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Old 17th January 2008, 05:29 PM   #1
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Default Horn/Transmission line help

Ok, so I fully understand horn equations and have now designed and built 2 absolutely fantastic functioning horn systems. I am now trying to design a compromised horn/transmission line as I am tired of having monstrous speakers sitting in my living room.

That said, I am having the hardest time figuring out how to alter the horn calculation (as per MJK) to place my TL resonant frequency at 50 HZ and changing the flare and length of the horn to take up the slack from the Fh down to where the TL action begins. I read MJK over and over and feel like I am beating my head on the wall. I am forever grateful for what he has done but a good deal of what he writes speaks only to mathematicians or phsics geeks. I understand a good deal of what he works with but get mired down by the extreme equations he discusses (such as those he uses Maple to calculate).

So, if anyone can help I would greatly appreciate it! SCOTT?! Thanks in advance!

We need MJK for dummies (ok, not dummies but non physicists/mathematicians.

For someone wanting to explain. I am trying a compromised 50Hz horn (1/16, .5 SD, for the FE 126).

Tom
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Old 17th January 2008, 11:29 PM   #2
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For someone wanting to explain. I am trying a compromised 50Hz horn (1/16, .5 SD, for the FE 126).

I think its called the Frugal horn or the A126.

I am forever grateful for what he has done but a good deal of what he writes speaks only to mathematicians or phsics geeks.

And?

but get mired down by the extreme equations he discusses (such as those he uses Maple to calculate).
I cant think of many ways you can explain the actions besides math/physics.

I try to present examples of things ppl can relate to, but the actual definations can only be given in math/physics.
Even my methods differ somewhat from Martin as i depend a great deal on vector analysis.

ron

http://fullrangedriver.com/forum/viewtopic.php?id=91

This is about as simple as it gets.
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Old 18th January 2008, 08:01 AM   #3
hm is offline hm  Europe
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Hello,

please look the data:
http://www.fostexspeaker.de/newprods/fe126e.pdf

Xmax 0,35 mm that is nothing, let you show measurements or simulation from the "developer"
if there isnīt any be careful.

Better take a tested enclosure.
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Old 18th January 2008, 09:22 AM   #4
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Quote:
Originally posted by hm
Better take a tested enclosure.
I can assure you that both the speakers Ron mentioned have been thoroughly tested. And further Ron has probably the most accurate simulation software for designing horns that exists.

dave
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Old 18th January 2008, 11:41 AM   #5
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show us the simulations and measurements!!
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Old 18th January 2008, 02:06 PM   #6
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Quote:
Originally posted by hm
show us the simulations and measurements!!
FWIW I'll give you my personal view on this respect.

1 - Simulations are just simulations. Well done, within the right context, they help a lot in a design or understanding of phenomena. If not done within the right context they mean nothing or even worse, they are misleading.

2 - Measurements are exactly the same thing, and if not done within a standard or at least very well defined frame of reference, with a specific intention (this is, to demonstrate or show a certain aspect of a system or device), they also could mean nothing.

Besides this is the fact that all things done or discussed in this forum are to be used in real rooms, outside of an anechoic chamber, and with heavily changing contexts. This is to say that I would personally take[B]any[B] measurement and/or simulation on loudspeakers as merely indicative, except under very specific conditions.

Now, this said, both designs we are discussing here (A126, FH) were built several times and reported as working and working very good, in several different environments and by different persons.
Regarding to Ron and MJK, I personally know neither of them, but the show of their work and the reading on what they express on their many posts speaks for them and to me (personal opinion) they are voices to be listened to in this context.

Now, if you think that measurements and simulations mean everything and other people impressions on the build summed to the designers background mean nothing, please put that clearly this way, and remark it as a personal opinion.

Gastón
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Old 18th January 2008, 03:06 PM   #7
hm is offline hm  Europe
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Hello do know this threats,
about what is real and what not,
main threat:
http://www.diyaudio.com/forums/showt...5&pagenumber=3
changed and stoped questions here
http://www.diyaudio.com/forums/showt...5&pagenumber=1


do you know what dynamic compression is, and what happened
with sound and distrotion, do you know how much Xmax
is needed in a horn?
I think not.

if it works so good, and so many,
why is there no one outside to take a measurement.

Most horns are not built and tested, and if I see a
moderator is there involved, than I think there
is a conflict of interests.

Sorry, you know my side and experience, single driver
with such a low Xmax are going only 0,3 W.
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Old 18th January 2008, 04:45 PM   #8
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What 'threats', O great God Paranoidus-Supremeus?

Sigh. I would honestly like to be on good terms with you Horst, because I like to be on good terms with everybody, but you seem to have an attitude problem which is nothing to do with language (plenty of people speak far worse English than you and never a problem either way). Your posts are simply rude. You seem to be unable to post anything without rubbishing someone else's speakers. Itpains me to say this, but I think quite a few people around here would be eternally greatful if you'd either a) stop patronising everybody and make a useful post without attacking someone else for a change (go on, you know you want to... it's really not difficult to be polite.) , or b) take your arrogant attitude elsewhere. Most people seem to fall into the second category. Surely you wonder why you don't often get many replies to the threads you occasionally start?

Perhaps we haven't been very clear, so I'll try to be now.

1) We do not require you to tell us how to design speakers.

2) People here are not little children. Please stop addressing everyone as if they are.

3) We have heard of all things such as Xmax, dynamic compression and many others which you don't actually seem to be aware of yourself, such as focused radiation, end correction, the fact that horns do not have to follow a specific flare constant, the use of a folding scheme to attenuate high frequencies, amongst others. So you're in no place to cititicise a design using one or more of these features until you learn about it yourself, and maybe even try it. Please stop, until you have done so.

You don't seem to realise that all speaker design is a compromise, and that those you accept are not those other people accept. And don't try & tell me you don't have any. You're using multiple drivers, so double the cost. There's a compromise straight away. You're going omni with the drivers in several cases. This certainly has its benefits, but it's a compromise too: you reduced maximum acoustic power from the drivers at the listening position, and you're arguably doing something similar at the terminus, which frankly, WRT anything horn related is not a good idea IMO due to the directionality inherent to this type of speaker. The list goes on. And I don't care how low your speakers may go on a graph, unless you live in a shoebox, the bass SPLs will be limited because there's only so much air those 3in cones can shift. That's why people in the days of yore, when sound quality actually mattered, used multiple 12in or 15in drivers (horn loaded) if they could. And so the list continues.

So. We accept different compromises. Typically, though not invariably, one driver. Greater use of boundary reinforcement and focusing of radiation. The use of dedicated woofers to handle the lower octaves (you see, we make the assumption that people are intelligent enough not to need us to tell them that a 4 1/2in cone is not going to play the 32ft rack of a pipe-organ at 105db 15ft away from the speakers). Power handling: speaking for myself, I tend to take the Earl Geddes view -watts at 1m or whatever makes you happy means very little in practice, so citing them is relatively valueless. And so on. You don't like any of that? Fair enough. Not to your taste. But please understand that it can be for other people. Accept it.

Now then. Horns on Frugal-horn which have been built... let's see...

The Frugel-horn (many, many across the globe)
The A126 (ditto)
The A166 (ditto)
Dallas II & III (ditto)
The Daleks (at least 4 to the best of my knowledge)
The Metronomes (too numerous to count the different builds)
Harvey (a couple of dozen so far)Sachiko (couple of dozen & someone even tried to steal the design & flog for $6,500 a pair)
Chang & Curved Chang (half a dozen)
Half-Chang (about a dozen & the same bloke who tried to steal the Sachiko design also tried to swipe this one & flog them at $1,750 a pair)

Should I go on with the list?

Now, if I can ask you another question: are all rooms and corners the same?
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Old 18th January 2008, 05:28 PM   #9
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Tom, you've set yourself a difficult challenge, trying to do a 50Hz hybrid horn for the 126, which frankly isn't an especially easy driver to work with. Small units frequently aren't. The Frugel-horn & Ron's A126, as noted, can do it, no problem, and by reputation, Ed's Horns too. So if acoustic music is your staple diet, then you probably wouldn't need any more.

If you're after setting yourself a challenge to design something from scratch, things get a bit more complicated. Remember, MathCAD is only a modelling tool. It can't design a speaker for you, and you have to be aware of what it does and does not do in modelling terms too. For example, it can't show you the effects of bends, or a specific folding scheme on HF in the horn (nothing available can at present to the best of my knowledge, aside from Ron's own private software). Nor does it fully show the effects of end-correction etc. None of this is to denigrate Martin's work -quite the opposite. It's probably the best suite of all-round software available (I'm keeping my fingers crossed for a new set of front-horn & isobaric sheets, and, if possible, a tapped-horn sheet might be nice too. Akabak & Hornresp are great as far as they go, & have some features Martin's worksheets lack, but I still favour MathCAD.

A few general pointers, because if we went into it in detail, we'd be here 'til next Christmas. Firstly, the 126 really needs a ~optimal hyperbolic with a flare constant just below 0.5 to work well in a pure horn. Even though you're after a hybrid QW / horn, this is still a good indication: a long path with relatively slow initial expansion is a good starting point, which is what all the aforementioned designs have. End-correction is worth having in a compromised horn -it will reduce potential ripple, though the software won't show this fully. Don't go for too small a throat or you'll end up with a ludicrously long path. That was a mistake I used to make. Don't use the Fostex specs BTW -they're way off. Troel Gravesen has some better ones on his site. http://www.troelsgravesen.dk/FE126E.htm Don't make the air-cavity too large -the A126 & Frugel-horn are 2.2 litres which gives a nice blend of loading on the driver & a suitable upper corner-frequency for the cabinet. Smaller & you risk a very 'shut in' sound with a nasal midrange quality. Finally, I'd go for gain. You can always loose what you don't need.
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Old 18th January 2008, 06:02 PM   #10
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Hello Scottmoose,

sorry I canīt understand all,
and didnīt read all, and I wonīt disturb a hobby.

But your list and the big sells make me wonder that there
is no measurement at all, more and more.

sorry.
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