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-   -   Tapped Horn meets Bandpass Sub (http://www.diyaudio.com/forums/subwoofers/128937-tapped-horn-meets-bandpass-sub.html)

Patrick Bateman 29th August 2008 04:48 PM

Tapped Horn meets Bandpass Sub
 
Over in my Tapped Horn for Dummies thread* I discovered tapped horns are a lot more similar to bandpass boxes than I realized.

Here's some simulations showing a few tricks you can do with tapped horns, and it illustrates how similar they are.

In particular it shows a new feature of horn response, which allows you to include a coupling chamber to shape the response.

* http://www.diyaudio.com/forums/showt...0&goto=newpost

Patrick Bateman 29th August 2008 04:53 PM

2 Attachment(s)
For today's simulations, I'm using a car audio sub called a Diyma 12. You'll see why I use this one in a minute. First, here's a simulation showing the Diyma 12 in a "conventional" tapped horn, where there's no coupling chamber.

Patrick Bateman 29th August 2008 04:55 PM

2 Attachment(s)
Here's the thiele small of the Diyma, which I measured personally after breaking in the driver:

Attached is a pic of the response, using the parameters from the previous post. It's getting 50watts in this sim.

* f(s)= 27.59 Hz
* R(e)= 3.77 Ohms
* Z(max)= 50.72 Ohms
* Q(ms)= 7.625
* Q(es)= 0.612
* Q(ts)= 0.567
* L(e)= 2.03 mH

Patrick Bateman 29th August 2008 04:59 PM

2 Attachment(s)
Here's where it gets fun. I take the exact same sub driver, in the same tapped horn, and add a coupling chamber. I also tweak the driver location using the tapped horn wizard. The overall volume is nearly the same, except the coupling chamber takes up a cubic foot. (That's the 28320cc in the VTC column)

Patrick Bateman 29th August 2008 05:06 PM

2 Attachment(s)
Here's the frequency response WITH a coupling chamber. First thing you'll notice is that it's dramatically tilted down. I actually did this on purpose. I haven't seen anyone put a tapped horn in a car, and the Diyma 12 is a good candidate. In a car you *want* the response to droop, as the car's cabin gain adds about 24db at 20hz, and 12db at 40hz. That's why small sealed subs sound so good in a car, and big vented boxes sound sluggish and boomy. The car's cabin gain ruins the flat response of a vented box, and augments the slowly decaying response of a sealed box.

But this tapped horn gives you the best of both worlds - the low excursion of a tapped horn, combined with a driver that can take some real abuse.

Once you add in cabin gain, the F3 of this monster will be around 15hz! And the power handling, thanks to the low excursion, will be downright absurd.

It could use a little tweaking, with a bit of work someone could easily make this fit in a smaller box, with even HIGHER power handling. You don't really NEED an F3 of 15hz in a car do you? Have fun!

MaVo 29th August 2008 07:35 PM

The compression chamber is indeed a nice variable to tailor the response to your needs. Additional to this, you should try making a 4 segment tapped horn, as you can shape the response even more to your needs.

winslow 29th August 2008 07:41 PM

Lot of talk as of late on www.termpro.com about tapped horns. Being the home site of dB Drag Racing, we are all about bass over there.

I just don't know if you could physically fit a 30 hertz tapped horn into a car trunk.

Patrick Bateman 29th August 2008 08:56 PM

Quote:

Originally posted by winslow
Lot of talk as of late on www.termpro.com about tapped horns. Being the home site of dB Drag Racing, we are all about bass over there.

I just don't know if you could physically fit a 30 hertz tapped horn into a car trunk.

Well once you recognize that a tapped horn is anything BUT a horn, it's really just a deviant bandpass box, life gets a lot easier!

Once you accept that, you'll see that you can make tapped horns preposterously small. It's really just a dual reflex bandpass box, with the advantage that you can tweak the response and the excursion a heck of a lot more than you can with a conventional bandpass box. Yay for the tapped horn wizard.

For example, I crunched the numbers on the Diyma, and came up with a tapped horn that's SMALLER than a bandpass. The bandpass actually as more output, but the tapped horns big advantage is less port turbulence, and excursion that's a LOT less in the passband. I'll post details, cool?

RobWells 29th August 2008 09:26 PM

Quote:

Originally posted by Patrick Bateman
In a car you *want* the response to droop, as the car's cabin gain adds about 24db at 20hz, and 12db at 40hz. That's why small sealed subs sound so good in a car, and big vented boxes sound sluggish and boomy. The car's cabin gain ruins the flat response of a vented box, and augments the slowly decaying response of a sealed box.
Hi Patrick,

I've been doing a fair bit of measuring over the last couple months as I'm in the middle of installing my stereos in my commuter hatchback and my weekend suv. In both vehicles a sealed box does not measure like the car audio sites would have us believe.

Rob.

Patrick Bateman 29th August 2008 09:40 PM

Quote:

Originally posted by RobWells


Hi Patrick,

I've been doing a fair bit of measuring over the last couple months as I'm in the middle of installing my stereos in my commuter hatchback and my weekend suv. In both vehicles a sealed box does not measure like the car audio sites would have us believe.

Rob.

I read your thread about that a few months ago. Here's what Rob is referring to:

http://www.diyaudio.com/forums/showt...=&pagenumber=2


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