Herman,

What you describe is fine. Over the course of last years I had a number of people who report identical things to what you do. Even if you change volume of back chamber and move resonance frequency then sound will change but it most likely will not produce proper sound. BTW, I would pay your attention that you did not mention what driver your horn use and how sound change when you move Fs 10Hz up.

Considering the amount of homework you did and own thoughts you put into asking this question I will collaborate on it but be advised that the subject you post is incorrect as what you complain has nothing to do with resonance frequency. In my view the Bruce Edgar’s midbass horn is wrongly built and designed, at least in the version that you have.

First thing first: Bruce Edgar is the most prominent and the most knowledgeable horn designer and builder alive today, in fact he has been holding this title in my view during many-many years. In addition he does hear the things very well, has cultural and cognitive capacity to interpret properly what he hears - a very seldom quality among individuals who are trying to make acoustic systems. Furthermore, I consider Bruce as my friend, consult with him sometimes and even during my midbass project we spoke a few times and we collaborated on some issues that I had. So, it would be greatly inappropriate for me to criticize the Bruce’s 80Hz horn.

However, one of the keystones of this site is honesty and respect to the actual sonic results. From this perspective I do not feel that criticizing Bruce’s 80Hz horn I violate anything. If Bruce’s, your, mine and anybody else objective to advance horn sound instead of patronizing horn people then  criticizing Bruce’s 80Hz horn will be a great respectful service to what Bruce taught all of us for years.

I do not like Bruce’s 80Hz horn. I heard it only once, I did not like it then but I even more do not like the design idea. 8-10 year back Bruce furnished his Titans with curved 80Hz horn, even that curved 80Hz horn had some problem it in my view was much more interestingly sounding horn. Then Bruce desired to bless the Morons with a straight horn – I think it was a disastrous move: the horn is too short with too large throat, and at least with drivers the Bruce use they shall sound in the way how you descrive.

The need to note that I used the word “Morons” in the last sentence very deliberately. There is Bruce and there are his customers. It was my vocal and persistent position over the years that Bruce Edgar’s customers in dominating majority are incredible idiots. Since I entered the horn field in 1999 I was dealing with them many times and I can testify that 95% of them are remarkable retards. I can publicize many events when I and the some “specific” Edgarhorns owners where involved and it will be absolutely self-evident how much Morons they are, the last even was 3 months back with a retard posted at AA under a moniker “Dan_ed”. The problem however is not only that I know it but that Bruce Edgar intelligent to know it as well. So, what Bruce doe it mitigate the design and implementation efforts in accordance with the level personal stupidity and sonic ignorance of his customers. I would do the very same in I were “in business”. So the short 80Hz straight horn was sort of Bruce’s Hoi Polloi horn for the Morons out there, sort of Bruce’s Volkswagen horn (I original meaning of Volkswagen).

So, I do think that you will be able to fix anything in the Edgar 80Hz straight horn. You can change driver, move Fs up and down, beef the enclosure with sand but it will be all half ass solutions.  I personally did not play with this horn but in my view, looking at the short straight horn with huge throat I do not see a horn but rather I see a direct radiator shooting through a pipe. Many Edgarhorn users do “upgrade” of their Edgarhorn replacing the old curved Bruce’s horn to the new straight one, so you might pick up the old one that will be much better. Alternatively fine some kind of idiots who would buy this appendix horn and ask Bruce to make to you a properly horn if you will be able to accommodate it in your system. (I personally believe that you will not as I feel that 80Hz horn is too large to be located under MF channel).  However, talking with Bruce you need to specify very precisely what you want. Bruce is not a fool and he very much sees what people are trying to accomplish and he will be able to support any level of your demands. However you need to truly have the evolve demands and very precisely nailed down the requirements for your project in order to make Bruce to do what you want. You need to understand that Bruce is accustom to deal with his typical customers – the fucking audio retards that will swallow anything as long it was chip and “recommended”.

Sorry, my reply was not in the direction you would like it to be. If you would like to play with Fs, then set it to 80Hz and it shall be fine, most likely Bruce has do it already. Decrease loading of your tube if you use tube amplification for this channel. More idle tube will lose gain n power but will give you more control over the diaphragm.

noviygera wrote:

My mid/upper horns play down to 190Hz. That is -- 188Hz is the Fs of the mid. It's a horn loaded a 10" Precision Device driver. So I need a section (or two sections) to cover the bottom (below 190hz).

Herman, if you use Precision Devices hen you are at mid-high 90 sensitively, I am right?

noviygera wrote:

1. direct radiator (or multiples) in sealed box

It might be problematic with one channel as a crossover point is too high for a single god bass driver to handle it.  If you have very small room then you might experiment with an array of driver like Altec 515B or 515E. The are basso the same driver but with different magnets type. They have around 30Hz resonance and have good tone under 200Hz. The key in using them do not let them to exert too much so you need to have ether a very small room or very many drivers – then become costly nowadays. Otherwise I would do with two channels separate bass chanals.

noviygera wrote:

2. "properly" made rectangular horn to play down to about 100Hz with as few compromises as possible + sealed subs below 100Hz

This would work as well. If you do rectangular then you might get 80-100Hz under your MF channel. Measure the clearance between your MF and floor and you will see how much space you have. If you go for 80Hz horn and chose parabolic profile then the problem of yours will not be the size of mouth but the length of horn. to make the horn more less EQ bass properly you would need to make the throat relatively small the will make the horn too long. Since the channels need to be time-aligned with MF it might be a true ugly looking configuration. Why don’t you think Bruce went for large-throat and short horn – to make it look acceptable. So, you would need to find a compromise between all parameters of the horn to make it to work propel and to look good in context of your frame. This might be a bit tricky and with all apparent simplicity of the task very few people managed to make this arrangement interesting.

noviygera wrote:

3. something like the Imperial horn sub:  http://www.decware.com/ImperialSO.htm

I don’t really understand what they are proposing to do.

noviygera wrote:

4. Fostex FW800HS 31.5" Super-Bass System, like here:  http://www.kcsloudspeakers.com/

I never heard this woofer but can presume that it will not be so great at 200Hz

noviygera wrote:

The problem is that I've only heard my own Edgar horns. I have NOT heard the other options I listed above. I know what I want to get in terms of sound -- It is the range below 200Hz produced properly: It must be, detailed texturally, effortless and quick. It must sound dynamically similar at low and high levels. It must NOT be boomy or bloated sounding. It must have a natural tone that does not stand out as specifically "clean" or "tubby" What options or configurations should I consider to meet the above goals?

noviygera wrote:

Question, Romy: Why do you suggest to add the extension on the back, not the front, as B. Edgar suggested. He specifically commented that the MOUTH area is too small and said the throat size was OK?

noviygera wrote:

Every time I turn them off and continue listening without them I notice that something good happens to the sound. It cleans up and becomes more engaging.

noviygera wrote:

And one last thing for now I'd like to ask you. Would you know of a builder in the USA that can design the horn based on my requirements so that I do not attempt to be a horn designer? I can get the design built locally.

Herman,  I am not exactly understand what kind upper bass you would like to get. Not that I need to but it looks like if you have your hart set then it is good. I do like that you think about your future upper bass channel as a complete package with respect to the existing channels.

Anyhow, you are looking for a person who would help you with design of your horn. It would be all depends from what kind help you need. I do not know if you looking for basic geometry of your design or if you need the detailed bulling plan. In case you need both, that in my estimation what you need then do not deal with online idiots who like to run mouth about horn but never build anything themselves or never made anything to sound respectably positive. You need somebody who has experience with materials, building methods results, intellectual and cultural capacity to interpret result and who will be able to give you further recommendation after the horn are built and you will be trying to make it to sound appropriate. Just from the top of my head her are a few named right here in US:

Bruce Edgar from California. He is pretty much a Godfather of horn building in States for our generation and he is incredibly experienced person who will be able to accommodate any service you require. The minor problem that you might have with Bruce is that quite many of his past and present customers are or retarded idiot of bottom-eating white trashes and as a result many of the Bruce’s “designs” and ideas are structured for much more simplistic and cheaper implementation then it shell be. Do not be fooled by frugality and stinginess of Bruce ideas. He knows very well what and how the things need to be done, he has perfect ability to understand sound and if you slightly multiply and make more expensive the implementation of his design and recommendation then you will hardly find any more qualified consultant.

John Hasquin from Tennessee or Kentucky, I am not sure where he lives now. John is quite unique person in my estimation: he has a lot of practical building experience, great ability to understand and to interpret results and in the same time he for some reason does like to waste his time with internet idiots of DIYAudio.com level. John will be able to consult you in all aspects of your project and I very much HOW he interact, approach and flow up with problems. You can find him shepherding Morons at DIYAudio.com and I do advise to pay attention to his online output.

Jeffrey Jackson from Tennessee or Arkansas, I am not sure where exactly he lives. Jeffrey is another representative of next generation of horn makers and I do like his thinking and his “making”. Jeffrey among all have tendency to go for off the beaten past projects. So, if you are trying to go for something “dangers” then Jeffrey might be your partner. From my conversations with Jeffrey I feel that is very intelligent in Sonic language not to mention the building know-how and he might be another perfect candidate for your project.

I would like to note that any of the mentioned people are no-nonsense and no BS-type of people. You need to have very strong sense what you want to do and do some of your home work in order to form objective for those people in the format that would make them beneficial to you. Do not dump to them your general frustrations but be specific what you know, what you are trying to accomplish, what you do not know and what you expectations from their services might be. BTW, it is high likely that they might build the things for you as well and this would be much more preferably then your local builder who never dealt with Sound.