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33 Posts
Discussion Starter #1
So, yeah my med doctor recommended I should involve myself
in a hobby. It would be a good complement to the meds, keep
myself from getting so agitated, and distract me from the
hallucinogenic side effects of the drugs he's giving me.

Sooo, I unveil my Master Plan.........


My first thought was to obtain 1000 blue butterflies from South America to produce the
finest blue pigments, travel the world for the reddiest red, obtain the most expensive
gold plated interconnects and melt them down to gild this diagram, but in the end
I said to myself, self....... NAH !!!!!

As you can see the plan calls for 1/4 inch MDF glued to 1 inch braces down the
corners to produce my marvelous box. Encased therein would be a PVC pipe.
Not any pipe, no siree, a foam core PVC pipe.

Now some haters would chime in and say this looks like Rock Rattle and Roll using
1/4 inch MDF, but remember, the pipe contains the speaker pressure.
Could vibrations in such a delicate structure still occur, Yes, but ......

As a very wise member of a secretive society of noblemen in London once proclaimed...

I have a cunning plan....
(His name was no other than that sage of widsom, Baldrick, and that secretive society
non other than those wealthy, esteemed DogBodies )

My cunning plan involves a space age development known in high tech circles as....

Foam, glorious foam, mighty foam.....

I will attempt to build two sides first of 1/4 inch MDF, braced with 1 inch
wood. Then handling that tricksy blue can of foam, I will strategically spray
foam braces at the middle and each end, functionally embedding the PVC pipe
into it. The other two MDF boards will be built with their bracing, and
will be deftly applied, after the previous foam has cured, onto the remaining
half of the pipe, all with this halve's foam bracing.

Note to self: Need more foam.....

After this intermdiate structure has been formed, quality tested and so on...

I will pour more expanding foam from each end to literally fill the voids.....

Plug the bottom with a couple of 3/4 inch MDF circles, cut out MDF rings for
the top speaker mountings and mis amigos we have what could be roughtly called
a speaker in a tube, encased in a box.. HAHAHAHAHA
( Thunderous lightening strikes, breaking glass, womens' screams.... )

Now if I could get out of this straight jacket they have me in, by
divinely inspired plan could become REALITY..........


Gotta remember to stick on the wires to speakers and stuff
them down the pipe, before closing everything up.

Thanks for reading

302 Posts
While your plan is sound in cross-section, there's a reason few speakers are placed at the end of a tube. Tubes resonate mightily. You must choose either to use that resonance and create a "transmission line" alignment, or absorb the resonances with massive amounts of acoustic fill. Both work, but anything inbetween has very ragged frequency response.

That said, you gain more internal volume for the driver by using 3/4" material... don't see the advantage gained.

Going this route, beware of expansion when using foams. The stuff just keeps growing...

Have fun,

33 Posts
Discussion Starter #3 (Edited)
Well after my last visit with my meds doctor, he was alarmed
that my new hobby would involve tools, such as, chop saws,
circular power saws, and 1/2 inch routers.

I started cutting the wood using my Porter Cable left handed circular saw.

Here's a picture to prove it.......

My PM2000, 3HP 1PH Table Saw, with 50" Accu-Fence System is at still at my
lake house in Colorado, so I had to use 2x4, 3/4 inch MDF and a cunning plan.

I cut each 2x4 foot 1/4 MDF down to 30 inches.... (Which is 2 inches longer than I need )

I used a little adhesive to make sure the level didn't jump around.

Stuff cuts like butter....

Next I measured sticks to accuracy of a few Higgs Bosons so I could cut
the MDF into the strips I need.

Okay, Okay, I had to cut a few, I made mistakes in measuring, geesh
I just can't take the hassle and persecution the members of this board give off........

A quick 6 second touch up with my belt sander made the strips equal in width.

So after a quick dry fit

Chamfering the inner most apex of the 1 inch bracing just for funs and giggles..

I glued up........

Hey, where else is a man going to put excess Titebond......

Now I have to admit... as any astute reader can plainly see...

I made a boo boooozzzzzzzzz..
( Like in Old Booozzz is up )
( Above should read Great Booooz's up otherwise it doesn't make sense )
( My apologies to the black vegetable )

I had to destroy everything cuz I should have nailed down the smaller
width strip and allow the wider one to sit on the 3/4 MDF.
PERSECUTION... I just can't handle it.......

Anyway I babied it for 15 minutes putting pressure here and there
and then left for home.....

Here's a bigger picture of my little insane asylum...
A little 3 bedroom house I'm getting ready to rent out...

Its dusty, but I'm dry fitting the vinyl plank...
I had to use 8 bags of self leveler and a couple of Planipatch with latex to
get it level and smooth....

Now I got 3 more to build before I can embed the PVC pipe
and all the rest.

Thanks for reading.........

33 Posts
Discussion Starter #4 (Edited)
Bad news guys...

My accuracy is not what I intended...

The Higgs Bosons I bought off Ebay from Guangdong China were used...
As soon as I opened the box, I could see those little suckers bouncing in
and out of existence in all the foam peanuts and knew they weren't new and stable...

(Bloomberg ran a story where the US military fell for the same used
parts in the electronics they use in their ICBM missiles and stealth fighters,
so I don't feel so bad... I mean its not the end of the world and the US
is not going to lose confidence in being the most advanced, powerful military
presence in the world, right ? Another view is that every taxpayer is receiving
a rebate on the cost in the defense budget when they employ used parts .....)

So, I thought who is the most accurate and precise people in all the world ?
Germans, I thought, they produce great cars, machinery ....
No one can argue that Italians produce some beautiful looking cars, but
I suspect they have some Germans building the engines and such.
The Swiss make all those grand watches with the tiny gears and springs...

Then I remembered, I'm half German !!!!!!!!
Its in my blood and DNA to be precise and accurate......
I scoured the bathroom and came up with the finest and most delicate hair
I could find. I'm using this as a reference point in all my measurements from
now on........

I cut the remaining 1/4 MDF strips and set up the second part of the first box
and the glue is drying as I speak...
This is just getting better and better.......
Wow I just love speaker building....


1,001 Posts
You seem to have a good grasp of reality and humanity. Go ahead and do the first iteration.
We'll be there to actually guide you through the second project and make it actually work as planned.

33 Posts
Discussion Starter #6 (Edited)
Well guys I made another boo booozzz.

In an attempt to glue another 1 inch brace unto one of the halves
of my glorious square box I inadvertently lined up the brace to
exactly the edge of the 1/4 inch MDF.
THIS is WRONG.....

( I don't know if this is the consequence of listening to too much Handel's passacaglia
or Shostakovich, you decide )
( A boo booozzz is not a mistake if I can rescue the materials I am working with
without incurring the destruction of said materials )

I started gluing up the other box and thought, "Hey this is going quite nicely".
I left the room and thought, "Something's not right, I better check again".
That's when I grabbed my hammer and chisel and started banging on the
first box to get that 1 inch brace off my nice clean MDF.

That titebond starts all smiles with its yellow glow and smooth texture when
I spread it with my fingers, but let me tell you, give it just 5 minutes and
I'm hollering, banging my hammer. It finally relented and I started scraping the
glue off the brace and the MDF.

I should have allowed 1/4 inch from the edge of the MDF for the short width
to rest into. ( I think everyone is hard wired to see nice lined up edges, at least
that's what I'm telling myself so I don't feel so bad )

I don't think I ever actually showed you what I'm trying to build.

Here is a pic and link....


Floor in the rent house is coming along.
Had to go to Lowes and consult the floor doctor there cause
my plan left a little 4 inch plank every other plank in the main room.
He suggested that instead of using half spacing I should use 1/3 spacing.
This news I like, don't bring me any other news.......

Pic of me dry fitting the 1/3 plan.. ( You can't tell I'm a floor expert ? )

After I get the pixie dust off, it should look gooodddd.....

33 Posts
Discussion Starter #8 (Edited)
Well guys,,,
I've had a set back....

I assumed that there were no flooring laminates wide enough to build
the speaker 1/4 inch speaker casing with the look I wanted.
I was wrong !!!!!

In Lowes, I was wandering about looking for materials for my rent house.
I found this....

This thumbnail does not do justice to the real laminate.
The samples at Lowes are just bootiful. ( Yes I know they pick the best
planks to display )
Its 8mm ( very close to 1/4 inch ) 7 inches wide and I could have built the casing
with this, without veneering !!!!!!!

Now I have to decide if I want to go the veneering route ( with all the mess
and no experience ) or to simply glue this on ( after reducing the width )
with titebond.

Oh well, should have looked longer and harder....

The house has consumed most of my time....

I think I'll just glue this laminate on and then the casing will be 1/2 inch
instead of 1/4 inch...

I've also have a Dynaco ST70 restoration going, and finished painting
the chassis in VHT engine enamel.
I'm using VHT black pearl and VHT burnt copper for the transformer covers.

I'll be buying a VTA main board and will have to buy a new quad capacitor
and sundry other parts, since this ST70 was in very poor shape..

Pic of the ST70...

Thanks for reading.........
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