# Can a single straight horn cover 50-500hz?

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#### steve71

I've been reading that you can't get more than three octaves out of a straight horn (less out of a folded) so that would indicate that 50hz-200hz is all you could get out of a single horn.

However Magnetar indicates that his 50hz exponential horn is usable as high as 800hz (see link).

Am I correct in thinking that it's just the lower frequency of the horn's/drivers bandpass that are boosted by the horn and above that the driver acts as a direct radiator?

Aside from being able to use a compression driver from 200hz-500hz, what would be the benefit of splitting up the 50-500hz signal and using two horns to cover this range?

I'm asking this question manly due to budget constraints. I can probably afford 3 or 4 way horn (to cover 20hz-15+ Khz) but not a 5 way.

Sorry if this is a dumb question. I've been reading a lot on the subject, but I'm new to horns and there is just so much to know before even thinking about making any sawdust!

#### kstrain

steve71 said:
I've been reading that you can't get more than three octaves out of a straight horn (less out of a folded) so that would indicate that 50hz-200hz is all you could get out of a single horn.

That's 2 octaves (factor of 4), 3 octaves would be e.g. 50Hz to 400 Hz , not far from your goal.

Horn design is a tricky subject (I'm learning). A minimum effort would seem to be to use hornresp and/or AkAbak to model (though neither tells the whole truth, and much care is needed). But I suspect substantial prototyping and measurement will be involved too (unless you adopt a readymade solution). There is a lack of convincing measurements of anything more than on-axis responses of a very few designs.

Learning how to do crossovers with horns is another potentially deep subject.

Fun though.

Ken

#### AndrewT

Hi,
the frequency range 20Hz to 20kHz is about 10octaves.
If this is divided equally into four 2.5octave bands then 4horns should just about cover the full audio range. 20Hz to 110Hz, 110Hz to 600Hz, 600Hz to 3400Hz, 3.4kHz to 20kHz.
If one were to narrow the band by an octave then 3 or 4 horns could be considered.

#### myhrrhleine

Yes, 50-500 is doable with one horn.

#### planet10

Paid Member
Generally 3-4 octaves is considered the maximum you can get a horn to cover. You have to choose a suitable driver, and it is going to be BIG.

dave

#### steve71

Re: Re: Can a single straight horn cover 50-500hz?

Thanks a bunch for the answers guys, much appreciated!

kstrain said:

That's 2 octaves (factor of 4), 3 octaves would be e.g. 50Hz to 400 Hz , not far from your goal.

Err... 400hz, yeah don't know how I messed that one up!

kstrain said:

Horn design is a tricky subject (I'm learning). A minimum effort would seem to be to use hornresp and/or AkAbak to model (though neither tells the whole truth, and much care is needed). But I suspect substantial prototyping and measurement will be involved too (unless you adopt a readymade solution). There is a lack of convincing measurements of anything more than on-axis responses of a very few designs.

Learning how to do crossovers with horns is another potentially deep subject.

Fun though.

Ken

Yeah I'll take the time to learn how to use hornresp. Since I can use one horn for 50-500hz I think the wife will be ok with the size... just!

And since I'm going to use a Behringer DCX 2496, a three way x-over means I'll only have to buy a single DCX.

I already have a pair of Altec 288 K's so I figured I'll have 500-15khz on up covered with this driver (with some eq-ing) and the right horn. Then I'll use a pair of (rather large) horns from 50-500hz. 50-20hz I'll do in mono with a single Tuba HT sub. Then later down the track I can add a super tweeter or HF compression driver & horn to cover 10K on up.

Anyway this is just a ball park outline so I have a size & budget to pitch to the wife. I realize there is a hell of a lot more to making a finished product than just sticking a bunch of boxes together that cover 20-20k. Lots for me to learn but as you say it's fun!

Link to Tuba HT sub: http://www.billfitzmaurice.com/TubaHT.html

#### steve71

planet10 said:
... and it is going to be BIG.

dave

Magnetar's 50hz horn looks to be about 1x1x0.5 meters. That's really pushing the WAF... wish me luck

#### MaVo

you could use a sub and make the lower cutoff from the horn higher, for smaller size. a 100hz horn will be alot smaller and you are not pushing the bandwidth of your driver to the extreme. a 12inch midbass could could perhaps need a phase plug in the throat for the higher frequencies, since the wavelength will start to get small in comparison to the throat size.

but if size is no problem, i would allways use the biggest possible and make it work somehow

#### steve71

MaVo said:
you could use a sub and make the lower cutoff from the horn higher, for smaller size. a 100hz horn will be alot smaller and you are not pushing the bandwidth of your driver to the extreme

I really want to cross over lower than 100hz since the single Tuba HT horn sub will have to be located in an (open) cupboard in the back of the room. I'm not even sure if such a placement will work well. So I figure if I have to scrap the hornsub idea and go with direct radiator subs (which should be small enough to be placed in the front of the room) I'm still horn loaded down to 50hz.

I though about stereo horn subs, but I don't know of anything that'll play down to 20hz and still be small enough to not block the screen.

I could go with two smaller folded Tuba (24?) subs (40-200hz), then a smaller horn to cover 200-500hz, but then I'll end up with a 4 way system, which I'm trying to avoid at least for the first iteration. Then again it'll be smaller than a three way with a straight 50hz horn and a 4-way is better than a "No way" from the wife lol.

#### SpeakerBob

Do a search here and on audioasylum for Bruce Edgars 80Hz midbass horns . They cover 80Hz - 500Hz nicely. Drivers for them are Electrovoice EVM 15L, Altec 515's (if you're rich / lucky) plus some JBL drivers with some caveats.

When modelled they do pretty nicely, and they can be made bigger if wanted.

Rob.

#### steve71

RobWells said:
Do a search here and on audioasylum for Bruce Edgars 80Hz midbass horns . They cover 80Hz - 500Hz nicely. Drivers for them are Electrovoice EVM 15L, Altec 515's (if you're rich / lucky) plus some JBL drivers with some caveats.

When modelled they do pretty nicely, and they can be made bigger if wanted.

Rob.

Thanks for the lead, I'll check em' out tomorrow.

#### MaVo

for a horn loaded "small" sub, go in the sub forum and look at the tapped horns. they compromise on bandwidth, around 2 octaves are what you get from them in general, but have great efficiency and deep cutoff in a relatively small box. You could still make the system three way with a good compression driver, that can be crossed above the midbass horns with crossovers around 80/800 hz. Such a combination should be relatively small, compared to a 50hz straight horn.

#### steve71

MaVo said:
for a horn loaded "small" sub, go in the sub forum and look at the tapped horns. they compromise on bandwidth, around 2 octaves are what you get from them in general, but have great efficiency and deep cutoff in a relatively small box. You could still make the system three way with a good compression driver, that can be crossed above the midbass horns with crossovers around 80/800 hz. Such a combination should be relatively small, compared to a 50hz straight horn.

Thanks for the idea. Those tapped horns have a small footprint while being pretty tall.... maybe I can stand them up in the front corners of the room, making an 80hz crossover a lot more feasible. I'll have to spend the week-end wading though that 40 page thread.

winslow said:

Yeah I've check out that site a lot and read though the Dr. Edgar pdfs. My wife liked the look/size of the horns as well. A 77hz conical horn would be great if I can do stereo subs in the front of the room.

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