New SB Acoustics 3 way from Troels

Can't say without listening. JBL did something similar with Lancer L77 PR being the same SD as woofer - didn't listen to that either but i know of its existance so its been done in the past.

Somehow i get the impression that everything from SB is well engineered and of good build quality. I intentionally avoid to say value leader because someone may interpret that as being satisfied with kinda good quality at low prices. I really think that quality of their drivers is excellent. I've been listening to my SB17NRXC35/SB29RDC-C0004 for some time now and it sounds fantastic for intended frequency range (from 150Hz up in my sistem). And it is not even their flagship drivers.

The only thing that bothers me is their Satori midwoofer line. Great drivers but that notch at 1200Hz and distortion peak at the same frequency really bothers me. My concern may be unjustified but it is how it is.

Cabinet rather than drivers Ie ported/sealed/radiator. I noticed Jeff mentions just one PR- Wd that be enough?

How does it sound?
 
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I have Beyma 15K200 for bass, -3dB at 40Hz. It sounds great to me and in room of about 16 sq meters. Tuned any lower and bass starts to lose control. IMHO low tuning is not desirable in small rooms - tends to mush up the bass and the rest of the sound with it.
 
Just read up on it, hadn't realized JB used this SBA 10". His design has 3 different options. Otherwise not much info on this woofer, tho he seemed to like it. Thinking to use it sealed in a design with 5.5 revs.

Is there any time alignement with Troels's version ? Or did he take simply the same cabinet shape with same numbers than J. Bagby (sam ?

WHere did you find the 5.5 revs with sealed volume please ?
 
Yes I think time aligned but the cabs look complex..don't understand why Troels kept the volume so small that the port had to be angled. Off topic but I loved his review of Munich high end, had me in stitches.

Bought the revs very cheap and still boxed..old stock Ruark (undoped) and had the wrong model number. So at a guess around 85.5db, ohm rating unknown. The SB's seem to be the right sensitivity to fill in.
 
Ah yes, found odd as well the angled port on the bass cab, why not one à la Proac firering towards the floor instead ??? Could be Noisy with such 90°,degree angle !!!! And after all the old rectangular ports worked better than long "tubes" !

Is there an official sealed Kairos ? Can be seen in Meniscus threads ?

Finally a MR16P-4 could be a good swap with a higher XO : 2K to 3K.... better sensivity matching too ! Ah less deep low end maybe ! (higher high pass for the mid should be needed...)
 
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Is there any time alignement with Troels's version?

For a SB29RDC+SB17NRX TM summation, SB_Acoustics measures and documents a relative time delay of 54usec for the SB17NRX, which is the equivalent of a 18mm = 0.71" physical offset (tweeter in front of midrange) in a normal room environment. Troels stepped-baffle cabinets add one 18mm thick baltic birch panel to produce this physical delay. Obvious.
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For a TW29R+MW16P TM summation, SB_Acoustics measures and documents a relative time delay of 61usec for the MW16P, which is the equivalent of a 21mm = 0.827" physical offset (tweeter in front of midrange) in a normal room environment. BUT ... Troels cabinet drawings with the 14-degree front baffle slope show a 35.6mm = 1.4" physical offset. Doh!

For a slanted baffle, an equidistant arc from the listener's ear to the acoustic center of the T and also the acoustic center of the M sets the physical offset. The challenge becomes finding the actual acoustic center of each driver. The lower the frequency, the longer the wavelengths, and the less critical the alignment is. For T-M, a 1600-1700Hz crossover design will likely time-align better on a slanted baffle than a 2-3kHz design. SO, a slanted baffle only offers perfect delay alignment at one listening distance. You can't use this model with "factory" "on-axis" measurements. You need to measure off-axis data for whatever angle you've got the drivers pointing above your head.
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Has anyone built an LR4/LR4 crossover for a flat baffle TW29R+MW16P? LR4/LR4 on a stepped flat baffle?
LR4/LR4 at 1700Hz should produce an on-axis constant directivity function from the bass baffle step frequency up to 10kHz, where the TW29R physical dome beaming dominates.

The extended high frequency coverage above 3kHz on the MW16P comes with 5db wiggles and waggles, and normal beaming effects for a 6" cone extending all the way to 10kHz. My normal TM crossover philosophy for a wide bandwidth mid(MW16P) is to use LR4/LR4 to assure at least 20db attenuation of the 3kHz+ MW16P wiggles and waggles. Wide BW midrange often fit the textbook LR4 filter. The MW16P starts to beam at 1600Hz. The TW29R has an Fs of 600Hz and is -3db ~500Hz. With proper baffle size and tweeter positioning, a textbook LR4 often works for Xovers between 1600Hz - 1800Hz. LR4/LR4 at 1700Hz for the TW29R+MW16P looks interesting....flat baffle? 21mm stepped baffle?.

If the woofer-mid crossover is set around the baffle-step frequency, an LR2/LR2 is wide enough to smear the baffle HxW step range. An M-W separation shorter than crossover/4 quarter wavelength is still important. A 42" high x 13" cabinet required for a 10" woofer experiences baffle step effects between 100-200Hz.
 
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Did a smaller "Wilson semi-clone" with SB15 (5") and SB26 tweeter with a powered 8" RE sub in the bass cab. Angled at 10 degrees front and back and 15 degrees on the sides. Worked out to symmetrical 3rd/3rd electrical and LR4 acoustic. So, I assume with the bigger MP16, that it would require more baffle slope. Also found that I needed a similar notch on the tweeter for a resulting peak at 4K which I attributed to the cabinet more than the tweeter.
 
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1) Irregular shapes can reduce internal box resonances.
2) The narrowing front baffle of the truncated pyramid shape can create a smoother controlled directivity function. The narrowing pyramid reduces front baffle reflectioned low frequency energy from the midrange and woofer, but maintains short wavelength forward baffle reflected energy from the tweeter. Cabinet edge diffraction creates new delayed phantom sound sources which can obscure detail in the treble. A pyramid shaped MT baffle helps improve high frequency clarity.
3) Looks cool. Avalon corp. also bevels the edges of its truncated TM pyramid in order to further reduce diffraction...and look super-cool.
4) Easier to manufacture than large radius rounded edges (e.g. Vivid), or spheres with rear truncated tubes like B&W.
 
I'm designing a cabinet like this in cad atm. It tapers in at the top and bottom but also at the back, with a bevelled baffle. And that bevel was the key to making it work. Took me ages to figure it out, so it could be relatively easy to build.
 
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5) Looks smaller. Anytime there's a reduced cross-section, even a pinched waste, it affects the whole. That was my main concern.
6) Looks stable. You would be surprised how many people are scared of these things falling over on their cat or baby, whichever comes first.
7)Keeps wife from putting plants on top.
 
Don't forgett the saucer bellow when putting water too !

I knew some whom are able to putt a climbing plant on a Vivid speaker !

To play Mozart to a David Austin Rambler roses, hey !

PS : this revelator looks nice : sealed cabinet > 150 Hz :)
 
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Bill poster: It will be interesting to see your design ideas.
Avalon's single box Eidolon and two-box ISIS are probably the best technical and artistic truncated pyramid designs. The ISIS aims the tweeter down toward the listener's ears. There are several diy-clones with construction details to study. Avalon's new Tesseract has crazy-complex angled cuts over all panels to reduce diffraction and panel resonances. Thanks to a cabinet shop wth a 3" radius edge cutter, I've joined the large-radius front baffle crowd.

Moovnutz: ----If you want to be a Big'er Man on Campus.....
The 7" Satori MW19P-8 looks capable of good performance with the same 1600-1800Hz crossover range as the 6" MW16P-8, but with ~1.5db higher sensitivity. The Satori tweeters can support this efficiency, but the 10" SB29NRX45-8 cannot match the 90db sensitivity of the MW19P . The 91db sensitivity 12” SB34NRXL75-8 provides F3=30Hz bass in 3cuft ported cabinet. A side-side pair of 8" SB23NRX-8 woofers can provide 94db sensitivity, but with a low 3.5 ohm parallel impedance without any series padding resistor.
 

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