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Enceintes Médium/Aigüe.
Objectif:
- Bandpass 300Hz... 20kHz.
- The same section as the bass speaker.
Calculation:
- The base section muste be identical to the bass-reflex speaker fabricated before (that is 30cm*32cm internal).
- The height is determined by loudspeakers: 12cm (Tweeter) 16cm (medium) 10cm (margin of manufacture) = 38cm of internal height.
- I would have a volume so more than being broadly enough for the medium. The filter will be put behind, by intercalating one walls
at 8cm of the back face.
- Choice of wood: panel of fir 3 coats of 27mm of thickness. I was very happy with the bass box, so I continue....
Panel Size:
After some small calculation...
Quantity
|
Size (cm)
|
thickness (mm)
|
4
|
31.0 * 32.0
|
27
|
2
|
32.0 * 43.4
|
27
|
4
|
33.7 * 43.4
|
27
|
2
|
37.4 * 43.4
|
18
|
2
|
32.0 * 38.0
|
27
|
2
|
37.4 * 43.4
|
27
|
2
|
25*43.4
|
6
|
Making:
Here are some photographs which I made while I rebuilds a new pair of speaker.
Then I begin by screwing and stiking on together boardwalk between them.
I used 2 screws by side.
Glue been cleaned on the following photograph...
Photo
Then once dryness, I stuck on the internal faces some semi-rigid rocks wool plates.
I forgot to take a photograph, but however we see it appearing on the following photographs.
Once finished, I add the second plate aside:
Photo
Then I sand the edges of the front face. I forgot the photograph, but we see results from it on this photograph.
Then we cut up the place which is going to take the loudspeaker. We see the result on the photograph which follows.
But on this photograph I'm already on the next stage that consist to do a conical hole on the medium. This cone being interrupted to
leave some wood to screw on loudspeakers, that complicates a bit.
Photo
And we see the semi-rigid rock wool on the previous photograph on the back face of the box.
A zoom on conical widening out. We just see a vertical blow of saw on the right of the apparatus to delimit cones.
There are in fact 4 screws located on the two 45° diagonals of speaker. I leave all wood therefore around these screws, then
I cut up a conical form between these screws.
This appears by a blow of saw from side to side and near the edge here:
Photo
Once ended, I begin the tackle of the side and the bottom.
Normally I dot it later, but since I still do not have HPs, I try to move forward as most as possible.
We also see the small plate of plywood of 6mm. At the moment I have just put nail.
Here is a view on the actual side of the box.
Therefore we see the semi-rigid rock wool of 3cm of thickness, more 2 wire of 4mm2, 1 by HP.
Photo
I have just received the components of the filter, I build the filter, and here is results:
Photo
Then it is necessary to cut up the footprint of speaker, on the 6mm front face.
I waited to accept HPs to make this, it is surer.
Photo
Then we add the tackle (cork) over and underneath, without forgetting 4 foot of 1cm high in the bottom, sticking directly on the
wood of the box.
Photo
Then we bolt on speaker, and we weld the cables. And here are results...
Photo
Then here is the final result...
Photo
Filtering:
Photo
Photo
Here is the schematics of the filter, then the photograph of the filter of 6WM and T120TI. The other parts of the filter is
on the bass speaker.
Inductance of 10.3mH can be build with the fine copper wire, and especially since there is one serial resistance. Finally it
is needed to substract the resistivity of the inductance for the resistance which must be added.
L5 / R5 is there to neutralize the effect of the resonnance of the medium on the filter.
R4 / C4 is there to neutralize the inductive effect of the medium loudspeaker.
R6 attenuates the sensitivity of the tweeter.
The medium speaker must be connected electrically in reverse (minus on the plus of the filter) to take into account the phase
difference of the filter and loudspeakers.
Simulation give following result:
Photo
Celle de gauche est la réponse sur l'haut-parleur de grave, au milieu celui du médium, et a droite celle de tweeter. Celle
de dessus est la résultante des 3, donc la réponse de l'enceinte.
Conclusion:
After some weeks of listening, impressions are the following:
- No vibration of the box face. 27mm 3 coats panels fir give offer undoubtedly amazing characteristics. It is lighter than
MDF, it is also rigid, and on top of that it knows very well how to amortize vibrations with a disconcerting easiness. Once
finishes, speaker box seems so hard than stone, while keeping a correct weight contained by their size. It is an impression
that I never have had with MDF, I find now that definitely MDF introduces a too strong tendency to to be vibrated or to resound,
what need to multiply the internal wood tube againts this effect, what complicates the making of a box or degrades its sound
quality. With the 3 coats wood in natural fir, this problem disappears. However, I put a pierced wood plate right behind
the bass of 21cm, to protect himself against stationary air wave in the box.
- The mediums (Audiom 6WM) are magnificent. This cuts vicinity frankly with 5V313 and back volume, about 20 litres, gives him a
wealth of sublime functioning. Thanks to the 3 coats fir, we could think that I put a wooden thickness of 10cm! Check I
however confess to have doubled really the thickness of the front face (what gives 54mm, with problems to find screws black M6*60mm),
it is a circumspection which I always takes.
- On tweeter side, one more appears in clearness in comparison with previous T120K and T120TI version. Flawless also.
realization of a speaker - photograph of speaker making
Created : 01 june 2004.
Last update : 11 november 2007.