2-way with wide dispersion and low distortion. Linear CTA-2034. Mechano26

-



Another take on a small two-way monitor design. 

While searching through various datasheets, I came across a driver setup that seemed to allow for directivity matching between the tweeter and woofer without using a waveguide. This would allow for both good control of the CTA-2034's characteristics and wide dispersion.

Drivers used:

SB15MFC35-4

SB26CDC-C000-4

18 mm birch plywood enclosure, dimensions: 314 x 184 x 278 mm HxWxD.

I took a complete set of measurements in both the horizontal and vertical planes. The driver choice turned out to be valuable; indeed, it was possible to design a crossover with good control of directivity and related characteristics. It's worth to note that the DI, even in the highest octave, doesn't even exceed 9 dB.


I built prototypes according to the design. There was a small problem however: the  measurements taken on the built speaker didn't quite match the simulations. A quick check of the connections revealed nothing. But it turned out that the characteristics could be restored by modifying some of the crossover component values. And that's where I left it for now, although the issue hasn't been fully resolved: introducing modified values ​​into the simulation again resulted in some discrepancies. But the measurements are now quite correct:


I had some scraps from 45-degree cuts. I glued them together and used them to brace the enclosure from the inside.




THD distortion:

Measurements were taken at 1m on axis. The graphs are normalized to SPL. At 86 dB, midrange distortion reaches a maximum of -49 dB relative to SPL, which translates to a percentage value of 0.35%. As the signal level increases to 96 dB, distortion locally reaches -41 dB, or 0.9%, still quite ok.


Filters (component values ​​after the modifications)



Preference ratings



Polar maps























Komentarze

Prześlij komentarz

Popularne posty z tego bloga

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

-
Obraz
 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 machin...
Czytaj więcej

"Mechano22" - new version of a small 2-way speakers, with linear on-axis and power response characteristics.

-
Obraz
Not so long ago, I made a small 2-way speaker design with the following goals: f6 around 40Hz with  8 liters BR 45Hz enclosure, generally balanced on-axis response and close to linear frequency power response. Experience gathered with that design led me to a conclusion that maybe it could be done a better and cheaper. And here is the new version, codemame "Mechano22".  It is based on  relatively inexpensive set from Dayton: ND25FW-4 tweeter with waveguide and DSA135-8 midwoofer. The box is really simple: rectangular 18mm birch plywood panels assembled (glued) with overlaps. Box dimensions: HxWxD: 290x174x263mm. The Box is filled with polyester fiber. Pic 1. Box dimensions (mm) The woofer has a flat basket edge, which, according to the manufacturer's note, allows application without flush so it wasn't implemented but there is a chamfer on the inner side of the mounting hole. Pic2. System on-axis and power response characteristics in comparison with target lines. For...
Czytaj więcej

3-way monitor with AMT (Mechano323)

-
Obraz
Trying a 3-way design. The goals as always: balanced SPL and directivity related characteristics (acoustic power response, in-room response etc). Drivers used: tweeter : AMT2-4  link midrange: RS100-4  link woofer: DC160-8  link II started from what I had of the shelf and these were RS100-4 and DC160-8. I had also a dome tweeter but I thought it was a good opportunity to play around with ribbon or AMT driver as the midrange (RS100-4) is a fullrange driver and can be filtered high. The box is made of 18mm birch plywood with external dimensions 185x395x293mm. The volume for the woofer is approximately 12.5 liters, for the midrange there is a closed chamber with a volume of 1 liter. Bass reflex for the woofer tuned to ~40Hz. The box is filled with polyester fiber. Front panel layout (mm): Due to the asymmetrical arrangement of the drivers, the measurements were taken for angles 0-350 on both orbits (H and V). Upgrading Clio Pocket to version 3 was very helpful for this task....
Czytaj więcej