Yes, too low efficiency, even worse than Altec 515, (when loaded with small throat, in proper FLH, NOT A7 type "horn" which disqualified it also for my usage... 
I don't know how "colored" Tannoy would sound with properly designed horn though... 
Seperate amps could take care of lack of efficiency compared to the rest of the system after everything else was dialed in. 
I would still like to try 15" Tannoy Red or Silver (Gold is lower quality?) in 65Hz horn, (and am building horn with capabilitys for this trial) running from ~ 80Hz to ~400Hz, but will need to be AFTER five-way horns are built, and DSET amps are built, and working (as the Tannoys are less efficient). 
Might be able to build "resonating oops" and mid-bass in same channel. 

I don't know if this is what Dresden is thinking in this thread of not; I'm still not clear on his design / goal. 

Perhaps it's something like this: http://cgi.ebay.com/Pr-Tannoy-15-Monitor-Red-Autograph-Speakers-Huge-Sound_W0QQitemZ190266415283QQcmdZViewItemQQptZUK_AudioVideoElectronics_HomeAudioHiFi_HiFiSpeakers?hash=item190266415283&_trksid=p3286.m63.l1177

Dresden wrote:

I've concluded that building at least two--and perhaps three--different versions of a Mid/Upper bass horn design will be required to determine which of the three configurations perform best.

Unfortunately it is not so simple. Even if you built three different versions of an upperbass horn (with is a crazy things to do but a commendable experiment anyhow) then it would hardly indicate which configuration “performs best”. There are 3 things that I would like to point your attention

1)    The sound of your upperbass horn will be 60% depending from the way in which it imbibed into your room.

2)    The sound of your upperbass horn will be 30% depending from the way in which the GIVEN upperbass integrated with rest of the channels

3)    If you go went the pain to read many post of this site then you will see that I very seldom, if ever, give a direct recommendation what to do. I know that it pisses a lot of simplistic audio-idiots out there but there a lot of reasons for me to do what I do. My “homework” to you, as to a person who would like make commercial upperbass horns: what do you think the relation of this third paragraph with the context of this thread? Mind you that it very loaded question.

I like the title of you post” The Purpose and Approach”. This in many ways is the answer to the idea of perfect loading, or the perfect loudspeaker, or whatever else is “perfect”. This view kind of subside my excitement about the “generic” commercial projects and one of the major ingredients – “the purpose” is not plugged in the recipe of the cooking….

Romy the Cat wrote:

Dresden wrote: I've concluded that building at least two--and perhaps three--different versions of a Mid/Upper bass horn design will be required to determine which of the three configurations perform best. Unfortunately it is not so simple. Even if you built three different versions of an upperbass horn (with is a crazy things to do but a commendable experiment anyhow) then it would hardly indicate which configuration “performs best”. There are 3 things that I would like to point your attention 1)    The sound of your upperbass horn will be 60% depending from the way in which it imbibed into your room. 2)    The sound of your upperbass horn will be 30% depending from the way in which the GIVEN upperbass integrated with rest of the channels 3)    If you go went the pain to read many post of this site then you will see that I very seldom, if ever, give a direct recommendation what to do. I know that it pisses a lot of simplistic audio-idiots out there but there a lot of reasons for me to do what I do. My “homework” to you, as to a person who would like make commercial upperbass horns: what do you think the relation of this third paragraph with the context of this thread? Mind you that it very loaded question. I like the title of you post” The Purpose and Approach”. This in many ways is the answer to the idea of perfect loading, or the perfect loudspeaker, or whatever else is “perfect”. This view kind of subside my excitement about the “generic” commercial projects and one of the major ingredients – “the purpose” is not plugged in the recipe of the cooking…. Rgs, Romy the Cat

Dresden,

So the first two could actually be just one actual build, with alternate rear chambers? 
Wouldn't you change the throat size, as well as the compression chamber size? 
Then arrive at your "optimized" compound horn design.

Then you could compare this to design #3 which would be a straight FLH, correct? 
This may be the best way to do it, to hear the difference, to "prove it to yourself" rather than the suggestion Romy made about the third paragraph. 
I had to go through all that mess, and learn the hard way... 
I really thought the compound horn design was a good idea @ one time too... 
Robert 

You're using a phase plug?  Why?  To try to get it to go higher? 
If using parallel drivers, and doubling Sd, it may be necessary to change throat area to not damage drivers... 

The third design type sounds quite different from the first two. 
In my opinion, so much better I've quit messing with the first two... 
Have you heard both type horns? 

"Compound Horn" is what I've heard many speakers with horns on both sides of the driver called... 
e.g. what I mentioned previously, & linked, what I've built,... 

serenechaos wrote:

You're using a phase plug?  Why?  To try to get it to go higher?  If using parallel drivers, and doubling Sd, it may be necessary to change throat area to not damage drivers...  The third design type sounds quite different from the first two.  In my opinion, so much better I've quit messing with the first two...  Have you heard both type horns?  "Compound Horn" is what I've heard many speakers with horns on both sides of the driver called...  e.g. what I mentioned previously, & linked, what I've built,...

serenechaos wrote:

You're using a phase plug?  Why?  To try to get it to go higher?  If using parallel drivers, and doubling Sd, it may be necessary to change throat area to not damage drivers...  The third design type sounds quite different from the first two.  In my opinion, so much better I've quit messing with the first two...  Have you heard both type horns?  "Compound Horn" is what I've heard many speakers with horns on both sides of the driver called...  e.g. what I mentioned previously, & linked, what I've built,...

Dresden wrote:

... two J-shaped horns back-to-back, as though it were a mirror image.  --the drivers do NOT share the same throat, but instead each driver loads its own horn.   I'm sure the 'picture' is now clear, correct?... If you take into account the amplifying effects of nearby surfaces, the reasoning behind my approach for a Mid/Upper bass horn design becomes obvious...

Dresden wrote:

In regards to a phase plug...  I will be using an electronic crossover in the completed system, to attenuate any unwanted frequencies outside of the target range... . Think of it as a consideration of 'no stone left unturned'.  lol.  I cannot prove on paper whether the time vested in implementing a phase plug will be a complete waste--the only way to be sure is to build the phase plug and test/listen to the horn both with the phase plug and with a conventional flat section in place of where the phase plug was, and comparing both tests.

Dresden wrote:

Think of it as a consideration of 'no stone left unturned'.  lol.

Dresden wrote:

Think of it as a consideration of 'no stone left unturned'.  lol.

A phase plug in J-horn? Hm, OK, whatever…

Dresden, what I find disconcerting is that you are talking about “design” without taking or thinking about your sonic objectives. That is all reminds me very much what the folks at diyaudio.com do. They keep talking about any imaginable subject and most of them do not even understand why they are talking about it. Those few from there who do understand what they are talking about are not able to associate whatever they do or think with any more or less rudimental listening experiences or own musical objectives, in fact they hardly even have any listening objectives at all.  I have seen many of those “angry designers”, I mostly laugh on them and they do not recognize why.

I do not know what serenechaos’ problem is with understanding of what you do but I am in on a same page as he is: in my coordinate system of “how the things done” and not sure what your project is all about. You won’t to build some kind of 40Hz that you wish to be “good” but the only more or less interpretable objectives that you brought up was… let me see… Class D amp, less cost, ability to market it to pro folks, no specific sonic objectives… did I miss anything?

I do not men to be critical but if you are trying to learn to lay a musical instrument then want would be the definition of your success if you are not planning to play your musical instrument or even listen it? I feel that people need to deign playback not in accordance to the deign concepts that some morons ( like me) from internet pass  out but rather to learn to recognize with themselves own listening objectives and learn how to communicate vise the  objectives goals and methods.

Otherwise it becomes the diyaudio.com-level of the BS collaboration and I personally have no interest in it.

Dominik wrote:

I print almost all posts from this site. For last months I study them a lot. I completly suck in by Romy vision of sound reproduction. First I decied to build melquiades amplifier and give it a try with my ob setup. Next step is "horns" I found on ebay german plastic horns, but anywhere I cant get not plastic but massive 115hz horn for a fair price. I spoke with german company but they want 12 000 euro for two 115hz horns!!!! I want to hear sound of this horns, I never heard it before. Yestarday I met my friend who run big company - they building agricultural units and have lot of cnc machines.He told me: "give me auto cad 2d project and then I can tell You if I can do it for You" I dont know how to use autocad. I tried but its to complicated. So gentelmans, Do You have  auto cad 2d drawings of 115hz horns with 4" throat?

Dominik, I ma not pleased with your “suck in by Romy vision of sound reproduction” but this is another subject.

Regarding your autocad and the horn things….

I would not advise to build anything as you have an idea what it might be. Find somebody and listen horns, get a grip what it is all about – horn are tricky, most of them are very bad an you might not like them.

Anyhow, there are many free circulation tools that would allow to get horn prose and dump it into autocad. I have at my site a tool for Tractrix profile, with which you calculate whatever you wish:

http://www.romythecat.com/Docs/TractrixCal.xls

Some might feel that 115hz horn might not be Tractrix but to have slower opening. There are some cone and pros for this view. I do not have exponential of another calculator handy but you might find them online. Still, I would strongly discourage you to make actions juts because any Moron on line, would it be me or anybody else, juts has a “vision of sound reproduction”. Get the reference points, correlate them with own objectives and then make a decision if it might benefit you.

Dominik wrote:

Nobody around dosnt have this kind of system, I didnt heard also that anyone in Poland have similar system and I dont want to "hard looking" for anyone who have it.

Hi Romy,
I hope I got this right when going through this long thread with LOTS of information.
Did you mention for upper-bass cross-overs Elko’s (electrolytic) only to be your preference?
If I have it right, any special preference at all as to 'smooth' (Mundorf = Glatt) or 'rough' (Mundorf = Rau)?
Thanks,
Axel

Axel wrote:

I hope I got this right when going through this long thread with LOTS of information. Did you mention for upper-bass cross-overs Elko’s (electrolytic) only to be your preference? If I have it right, any special preference at all as to 'smooth' (Mundorf = Glatt) or 'rough' (Mundorf = Rau)?

I do not know what Elko is and I most likely was not talking about any upperbass crossovers but only about high-pass upperbass crossovers. You shall not worry about it as you do use horns but among certain types of upperbass horns the unloading unused bass is very beneficial and the capacitance volumes in there is very high. Also, I was not taking about any electrolytic but about the actively biased electrolytic

 http://www.GoodSoundClub.com/TreeItem.aspx?PostID=4067

..that in my experiments with upperbass horns any film caps. I did not try Mundorf. Well, I did 10 year back before the Mundorf become the high-end capacitor company. At that time Mundorf caps were dirt cheap and used by people in car audio. They were OK, the actively biased electrolytic (I use only commercial grade Nichicon) were better. Mind you that the channel did not care HF signal…