Before I get into the build... a note about the shop. Built under some decaying ash trees I decided to make it with a 12 pitch roof. Not only that, but with everything at 16 inches on center and 100% screwed together. The roof is super strong. The pitch is so steep and so frikin high that I almost pissed my pants at least 50 times framing it.  

Last night I got to see it in action, as a huge tree fell splitting two other trees all onto the roof of my new shop.  Slid right off like rain.  No structural damage.  The shed behind the shop was smashed.

I purchased 20 BF of African Paduke and 20 BF of Wenge. The Wenge delivered is $22 a board foot. The Paduke is about half that. Nevertheless the total cost of materials gave me real pause. I had to think about it for a couple of days knowing I could probably make the same thing out of plywood with veneer for a fraction of the amount. To get myself over the hump I simply calculated the materials wrong and purchased less than I'll actually needed.  

Whoops.



Before it was over another 18 BF of wedge was needed, and 20BF of oak.  ::)

In this picture I have run the Paduke through the jointer and planer as well as two of the Wenge boards.

Interesting note... hating to waste an 1/8 inch for each cut on the table saw, I ran the Paduke through my band saw and it cut it like butter with precious little waste.  When it came time to do the Wenge, which I was already short on I knew I was going to do the same thing.  However, when applying the Wenge to the bandsaw, the bandsaw dropped its first F-Bomb and proceeded to cut the opposite of a straight line.  Wenge is really unbelievably hard and heavy wood.  A single one of those black boards you see in the picture probably weighs 30 lbs!

Haha, looking back on it, I would have to be a real wood craftsman or desperate for money to build a pair of these with this much Wenge.  Of course ignorance is bliss until you reach that moment where you wonder what you have just gotten yourself into!

Somehow we have to make two giant Betsy baffles out of these boards.

-Steve

Here is all the boards machined square and to the same thickness.  

After a few days I came up with this...



As if it wasn't stressful enough trying to stretch the wood (at $22 a BF) HALF of the Wenge was 1/4 sawn, and half was not.  Now, Wenge that is not quarter sawn looks like frikin black and yellow plywood.  It's hateful looking so now two of my 8 inch x 48 inch boards had to be cut into 1.74 inch strips and rotated 90 degrees to and glued back together to create the illusion of a quarter sawn board.


Steve

The next big thrill is to try to cut the arc perfectly...  the bandsaw option is out, panel is too heavy to lift.  We all know the only way is the dreadful router.  This is too serious for a mid-fi router, so I had to remove the PC from my router table and make a jig big enough to swing the arc.  

Interesting note:  The radius of the arc will end up being the same length as the height... around 42 inches.  Sacred geometry at work here...



It took a carbide spiral SATAN bit to make this cut.  It's a SATAN bit because if you run it too slow it will worm it's way at mach 6 through your board and then through side of your building with the router and you attached!  Baddddd asss bit... scares the crap out of me.


Steve

It was a perfect day for it... idillic in fact.  72'F nice breeze, birds chirping, low humidity, no bugs.  Don't worry I appreciated every second of it.  



Both sides of the first panel are done with no flaws.  Trying to do the second one without waiting 24 hours would be certain disaster... can't chance it.  Going too well.

-Steve

I guess he was done with it!  

Those slabs of gorgeous wood look incredible, can’t wait to see more of this endeavor.

Best,
Scott

Tell me more about the router bit. I would assume solid carbide with some sort of coating??

The shop sounds very respectable.  It would drive me nuts if it didn't.  Absorption on all four walls and the roof.  Bass is wonderful out there.

Steve

Wow !!!

Very cool .....

Steve ..... might I suggest that this baffle be named the "Big Bertha" .....

Looking forward to seeing (and hearing) the finished project.

Happy listening,
Randy

Here is the tree this evening... still moving slowly towards the ground through my shed.



Steve

Getting ready to cut the hole for the woofer...

Letting it swim in linseed oil for awhile before I wipe it off.



Steve

Next I have to figure out how I want to handle the base that keeps it upright.  I can make a nearly 24 inch base scaled from the original Betsy which is about 12 inches... or change it.  I pondered this for a long time.  Despite the fact that I can not even lift the baffle, when it is on the floor it becomes weightless.  That means precious little effort to tip it forward.  Since I have cats and grandkids I don't want to see smashed, I decided to shorten the back to 12 inches and put 7 inch feet on the front.  This way even the smallest amount of pressure from behind will cause the baffle to lift up off the floor at which point it is no longer weightless.  Also, the thought of 24 inches behind the speaker was scary since I'd be tripping over it all the time.

So with the following sketch I went to work...

Now to figure out how to attach them to the baffles.



Steve

Steve, looking good. I can't wait to see how they look all put together. They are going to be one heavy speaker. You will need to get a dolly to move them around.

Steve said "Fixing the side where on the last cut I blew out a large chunk of Wenge... and then lots of sanding."

Yep ….. when routing the outside edge of just about any hardwood, it is VERY easy to blow a chunk out of the wood …..
I have done that several times and it makes you sick to your stomach to mess up a beautiful slab of hardwood.

At this point ….. I just use a band saw, trace the shape of the baffle from a template, cut out the baffles on the band saw close to the line and then clamp the two baffles together and use my belt sander to make the edges as smooth as a baby's butt …..

Of course, Steve's baffles are too big to easily (if at all) run through a band saw ….. so he did something different.

I am impressed ….. for anyone who has never attempted a project like this, there is a lot more to it than you can even imagine.

Very nice ….. !!!

Happy listening,
Randy

Yes, these are intended to be bass baffles to pair with the Alnico Betsy speakers. My hope was to find a lower efficiency woofer with a steep natural roll-off that I could either series or parallel with the Betsy and in either configuration not use a crossover. Since the Alnico Betsy driver is more sensitive and has over 3 octaves higher response, even though both drivers are hooked together, the high frequencies will naturally go to the Betsy driver, and the low frequencies will naturally go to the bass driver. Any overlap is seamlessly canceled by running the bass drivers out of phase relative to the Betsy drivers.

I found the perfect drivers, some Seeburg DDS1 drivers. Basically vintage disco tech drivers with alnico magnets and cloth surrounds. Probably about 88/89dB from what I can tell.



I painted them black to match the Betsy drivers. You can see them in one or two of the previous pictures in the background of my shop.

When I got these drivers I laid them on the floor next to my Betsys and hooked them up as described without a baffle.  It was perfect.  You practically couldn't hear them which is what I wanted.  I could have lived with that just fine, but once I got the image in my mind of a 2 inch thick solid hardwood Betsy at a full 42 inches tall I just had to make a pair.  Couldn't help it.

The first full listening test was to be honest a lot more bass than I was expecting which was great!  Then when I figured out to wire the woofers 180 degrees out from the Betsy drivers the mid-bass overlap disappeared and so far it was for my personal taste the best sound I've possibly ever heard.  There was zero mid-bass bloat or room contribution in that critical area and I found it so refreshing that I was just spellbound by it.

I'll put together some photos and more impressions about the sound in the next couple days.

Steve

So here are a couple more shots of the front feet getting put on, and from this point forward, they got carted into the listening room.  I'll take some pics of the finished baffles next.

Quote:


Hehe... seeing that saw set out in the rain all those years was instrumental in motivating me to build the shop.

Steve

Ya know... If the woofer thing doesn't work out what a beautiful coffee table with a space for your bowl of chips.

Or maybe a pair of subwoofer coffee tables that way you wouldn't have to worry squashing the guests when they get a little rowdy.

Actually thanks for sharing I hope they sound as good as they look.

Dana

My bass baffle implementation is non-duplicatable because it is based on obsolete vintage alnico Seeburg drivers from the 1950's.

The full-range drivers shown in the picture are a current production driver from a small company called Lii-Audio who specialize in crossover-less full-range drivers.  The model is the F15 which is the largest driver in their line, and the least expensive.  I'm not sure it would be priced so reasonably if more people heard it in this magic Caintuck Audio Betsy Baffle design.  I'm not blowing smoke here either.  This combo is producing more low bass than the smaller sized baffles featuring multi-15 inch driver arrays by a huge margin.  

Here is a spec sheet on the drivers used.




Steve

The efficiency of these drivers in combination with these baffles is easily at or over 100dB 1w/1m and that is all the way down to 50Hz at which point it begins to roll off. I realize there are many 100dB speakers out there but consider this, many are rated at 2.83v not 1w/1m which translates to a lower figure, usually by around 2dB. Also many 100dB speakers are using a crossover and more than one driver. Also many full-range drivers that claim to be 100dB have absolutely no bass compared to this, which is a crossover-less full-range 15-inch driver with only 14 grams of moving mass.

As a result, its sound is unique, reminiscent of the vintage drivers from the 50's that were nice and tight, which this certainly is. The difference is that there is no cone break-up at the listening levels you would be able to tolerate in your home. It sounds exactly like the original Betsy driver, but with an octave lower bass. The top end is the same, slightly rolled response that I never have a problem enjoying.

The Alnico Betsy drivers by comparison are faster and more extended in the top end. A pair of the Betsy speakers with either driver create a believable you are there sound stage with reference precision.  The F15 drivers in the big betsy baffles create a believable they are here sound stage (which is rather different) with dynamics and projection better than any speaker I have ever heard, proving the validity of the special shape of this baffle design.

The F15 drivers in these baffles will get louder, hit harder, have more bass, and sound bigger than any other Decware free-standing speaker driven by our larger TORII and ZMA amplification with nothing more than a 2 watt Zen Triode amplifier! It's simply insanely good and incredibly hard to believe when you hear it. For all those who own a 2 watt Zen Triode and wondered what it would sound like with a 40 watt ZMA, this is the same result only better because no other speaker has this projection, not even my corner horns.

However with the F15 driver there is no doubt in my mind, especially for Zen Triode owner's that even a triple-sandwich of MDF or cabinet grade plywood used to create a Big Betsy on a budget would provide reasonably similar results, which is scary exciting since the drivers are less than $500 a pair.

I will have these set up in my room indefinitely, so a great time to hear them would be 2019 DECFEST in October 4th, 5th, 6th. Between these and Bob's re-designed HR-1's , the Omegas and Randy's baffles there will be quite a bit of new sound this year! Of course that doesn't even include all the anniversary mods and the new soon to be released CSP325 preamp!

Happy listening!


Steve

I just thought of how to describe the sound...

The sound of this speaker is what you always wish would happen when you turn up the volume of your stereo but never does.

Steve