PLEASE NOTE: Just to clarify some misunderstanding over the Directiva tweeter selection. Earlier I had posted that I was finalizing the tweeter selection. The context here was amongst the existing team and sharing some of where I had sought (past tense) help with tweeter selection. Some have misread my post as a though we were still looking for tweeters.
I regret if this was unclear, but the Seas DXT is the tweeter we have selected. Later derivatives may consider other tweeters, but for the first implementation, I consider the tweeter selection to be final.
So while
@ctrl was simulating directivity, I had been modeling and prototyping the cabinet tuning. If you had not previously noticed, I have posted the effort here:
Can Purifi's SPK5 be improved with a passive radiator? | Audio Science Review (ASR) Forum
With the equalization and filtering available with an active design, we can address some of the challenges of getting low bass out of the Purifi woofer more readily than if the design were passive. As you have read, I have tried to ensure the Directiva is affordable. An important part of determining the final cabinet is the volume needed. My prototyping has been with the SPK5 cabinet, so had to consider how ports or passive radiators would fit into the Directiva cabinet. I think I have a handle on a vent size that does not have major misbehavior, but the passive radiator has more potential price/performance considerations.
The SB 5x8 passive radiator is inexpensive, but has a large footprint...
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So, the other consideration is the passive radiator that Purifi designed for the woofer. Like the woofer, it is pricey. But as it is smaller, it is easier to incorporate on the Directiva back panel.
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I had to order the Purifi PR and they just arrived today. As it is part of finalizing the overall design, will be taking some time away from posting to finalize the cabinet alignments. Before I do, will preview the proposed final cabinet. While I liked latest design, I had some reservation about its complexity, so I proposed a truncated pyramid. We had some back and forth over the dimensions, how the drivers would fit and angles that would be easier to cut. After more simulations, here is what we designed...
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This has about the same directivity (maybe a bit better) than the prior cabinet shape. As I mentioned, my plan was to offer options for a choice of cabinet, but this is the one I plan to build and have Amir test. For comparison purposes, I think it would be valuable to build a version with the unmodified Denovo cabinet. But one step at a time for now.