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-   -   horns (http://www.diyaudio.com/forums/multi-way/38346-horns.html)

Shpoop 24th July 2004 12:18 AM

horns
 
ok...so first off, what frequencies are horns generally effective at? like if i attached one to a full range driver, would that pretty much kill it as a full range?

also, can you put curves in between the speaker and the horn?...and on the same idea, can you but pipes or something inbetween the horn and teh speaker, if they arent curved? my intuition says no, but id rather ask the experts. If my wording was difficult to understand, just tell me and ill try again

Nappylady 24th July 2004 06:22 AM

Read about horns. Read about horn theory. It's really not that complicated.

A horn is an acoustical impedance matching transformer.

Speaker cones have very high acoustical impedance compared with the air; it's very easy for the speaker to push on the air, but not vice versa. When the cone does push on the air, huge amounts of energy are wasted because the cone has so little mass to push against.

A horn works because (basically) all the air inside the horn becomes coupled directly to the speaker cone--the cone, then, is acting on a much larger amount of air, so the impedance mismatch is greatly, greatly reduced.

As with ordinary boxes, Hoffman's iron law rules: you can have a box that is small, loud, deep. Choose any two, at the expense of the third. :D

While most horns are designed and used for treble reproduction, the theory can be applied to any scale--there are basshorns out there that play down to 10hz. The one that comes to mind is actually someone's basement. (No, I did not mean to type "in someone's basement". The horn *is* their basement.)

What have you got in mind? Let's build something :-)

TheoM 24th July 2004 06:55 AM

The Horn *is*....
 
This is the sort of thing that gets my deepest respect. I'm really interested in the "out there" ideas.

********he guy who made a sealed cab from a huge concrete casting. (wish I had the link).

The 25 driver per side line array

10 foot high sonotube subs

the servo subs that according to urban legend killed a guy.

Are there more? Its my ambition to do something like this.

Could I make a horn from a geological formation like a cave entrance?

There's art here... somewhere.... Any ideas out there?

paulspencer 24th July 2004 03:50 PM

Shpoop,

Horns can cover the full audio bandwidth BUT each horn has a limited bandwidth. Some use something like an Oris horn with a full range driver which will go down to about 300 Hz I think. Below this approx range the horn gets quick large and it becomes necessary usually to change strategy. You might add a bass horn. You might use some very large high efficiency PA drivers to cover the midbass up to 300 Hz. A good horn system is likely to be 3 way or 4 way.

Have a look around at some horn systems before you build anything to get an idea ...

Adrian Mack horns

architectural horns example

Oris horns

Some comercial horn examples

John Sheerin's horn website

Lab Horn

Royal devices huge basement horn

Ultra fi horns page

There's some food for thought ;)

You might also search this forum a little, you willl find quite a few horn projects. Magnetar has done a lot of horns ...

Shpoop 24th July 2004 05:52 PM

2 Attachment(s)
well attached is what i originally had in mind for a full range unit...so perhaps my most important question still stands...can u lengthen the pipe between teh horn and speaker with minimal negative effects?

beautiful art, eh?

paulspencer 24th July 2004 06:16 PM

I don't understand that pic and what it shows! :xeye: :confused:

It looks like a tweeter attached to a vent then a tiny horn in the middle of a W frame dipole woofer!!!!!

I'm also not sure what it is you are trying to achieve, which makes it hard to give a reply! When you say "can I do X?" the question remains "what are you trying to achieve?"

Shpoop 24th July 2004 06:56 PM

haha excuse my crappy paint skills...but you are right, its a horn in the middle of a W frame dipole sub...the first pic is simply a front view, the second is an overhead

the speaker for the horn would need to be further back, so that the sub has some room to breathe, hence the extension

im just toying with full range designs is all, wondering what can be done

GM 24th July 2004 07:16 PM

>can u lengthen the pipe between teh horn and speaker with minimal negative effects?
====
The answer is a resounding NO for what's depicted. With FR drivers you want to limit the compression ratio to < ~2:1, with little/no reactance annulling section since a FR driver's flexible diaphragm construction doesn't lend itself to doing much in the way of annulling.

WRT to putting curves between the horn/driver, if you mean have different flare rates at different points along the horn's expansion, such as starting off with a 50Hz flare for some distance then switching to a 100Hz, etc.; then , yes, you can do it, but unless you know what you're doing I don't recommend it. Indeed, some of the better FR backhorn designs have multiple flare rates.

Front horn versions are CD type horns, trading pattern control for flat response/HF extension, so some EQ is required. For FR drivers it's best to use just one or two low gain flare rate(s) to keep distortion low/HF attenuation minimal.

GM

joe carrow 24th July 2004 07:17 PM

Quote:

Originally posted by Shpoop
haha excuse my crappy paint skills...but you are right, its a horn in the middle of a W frame dipole sub...the first pic is simply a front view, the second is an overhead

the speaker for the horn would need to be further back, so that the sub has some room to breathe, hence the extension

im just toying with full range designs is all, wondering what can be done


I don't think that it will work as you have drawn it, not the way I understand your description. Are you proposing to run a pipe as an extension from the horn mouth to the driver? In a full range configuration, I would expect all sorts of coloration of the sound from pipe resonances and stuff. Like yelling through a tube.

If you use the links above, you'll probably learn about how a horn has to be shaped, and how some horns would have a long section that's nearly straight before it flares out- and you'll see that there are trade-offs. I think that a long tubelike section like that could work for a bass horn, but probably not for higher frequencies.

paulspencer 24th July 2004 07:57 PM

It pays to understand firstly what you want to achieve and the strengths and weaknesses of different designs.

To put a dipole woofer with a front loaded full range driver horn - this would make it difficult for the dipole to keep up - a lot of displacement would be needed. There is no reason to try to interweave them together. The horn can sit on top, and it wouldn't fit inside the dipole.

Nothing wrong with this approach, but it might help to look first at what people conventionally do and to understand it. Innovation usually comes from those who understand convention, then push the envelope one step further ...

You might look into rear loaded full range horns. ie use a full range driver that doesn't have much bass. You then horn load the rear of the driver to bring the efficiency of the bass to match the rest and then you get a full range response. The bass will normally only go down to 50 Hz but some like this approach.


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