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Three way with BMR build

mightycicadalord

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Started a new project, one that I wanted to design myself from start to finish. I have made many kits but this time I wanted to do it all myself as I didn't really learn much from them aside from woodworking skills. I wanted to document the build here and start a hub for the many questions I have, rather than PMing a bunch of folks.

I am going to attempt to utilize as many parts I have around for this, and meet a few goals. So far I have the cabinets made, I'm sure you can see where inspiration came from. Driver recesses are made but I may decide on different drivers as time goes by, I attempted to keep the recesses within 1-2mm of other driver choices. I speculate the tweeter may be changed, the recess should accommodate many options but a faceplate will be 3D printed if need be.

At my current stage I am attempting to develop a passive crossover for the speakers, and I plan to load the cabinets to generate some FRD and ZMA files to load into VCad. I tried a round today but think I kinda borked it so tomorrow may yield better results. I did land on a good amount of stuffing I can recreate for both chambers that has the BMR driver measuring and sonding very, very nice. I'm learning a ton at this stage, mostly that you should gather as much possible information about the speaker before attempting to start a sim of the components. This is probably the biggest challenge and if I can't quite reach the results I want, I will simply go digital and control these with DSP + Amps. Any help there is much appreciated.

Nicest cabinets I've made so far, I plan on veneering them but they came out so nice I might not.
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Fancy shot of the BMR driver. I toyed around with them before building and I immediately felt there was something special about the midrange coming from them. Even just one in mono yields some interesting spatial qualities.
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These were tough to route, but I think I nailed it. Pretty good with a router if I do say so myself. It's so snug I have to use a little tool to wiggle the drivers out, perfect :)
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fluid

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Good luck with your build, I suspect you will have some balancing to do in the crossover of the on vs off axis response of the BMR using a baffle that is wide in comparison to the driver with sharp edges.

You can see a similar trend in the Audioholics measurements of the BMR tower, circled in red, without the edge rounding this would be worse

BMR Tower Audioholics.png
 
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mightycicadalord

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I can do a 3/4" inch round over, can you veneer that tight of a radius?

Considering grabbing a hivi RT 1.3 to test, I wager it will be wider than what I can achieve with 1" domes I have. I will be testing dx25 and bc25 as I have then on hand.
 

fluid

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I can do a 3/4" inch round over, can you veneer that tight of a radius?
If it is thin paper backed veneer sheet definitely you can, if it is thicker veneer it gets more difficult.

There are plenty of youtube videos demonstrating how to veneer curved edges

3/4" is better than nothing from a diffraction perspective but the issue will still be there.
 

Exurbia

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For tight curves using steam on the cotton or linen setting usually works. I sometimes steam with a damp cloth. My favourite Aussie veneer is Tasmanian Myrtle Beech
This a tough unforgiving veneer, but, using steam it bends like Aluminium.
 

alex-z

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A 3/4" roundover will help, but going bigger is definitely better. Especially with how wide the BMR radiates.

You can do really big roundovers easily by attaching PVC pipe or concrete form tubes to the sides. Then epoxy them in place, and stuff lightly with insulation so they don't have cavity resonances.
 
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mightycicadalord

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3/4 inch is the max I can do really, I think thats where roundover size stops for 1/4 shank. adding pvc sides is something I'd have to have considered at the start of the build.

I got a good review from another user on the wondom dsp amps and ordered the jab5 which is a 4 channel with dsp, if that thing works out well I will just order a second and go all active.

Also got in a nice router bit to trim bit for veneer on the speaker holes. Probably going to grab a new router as well, my craftsman from the 80s is literally falling apart. Going to have to try some in person, my walk through the local big chain hardware store left me surprised at how poor the locking systems were on some of the routers.
 
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mightycicadalord

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I got some veneer in, first time doing this sort of thing but it looks like it just bends right over the radius no problem, thought I'd need softener but nope.
 
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mightycicadalord

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Wow I thought veneering would be hard but this is the easiest part of the whole build process. Using heatlock with wood glue method, works great.
 

D!sco

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I'm sure I speak for everyone when I say

FOR THE LOVE OF GOD PICS
 
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