How big a Khorn to reach 20Hz?

[Colin]

the ear hears as low as 20-Hz at loud volumes, music has harmonics that descend as low, doesn't seem so unreasonable to me, although I admidt that at some point a sports car becomes more attractive than a fancy stereo, but for awhile, I was adding to mine in $500 and $1K annual increments, can't do that with a sports car...

[garyrc]

the ear hears as low as 20-Hz at loud volumes, music has harmonics that descend as low, doesn't seem so unreasonable to me, although I admidt that at some point a sports car becomes more attractive than a fancy stereo, but for awhile, I was adding to mine in $500 and $1K annual increments, can't do that with a sports car...

The lowest note I know of is the very rare 16 HZ Theater Organ note. The first harmonic would be 32 Hz (which, by coincidence, is the lowest note usually found on a Church Organ). I think there is "beating" when two bass notes are very near one another in frequency. I believe the beat is at the frequency you get when you subtract the frequency of one note from that of the other nearby note. There was an article in Scientific American (several decades ago) called
"Binaural Beats in the Brain" which, I believe, supported the idea that
the beats happen in the brain, not in acoustical reality (???). I don't think the beat would be considered a harmonic -- I think harmonics ascend and beats, if present, decend. Does this mean when you have two bass viols attempting to play the same bass note, but failing by being off, say, 10 Hz, that we would want out sound systems to reproduce that 10 Hz beat? Oh, wait, if the beat happens in the brain only, the system would not need to be capable of reproducing it! Does "room Rumble" from the original recording site cause some beating? IMO, for almost all music, we only need to be able to reproduce frequencies at or above about 32 Hz. The piano goes down to 27.5, but how often do composers write notes down there? In running movies, we may need a speaker that covers the zone in which the infernal bass machine makes its sounds, usually down to 20 Hz, but sometimes (reportedly) as low as 8 Hz, endangering many home subs, and even a few in theaters (unless everything below ~~~ 20Hz gets filtered out electronicallly).

[DrWho]

here is my math on the horn length.

K Horn is a quarter horn, so the horn length is going to be 1/4 of the frequency wavelength.

Frequency wavelength of 30 Hz = 37.53'

Frequency wavelength for 20 Hz = 56.3'

20Hz wave 56.3 - 30Hz wave 37.53 = defference 18.77'

1/4th of 18.77' = 4.6925' or 4' 8 1/3"

Couple that with the horn area mentioned previously (Formica: 31.37 sq ft area, and 6.32' diameter), and you should have your horn extension. The horn will stick out into the room about 5' farther, and the mouth would be 5' tall by 6' wide roughly. As the Khorn is corner loaded, does that mean a couple more turns then shoot back toward wall?

The rate of area expansion affects the acoustic coupling differently at different frequencies. The 32Hz'ish flare of the khorn would require a much longer extension. Also, the rear chamber is set to reactance annul at a higher frequency and I'm not sure you could find a low distortion driver that would work in that space without causing suspension issues (flexing due to high pressure on a soft membrane).

[Mallette]

Somewhere a few years ago I posted a drawing of an "easy" way to get 32' or more straight horns into a listening room. If you are lucky enough to have an existing home with the right parameters...either a room with a cathedral cieling that connects to an attic or high cielings that can be lowered to standard height in the listening room, it's easy. With new construction, even easier.

I will do this if I ever build a new house again. I think a couple of thousand at most would do the trick and it would be so cool to have clean bass to earthquake levels without taking up any room at all except in the attic.

Granted, you can do this with a sub floor as well. Why do you think they call them "sub" floors, anyway?

Dave

[Guest " "]

the ear hears as low as 20-Hz at loud volumes, music has harmonics that descend as low, doesn't seem so unreasonable to me, although I admidt that at some point a sports car becomes more attractive than a fancy stereo, but for awhile, I was adding to mine in $500 and $1K annual increments, can't do that with a sports car...

Our senses can actually feel LFE below 20hz. Part of our survivial engine that helped us figure out which way the herd of wild animals was running (toward us or away from us).

[CECAA850]

I think a couple of thousand at most would do the trick and it would be so cool to have clean bass to earthquake levels without taking up any room at all except in the attic.

You've just described an IB[].

[Mallette]

Actually, I'd think an IB would be even cheaper poured as part of the slab. Nice and rigid, too.

Dave

[CECAA850]

As far as 20Hz horns are concerned HERE is the most cost effective FLH (Front Loaded Horn) I've seen to date AND it won't take up all your living room.

[Mallette]

As far as 20Hz horns are concerned HERE is the most cost effective FLH (Front Loaded Horn) I've seen to date AND it won't take up all your living room.

Interesting you should mention that. I downloaded the plans this morning. Looks to be within my tool and skill level.

Dave

[CECAA850]

As far as 20Hz horns are concerned HERE is the most cost effective FLH (Front Loaded Horn) I've seen to date AND it won't take up all your living room.

Interesting you should mention that. I downloaded the plans this morning. Looks to be within my tool and skill level.

Dave

The designer (Lilmike) has done several designs. I've got all the wood, driver and sub amp to build a 6 1/2" tapped horn he designed. I just need a little time.

BTW, Dave the offer still stands to use my router if you get around to a build.

[boom3]

In the 6+ years since this thread started, I've changed some opinions. Mike is right that the size of the room is not the issue, but wall flexure and openings for windows & doors continues to be a problem. My listening room is pretty much open on one whole side, opening onto a hallway, but at least it does have a cathedral ceiling and wood flooring over slab for rigidity.

I built a Rythmik Audio 12 subwoofer about 5 years ago. It's not just the pipe organ and sound effects that it has improved. It's set to 60 Hz turnover (the lowest available on that model) and it has cleaned up the midrange of the Corns by taking the stress off the woofers, which are expected to operate up to the nominal 600 Hz crossover point.

A criitical part of the decision process (SAF aside) is that a bigger bass horn implies a lower high frequency limit. So instead of a manageble 400 Hz (nominal) mid horn, we will be driven to a 250 Hz (or so) mid horn. Also remember that especially with a first-order crossover, a mid horn is going to be operating a full octave below its nominal "electrical" crossover point and therefore the mouth must capable of that "minus1' octave point . It's easy to see that the cost of a bigger mid horn and driver could exceed that of a bigger bass horn in short order. And a bigger mid in turn, implies a lower HF limit for that, too, which is why that "last ocatve" may steer us to a 4 way design.

If a bigger horn doesn't work out, you at least have a deluxe doghouse; but then you have to buy a bigger Fideaux to suit it.[]

[BE36]

Not a K-Horn but could be combined with one.

http://www.volvotreter.de/th.htm