Holy crap Batman!    I just had to say it.  It's Steve's catchphrase.  



I've been in communication with LII Audio regarding their Crystal-10 vs their F-15.  This is what they had to say:

Quote:


Since we are discussing open baffles here, I think this driver is out of contention and I'm back to building HUGE baffles.  

Quote:


Hi Archie,

No, I do not.
The hardwood on my baffles is about 3/4" thick after processing.
If I recessed the driver, there would only be about 1/2" of material behind the driver and the screws I would have to use would not be long enough to secure the drivers properly, in my opinion. I also don't want to take the chance of cracking or splitting the narrow center section of wood on the two tone hardwood baffles because of it being too thin.

The packaging materials I use have to accommodate the 3/4" plywood that I use for the less expensive speakers, so I just make the two tone hardwood version 3/4" thick as well.

For what it's worth, I did build a pair with recessed drivers and did an A / B with a stock pair. I could hear no sonic difference.

The surface mounted drivers look fine to me from the listening seat, so I never gave it any additional thought.

Best wishes,
Randy

I guess I'm committed to building a pair of the mega Betsy's as I just ordered a set of drivers.  

Drawings are in process!
I hope to have a pretty good looking drawing of the Big Betsy's this afternoon.

Very cool Donnie.  We should soon know of the sound from big, mid and original besty sized baffles.

I have to figure out the best way to draw/cut the arc.  I have a new router but may do some freehanding.

I use one of these for inside and outside holes and radii.
https://www.lowes.com/pd/Milescraft-CircleGuideKit/1000233663

Just a nube here.... where do you purchase the Betsy alinco drivers ?


Tom in Lafayette

I think just contact them and ask:

http://www.wildburroaudio.com/contact.php

Circles with a router:
https://www.parts-express.com/jasper-circle-jig-model-200--365-250
Been using it for years, works great.  Diameter from about 2" to 19" in 1/16" increments.  Only down side is you pin in the exact center, so once you've cut a circle you can't cut a larger one (without gluing the cutout back in - which I've done on occation).

I need to figure out the jig for the sides.  I’ll just make a board jig.

Those are good circle jig suggestions.  However, now that I'm into the project I'm determined to spend a little as possible.  So far I have the baffles cut (but not smoothed) and my cost is "0" since everything was already in my shop.  I think I'll cut a circle on my band saw and then make the negative template using my router and a guide bushing.

One thing I did wrong was I didn't see the top and bottom dimension and I used Steve's "sacred Geometry" of R=42".  I missed the "around 42 inches" in his early post.  So mine have a top and bottom around 21 1/2".  Mine truly are sacred geometrically correct!  

Since I had to glue up my panels from two pieces of butcher block, I went ahead and cut the radii on my bandsaw.  I'll do like Randy said he does and clamp the baffles together and belt-sand the edges smooth.

What driver hole diameter is everyone using?  I saw that Randy thought 14 1/8" might be good.  I'd like as small an opening as possible to leave plenty of meat for the screws.

These baffles made out of 1 1/2" maple are beasts to move.  I can't imagine how Steve maneuvered his around his shop given how much more they must weigh.  Once the bases are on I might be using a hand truck.

Mine fit just right in a 14" cutout

Big baffles:  Something's not adding up -

Steve's drawing and Donnie's show the big baffles as being 32.66" wide at the widest point and 20.56" wide at the top and bottom.  This should correspond to a 42" height and a 42" radius cut on the outer arc's (but I lack the mathematical skills to verify this radius cut measurement).  Donnie's drawing shows this is a 39.6" radius cut, which is way off from 42".

But Steve's drawing also shows the widths of the boards used:  7.22" (outer wenge), 8.39" (inner paduke), and 3.81 (center wenge).  If the 3 middle board widths are added up you get 8.39 + 3.81 + 8.39 = 20.59" which is wider than the baffle width at the top and bottom.  This leaves nothing for the outer board's width at the top and bottom which is clearly wrong, as can be seen in the pictures.  So, are the board width's the pre-planed widths and have nothing to do with their final size, or are the top and widest width measurements off?

Unfortunately, I went with the board sizes and came up with 35" wide at the widest point, and then measured / guessed / interpolated the width of the two outer boards at the bottom from the photo and came up with 24" wide at top and bottom.  This turned out to be a 43" radius cut which I thought was "close enough".

However, while sounding very interesting and different from other speakers, (my first impression was "holy crap, I need to get a bigger room") I am definitely NOT getting the bass and bass slam that Steve has been talking about.  I may need to trim my arch's a bit.

Randy - what are your original baffle's width measurements at the top and the widest point and the height measurement?



Dan

Quote:


Sorry dank ..... that's a trade secret .....



My baffles are 22.5" tall x 17.75" wide at the center.
The top and bottom width is 11".

Best wishes,
Randy

My numbers are what the software came up with.
It may be wrong, it may be right.

I found a pretty cool arc calculator on line

https://www.mathopenref.com/arcradius.html

that confirms Donnie's radius of 39.6 (it implies 39.36).

Scaling Randy's numbers up to a 42" height yields 33.13" at widest point, and 20.53" wide at top and bottom/  These numbers imply a radius of 38.15".  So I probably need to run my baffles thru the router again...at least my mistake made then too big instead of too small.

No way was I going to recut my baffles for a half inch per side at the tops and bottoms.  I'm not even sure linear scaling of Randy's baffle relative to the driver is completely logical.  We all will have differences one way or another.  Heck, Randy isn't even making his baffle bigger for the F15.

Today I smoothed the edges, cut notches for my footers and cut the driver holes.  This was a full day!  Moving these monsters around and making jigs takes a lot of time.  When Steve starts selling them don't be surprised at the price.  They are a bear to make despite their simplicity.

BTW, removing 14"D by 1 1/2" thick maple blanks lightened things up considerably.

Palomino wrote on 07/23/19 at 15:08:33:


Have you seen the stands on the new Spatial Audio X Class?  Something like this would look pretty cool.

Archie, my use of MDF is limited to "just enough to know I do not like it" but I wonder if the OSB (oriented strand board) might be of some use as a replacement?

Arch, I transitioned from MDF to Baltic Birch for my OBs because I felt the Baltic had a better, more lively sound.  

My initial test for these new drivers will be in MDF because I hadn’t cut up the old baffles and burned them yet.  Not a fan of mdf but use it some times.

Last night I cut them down and put a little paint on them so the low boys are ready to go. In essence they are the same height of Randy’s but about 5 inches wider.  A lot heavier.

Lasb, LOL!  The only thing I hate more than MDF is OSB!  

I'd bet OSB is fairly dead too.  I don't know all that's involved in making sound with OBs but if the baffle is part of the sound then I suspect it would have to be lively like a wood stringed instrument.

Spending WAY too much time with my baffle build.  I sure hope it's worth it.  Mostly sanding, routing edges and building the feet.  I thought I had a simple solution to the footers but I have consistently found nothing is simple with this build.  I plan on painting mine since the BB is too wild.  I know if I ask for color suggestions, Donnie will say red.  

Not just red, Rust-Oleum Safety Red over Zinsser B-I-N shellac based primer.
4 coats of primer, sanded smooth as your first real date's thigh, then about 6 coats of red, again smoooooth, sand with wet or dry paper, from 500 to 2000, some anti swirl compound, and finally a dozen coats of wax.
You will be able to see a reflection of yourself in it.
I may go overboard in finishing sometimes.....

Donnie, did you write something about paint?  I was completely distracted by " smooth as your first real date's thigh".

Krylon is your friend!  I'll go with satin black.  Or I could embrace the wildness of butcher block and filler and just clear coat.

I used up my town's supply of Krylon satin black so I had to switch to Rustoleum Semi-Gloss.  It's not too glossy but boy does it take a long time to dry compared to Krylon.  I should have brush painted them.  Hides better and not so toxic!