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Posted by Teodor on
07-22-2011
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fiogf49gjkf0d This project started in 2007 as an attempt to demonstrate that drivers different from the widely accepted low-Qts ones could be used in a back-loaded horn enclosures.
Visaton BG13P, a cheap and easy-to-get (at least in Europe) driver was chosen, basic T/S data as follows: Qts 1.04, Qes 1.58, SPL 92 dB/W/m, Fs 168 Hz. [paper voice coil former, not stated on manufacturer's site]
Nothing special for the back-loaded horn design, I think, throat area 27 cm2 (4.18 sq.in), mouth area 1438 cm2 (230 sq.in), horn contour length 215 cm (84.6"), hyperbolic-exponential type of contour [М(Т)=0.55], cut-off frequency set to 57 Hz, horn enclosure internal width 200 mm (7.9"). The volume of chamber behind the driver is less than 1 l (61 cu.in), maybe around 0.5 l (30 cu.in). Lowest audible frequency expected to be 10-12 Hz below the cut-off frequency, i.e. 45-47 Hz. Corner placement.
During the first listening tests, when placed at room's corners (a room with a relatively low /and sloped/ ceiling, though) these horns with these drivers indeed demonstrated lowest audible frequencies around 43..44..47 Hz, of course - with lower sound level than at 55..60..80 Hz, although this unevenness is not so embarrassing. No measurements have been ever taken. For me, surprisingly to some extent was the extremely small diaphragm displacement at sound levels such that the conversation between the listening tests participants was hardly possible. The overall impression of these horns is of not a quite bad sound reproducing devices 
OK, let me here now your comments. Any kind of opinion would be much appreciated. Thank you.
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Posted by Romy the Cat on
07-23-2011
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fiogf49gjkf0d Teodor, if you read my site then you know that I am not a big supporter of the acoustic system topology that you describe. It is not matter of driver but many other aspects. So, I do not think, or frankly speaking do not care about back-loaded single drives regardless of their type, enclosures or anything else.
Rgs, Romy
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Posted by Teodor on
07-24-2011
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fiogf49gjkf0d Thanks for the response. And please excuse me for not having read such basic threads of yours as "About Single Driver Speakers and their idiots owners.", "Burn any single-driver speaker in hell."
Maybe I'm wrong but a simple search through forum's topics found no results regarding any comments on D.B.Keele's paper on Optimum Mouth Size. Is this another 'forbidden', or 'idiotic' issue here, in this forum?
P.S. However, I will not burn down to hell these single driver BL horns
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Posted by Romy the Cat on
07-24-2011
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fiogf49gjkf0d Teodor, there is nothing to ask excuses for. You do what you do and it shell be absolutely irrelevant to you what others think. There are no forbidden topics in this forum. It is not about being forbidden or following some kind multi-channel religion as you might think. It is just that I did not find among an single driver back-loaded acoustic systems anything that would consider worthy looking into deeper and I did not find among the judgments of the single drivers speakers devotes the reference points that I would appreciate.
You are trying to solicit opinion about technology that I fundamentally do not believe: do you blame me that you will not find understanding? It would be very similar if you ask a vegetarian man about the kinky specifics of Pilaf cooking on a fat of fat-tailed sheep. What kind expectation would you have to talk with this vegetarian?
I do not know what Keele's paper might or might not do with the subject. The fact that the specific pepper is not mention makes it 'forbidden' or 'idiotic' issue? It does not sound logical to me.
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Posted by Teodor on
07-24-2011
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fiogf49gjkf0d Well, this paper on front-loaded exponential horns is rather
interesting, I think. Since some Greek symbols and simple equations are
used, I allowed myself to present here my understanding of this paper in
the form of the following picture. Of course, it is quite possible I've
got it all wrong.
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Posted by Teodor on
07-28-2011
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fiogf49gjkf0d Sorry, you failed. Seems we're livin' in different times, or planets and have little in common with to talk about.
......................
Laudate Dominum 
......................
P.S. Farewell & good luck; sleep well, you won't be hearin' of me anymore here.
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Posted by Romy the Cat on
07-28-2011
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fiogf49gjkf0d Sorry, Teodor,
I do not know what Keele's paper has to do with anything, where I failed and what you are trying to say. The fact that I will not be hearing of you anymore will certainly help me to sleep well as I was desperately afraid that you will be posting other immaterial audio documents. Do not burn bridges however - if in future you will lose your virginity and develop interest to multichannel horns, compression drivers or God forbid: some serious musical experiences instead to cure the frigidity of your spectra analyzer then you might (or mish not) discover some interesting thoughts at this site. For now I will return back to sleeping, I do except your apologizes for the noise.
The Cat
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