70 - 700 bass horn in Hornresp

I'm fairly new to Hornresp, I took the time to actually read the instructions this time. It's not as user-friendly and self-explanatory like WinSpeakers and WinISD, so when I looked at it a few years ago I just didn't get it and gave up on it too easily.

Anyway, I went through many pro-audio 12" woofers trying to design a good bass/midbass horn to cover from roughly 70 or 80 up to around 700 or so. The plan is to crossover to a 1.4 or 2" format CD with a mid horn (Le'Cleach, SEOS, Yuichi, or one of JBL's horns used on 4367 or M2). This is what I came up with. What did I do wrong or overlook? The performance seems almost too good to be true...
 

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I just simulated and built a pair of hypex midbass horns. They replace a two part conical horn using the same driver, a Richard Alan super 12". I sim'd with quite a few 12 inch drivers and most weren't as good, B&C 12PE32 was slightly better. The RA are from the 70s and were in stock.
Mine are 100cm long and "~95hz, I knew from my last horns that my room would cause them to be flat to 80 which they are.HR said -3Db at 800 ish but they are good till about 1100. I'm crossing to a DH1a, still lots a tweeking to do, but that's what Christmas is for.
One down side to new design is moving from 400 cm2 throat to 200 may have caused a pretty steep drop in efficiency, not what HR suggested.

I forget what 0.5 pi is, us it full corner loading? If so hard to do with a straight horn.
 
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The plan is to crossover to a 1.4 or 2" format CD with a mid horn (Le'Cleach, SEOS, Yuichi, or one of JBL's horns used on 4367 or M2). This is what I came up with. What did I do wrong or overlook? The performance seems almost too good to be true...
Heathkit,

Most speaker designers strive for uniform dispersion though the crossover region.

Though the on axis response will probably be quite similar to the simulation, the dispersion of the 12" horn at 700 Hz will be very narrow compared to any of the HF horns you mention. The HF horns are over 90 degrees in the 700 Hz range, while your horn design would probably have less than 30 degree -6dB coverage down to the wavelength of the horn diameter.

Art
 
The performance seems almost too good to be true...

You have specified Ang = 0.5 x Pi which means that simulation assumes the loudspeaker is located in a corner, and that the horn mouth is reasonably tightly coupled to the corner over the frequency range of interest (similar to the folded bass horn in a Klipschorn system). Is this how you intend to position the speaker?
 

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@Art
Thank you for pointing out the dispersion will be different between the bass horn and mid horn at 700 Hz. Any solution to compensate for that? Sounds crazy, and I don't have enough room but, maybe use 2 bass horns on each channel pointed 30 degrees apart??

@David
Yes, they would be placed in the corner. Maybe due to the length I should use Ang = 1.0 x Pi? enzoastro points out it's hard to get .5 x Pi with a straight horn.

Are there any thoughts on the "best" midrange horn out of the ones I suggested or any others?

Thanks!
 
1)Thank you for pointing out the dispersion will be different between the bass horn and mid horn at 700 Hz. Any solution to compensate for that?
2)Sounds crazy, and I don't have enough room but, maybe use 2 bass horns on each channel pointed 30 degrees apart??
3)Are there any thoughts on the "best" midrange horn out of the ones I suggested or any others?
1) A short horn profile like an Altec A7 or JBL 4560 using bass reflex ports to augment the low frequency below Fc is a "solution" used for the better part of a century. Multiple entry horns with cone and compression drivers sharing the same horn are another possibility, as well as simply choosing a front loaded driver with dispersion similar to the HF horn at the crossover point.
2) The midrange will then have multiple "finger lobes", not a good solution.
3) To determine what is "best" requires defining what is most important in a design- SPL requirements, sensitivity, frequency response, dispersion, point source integration, lack of diffraction artifacts are some starting points. What is most important to you and the weighting of the various design aspects would help to evaluate what is "best".
 

mark100

Member
2010-12-24 5:49 pm
1) A short horn profile like an Altec A7 or JBL 4560 using bass reflex ports to augment the low frequency below Fc is a "solution" used for the better part of a century. Multiple entry horns with cone and compression drivers sharing the same horn are another possibility, as well as simply choosing a front loaded driver with dispersion similar to the HF horn at the crossover point.

That's gotta be perhaps the best single sentence for laying out the options, I think I've ever read...
 
1) A short horn profile like an Altec A7 or JBL 4560 using bass reflex ports to augment the low frequency below Fc is a "solution" used for the better part of a century. Multiple entry horns with cone and compression drivers sharing the same horn are another possibility, as well as simply choosing a front loaded driver with dispersion similar to the HF horn at the crossover point.
That makes sense and is definitely a proven design solution. I read up on the A7 and 4560, and sounds like the direction I need to go, BUT they are pretty big, the width being the problem. My listening room is not that wide at about 11.5 feet, I have room for a deep speaker, 24 - 30" deep is ok but 30" wide is pushing it. Do you know of any plans for building something like the 4560 but "vertically" so it is not quite so wide? Any issues or deal breakers if it was built this way?
 

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Front horn b&c 12pe32 will get up to 700hz.

But true bass loading, 70hz will be big mouth.
Floor loading is not really floor loading.
Shooting from the hip, 70 hz horn would be 10ft2 mouth (true mouth exhausting into the middle of a concrete floor), and 5.4' deep (ideally horn length is 1/4 wavelength of1/2 octave lower than mouth).

And you will need to be a wavelength away to get bass (even dr edgar agrees, my w-bin had no bass standing near it), so 100hz is roughly 11' away.

Djk posted some nice double 12" lascala that would do 100hz by playing with the back chamber (making peaks to fill in response), but reactance annulling is beyond me.
https://www.diyaudio.com/forums/mul...nt-fit-la-scalas-form-factor.html#post5755702
 
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Do you know of any plans for building something like the 4560 but "vertically" so it is not quite so wide? Any issues or deal breakers if it was built this way?
Both the 4560 and A7 horns are quite similar, and are designed for the wider dispersion angle to be with the curved portions placed horizontally. Rotating the 4560 as pictured would reduce horizontal dispersion and increase the center to center distance between the drivers, making vertical polar response worse and increasing the distance before the two horns integrate well.

Scaling the A7 or 4560 to use a 12" rather than a 15" (12/15) would probably get it close to the width you desire.

The assertion made by Norman Bates "you will need to be a wavelength away to get bass" is a misconception based on room problems, not cabinet type.
That said, the cabinet L/R separation distance, distance to side walls, distance to the listening position, and the room area desired to have an even coverage are important considerations to determine the dispersion desired in a horn system.

Art
 
Really art ?

Ported sub, sealed sub, w-bin, same location.
W-bin had no bass standing right next to it, but was pounding further away.
Completely different from the sealed/ported.
Norman,

I've experienced what you are describing, but since the effect does not occur outdoors with different designs, it is not due to any aspect of horns vs front-loaded.
Your description of output differences is again based on room modes.
The "w-bin" location to the surrounding walls and ceiling was different than the ported sub or sealed sub, which resulted in a corresponding difference in room excitation.
Bruce's comments regarding the subjective difference in the sound of his various mid horns based on length could be related to not only the dispersion (the lower, longer horns have a more narrow pattern), but the horn entrance location in the room.

Art
 
Midbass is 40-80 Hz, so it won’t do much of that.

Also, pushing a horn much past 3, 3.5 octaves is difficult. Here we haveclose to the max.

Artichoke Horn

post 57 and 60

That's a quick and simple horn in an open field, with a Faital 12" driver.

60-1kHz with about 7dB of EQ.

If I re-designed it with a phase plug, I'd probably get a similar range with less eq.
 
After a lot of digging, you are right.

Bruces seismic horn mouth exhausts directly onto the floor (firing down), stimulating all room modes.

I'm still wrapping my mind around his comments about the horn is more of a far field device

So can we say smaller rooms don't work well with front bass horns ?
Because there are minimal room modes stimulated ?
That we like ?

Audio Asylum Thread Printer
 
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the separation of the red line from the blue line that the last ocatve is all driver.
Are you sure?
Post 57 said:

"blue = open rear chamber & minidsp 400Hz lowpass filter"

I's have to strain to remember what was going on in post 60 :)

Note that the horn was (literally) a rough country job. With a phase plug and rear chamber tweaking, I reckon it'd give flatter / more extended response.

As is, the only thing I did to potentially improve bandwidth was using a rectangular throat rather than square (in tests with smaller horns, I found that reducing symmetry = better HF).
 
1)I'm still wrapping my mind around his comments about the horn is more of a far field device
2)So can we say smaller rooms don't work well with front bass horns ?
3)Because there are minimal room modes stimulated ?
4)That we like ?
1) Not sure what comments you refer to, or what definition of near and far field you are using, but every audio transducer in a room will have a transition point between the two where the direct sound and the reflected sound are equal. Using a horn with narrow dispersion, one could be in the "far field" when listening off-axis at a much closer distance than when on-axis.
2) "We" can certainly say that small room modes can result in extreme (more than +/- 10dB) variations in low frequency response due to location of the listener and transducer that don't correlate to the usual inverse distance reduction (-6dB per doubling of distance) in free space.
The physical size of a horn may result in non-optimal small room locations that might be avoided using smaller cabinets.
3) I don't understand the question.
4) I don't understand the question.