given the steep price of admission limiting the numbers of these entering the DIY community.

Also, all Cube Audio drivers on the US distributor site are presently listed as sold out.
 
xrk971,

Given your experience with Karlsonator type enclosures, I'm curious as to whether you've considered cutting a K-coupler aperture in to the end of that line, instead of just an simple rectangular port? It seems like a fullrange driver, such as the Cube F8 or F10, that's backloaded in to a tramsmission-line enclosure terminated with an K-coupler aperture could be a very synergistic combination.
 
Even at 5000 Euros/pair stuff can sell out. The website says there will be more stock in 6 weeks. I am sure they don't have a lot of inventory as these look like hand made drivers using "just in time" manufacturing to save on cost of inventory.

@Ken Newton,
If you look at the predicted output from the port using the TL (green curve), it has most of its output from 30Hz to 100Hz. The output is smooth. The characteristic 1/4-wave length of 30Hz sound is about 10 ft long, and 100Hz is 3 ft long. To make a Karlson aperture that would blend these frequencies would require it to be of order 3ft to 10ft long. So for a 3ft tall speaker, I can't dedicate the entire length to K aperture for the vent, especially when the simulation predicts it is pretty smooth.

820610d1582809062-praise-10-fullrange-driver-based-loudspeaker-43d0dfbe-1fe2-45f0-a590-526df1fa8fb7-png


The typical K apertures we see on a Karlsonator or K-15 etc, have profound influence on the mid bass 300Hz to about 1khz.
 
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Nice polar plot!
Who'd a have thunk that listening 60 degrees off as default, could possibly be preferred‽
Also impressive is the cone. It looks quite heavy, but still the efficiency is good. No doubt thanks to the huge magnet.
Would love to see the impulse response, if you get your hands on a pair X.
 
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Are you planning some base line frequency plots of your own before the start?

This plot seems kind of useless:
dbb9c8_d08ae7cf1875486bbc6c211179e13c80~mv2.jpg


With this kind of vertical scale every driver will look flat. :D

Nice polar plot!
Who'd a have thunk that listening 60 degrees off as default, could possibly be preferred‽
Also impressive is the cone. It looks quite heavy, but still the efficiency is good. No doubt thanks to the huge magnet.
Would love to see the impulse response, if you get your hands on a pair X.

About a 12 dB difference between 1 and 3K at that angle, what's nice about that?
 
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Of course, once I have a sample in hand I will take frequency response sweep as well as impedance sweep and measure TS parameters. We have to start somewhere and that’s with manufacturer’s data.

The plot doesn’t look that bad given what I have seen from other boutique full range driver makers.

So a DBR looks interesting and reminds me that a DCR might be useful here as well. I have always wanted to make a TCR (Triple Chamber Reflex). But wonder if it is already at point of diminishing returns at deaux.

Passive radiator is also an option as long as well are entertaining reflex designs.

Big spiral sealed tapered TL aka Nataloss is another one.
 

mp9

Member
2006-06-07 7:00 am
-
Also impressive is the cone. It looks quite heavy, but still the efficiency is good. No doubt thanks to the huge magnet.
-
Yes probably, F8-Neo "2.1 Tesla in the magnetic gap that is 12 mm high."
No such data on the F8-Magnus but I'd guess it's also high as the sensitivity spec 94dB vs F8-Neo 91dB.

Cones and Wizzers: "Once we had the motor ready and capable to control heavier moving cones and suspensions mass, it was time to do the cones. ".

The website info is a little wacky, both F8 variants, Magnus and Neo state: "The final design consists of 4 cones. One being the main cone and 3 whizzer cones".
Website pix of the F8 Magnus only show the main cone and one whizzer cone. F8-Neo, a secondary smaller cone between the main cone and whizzer cone, adds up to three, not four.
 
Ah, as I noted on another thread, I've been wondering how long it would be before the Cube drivers got more attention on this forum.

Standmount BR (I htink):
dbb9c8_3d4e1b3e70b04b32a590e63f9dc9ee93~mv2_d_1300_1500_s_2.jpg

Yes, straightforward vented box.

Floor standing MLTL:
F10_black_cabinet_345x345@2x.jpg

It's a folded [single] tapped horn (TQWT if you prefer) rather than an MLTL as I recall.

This looks like their version of BR mounted on top of a powered side-firing sub:
dbb9c8_26fcb59fb7924de88fdf623543b8475b~mv2.jpg

It is.

Just wanted to see if folks have any other ideas for a great speaker cabinet for this driver that will give nice articulate and deep bass, great lifelike imaging, and super dynamics.

Well, I see Dave has posted one example we did back in February 2018; the LF aspect needs little reference; 'great lifelike imaging and super dynamics' though rather depend on how you define them. Assuming a low diffraction signature and a relatively low acoustical low pass from whatever the enclosure is, then the former is dominated by the innate response charactertistics of the drive unit; dynamics [assuming dynamic range] is also ultimately defined by the drive unit and in the LF a question of load efficiency.

Not that my opinion counts for anything, if run as a 2-way I would ensure any major bell mode peaks from supporting woofers are suppressed by at least 36dB (preferably more) from the nominal, especially if they do not have particularly low distortion motors, or the HD products & IM resulting from it will ultimately be audible.
 
Looking forward to your follow up's as the commissioned project progresses.

It would be interesting to see what @ScottMoose could design for the driver but I don't think he will spend time thinking about it given the steep price of admission limiting the numbers of these entering the DIY community.

Not at all, as Dave notes, we've actually done a number for various Cube units (7 and counting, plus a few design exercises on my part); the hybrid horn variation was back in February 2018 & we completed a rather nice MLTL / MLQW for a client only a week ago. It's simply that the drivers haven't had much attention here & the ones we've done have either been custom commissions or created as 'stock' for adding when we next revise the Woden site. It's overdue for it, but what with one thing & another, we simply haven't had time.
 

HelmutHolz

Member
Paid Member
2009-03-16 7:53 am
Germany
I put my Cube Audio Magus into a home brewn TQWT, dimensions very similar to these from the Cube web side. 22mm multiplex and the front 25mm "Panzersperrholz" (Delignit). Really nice bass, fast and deep. But very hot in sibilants, even in 30° listening position. I plan to use some active smoothing, otherwhise the speakers are worthless for me. Amplifier: 8W Monster Hiraga, very clean sound without harshnees with Sonidos 222

br
Helmut
 
Cube Audio’s website called it a MLTL but the plans show a folded tapered (wide at exit) TL with a mass loaded vent:
https://02637fff-b463-452b-ba09-792...d/dbb9c8_09b0e08c038b48f98b1a8dc1c832e149.pdf

Right, ML-horn or ML-Voigt if you prefer, but that's their DIY box design. The image you've got is of the Nenuphar Mini production speaker which is a floor-loaded [single] tapped horn / Voigt; the small amount of terminus choking is provided by the slightly adjustable spacing to the floor.

I think a FAST would be the way to go with this.

Definitely one good way, apart from the acronym. ;) Ultimately depends what your client's goals are though.
 
I put my Cube Audio Magus into a home brewn TQWT, dimensions very similar to these from the Cube web side. 22mm multiplex and the front 25mm "Panzersperrholz" (Delignit). Really nice bass, fast and deep. But very hot in sibilants, even in 30° listening position. I plan to use some active smoothing, otherwhise the speakers are worthless for me. Amplifier: 8W Monster Hiraga, very clean sound without harshnees with Sonidos 222

br
Helmut

Thanks for the feedback from an owner of a Cube Audio. Although the Magus is different in motor construction, probably similar with F8 Neo in whizzer approach. The sibilance is a concern definitely. We were told that we have 30 days to listen and make a determination if a keeper.
 
@xrk971

In selecting the F8 neo, did you consider the F10 ferrite/neodymium driver, which costs about $1,000 less than the F8 neo?

Cube Audio F10 Driver
– Refined Audio


The 'plain' F10 driver appears to have an identical cone, suspension and basket to the F10 neo, and almost identical specs. Speaker design isn't an area of expertise for me, so I'm just wondering.