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# Posts by diy speaker guy

Comparing the Hornresp sim, the Akabak sim and the measurementsLet's see if a simple Akabak simulation matches the results better than Hornresp. The Akaback sim has enough segments to fully capture the horn flare including the corners that stick out above the red line in Figure 8 but otherwise it's still a simple simulation. I'm not advanced enough to simulate acoustic mass, acoustic compliance and acoustic resistance and I can't make Akabak simulate losses due to less...
Why don't the simulations match the measurement perfectly? I figured I would include this addendum since I did the work anyway. Lilmike and I had a great conversation about this topic while I was working on the folding experiment. There are a great many things that can make a measured product deviate from a simulation's predictions. These are some of the factors we discussed, both of us already knew about all these but we found we are in agreement for most of these...
A method even more advanced than the advanced centerline method to simulate a hornThe real professionals probably aren't using the centerline or advanced centerline method. Danley doesn't and soho54 didn't either when he was being serious about accuracy. It's best to let him explain this in his own words with a direct quote from his post here - http://www.avsforum.com/t/1258118/akabak-for-dummies/30#post_19114195This is also a good post to quote here because he talks...
Conclusions restated If you start with a simulation and lay out your fold with the advanced centerline method the physical horn should be a bit longer than if you laid it out with the centerline method. But when reverse engineering from a plan, the sim you end up with using the advanced centerline method should end up a little shorter than if you plotted it out with the centerline method. If a folding method is to be considered "correct", you should be able to start...
Refolding the F20 using the centerline and advanced centerline methods The next step in this experiment was to refold the horn using both the centerline and advanced centerline methods to see what would happen. I've already shown that my reverse engineered advanced centerline sim is closer to the measurement than the centerline sim. The advanced centerline sim is also almost exactly the same as the designer's orignal sim that he used to fold the horn in the first...
Comparing the simulations to the measurements The next step was to run the sims I made (both the centerline and the advanced centerline versions) to see which matches the measurements of the physical horn the best. Below is a picture showing both sims, advanced centerline on the left and centerline on the right. FIGURE 10 The advanced centerline sim (left) gives a very slightly higher tuning. When compared to the F20 measurement (Figure 3) the advanced centerline...
Reverse engineering the F20 using the centerline and advanced centerline methodsSince I started with a plan the first thing I had to do is reverse engineer it back to an accurate simulation. Lilmike did post his Hornresp inputs but I needed to reverse engineer my own to create two simulations, one based on the centerline method and one for the advanced centerline method.To begin the reverse engineering I used Sketchup to chop the blank F20 drawing into 37 segments. When...
The test subject Lilmike offered a blank Sketchup file of the plans for his Cinema F20 front loaded horn as a subject for me to study. When opened it Sketchup it looks like this. FIGURE 2 And he had built it and measured it too. Since his measurements are trustworthy, this is the perfect example to study, it means I wouldn't have to design a test protocol and build and measure my own example horn. Here's the F20 measurement. FIGURE 3 And a link to the F20 thread...
IntroductionSoho54 has been MIA for a couple of years now but while he was around he was one of the best resources for horn info in the forums. From his EZ horn design spreadsheet to his Akabak tuturial to his horn folding using sketchup tutorial, this guy did all the heavy lifting and gave us his results on a silver platter. And although I've only actually read a small percentage of his posts on the various forums he participated in, I've never seen anything to make me...
There's a lot of information here so for the people that don't want to follow the process to see how I conducted this experiment I'm showing my conclusions at the beginning (and also at the end). The conclusions are all you really need to read if that's all you are interested in. Conclusions If you start with a simulation and lay out your fold with the advanced centerline method the physical horn should be a bit longer than if you laid it out with the centerline...
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