As promised, here is an r2 update...
First of all, let me say that most of the work was done by @TimVG
. Other team members helped with driver selection and my main role was to rebalance requirements as needed. I anticipate they may add some commentary to this post, but both are very busy with other projects rn. So the first target was to design a small monitor with better directivity than r1 and at a lower cost. Am pleased to say, we meet this goal with one noteworthy exception. We had hoped that we could get enough bass extension to use with a subwoofer, but fell back to needing to pair with the planned bass module. We plan to revisit a derivative monitor design with lower bass extension later.
I had mentioned that simulations indicated a need to narrow the baffle to get better directivity, so we went with a simple shape that is like a small Salk Veracity. To push constant directivity even lower in frequency, we decided to use the approach used by the Dutch & Dutch 8C. @TimVG
had some experience with the approach and @ctrl
did several sim iterations to refine. Once this was done, Tim had gotten a CNC and decided he wanted to deploy it to build the prototype. His design takes the original shape and rounds off the top. So, it is reminiscent of a mantel clock as show here...
The tweeter as expected is the Seas DXT and the woofer is a SB15NBAC30-8 midwoofer. The SB was chosen as a balance of size and price performance. Here is a look at the normalized horizontal directivity:
As you can see, the prototype exhibits fairly constant directivity well below 1 kHz.
And here is a preview of the frequency response with an initial crossover:
While some aspects may still change, will know better once I build the less rounded cabinet and we test it. Like my r1 measurement system upgrade, Tim is in the process of upgrading his. I will start as soon as I wrap up the passive crossover for r1 (hopefully this week).
Rick and the Directiva r2 team.