A visitor of my site sent me email with following:

“I take it you don't like the Rogero style (or Johan Dreyer) bass horns with wings, but you could add compression to a similar setup and make it work properly. I have made several designs with ….”

This idea of bass horn arrangement that those guys use is very interesting in context of this thread. Bothe Rogero’s system and Johan Dreyer’s were mentioned before and I the Johan Dreyer’s horns were discussed:

http://www.romythecat.com/Forums/ShowPost.aspx?postID=6605#6605

Johan Dreyer’s showed up occasionally at this site

http://www.romythecat.com/Search.aspx?Phrase=Dreyer

Both Rogero and Johan had the same type bass horn installation that is certainly very elegant and invisible. My major problem with this approach is that those have very large mouth and work at lower frequencies rather as direct radiators line-array then horns. In this configuration those guys shell not use 515G drivers but rather for 515B drivers that have always 25Hz lower resonant frequency. So, the idea of Rogero’s or Johan Dreyer’s approach is to put one ass on two chairs and to get lower bass from essentially midbass horns.  It would be very interesting to see the Rogero’s or Johan’s equalization curve. We need to subtract the room gain, then we need to measure the acoustic pressure with horn and without horn at 40Hz. (resonant frequency of 515G is about 37-40Hz). If with horn it will be 6dB or more then whatever I say of BS. I do not think it is. If you look at the picture of Johan Dreyer’s horn then you see that is it very large horn but short with relatively large throat.  This time of horn might be fully-horn loaded (have +6dB or more) only down to relatively high frequency. I see no way it will have horn loaded all the way down.

http://cgi.audioasylum.com/systems/8608.html

It is not the way how I would like to go with my own solution. I would like my midbass to have resonant frequency around 45Hz, the mouth rate to be around the same and the horn do not out (anechoicly) anything under the mouth rate. In this case the mouth will take care of the throat reactance and the driver will be properly operating on its own merit with no excessive excursion and with fully loading the horn down to the lowers horn band-pass frequency. So, I would like the lowest octave of the horn to be the effort of horn, not the horn’s driver. Sure the total sound in the room will be less extended to the bottom but it will be much cleaner, much SOFTER (which is the key) and will never sound like elephant belch – the characteristic that 95% of all midbass horns sound out there.  I do not propose that it is how the Rogero or Johan bass horn sound. I never heard them but anyone understand that all those conservations are purely speculative and all that I am trying to do is to furnish (based up my other experiences) the best conditions that might (or might not) lead to superior/maximum result for chosen topology.

So, would it be possible to optimize the Rogero’s and Johan’s idea to make it suitable with my objectives. I think it is and I think it might be an interesting direction as well. If to make the horn like Johan Dreyer did only to drive it with a single 8” throat then the horn will be longer but it will be properly loaded. In this configuration the curve will not be only on right and left but also atop and at bottom. Sure, I would like to use only long walls for my playback, so I was playing with the Rogero’s and Johan’s idea true to do it effective, elegant and small. Below is what I come up with. An additional good part for this idea is that it has no extended attributes outside of building and it will not have any zoning problems or the need to have neighbor compliance.

Also below is my sketch of a “perfect room” (in terms of dimensions) I posted a week ago in other thread.

It is very self-explanatory and liked it a lot. The advantage is that it might be used in any rectangular room and the most important that it is VERY simple to build this way. I think that if I have room then I might stop by in a local architecture shape and proposing a few cases of beer I might recruit local students to build foe me a set of plaster walls like this. The wall insets might be even easily removed if I wish so. Very cool!

Romy the Cat wrote:

It is very self-explanatory and liked it a lot. The advantage is that it might be used in any rectangular room and the most important that it is VERY simple to build this way. I think that if I have room then I might stop by in a local architecture shape and proposing a few cases of beer I might recruit local students to build foe me a set of plaster walls like this. The wall insets might be even easily removed if I wish so. Very cool!

A site visitor sent me emails saying:

“Johan Dreyer says he can hear no time delay with his bass horns…”

Well, first of all I disagree with it. The fact that Johan Dreyer can hear no time delay is not an indication that delay is not auditable. Johan might not know what specifically to listen or he says it as he has no options to time align his midbass. I would agree that one need midbass time aligned with fraction of inch precision but, even inch does not a lot of difference.  But a number of feet of differences is not a good idea. I might say a lot about the subject as I have a LOT of experience to deal with various aspects of time misalignment.  However, my objectives are not to criticize Johan’s view but rather to use the examples of his (and others) decisions and implementation to nail down what I would like to do with my own playback. My standing is that to use horns without time alignment is not good. I am not saying that if a meticulous time alignment was not implemented then the playback shall be dynamited. BUT, I feel that if the objectives of meticulous time alignment are preliminary goals during the period when a system is architected then why do not consider the alignment? Johan Dreyer has no ways to hear his playback in time-aligned mode, I still do…

Now about the diagram with different time alignment scenarios that Saturntube posted.

The top row is unquestionably the best way to time align. The alternative might be turning the horn way off – it is not a problem at all. A midbass horn does not have need to fire directly to a listening spot and to be on axis. The midbass horns might be even parallel to the walls shooting to the back and to be locate at arrival- aligned location.  In case of rectangular hors it is even a preferable way to do the things as it would allow to use lower low-pass filter and to remove more HF from the horn. The only exceptions from this I see in the Jessie-type horns. Jessie’s horns are full spherical midbass and made to be hanged in air above the MF in time-aligned position.  In my view it is absolutely perfect way to do the things but I am pretty sure that I will not have bolls to go for such a radical (but beautiful) solution.

The bottom line looks like the proper alignment but it is not, particularly the left image.  The alignment is not a pure geometry but the equalization of time arrival. In left bottom image has diaphragms in equidistant position but the wave needs to travel across the bend of the horn and this time need to be considered.  So, in the left bottom scenario the midbass horn needed to be moved closer to listener…

Romy the Cat wrote:

It is very self-explanatory and liked it a lot. The advantage is that it might be used in any rectangular room and the most important that it is VERY simple to build this way. I think that if I have room then I might stop by in a local architecture shape and proposing a few cases of beer I might recruit local students to build foe me a set of plaster walls like this. The wall insets might be even easily removed if I wish so. Very cool!

Yep, if I do it then I will do it right: with a single driver, with full length, with proper mouth, with slow profile and if it had curve then it will be properly linearly expending curve, not with the resonant chambers or with steps. The problem with it only size, positioning and cost. I hope the size and positioning will be resolved in 800 sq feet room. The cost? Well, people do it once in life… How much those things might cost $10-$15K-20K? I do not know. I still hope that if I ready to proceed then I will spend affords and find a right maker (hopefully locally) whom I will be able to motivate not only by the money I pay to him but rather the uniqueness of the project. I have a recursive wet dream that I’ll found at a next street a good carpenter who I will be able to hook on the idea of “better sound” and who would be inspired to hear what his horn will be able to do.

From how I see it now it might be one of 4 scenarios:

1)    If a new home has this option then I will gladly build the things into house structure

2)    If I add in my 800 sq feet to the house then I will consider how it will be done.

3)    If I end up with 1200-1400 sq feet loft in city then it would depends of the width and height. If I have width not 10-15 feet height then it will be rectangular horns on the side parallel with the walls.

4)    If I have 15-25 feet height then it would be hardly anything more beautiful then what Jessie it trying to do:  full size spherical horns hanging ay ceiling above Macondo in time-aligned position. Call be a person with a corrupted sense of esthetics but if those horns are nicely finished then might not looks like two Hindenburgs but rather like two Dally mythical animals, sort of Pink Floyd’s flying Pigs… I will work with light to make is very “interesting”…

JLH wrote:

Alingment is another problem. Maybe an all pass filter could help here without messing things up?

Since I started this thread I have received a number of emails from people bitching that I do not like this, criticize that and that they can’t figure out what I do like. I reply to them invariably – “Do not read my site as you are too much a Moron”. However, besides the devaluing a “secretive” fact that there are plenty of idiots who visit my site there is a useful side element among the inquiry  that those people ask and the question would be – are any properly made commercial midbass horn available out there?

It would be safe to say that I know probably all public commercial midbass horn available and frankly I do not like any of them. It is not that that all of them sound bad (and most of them are) but rather from a perspective of conceptual architecting not of the commercial midbass horn appears to me.  As I said before - I want full length, small through, sufficient mouth, no chambers, no steps, properly continuing-expending slow profile. Any anyone does it commercially? Nope, everyone cheat.

There is only one commercial midbass that remotely fulfill all my demands. I am taking about Western Electric 15A horn. Then 15A is well-know horn with 57x57 mouth and with a very properly made continually-curving neck.

http://www.audioanthology.com/building.htm

http://www.moviemice.com/we/horns/index.php

it has all attributes  to feet my bill of being good horn.

Still being the most properly made among the much worse midbass comparators I am not in complete agreement with what 15A does and would like not to repeat their mistakes. The 15A has near 60Hz mouth but was designed to use with WE555 driver that feel hardly comfortable at 100-150Hz.  The 15A has a presses stress zone at the last bend.  The 15A has a bit too low level of horizontal expansion. And in the end the 15A is something that I call wall-stressed horn. The wall-stressed horn is a horn where circumferential force not evenly presses one side of horn bell. The sound that runs across the 15A horn is like in centrifuge pressed to the outer skirt. The presence of the wall-stressing itself is not so bad - the question is how the stress is handled. If it handled with proper dumpling or proper mass-lording of the stressed surface then it is OK. The 150 point of the 15A is not nearly enough to handle the circumferential force of pressure so the 15A sounds as good as many butterflies will lend atop the 15A while it is working. Sure, there is no “movement of air” in horn a horn and the circumferential force in horn might be visualized only conceptually. I do not have data or evidence about the different pressure in the wall-stressed horns. But I do know that wall-stressed horns with all the rest equal conditions do sound always more surface-colored then horn with mouth that have no pressure obstacles or stressed walls.

What is necessary to make the 15A to sound better then it is.  The 15A must weigh 800 pounds for start and the walls shall be 4 times thinker. Alternative to the beefing up the horn wall would be axis-curving of the stressed surface. In this approach the stress will not be applied to the flat surface as it is done in 15A but despaired across curve that located  transversely  to axis of the horn (the way how it done in Silbatone‘s Aporia). The last curved need to be slightly smoothed up. A ultra-low- exertion driver, capable for full 50Hz , good  TTH characteristic, with the same little throat has to be found - good luck with this one! The 15A as it now shall be OK sounding horn - primary because the small throat and slow horn rate. Could it be better, I bet it might. Still, as it is the 15A probably the less problematic commercial midbass horn among all made.

What would be fun if someone would make the replica of 15A only magnified twice larger! That horn will be able to go an octave lower, will be able to use 4-5” throat with more LF able driver. And the most important is that it will be able to have more space in the curved neck and everywhere else to make the walls of this larger horn very tough and very stiff. If somebody makes a pair of those 1000 pounds double-size 15A horn then invite me – it would be worth to listen. I just afraid that to make the double-size 15A horn will be for somebody much harder than to make the same straight horn.

It is a bit far…

http://atlas.mapquest.com/maps/map.adp?searchtype=address&formtype=latlong&latlongtype=degrees&latdeg=42&latmin=16&latsec=12&longdeg=-70&longmin=45&longsec=30

but it has 114-foot ceiling and it is FREE

 http://www.thebostonchannel.com/news/20303604/detail.html

... and it is "romantic"

 http://www.lighthousefriends.com/light.asp?ID=474  (great read!)

The Cat