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26 October
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Here is an option for the mid-bass unit that makes this an even more sensitive dipole than the initial proposal. And that is to use a Lambda Acoustics TD15M woofer. Here is the modeled response of this driver in infinite baffle, with 55W input power: With the higher rolloff frequency, the subwoofers will definitely be required for this version. However, with a nominal sensitivity of 97 dB/W/m, we gain a lot of transient capability in the 100 to 600 Hz region (or wherever the crossover ends up being). The gradual rolloff is because of the driver’s relatively low Qts – it’s not ideal for dipoleRead More →

Simulated response of midrange 0 to 60 degrees
20 October
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Thanks to Rudolf Finke, I’ve realized that I can do off-axis simulations with the Edge, by changing the microphone distance and horizontal offset. This is important to ensure that the polar response of the drivers is not mismatched at the crossover point. Here is the simulated response of the woofer at angles of 0, 15, 30, 45, and 60 degrees: Note: the microphone is at 3m distance and 1m height. It’s not on the woofer axis. Here is the simulated response of the midrange at the same angles: From these curves, it look like a perfect crossover point to match the dispersion of the twoRead More →

Baffle shape and woofer location
20 October
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Since I now have some confidence that the Edge will give results that are consistent with measurements, I decided to actually “design” a baffle this time. It’s basically rectangular, 40cm wide and a meter tall, but with the top corners chopped off. The tweeter will sit just above the baffle in free air. Here’s the shape of the baffle and the positioning of the woofer: Here is the simulated response, with the microphone in the center of the baffle, at 1m height: The center of the woofer is 57 cm off the floor. (The interesting thing about that is that the “best” woofer height dependsRead More →

6PEV13 Frequency Response
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20 October
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This project is aiming to build a dipole with more sensitivity and higher output than the Francesca prototype. Again, this is going to be a learning exercise and not the final product! Starting with the tweeter – upgrade to the regular (non-PDR) Neo3. This has about 3 dB more sensitivity, and a narrower dispersion pattern, which is actually what we want for a dipole. Also, I’ve read some comments online that it sounds better (in “naked” dipole configuration) than the Neo3PDR. So, worth a try then. Since the crossover to the tweeter is now at 5 kHz, I’m also thinking about trying a small compressionRead More →