Mechano23: small 2-way speakers with linear on-axis and power response characteristics with Scan Speak H2606/920000 and SB Acoustics SB13PFCR25-4,

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 Another version of a small and inexpensive 2-way system with linear spl/PR characteristics.


Drivers used in the design

  • Scan Speak H2606/920000 LINK
  • SB Acoustics SB13PFCR25-4 LINK

The box is actually identical as in the previous design (i.e. Mechano22 LINK). 

External dimensions HxWxD: 290x174x263mm (volume approx. 8 liters). BR tuning around 45Hz (fi=35mm d=145mm).

There is a reinforcement inside that connects the centers of the side panels. It is a piece of plywood with dimensions of approx. 135x40x18mm.




The box is really simple: rectangular panels assembled (glued) with overlaps. No detachable panel, the filters are mounted to the rear panel through the woofer mounting hole.

   

The box is filled with polyester fiber. To prevent it getting into the speaker basket, I put a thin mesh on the filling.


I made measurements -180..+180 degrees (V orbit) and 0..180 degrees (H orbit) with a step of 10 degrees. I used a manual turntable.

Filter design. The machine apparently needed a 2uF capacitor which is not on the E12 list. It was assembled connecting two values of  E12 in series: 2.7uF and 6.8uF.


Spl on-axis and Power Response characteristics with the target lines (simulation).


Filters transferred to VituixCad and slightly modified (series-connected 2.7uF and 6.8uF capacitors were replaced with a single 2uF cap.).


L and R filters assembled on plywood scraps.


Wiring diagram


L and R spl measurement (f6~=48Hz with reference to  the average level)


L and R impedance measurement (minimum 4.1R at 220Hz)

List of components:

Inductors

  • L1 330 uH 0.258 R
  • L2 560 uH 0.51 R
  • L3 1.5 mH 0.94 R
  • L4 390 uH 0.42 R

Capacitors

  • C1 6.8 uF
  • C2 27 uF
  • C3 18 uF
  • C4 820 nF
  • C5 3.3 uF
  • C6 2 uF

Resistors

  • R1 12 R
  • R2 8.2 R
  • R3 15 R


VituixCad VXP file LINK

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