GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Horn-Loaded Speakers
In the Thread: Vertical Axis Midbass Horn

Post Subject: A vertical midbass.Posted by Romy the Cat on: 8/9/2012

skushino wrote:
My desire is to use a pair of bass horns for each channel, both vertically oriented, one each exhausting to the floor and the ceiling. I have an idea that spatial presentation will gain a big boost with both up and down firing bass horns.

An idea of using boundaries to get more interesting midbass is great idea. The problem I see in the actual implementation. Midbass from horn in small room can be hugely benefited if it bounces but to make the assembly of horns visually pleasant, time aligned and functional at the same time is a big question. I do like the notion of Midbass fires to the floor but did you see any attempt to do it esthetically pleasing? For sure the beauty id the eyes of beholder but I personally do not like visually any inhalation I have seen with vertically positioned midbass. Also, the vertically positioned midbass are always undersized… Anyhow, I am still looking for some kind of innovative industrial design solution that would implement vertically positioned midbass but in a pretty way and that would not make an acoustic system to look like it’s trying too hard to make sound.

skushino wrote:
Which driver to use? 12" - 15" are the obvious choices to balance low-end displacement and seamlessly match lower midrange @ 200hz

There many 15” drivers to choose but if you do for 55Hz horn then probably 12 inch driver would be preferable. The park of 12-inchers is strange. It looks like companies did not do a lot of good 12” drivers. You might look for some older Electro-Voice 12” drivers, or perhaps find something new. You need to look for high-sensitivity before a horn, at least 98-100dB and then look for everything else.

skushino wrote:
Time alignment with other channels. Need clarity on how to measure. Is it distance from driver to listener, or need to include horn path length in consideration?

Yes, the time alignment will include the horn path length, the distance from the boundaries sand so on. In case of boundary use you will be at much less critical time alignment demands and you will have a lot of diffusion of sound and your midbass will not shape an impulse too well. So, I would take the time alignment in consideration but would not go too anal retentive to it as I insist to do in case of direct radiator horns. At 55-200Hz and with indirect radiation you will have a LOT of room gain going on. You might pay a toll and have some kind of funny imaging but you might gain in many other aspects.

skushino wrote:
Hf limit

I would say 200-300Hz and do not expect that your upper region will be too great. The lower you go the best.

skushino wrote:
Imaging and soundstage considerations with horns not pointing at listener

It is very hard to estimate what will happen with imaging. If you wish you can flip you current midbass horns vertically and to see what happen. Be advised that you would need a good month to work on your playback and to modify the associated channels in order to make your playback to sound properly with flipped midbass. Will you go for that investment of time and efforts?

skushino wrote:
Driver cone sag in vertical orientation. Is this a credible concern or too much hand wringing about nothing?

Yes, the drivers sag and they sag even a driver hung in horizontal plane. How many people flip the drivers 180 digress each 2-3 years? However, the sagging is most applicable for drivers that are trying to be full range and have large excursion. In your case you will pick a high sensitivity driver that most likely will have very hard suspension and very limited excursion – this type of drivers is suited for horn loading. With very short and hard suspension I would not worry about sag.

Rgs, the Cat

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