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Part Four

 

CONSTRUCTION DRAWINGS AND NOTES

 

PLEASE NOTE WAVEGUIDE REQUIREMENT CHANGES FRONT PANEL

 

PLEASE SEE NEW! BELOW

 

I

 

 Bernard and his Masterpieces (Proud Daddy)

(He may still build them for A$600 each as shown)

 

See Construction Drawings further below.
 

IMPORTANT: The way you implement the Waveguide will influence your box design, Particularly the Front Panel construction. There is basically two ways this can be done, the original construction using a Waveguide similar to that constructed like this:

 

 

We can call this the Square Waveguide. The alternative is the Round Waveguide as shown here:

 

The difference is clear, the 18mm Front Panel becomes a single piece rather than two. The 25mm Sub Front Panel stays the same.

 

Want to buy a Round Waveguide?

 

Contact Joel Wesseling neverenoughmusic@hotmail.com.

 

 

Post Box Construction
 

After the box has been assembled, then use plenty of white wood glue as a sealant. Use your finger by running glue up and down on all internal joins. This will ensure that joins are air-tight.

Some may question why a vented box should be air-tight when it has a dirty big vent there. Surely any pressure would escape there rather than gaps in the woodwork. This also means that we donít understand how a Helmholtz resonator works. At the box frequency, when the cone moves in, so also in the vent the air is also moving in. Both the cone and the vent is pressurising the internal volume. In fact, the pressures in a vented box are potentially larger than those of a sealed box. So, bottom line, make sure that only air in the vent can get in and out of the box.

Other than that, if you have DIY experience, the rest is doable. Please note, this is a sizeable box of considerable mass, so if you have a bad back or not prepared to lift some weight, then beg off or get a friend or other to help. The finished boxes are likely to be 40-50Kg each.

The internal of the box will be stuffed with 60/40 Wool/Dacron bats made by Insulco (although Bradford makes them too). About fourty to fifty percent of the volume will be covered. The stuffing will be kept away and not to close to the rear of the drivers, especially the two top ones. Some experimenting may be needed, but this is excellent material that breathes a great deal and has low mass. The Dacron (polyester fibres) keeps the 60% wool as a binding material and becomes a Ďslabí about 75mm thick. Itís very easy to work with; gives excellent results and non-critical as well. Canít ask for more.
 


 

CONSTRUCTION DRAWINGS

 

Note: Old is Square Waveguide and New is Round

 

 


 

The Driver and Waveguide Cut Outs For Mark 6

 

 

 

Note: The Waveguide Cut Out here is based on 150mm Diameter

 


 

OLD SQUARE WAVEGUIDE:

For Mark 6 using Old Waveguide - use  above as Cut Out Diagram as it still applies

 

   NEW:

New Round Waveguide

IMPORTANT: With Mark 6 using SB Acoustics MidBass Drivers, see above.

Now the 18mm Front Panel will become one piece, not two. Mostly the cut-out for the Round Waveguide will be 150mm as it is made out of 150mm round aluminium. I recommend that you do not cut this until you have the Round Waveguide on hand, as that 150mm may need to be a little larger in diameter?


Please Note: The Sub Front Panel does not change

The Tweeter mounts behind the Waveguide on the Sub Front Panel. The square Cut-Outs allows the back of the drivers to have good air-flow into the internal volume.


This is added to the rear of the Sub Front Panel.

Please Note: Cut-Out must be precisely in the centre and lineup with the Tweeter on Sub Front Panel.


This is how the above are fitted together:

OLD:


 

NEW:

If you are using a Round Waveguide, then this will look a little different.


The Main Brace sits 170mm behind the Sub Front Panels. Later we will show what part of the volume will be treated with Wool/Dacron Bats.

NOTE: There is a TOP and Bottom - so orientate in the box as shown.




  

Mark 6 Shown

IMPORTANT: The UPPER round 78mm Cut-Out is for the Tweeter Terminal (two of them). The square Cut-Out is for MidBass & Bass Terminals (four in all). IF you are using different types of terminals, then do these Cut-Outs accordingly. Same applies to 91mm Port Cut-Out. This may need to be changed, so check that the outside diameter of your port you will be using.



Next: Internal Wiring & Box Damping


Only Mark 3 Felt Pieces

The Felt is nominally 6.4mm from our supplier - but uncompressed it is near 8- 9mm thick.

 

 

Send mail to joeras@vacuumstate.com with questions or comments about this web site.
Copyright © 2003-10 Joe Rasmussen & JLTi
Last modified: Monday June 08, 2015

Just had a terrible thought. If "intelligent design" is unscientific, then who will design our audio equipment?