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 →

Midrange at 1m
20 October
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Earlier I wrote about a measurement anomaly in the initial measurements of the baffle. Here is the response of the mid again, at 1m: Having just been trying to learn how to use the Edge simulator, I modeled an 80mm driver in a 300x900mm baffle, with the microphone at 1m distance. Look at this: So there’s the notch at 1700 Hz (more or less), in the open baffle simulator. It’s good that there is at least some match between theory and the actual measurement, although I still don’t understand why the notch is where it is, as I thought it should have been at aroundRead 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 →

Open-baffle speakers and electronics from left side
11 October
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Over the weekend, Francesca turned into a fully-active three-way. This was done at the famous “Bathurst GtG” of terry j, with help and advice from several people who listened and commented as things went along, but in particular with assistance from Andrew Ward and Paul Spencer. The heart of the system is now a pair of miniDSP 2×4 modules, each running as a three crossover/eq unit. (They can also be used as a four-way, which is I think going to be part of Francesca II….). While they take power from USB, I have an external supply connected – something that is really necessary if youRead More →

09 October
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With much help from Paul Spencer, I was able to do some gated measurements on the Francesca prototype. One thing we puzzled over was the frequency response of the midrange. Here is the 1m measurement (gate is about 8ms): Red is on-axis, blue is at (approx) 30 degrees. The frequency of the dip, around 1700 Hz, doesn’t correspond to any of the baffle dimensions! If it were the first dip in the dipole response, a 30cm wide baffle should exhibit this dip around 1150 Hz, not at 1700 Hz. And why does the depression continue up past 5 kHz? This was a puzzlement. In theRead More →