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[Jamin Lynch]

I recently read an article about folded horn subs which said they are not a good choice in smaller rooms where the distance from the speaker and back wall is relatively short or outdoors when the audience could be close to the subs. According to the article, they are best when used where the audience is 15-20ft away and farther.

Can anyone shine some light on this?

Thanks

[Jerome Malsack]

I am clipping a note from the article on the web site. 
http://www.prosoundweb.com/article/loudspeaker_enclosures_horns_what_they_do_how_they_do_it/P3/

Horn designs can be “straight” (you can look down the mouth and see the throat), or folded forward, sideways, or even backwards upon themselves and then forward again. Folding conserves space within the enclosure while keeping the horn length long enough to reproduce low frequencies.

One downside of folding is that energy above a certain frequency, depending on the shape and abruptness of the folds, will reflect back on itself and cancel. Therefore, most folded horns have a limited range of operation, usually not more than two octaves.

Directivity
In addition to increasing the transfer efficiency of the driver to the atmosphere, often as much as 10 dB or more, acoustical horns provide the added benefit of pattern control of the radiated energy.

There are some folded horns that use a corner of the room to complete the horn, like the Klipschorn.   http://www.klipsch.com/klipschorn-floorstanding-speaker  This design would not work well when taken out of the corner of the room, or outside. 

[Kevin McDonough]

And so we come on to the much argued over concept of "throw" lol 


There is a property that many people describe hornloaded speakers as having when compared to reflex speakers. The have the impression/sensation that the sound seems to travel further or be louder at distance than the equivalent reflex speaker. In some cases, where tops are very hornloaded/narrow dispersion or with the longer wavelengths of subs, that the sound actually sounds 'not right' close up to the speaker and it takes a little distance for the sound to 'develop' or for it to sound 'normal'.

While I am not aware of any proper scientific studies of this, there are countless anecdotal accounts and some people believe this to be simple fact.

However on the other hand, many people will tell you it's impossible. They'll say that sound is sound, and it drops at 6db per doubling of distance no matter what the speaker and so "throw" isn't an actual thing, its just a combination of directivity and/or having a higher SPL to start with due to the extra sensitivity afforded by the horn.

For whatever reason though the idea of throw will not go away and many people are still convinced they have observed it's effects.

It's been argued about many times and I'm sure if you search you'll find some more information.

For me, I have my own half baked theories in my head about what's happening and why there seems to be some sort of perceived difference, but I've never really tried to explain them or investigate them in any real way.


k

[Jamin Lynch]

I'm not referring to the one style sub having more throw than another style sub argument . My question about is short distances...not long distances.

I think this is more about "wave development"

I'm in the camp of "inverse square law is constant".

[Kevin McDonough]

I'm not referring to the one style sub having more throw than another style sub argument . My question about is short distances...not long distances.

I think this is more about "wave development"

I'm in the camp of "inverse square law is constant".

I agree with you in that I agree with the inverse square law. I do think there is an effect of some sort but look at it more as some combination of wave development, less comb filtering caused by more directivity (for relatively shorter wavelengths) and something which I can kind of picture in my head happening that I would call "coherence" of the sound travel, though that's not used in any scientific way just now I picture things in my head.

I realise you are discussing short distances but I bring up "throw" because most people put these two effects together in discussions that I have seen about hornloaded cabs.

They argue that whatever mechanism is at play that makes a hornloaded sub sound wrong/different at close distance and that seems to cause the audience to have to be a little further away compared to the sound of reflex is also what gives it the apparent ability to "throw" long distances better.


k

[Len Zenith Jr]

My take is that in smaller rooms you would have lots of nulls (dead spots) in the longer frequencies and with a front loaded box the harmonics (THD) given off would give the illusion of there still being bass at those spots.

[Scott Harris]

This should be on Snopes......  No, it is not true.  Check the subwoofer forum.  It has been discussed many times.

[Ivan Beaver]

I think this is more about "wave development"

I'm in the camp of "inverse square law is constant".

The idea of "wave size" is totally wrong.  If it were true-how would you hear bass in headphones and in cars?

Inverse square is not completely constant.  It is once you get into the far field of a loudspeaker. 

How far is that?  It changes with the freq of interest and the size of the cabinet.

Up close the decrease in level is less than a little further away.  But once it starts the "6dB"  dropping-it will remain that way.

[Jamin Lynch]

The idea of "wave size" is totally wrong.  If it were true-how would you hear bass in headphones and in cars?

Inverse square is not completely constant.  It is once you get into the far field of a loudspeaker. 

How far is that?  It changes with the freq of interest and the size of the cabinet.

Up close the decrease in level is less than a little further away.  But once it starts the "6dB"  dropping-it will remain that way.

That's what I meant by "constant"

[George Dougherty]

My take is that in smaller rooms you would have lots of nulls (dead spots) in the longer frequencies and with a front loaded box the harmonics (THD) given off would give the illusion of there still being bass at those spots.

As I understand it, this is mostly what's being described. Folded horn paths filter out the upper harmonics that emanate from a direct radiator that give a perceived increase in output.  Those harmonics get absorbed more easily by things in the environment and at longer distances the folded horn will have more perceived volume if the direct radiator sub volume is set by perceived loudness in the near field.

[ProSoundWeb Community]