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In the Forum: Horn-Loaded Speakers
In the Thread: The tapped horns: cons, pros and Sound

Post Subject: Benefits of using a compression chamber on push-pull tapped horns.Posted by JLH on: 5/5/2009

There are at least three benefits of using a compression chamber in a tapped horn design.

1.) When using push-pull woofers with a compression chamber second order distortion is cancelled. This effect is very audible. You must hear it to understand.

2.) The air volume in the compression chamber can help flatten the response without resorting to adding inductors. On my dual W8-740 tapped horn, the response was flatter with the compression chamber.

3.) The large air volume in the compression chamber acts as an air spring which can help protect the woofer’s cone from high throat compression ratios. I’ve blown up my fair share of woofers. I’ve trashed some B&C 8PS21 woofers in a conventional single woofer tapped horn; blew a hole right through the cone. However, in another push-pull tapped horn using the same woofers I’ve had no problems and it has a higher compression ratio!

I am very certain about the air chamber serving to protect the woofers. With less than 260W into one of my 8PS21 tapped horns I blew a hole through the cone. I then redesigned for a dual woofer setup. I started the redesign by keeping all the path lengths the same, but doubling the areas. I then arranged the woofers in push-pull with an air chamber. After much simulating, I actually had to reduce the throat area to get the smoothest response. Therefore, my throat compression ratio went up. Once I built it I was able to put about 600W into the push-pull tapped horn before I had to stop due to high SPLs. After inspection there was no damage to the woofers. I don’t know of any other way to be more convincing then that.

Rgs, JLH

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