Ohm Walsh Micro Talls: who's actually heard 'em?

After a few cup of Joe's.......I'm up

The problem with being semi-retired is that I have way to much time
on my hands, I'm not complaining or bitching about it, but My mind I kind of welded to the project at hand and with that nothing else gets done. 

So in the middle of the night right after the last post I had an idea.
You see the image of my vacuum pump for composite work....You can see were this is going lol 
Damn I really wanted to shy away from the expensive stuff, but a few layer of CF won't kill the project money wise, plus working with composites is fun as you can make shapes that otherwise would take a rapid prototype machine or a five axis machine to produce.

There might be more this afternoon, but I need to get stuff ready for 
the Sweden trip later this week.

Here is my vacuum pump.
https://www.flickr.com/gp/147883144@N08/59ujV5

Hej då......🇸🇪

Greetings from a gorgeous day in SoCal...

With my Sweden trip approaching in a few days I'm running out of available time for fun stuff like working on the Ohms....

After the CF ring was installed I did have one more layer to go and that was today's one hour project. The layer from top to bottom contains everything from Butyl rubber, 1/8" aluminum, 1/4" steel, neoprene, 2 types of glue, and finally some 1" felt as you can see in the image (8 layers of metal).
 The last layer was compressed and glued together with Gorilla glue. If you look closely you can see the the compression bolts pulling it all together. There is also an inside thick layer of non drying clay, neoprene, CF and Gorilla glue bonding the layers together. WOW  I know it's a lot but I do want the Walsh drive to be on a super inert
2 3/4" thick surface, no bad vibes....lol
https://www.flickr.com/gp/147883144@N08/277b0L

The second image is after the compression screw were installed. These will be replaced 
with real bolts and then Loctited with the red stuff and a big blob of epoxy to lock it in forever.
https://www.flickr.com/gp/147883144@N08/F7mV30

The third image is the first of the cabinet reinforcement puzzle.
the first layer is the checkered neoprene which allows the glue to
wet through the layer and subsequently stick to the inside wall.
The thicker part of the part is cement board, totally dead and great to work with.
https://www.flickr.com/gp/147883144@N08/56r210

Fourth image is the part installed on the inside wall, you can see the 
Gorilla glue expanding which is great as I will know that the glue is filling up all nooks and crannies:) Removing the expanded foam does take some elbow grease, but a sharp chisel and some acetone will take care of it. To keep the part from floating away you do have to clamp the piece down.
https://www.flickr.com/gp/147883144@N08/56r210

The idea to keep standing waves waves from building up in the cabinet I will stack the surfaces in an unusual pattern allowing the surface To avoid it as much as possible. The edge of the part is 
were the first horizontal brace start. It will be built up with hard board
honeycomb and carbon fiber. Attached will be a special secret sauce aluminum extrusion that will be a vibration damper attached 
with a very low shore hardness silicone ;) 

The difference between stock cabinet and the new layers attached is 
amazing. A thud and no ringing is very exciting indeed.

Here's the cabinet knocking from inside out...
https://www.flickr.com/gp/147883144@N08/90Dku7

Here's the new layer I knocked on...
 https://www.flickr.com/gp/147883144@N08/2dk21o

More to come and Im loving it.....🇸🇪

So the first 4" layer is complete, but not finished.
The opening for the Walsh driver is precariously close to the edge of the
side wall build up so now I have to make a decision if the I can make the material intrude past the sight line of the driver cone, or the option would be to utilize a softer shapable material.....Hmmm
So what should I do? A few options contemplated  is leave it alone add some polyester fil
glue it in and make it a day..... Or use a material like "Blackhole" to dampen the sidewall surface. I could shape the foam surface a bit so I have a gradual slope in to the cabinet. 
Lots of ideas in my head, but I would love some input. throw it at me
nothing will be discounted unless it's really stupid stuff like depleted uranium, quantum dots and elk horns for bracing...🤓💯

Tomorrow will be tight as I'm leaving for Sweden on Saturday
but part of the first horizontal layer is layed out, and all I have to do
is making sure the exact dimensions are finished so I can start the CF layup and bagging as soon as I get back....

Bättre brödlös än rådlös.......🇸🇪

The final piece before vacation....

This is the beginning of the horizontal plates, each level will have a different pattern and different size holes, all to prevent standing waves inside the cabinet. There will also be a fair amount of vertical 
bracing all to make the stiffest and least resonant parts....

I do have a fair amount of knowledge from the automotive world 
and with that I like to apply some airflow management to the surfaces. Don't want to give away my ideas yet but I'm sure you will like my ideas.

The image shows the plate with some aluminum bracing, I might or I might not use the bracing we'll see when I get back.
https://www.flickr.com/gp/147883144@N08/Th8wcv

Anyway that's it for now...🇸🇪

The Sweden trip....

Is there a better place but on an airplane to think? I don't think so, but again there's not much to do, unless your next seat neighbor wants to chat away. After a few pleasantries I started to think about the project. Could there a better approach or should I just go with the pre-planed ideas? .........Nope my brain is going as fast as the
outside vista is flying by at thirty five thousand feet.

There are many questions, should it be stiffer, should it give some, might it be better to have layers that absorb but gives a bit? Is there a way to delineate layers, sections, or should the layers have separate pockets of dissimilar materials so it can be dampened in a horizontal plane. The solutions what ever they are, will ultimately change the character of the speaker.

I will come back to these ideas, but I like to give aerodynamics a thought. Does hard, or soft surfaces change how air is pressurized through the cavity? Would it better to make the surface
uneven preventing reflections? It wouldn't be to hard to give the
surface a mini skyline effect. That could be a good idea in the first cavity as back scatter in to the Walsh driver would be deleterious to the sound quality.

Does adding filler or sound deadening materials minimize the air cavity interaction to the Walsh driver ( the answer is yes but how much is the question). Will a smooth surface build up boundary layers ? I guess at this point (in the plane) a simulation ain't happening on my iPad unless there's a CFD app available...... lol.

So if you took the speaker cabinet closed of the top part with a plate
and some sealer, I would use a shop vacc in reverse, a speed controller could be electronic or a simple restrictor plate. A led light inside the cavity, small tuffs of yarn taped to the surface and finally a bore scope so you can see how the air flows between the stiffening layers.

Will the shape of the holes in the plates impinge or add to the flow?
Would a convex or a concave surface change anything? Should the holes be rounded over, or is a sharp break in the surface better?
By changing the flow over the surface will the vent tube efficiency
Increase, or decrease? Would vortex generators break up the boundary layer??

Will the change in the boundary layer give you better sounding or tighter bass?
As you are changing the efficiency of the tube will it be possible to change length, ID, or shape. Is it possible to up the efficiency by utilizing the "Coanda effect" by proper shaping.....???

Back to the science of minimizing vibrations, in the horizontal layers/dividers.
Each divider sections (as seen in my latest pictures) is made up of dissimilar materials hard, soft and dense. All this to prevent the speaker from leaking out sound that can
throw of imaging and proper sound staging.
Right now the section is built up of neoprene rubber, glue and cement board. Next layer will be a lead sheet only 1/16" thick
glued in with epoxy on top of the cement board.

The first layer of horizontal bracing butts right up to this layer and I have not decided if decoupling the vertical wall from the horizontal brace would be important or not, but I'm leaning towards......yes and no!
I am thinking that I will cover the vertical walls with E-glass and CF
(On top of the lead sheet) and at the joining surface of the horizontal brace I will use a high shore hardness rubber that will be covered with composite. This will Allow me to have a stronger joint between both surfaces. The horizontal brace will be vacuum bagged allowing a much stronger part. At this point the plan is to use a layer of hard board (as per last image) urethane foam board, E-glass with micro-balloons and CF, the CF will be stacked and clocked for high rigidity
In compression. I will also have vertical CF standoffs were applicable.

The vertical surfaces are harder to vacuum bag, but by using a bladder that expands in the cavity it will simulate vacuum bagging but in reverse and it works incredibly well.


Sorry about the length of this post, and I hope someone is reading
these thoughts and if not.......Sad! 🇸🇪

Just a pretty picture from somewhere over Iceland...

https://www.flickr.com/gp/147883144@N08/rv8j9y