Projects - JKN 01 Speaker Project

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Construction of Raal JKN 01 MTM






Threaded Inserts for PHL Mid/bass drivers had to be fitted.

Before closing the speakers off I had to measure the speakers with and without long wool.Basically I tried to determinee how much long wool should be placed in.
Here is a note from the designer after I took some measurements.


The idea is to have the back wave absorbed as much as possible.
As for the absorption material quantity, it would be good to measure impedance, as that will show the reactive component of the box loading, and we need that as small as possible. However, the audition will show any major problems if the stuffing is below some minimum that is needed Your measurements show too much room influence, and if you want to get rid of the room reflections, place the speaker outdoors on the parking lot, side down (so the speakers will be close to the ground) and then do the measurements.
Use thick felt on the sides close to the magnets.






Rings - Spacers had to be glued on. These spacers adjust the depth of the driver (phl) to finish flush with the front baffle (Subdue 909)






Now it is time for the most precise job on the project, cutting Subdue 909 on 45 degrees .We new it from the beginning that this  would be the hardest job on this project and it gave me a headache every time I think off subdues.

To be more specific and follow the design properly the tweeter has to be mounted on the top of the ply only without any screws penetrating to the other layer. In this case the tweeter is completely isolated with the wave bar from the box it self. The same scenario will apply to the Mid/bass drivers completely isolated from the tweeter going the opposite way.
Note all this above is achieved only if all the pieces (top, bottom, sides .are mitered etc cut on 45 degree) so the wave bar meets all around and isolates the box.

See picture



We came out with two options:


First option is to cut the Front baffle first, as it has a 1 mm clearance for a spacer to be glued for the mid/bass drivers (note that the mid/bass is not connected to the subdue at all). Anyway cut the front baffle first, glue it, then measure the sides do that then do the top and bottom and last do the back bit.

Second option is to cut all bits at once using screws to hold the individual pieces in place


All the screws have to be removed latter so there is no penetration through the 2 layers (subdue 909 & Hardwood ply)




I decided to go for the second option.

First I cut the front baffle with (CNC). It turned out to be too tight around the mid/bass drivers so I had to re cut it againand  ended up with 3.5 mm clearance 




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