Big multi-way build.

Hey folks,

I've been in the planning/design stages of a fairly large multi-way for a few weeks now and thought id share some details for anyone who is interested.

I grabbed a half dozen SDX10's from Bob over at Creative Sound as the price was right and I was doing a Sub design for someone. I had no concrete plans in mind for the extras, but picked em up as I figured I could put them to use somewhere down the line.

Currently, I'm looking into using dual SDX10's in the bass section plus the following driver combinations:

SB Acoustics 8" midwoofer
SB Acoustics 4" midrange
SB Acoustics SB26 tweeter

or

SB Acoustics Satori 7.5" Midwoofer
SB Acoustics Satori 5" Midrange
Fountek Neox1.0 or CSS LD25x (Ive got a lead on a functional pair at a good price).

Alternately I may opt to cut this back to a 3 way and use the Satori 6" midbass with the SB29 or LD25x to keep costs a bit lower if using the Satori line.

Crossover points will likely be in the 120/600/2800+/- range, all depending on driver choices and measurement results mind you.

Lots of modeling and thinking to do!

I'm very much open to input. This is meant to be a fun project and simply an exercise in big, dynamic speakers. This will reside in my personal listening room.

PS. this will take some time, and this will be Active for now. I may convert the upper section to passive and use an active bass module. My passive crossover skills are rusty as I mostly deal with active designs and full range.

PPS. the attached drawing is just to get a feel for the cosmetic design. Inspiration comes from the Focal Utopia line. Dimensions are (almost certainly) subject to change. My listening room has tall furniture, and we are fairly tall people, as such the tweeter height may seem a tad higher than what is typical, but it suits our specific application.
 

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Personally, the only application where I find the close spacing of drivers (tweet, 4", 8", 10" or tweet 5", 7.5", 10") is when multiple different principles of physics driving you in different directions constrain you to such choices, like a narrow baffle dipole where the conflicting interests of small driver size to reduce dipole path length and volume displacement needs to reach target spl. Or in an MTM where you're really trying to minimize interdriver spacing for vertical lobing considerations and still want to maintain a high spl target.

I'm not sure I see that focus in your design. So I'm not sure if the tradeoff in complexity is worth it. Your layout limits interdriver vertical lobing considerations to just the crossover frequency between say 4 and 8, or 5 and 7.5, instead of the upper xo frequency with the tweeter, which is a benefit, but will still have some interesting vertical response patterns and at a huge cost of complexity.

Picking one driver that can cover the range in a 3 way usually works out better unless as above you have some other goals that take priority and force you to deal with the consequences.

The Satori 5" and 6" are both really nice, and either could be used depending on tweeter choice.
 
Thanks for the input. I certainly see your point regarding the issue and complexity that arises from the layout. Moving the midwoofer below the midrange would help but raises the tweeter height considerably.

I considered a design with dual midranges in an mtm to better handle the issue, but cost and complexity only increase further.

A 3 way would greatly simplify the design and help deal with the issues of driver spacing. I've debated midrange size in this instance to find the sweet spot between displacement and dispersion. I believe a 5-6" might be the ticket.

This will be the most complex design I've done and certainly a learning experience. Truth be told I've been leaning towards a simpler 3 way. The 4 way shown in the sketch may be a bit ambitious.
 
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Jeff Bagby uses the SDX10 as the Self-powered woofer for his three-way Kairos.
Two SDX10 approach the correct SPL/watt for: SB Acoustics MW16P Santori 6.5" midbass and the SB Santori TW29R tweeter.
The lower cost SBacoustics SB29RDNC tweeter also models well with the MW16P.

MANY, MANY very positive reviews for the Santori TM drivers.

GOOD CHALLENGE: The Duelund 3-way crossover filter function approaches a transient perfect response, and the smooth SPL from the Santori drivers should help implementation.
 
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linesource - Jeff's design is what pushed me to grab the SDX10s. I was debating a pair of Seas L26ROYs for this multiway project as well as the Sdx10s and when I saw Bobs sale on the Sdx10s combined with Jeff's success with his design I pulled the trigger.


I'm very keen on the Satoris and am likely to use them here.

Cal - Thanks pal! These will start as Baltic birch prototypes, but will be rebuilt in cherry with something special for the baffles.
 
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My pr of push-push SDX10 are certainly nice.
dave

The SDX10 is 6.7" deep with an Mms of 112g, SO,
... a front mounted pair with 1-front_cone and 1-rear_cone can reduce some even harmonic distortion BUT have enough Mms to shake-rattle-and-Roll modest weight cabinets.
... a side-side counter-force mounted pair needs a cabinet width of about 16" to maintain a safe magnet-magnet gap, unless up-down physically staggered.

Quoting Kairos 3-way designer Jeff Bagby: "We have already discussed using either the CSS SDX-10 or the SB Acoustic SB29NRX-75 woofers, using them sealed or vented, and locating them near the floor or near the monitor speaker, but now we will brainstorm some other options as well. Although I didn’t take pictures or measurements I also turned the woofer module 90 degrees and listened with the woofer mounted on the side. Due to the low crossover point I could really hear no discernable difference in this location compared to facing straight ahead when I was at my normal listening distance of about 8 feet away. So, based on this, I think side-mounting is a viable option for anyone who would prefer to go this route."
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Robert,
As Canada's King of Kabinet Konstruction, have you developed a clever very-low diffraction front baffle design?
 
a side-side counter-force mounted pair needs a cabinet width of about 16"

My cabinets are 14" (external) square prisms made of well-braced 12mm BB. Drivers are holy-braced together. To get the box to move (the top goes 1st), i had to turn the mains off as things got too loud and then turn it up another 10-12dB. Boxes way very little, with 2 SDX10 installed it is a serious lift.

push-push-SDX10-inside-view.jpg


dave