Jessie, 45Hz horn with 6”-7” throat around AK151 driver is from my perspective is the best thing might be theoretically built around a cone driver. I really envy of you and if I had room I would unquestionably go for it; this is why I keep a pair of AK151 and pair 15/40 in my storage.

Regarding the crossovers. You “might” need to cut off the LF that doing into the horn. Consider ~20Hez high pass, preferably line level. As far as low pass – it is very complicated subject. Of course everyone would like to get more LF out of LF horn and they drive it as low as the horn’s mouth allows. However, it is not necessarily good thing to do. You see, what I learned that all drives with back chambers (cone, compression… you name it) when they go down near their resonance frequency they become “congested” and not as relaxed and free as I would like them to be. I good solution is to let electrical filter to kill Sound before the diaphragm before stresses. Think this: a diaphragm dumping is good thing for mechanical calculation of suspension but a damped diaphragm is not a good transducer. Try to play any string instrument when you do not push a string strong enough to the deck – the string sound dull and subdued – exactly how most of the upper bass horns sound at thier lower knee. So, you would need to make your own conclusions where to cut it and how to use it. Do not forget that in your case many other variables will be playing: the boundaries gain, the room mode and so on…

Regarding the back chamber. When you lower back chamber it rises resonance frequency. Some people try to drive resonance frequency to the horn rate; some would like to be having the resonance frequency below the horn rate. I do not think that any rules might be in there. You have to listen how your given horn will behave and sound in your room. I can assure you that the level of freeness of the cone of this driver will be very-very much describing the sound you will be getting out of this horn. It will take for you a few weeks to play with it when you will be done. It is very interesting to change slightly the depth of the hermetic-ness of the back chamber and to see how sound from the horn will change HUGELY. I would say that a good staring point would be look what Vitavox did for their System 191:

http://website.lineone.net/~empson/Sys191.html

Find plans and see how they use the AK151 (chamber), then compare with your circulations… I would go for 1.2-1.4 times larger chamber to have some spare space. It is always possible to patch it with none-elastic foam and to make the chamber smaller…

Also, Jessie, there is another very important point. A construction of your systems should not be a pure DIY efforts or it will be just another stupid DIY project. Your should have none-DIY objectives and use those horns to resolve those none-audio objectives. You need to clearly visualize the result, to breed the result within yourself. Try to listen and to understand Sound that your horn does without even connecting the horn… The moronic DIY people always miss it and end up with garbage result but the problem is that they do not know where they are doing.  Good result come to people who are ready to recognize good results and you have to train and evolve own perception and understudying of Sound in order to be able to acknowledge and discriminate the result when and if you get it from this big new horn.  Without an evolvement of own awareness any DIY project is juts a pile of stupid activity resulting with typical nothingness… Try to develop some “leading” interests in  music and build this big horn to fulfill this “leading interest”…

Rgs,
Romy The caT

Also, Jessie, there is another very important point. A construction of your systems should not be a pure DIY efforts or it will be just another stupid DIY project. Your should have none-DIY objectives and use those horns to resolve those none-audio objectives. You need to clearly visualize the result, to breed the result within yourself. Try to listen and to understand Sound that your horn does without even connecting the horn… The moronic DIY people always miss it and end up with garbage result but the problem is that they do not know where they are doing.  Good result come to people who are ready to recognize good results and you have to train and evolve own perception and understudying of Sound in order to be able to acknowledge and discriminate the result when and if you get it from this big new horn.  Without an evolvement of own awareness any DIY project is juts a pile of stupid activity resulting with typical nothingness… Try to develop some “leading” interests in  music and build this big horn to fulfill this “leading interest”… Rgs, Romy the Cat

Wojtek wrote:

I heard that some audiopholes don't like to go to classical performancess because their gear just SOUNDS BETTER

There are many very reasonable explanations of this sentient. I do not go in there as it is what of the subject of this thread.

Wojtek wrote:

I still don't understand how playback system at home can trough different perceived (?) qualities stimulate similar to life music emotions. Either I missed the post or did not comprehend it could you elaborate more on this Roman?? Maybe thats the key to success.

I made a point a few months back replying to somebody that audio and music at a certain level are not related. Although it immediately sounds for an ordinary audio person as the typical audiophile heresy but there is a LOT of more behind the differentiation audio and musical context. It is way more complex topic then it might immediately appear. Audio is a stand alone subject and nothing else. It should be view as a stand alone subject

Wojtek wrote:

Also still there is a problem with recognizing "the problem" And finally it became painfully evident that in most DIY installations people just put in the play whatever crap they have in hand and after that try to justify (or defend) their choices or build philosophy around it and I tried that too (defend & justify) and the best I could come with was ,well it was cheap or I already had the junk in my hand ,and yes I was wrong in some of my stupid posts.I'm really sorry.

Stupid of not your post was is irrelevant. What is relevant is that it is reasonable subject but in the very wrong thread. I have very little rule on my site, if any, and one of the few know to me rules is that posts in the thread should be in some way bind to the subject of the thread. Let keep it this way.

Still, I intentionally injected into my reply to Jessie the subject of above-audio objectives because without it the definition of success will run through the fingers like beach sand. I sincerely hope that Jessie, or anyone else would recognize that building a high capacity playback installation should be affinity with development of evolved reference points, civilized methods of playback assessments and original objectives in classical music. With it all those attempts are not real audio but just a habitual self-entertainment – exactly what the Morons DIYesr do.

Rgs,
Romy the Cat

Here is an interesting, atypical nowadays, attempt to get 45Hz. With massive (not plywood construction),  use one diver instead of two drivers, use better drivers and with proper tuning of the back chamber (it is wrong there) it might be a good solution.  Ironically this horn semi-uses some of my ideas that I came up while I was playing with “resonating oops”....

http://cgi.ebay.com/Altec-Vintage-Bass-Horns_W0QQitemZ110150740342QQihZ001

Jessie,

I can not speak Swedish and have no idea what they say but here is a Swedish 50Hz horn project. I admit that I have difficulties to like people who design horns in Hornresp but… for whatever it worth…

http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=61668&whichpage=1

Romy the Cat wrote:

I can not speak Swedish and have no idea what they say but here is a Swedish 50Hz horn project. I admit that I have difficulties to like people who design horns in Hornresp but… for whatever it worth… http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=61668&whichpage=1

Discussing the Jessie project we multiple times mention the idea of the large midbass horn handing above MF section. Where else the 7”-9” might be positioned? The rational was to have it positionally contra-react the output of the upperbass horn. It is all good and it is what I would do in context of Macondo alternation is I have space but do we automatically assume that the hanged horn would be a flimsy horn?

Well, among a few midbass 50Hz that I was exposed I heard today one that I actually like. It was a straight 50Hz, hyperbolic, rectangular, with two 12 inchers loaded into 6” trout each. I do not know the specifics of design but the wall are wood-sand-wood   and they are 2” thick – good construction and … you would never hang this time of the horn.

 The midbass horns were positioned outside the MF channels, time aligned with mouths extended far into listening position.  It was running 50Hz to 800Hz and despite I would have some objection to this configuration but the midbass of the installation was quite pleasant. I would leave aside and opened the question if the midbass might be better even in connect of THAT installation but the brief listening of that playback suggested some thoughts.

How high we can go with midbass horn? As far as the driver allows? As far as other solution would not defeat the midbass horn in term of quality? As far as other horns we do not want to build? There is no answer but this thing should be well thought. Yeas the use of midbass horn as the only horn the sit on the ground is a good idea but it lives the space under the MF channels empty and slightly increase the minimum integration distance. Still it looks like it might be worked out or at least attempted.

Romy's quotes in blue :

"...Discussing the Jessie project we multiple times mention the idea of the large midbass horn hanging above MF section... The rational was to have it positionally contra-react the output of the upperbass horn... But do we automatically assume that the hanged horn would be a flimsy horn?..."

Well... Apart from really slowing progress on this project, the move to a new "house" means that for as long as I stay in this place (???), I too will be placing the bass horns (45 Hz) down at floor level, outboard of the main left and right channels.

"...The midbass horns were positioned outside the MF channels, time aligned with mouths extended far into listening position.  It was running 50Hz to 800Hz...How high we can go with midbass horn?..."

I will admit that in the case of the smaller upper bass horns (10" driver into 115 Hz horn) I have recently been letting them run with either a high-ish cutoff, or no cutoff at all, other than that which naturally occurs due to the architecture of the driver/horn combination. This is in the interest of increasing output down low, as a coil tends to choke output way below the cutoff frequency (6dB/octave). I am wondering if the decision to let a 50 Hz horn play all the way up to 800 Hz (see previous post) was not made in order to get enough volume out of the horn further down.

"...but do we automatically assume that the hanged horn would be a flimsy horn?..."

As for construction of the 45 Hz horns, the plan allows for hanging or placing down at floor-level... The horns will not be flimsy... Construction will be as follows : Everything down stream of the driver mounting plane will be from glass fiber laminations. These will be true round-section horns... Not so much for sound, but because I am lazy and want to make the horns from as few segments as possible; the compound curvature involved would be more rigid than single curvature construction for the same mass and number of segments... Anyway, given the process it does not entail much more work. Additional stiffening ribs can be molded into the outer surfaces. There would be eight identical laminations to make (four 90° segments per horn). I absolutely hate working with glass fiber, but given my resources and objectives, it makes the most sense (it will mean checking into a hotel to sleep while the resin cures, as I just can't afford additional brain damage). Horns made this way should not be too heavy to suspend if one day I find the right room... Which brings up another of my objectives, this installation must be mobile; a two-man job at max, and all the pieces must fit into a standard 2m-wide sea container. Rear chambers would be one-piece bolt-on castings made via a process similar to that used in the construction of the smaller horns.

I will soon have no excuses for putting off the construction of these horns, as I have finished everything else; the frames which locate the other horns are finally done (still need to paint them), they were a lot more work than I expected. I swear I will post photos soon.

jd*

I was thinking about a space-economical way to arm playback with midbass 50Hz horn. It is not that I am into it myself but conceptually I was wondering how to put all of necessarily things within a minimum compromise in minimum footprint. I came up with following:

The configuration has time delay from midbass horn. It is a big fault, terminal fault in my book but it is what it is. I did not try it but it would be very easy to model this behavior by running my injection channel in midbass region at 0dB with ~11mS time delay.

Chris,

The point of digital delay is well taken. Digital has no problems to delay and if someone had only digital as source then it is very simple to use tow parallel DACs and to stick temporary storage memory in one or them. In case of multiple sources and the need to delay not the bass horn but the full-range bandwidth the situation is grimmer. What I would like to see is a small box with AD/DA from a common clock and time delay between. There was many unit made in 80s for pro audio but none of them where up to the level of true transparency. In today would it would be possible to have 32bit/381K on few chips and a powerful buffer. Unfortunately there is no market for a such a devise and high-end level of performance and transparency. It is very unfortunate as it might be a very useful tool.

Macondo does not need a time delay. Even if I personally go with Macondo for 50Hz horn then it will be only positioning-align and I will not use any artificial aligning methods.

Jessie,

Unfortunately it is in my view it is absolutely imposable to predict anything juts based upon the CAD modeling. The entire criteria that you for founding the right positioning of your instantiation are wrong, at least in my view. You use the consideration of time arrival, esthetics, light of sight, localization… Do not get me wrong – they are very important criteria but there are even more essentials criteria – something that overrides everything and something that will dictate to you how and where your installation will be organized. Truest me, you will not have a lot of chooses if you will be using the right criteria. From there you will use the rules of time arrival, esthetics, light of sight, localization etc but it will be in a given framework, the only framework that your room will dictate.

In my view you will hit two major aspects, answer to which will dictate how to position your playback. The very first will be something that I described in the “About speakers Imbedded Macro-Positioning” article:

http://www.romythecat.com/Forums/ShowPost.aspx?postID=4421#4421

Fist: The midbass big horns would have over 10dB difference between being imbedded in the room hot spot and placed somewhere else. In the “hot spot” the midbass horns will load the room in a manner that shell make to stop even thinking about other location for the channel.  Everything else will just flow from the only positioning of the midbass horns.

Second: the LF channel. In your room you need to measure what your LF channels outputs. You might position them between the midbass the MF horns tower of your might put then outside of the midbass – you never know. If you cross then at 30Hz-40Hz for instance than in one spot it might more or less evenly load the room, in another spot it will have plus or minus 12dB somewhere. If you do then it is imposable to cure anything besides just moving the woofers 3-5 meters away to a completely different location.  Usually sane size rooms have those bass suck outs and influxes at 50Hz -100Hz – you with your hypothetical 30Hz-40Hz crossover will be beyond this level. Still the woofers might hit you with problems with their tail response. Do not take out of consideration the opportunity for lower bass channel to work TOGETHER with midbass horn. You might accomplish it by crossing the woofers at 100Hz for instance. Let patent that your naked woofers have 95dB flat from 200Hz to 50Hz and then at the bottom then have in a given location a huge boom of plus 12dB from 50Hz to 25Hz. Why to fight with it if you can use it: you might declare the 107dB of the sub 50Hz and the woofer new reference sensitivity, crossing the woofers at 100Hz and letting the woofers to run 12dB behind the midbass.

The point I am trying to make is that the actual measurement of the footers, midbass and partially the upperbass will dictate where to position the system. When you found the strategic positioning then you can go for tactical positioning. For instance the MF island will “read” the proximity to the back wall and you will curves the leading edge of imaging accordingly – you will play with those details lately…

Anyhow, I do not think that an abstract CAD modeling might say anything indicative. I have somewhere else in my site somebody was asking about the specific positioning of speakers and I was very none-cooperative. It was not an accident and not my desire to be a jerk. The proposer positioning is an ability of the system owner to assess the results and to react to outcome. I think having any precompiled concepts in this is not a good idea. I am sure, you Jessie, will find the way how to load you room with speakers. In the end do not forget the following:

http://www.romythecat.com/Forums/ShowPost.aspx?PostID=2553

Try this:

http://www.realhorns.de/index.html

and then keep clicking it until you get this

There is some text in there with data, I can’t read German but I do like the shape of this thing.  I particularly very much like the idea (I do not think that Germans use it but it came to me when I saw the Cow Horns) to make the mouth from a relatively light and resonant material but then to have that bungy cord in the peripheral of the mouth. By straightening the bungy cord it might be possible to press the leafs of the mouth and to dump them, effectively controlling resonance. If I will be making my 50hz horn I would most like would do something in this direction, only with smaller throat.

Wow, 6 x 15" drivers (!!!); though the curved profile certainly imparts rigidity, I'm guessing this horn must resonate more than a bit (no bracing until the mouth) -- but I like this thing.

Interesting, the phase plug-like device in the center.

If ever traveling near these people I will definitely try to arrange a demo.

About the idea of harnessing and trying to "tune" resonances... It reminds me of the "argument" that a flexible automotive chassis has merits (yes, perfect if you wish to "confuse" the suspension and fatigue the occupants! Never mind, I'm starting to sweat). I know, horns are not cars; apples and oranges etc.

In any case, my instincts tell me that energy would be more properly channeled by allowing the excited medium in the horn (the air) to "work off of" a solid foundation (Ever stand on the top rung of a ladder and try to hammer in a 10-penny nail?). Also, I don't like the idea of a driver working in the presence of a secondary source of excitement, regardless of its phase; in this case, air in the horn re-excited by resonating walls, causing pressure to feed back to the driver (An exaggeraton : The pulsating pressure one feels when speaking into the rear of a fan) But this all just theory.

Though I may be wrong, this is why I went the other rout and used a material that is really dead and heavy with loads of bracing.

jd*