Coaxial Wedge Collaboration

Re: Coaxial Wedge Collaboration

Jeff Babcock said:
Great! Are you making more wedges with them, or do you have other plans?
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Yep, more wedges.

One of Bennett's recent posts mentioned that B&C sell a passive crossover: XO-4 (1.2 kHz). The flush mount horn in the B&C means the overall cabinet can be a little lower in height than with the BMS. The B&C horn is plastic and does ring a little when tapped. Whether this matters or not I don't know. It can be damped by touching so I may put a rubber spacer on one edge and run a bar across the driver.

Best,
 
Re: Coaxial Wedge Collaboration

I completed a 2nd pair of wedges based around the B&C 12FHX76 and this time opted for biamping. (My mistakenly said 12HCX76 in the previous posts.) Today I created DSP settings and ran one side by side with the previous BMS 12CN680 wedge. The passive BMS was already fairly flat. I EQ'd the B&C quite flat and close to the BMS.

Overall I really like both. They're excellent drivers, don't need much EQ and sound very clear.

Some brief observations.
The B&C horn (60x40) horn is noticably more sensitive to moving off axis that the BMS (80x60). I think I prefer the BMS.
The BMS magnitude response has a 5 dB bump at around 16.5 kHz. With both drivers broadly EQ'd flat, the BMS is higher above 16 kHz and to me it's subtle but audible. (I was reluctant to push the B&C with a filter to get a closer match.) I think I prefer the extended HF of the BMS and there's something nice about it's smoothness.
Both cabinets are ~24 litre and have ports tuned at about 60 Hz, but the BMS extends just slightly lower in frequency: in measurements and faintly audibly.

I only listened at low to moderate levels. When I get some loud time, I'll post again.
 
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Re: Coaxial Wedge Collaboration

Hi Michael,
Anything further to report on the 12FHX76? I've made one wedge sort of prototype using one and am anxious to hear what others are experiencing with them. I plan to make 3 more once the drivers are available again here in the US.
Would you be willing to share your crossover settings?
Best,

Don
 
Re: Coaxial Wedge Collaboration

Don J Davis said:
Hi Michael,
Anything further to report on the 12FHX76? I've made one wedge sort of prototype using one and am anxious to hear what others are experiencing with them. I plan to make 3 more once the drivers are available again here in the US.
Click to expand...

Don,

Just FYI we now have a limited stock of 12FHX76 (many more on the way) again, and a pretty solid stock of 12FCX76.
 
Re: Coaxial Wedge Collaboration

Michael Smithers said:
Thanks for the heads up. I don't think the FCX was released when I ordered the FHX. I would have preferred it.... :)
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It wasn't, apparently the alignment and horn are more complicated to work out - which took a little longer. We just did the first production run of these new coaxials a month ago, so they may take a little time to arrive at your distributor.
 
Re: Coaxial Wedge Collaboration

Thanks. So do these 80 deg have the horn in front? Or under the LF dustcap? None of the product photos give any clue. In fact it would be really useful if all the coax photos (on the website and product documentation) were updated to clearly show the front of the drivers.
 
Re: Coaxial Wedge Collaboration

Michael Smithers said:
Thanks. So do these 80 deg have the horn in front? Or under the LF dustcap? None of the product photos give any clue. In fact it would be really useful if all the coax photos (on the website and product documentation) were updated to clearly show the front of the drivers.
Click to expand...

Michael,

The 12FCX76 (and all FCX and CXN models) have what we call a "Pole-Piece" or under dustcap horn. It's conical and machined into the pole piece of the woofer's magnetic structure. Most of our woofers have a front view available if you click the little triangular "play" button next to the photo on the web spec sheet, but it looks like this was omitted on the 12FCX76. I'll get with IT on it, but in the meantime below is that image from the 12CXN76 page which will be more or less identical.

Screen Shot 2013-03-04 at 1.57.12 PM.png
 
Re: Coaxial Wedge Collaboration

Awesome. Thanks very much.

Bennett Prescott said:
Michael,

The 12FCX76 (and all FCX and CXN models) have what we call a "Pole-Piece" or under dustcap horn. It's conical and machined into the pole piece of the woofer's magnetic structure. Most of our woofers have a front view available if you click the little triangular "play" button next to the photo on the web spec sheet, but it looks like this was omitted on the 12FCX76. I'll get with IT on it, but in the meantime below is that image from the 12CXN76 page which will be more or less identical.

View attachment 6178
Click to expand...
 
Re: Coaxial Wedge Collaboration

Thank you to all for an excellent thread. I hope that it will be revisited by all that were interested. I followed this thread during the height of activity hoping that it would guide me in my own coaxial wedge monitor development. My project monitors, designed as dual purpose small venue front of house and monitors for Fractal Axe-FX guitar rig, are approaching completion.
I read this online forum and others extensively. I studied designs. Read white papers. Spoke with experts, and I sought the advice of Jack Arnott. He provided excellent advice and even put me in contact with Curtis List and John Halliburton to help engineer crossovers and cabinets. And to their credit, the recommendations they provided did not necessarily center on buying products and services from them. Curtis List, helped me find alternatives to custom engineered (read very expensive for a one-off build) passive crossovers. Despite not clearly being significant commercial customer, Jack offered to send me a BMS coaxial floor monitor to test with my Axe-FX rig.
My build ended up using the BMS 12CN860 triaxial point source driver. This project is not unconstrained by costs. In fact, I have a wife that must never know how much I spent on the drivers…or the plywood, or for that matter the Fractal. In order to save a little money, decided to become my own design engineer and cabinet builder. It turned out to be a fun, frustrating, educational, and time consuming endeavor. Now that I’m done, I’m sure paying an experienced cabinet builder is a good investment. However, if I had it to do over, I would do it again.
I wanted my floor monitor to have three potential placement options. That would be two angles firing up from the floor and one as a stacked or pole mounted main front of house type placement. I’ve noted many floor monitors are designed to provide a 60 degree or 30 degree (to the floor) play angle. I looked at several configurations and decided to use a less pronounced 50 and 40 degree angles. For the sake of simplicity in cutting and joining the cabinet sides, all of the angles, except those that establish the baffle board’s angle to the floor, were made to be 90 degrees.
The nature of the 12CN860 favored a ported cabinet. I made my first draft blueprints using a big role of Post-It Notes graph paper. I was able to draw an end view to scale to make sure my design and driver placement would accommodate the driver’s depth. I even made a big Post-it cut out of the driver’s profile to move around on my drawing. Once satisfied with my basic design, I moved it into Sketchup. I used Kristian Ougaard’s Unified Box (Unibox) Model spreadsheet to estimate ideal volume and port length. Ideally, I would have built several test cabinets and measured the drivers’ behavior to optimize my results. Time and money constraints prohibited real-world prototypes, so I trusted that Unibox predictions would be better than my uninformed guesses.
I used 25mm Baltic birch for the baffle board and constructed the remainder of the cabinet out of 18mm. Most of my joints are simple butt joints. I did use a biscuit (or plate) joiner for the end pieces but more for alignment purposed than anything else. To minimize the number of bar clamps needed, I drilled slightly oversize screw holes in the flat side, and pilot holes in the edges sides of my butt joints. I could then glue and screw the joints together, with a little play to adjust alignment. I made 45 degree cleats to reinforce my right angle butt joints, which I again used screws to pull in tight while the glue was drying. I ran the angled edge of the backs into the opposite cuts of the doubled sides. This gave me a offset v-shaped channel, to create a joint with a lot of surface area. I over extended my butt joints so the grain end edges could be sanded or trimmed with a router flush with the flat sides. Finally, I used a half inch round over bit to finish off the edges.
I lined the cabinet with 2 inch poly fill from a set of old JBL studio monitors. It was nicely dyed black on one side. I installed a prefabricated jack plate with two Speakon connectors, paralleled to a pair of ¼ inch phone jacks. The plate has room for another, “full range”, Speakon jack and a switch, which will be used if/when Curtis List designs some crossovers for the 12CN860. The 4 inch ports are from a set of Klipsch subwoofers. They are made of flared plastic fittings at both ends and cardboard tube in between. I was able to cut them down to an appropriate length and re-glue the ends. I bought the poly fill, jack plates, and ports on eBay.
I’m still doing some testing but so far, they are vastly superior to the RCF 12” two-ways they are replacing. The sound jaw-droppingly good. Easily EQ flat. And their smoothness, camouflages how loud they are. I can listen to them at higher volumes than the RCFs, for extended periods, without ear fatigue.
 
Re: Coaxial Wedge Collaboration

Michael Smithers said:
I completed a 2nd pair of wedges based around the B&C 12FHX76 and this time opted for biamping....
Click to expand...

It's been sometime since I last posted about these. The photo below shows one of the 2nd pair in the foreground and one of the original BMS based pair in the background - see "sticky" post at the top of the DIY. For the 2nd pair I designed all the parts in CAD and had 18mm birch CNC'd. I'm completely sold on CNC. One of my aims was to make the speakers as compact as possible whilst maintaining as much internal volume as possible. CNC really helps with intricate parts.

DSC_2692.jpg

Recently I just converted the design to parametric CAD - Cubify design - and had another pair CNC'd from 16mm birch ply. This new pair is designed to use Powersoft D-Cell DSP plate amps and the BMS drivers. Here are the two in progress and a plate amp (in a test box). The DSP programmer isn't shown.

DSC_2700.jpgDSC_2701.jpg
 
Re: Coaxial Wedge Collaboration

Hello

I have been planning coaxial allround cabinets as well. It happens I have over ten JBL2426J waiting to get some action. I Bought one 12-inch Eminence coaxial woofer to test this. I have feeling that 2426 might be overkill - so does anyone have better candidate for woofer than Eminence Beta 12CX - 15-inch is also o.k.

Edit - both screw- and flangemount will do.

Thank you
 
Re: Coaxial Wedge Collaboration

Timo Ulkuniemi said:
I have been planning coaxial allround cabinets as well. It happens I have over ten JBL2426J waiting to get some action. I Bought one 12-inch Eminence coaxial woofer to test this. I have feeling that 2426 might be overkill - so does anyone have better candidate for woofer than Eminence Beta 12CX - 15-inch is also o.k.
Click to expand...
I have 8 monitors using the 10CX and a Paudio HF driver that are quite mind blowing IMO. They obviously don't have the output of the B&C and BMS drivers but work well within their limitations. I have them powered at about 300w each and HPF'd at 100Hz - even use them for bass monitors (usually a pair) for ampless situations no prob (the backwash from the subs fills in the low end nicely). They have passive crossovers that were designed for minimum feedback (no peaks, only dips) rather than maximal flatness.
 
Re: Coaxial Wedge Collaboration

Hi Michael, nice to see you're still building more of these. The new versions look really great. Perhaps you could re-post some of your last posting into the sticky thread about your wedge design so it doesn't get lost in this rather large thread.

Great work. I have been considering building a few of these for a venue that needs new wedges.
 
Re: Coaxial Wedge Collaboration

Timo Ulkuniemi said:
Hello

I have been planning coaxial allround cabinets as well. It happens I have over ten JBL2426J waiting to get some action. I Bought one 12-inch Eminence coaxial woofer to test this. I have feeling that 2426 might be overkill - so does anyone have better candidate for woofer than Eminence Beta 12CX - 15-inch is also o.k.

Edit - both screw- and flangemount will do.

Thank you
Click to expand...

Timo,

As far as I know, Eminence are the only coaxials you can buy without the HF driver attached already.

Why not design a dual 12" coaxial, where the second 12" driver is just a woofer? The crossover point should be low enough so comb filtering is not huge with the drivers so closely configured on the baffle.

Seems that otherwise getting value from all those 2426 drivers is diminished greatly.

Best regards,

John
 
Re: Coaxial Wedge Collaboration

Michael Smithers said:
... I just converted the design to parametric CAD - Cubify design - and had another pair CNC'd from 16mm birch ply.....
Click to expand...

I was asked in a PM about the design workflow.
- The 13 parts are designed in Cubify (a cut down version of Alibre which is now Geomagic). The parts include parameters for plywood thickness and drill hole sizes.
- I create an assembly in Cubify to check how all the parts fit together and alignment of holes.
- I create a 2nd assembly in Cubify with all the parts laid flat and spaced no closer than 15mm (0.6"). Behind the parts I place a part matching the size of a standard plywood sheet; 2400x1200mm (94.5" x 47.25"). The parts are laid out no closer than 20mm (0.8") from the edge of the plywood sheet part.
- I export a drawing (DWG file) of the flat view of the 2nd assembly.
- I import the DWG file into TurboCAD LTE and remove any lines not related to interior or exterior edges of the parts.
- For each part edge, I join all the lines into a continuous polyline. (This is important for the CNC software when it sets up cutting paths.)
- I move the part edge polylines onto layers: 1 layer for the plywood rectangle, 1 layer for interior part edges (line the loudspeaker driver hole or the handle cutouts), 1 layer for exterior or part-perimeter edges, and layers for each drill hole diameter. (Again this helps the CNC software with the order of cuts.)
- I then save the file in TurboCAD TCW format and send it to the CNC company.

Since the actual thickness of plywood is never accurate to it's rating, the CNC company sends me the (caliper) measured thickness and I update all the parts by setting the plywood thickness parameter then generate the drawing. Also, the 15mm and 20mm spacings were at the request of the CNC company.

I have all the CNC cuts done vertically (90 degrees) and some edge angles I cut later on the table saw. (The CNC company I use can cut some angles, but it complicates the setup and part spacing, especially for thick plywood.)

There are modules or plugins for Geomagic that enable going straight to CNC, but Geomagic, SolidWorks and the like are orders of magnitude more expensive than Cubify and TurboCAD.

I know CNC isn't in the spirit of this thread but it is becoming a lot more accessible.

Cheers,
Michael
 
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Re: Coaxial Wedge Collaboration

Michael Smithers said:
Yep, more wedges.

One of Bennett's recent posts mentioned that B&C sell a passive crossover: XO-4 (1.2 kHz). The flush mount horn in the B&C means the overall cabinet can be a little lower in height than with the BMS. The B&C horn is plastic and does ring a little when tapped. Whether this matters or not I don't know. It can be damped by touching so I may put a rubber spacer on one edge and run a bar across the driver.

Best,
Click to expand...

Is there a US supplier for the B&C XO-4 crossover? I was not able to find one in an online search (did find a few in the UK and elsewhere).
 
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