August 5, 2010

Tutorial: Hornresp tweaking

Want to know how to get better results with Hornresp? Read on.

Here is our front loaded horn with the Peerless XLS driver. It's designed to extend to 40 Hz and has some compromise to make it smaller.

Changing the compression chamber

Press F4 and you will see in light grey the previous plot for all charts. In grey you can see a rear chamber of 10L, but in black 15L. You can see how it smoothes out the knee, and also shows up in the excursion plot:

You can see greater volume means higher excursion. In this case, the bigger volume means xmax is exceeded with 500w. You might think this would not be an issue as the output would not be needed, but in reality these levels would not be reached as they are based on a perfectly solid room with corner loading.

The 15L version has the maximum volume that should be used. If the chamber were made larger, the excursion would increase further. As it stands, this design is fairly robust and the 10L version is even more robust.

Let's see what happens if we make the volume bigger or smaller. Too big: 100L and too small: 5L.

The undersized chamber causes a sharp knee and loss of midbass as well as early roll-off. The oversized chamber isn't too bad, although it doesn't help if we are trying to extend the response a bit lower.

The excursion chart tells us more. 5L leads to very low excursion and this is why we see the midbass dip, but the 100L version loses it's grip on excursion to the point that we need a rumble filter to protect it! The obvious solution is to use a sensible rear chamber volume so that a rumble filter is not needed. In this horn, 10 - 15L should be used. The smaller volume will suit high power use.

Next: How to get a small horn to play deeper >

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